What You Should Know When Your Cat Has Diabetes

What You Should Know When Your Cat Has Diabetes

Care Of Your Diabetic Cat

Ron Hines DVM PhD

See How Diabetes Affects My Body

 Controlling Diabetes Can Be Difficult 

  Cat too Fat?

Some Information About Your Cat’s Pancreas 

Your cat’s pancreas is a small, pinkish organ that is nestled in the folds of its small intestine. You can see it if you enlarge the fanciful image I put at the top of this page. Although it is quite small, the pancreas has two very important functions. One is to produce enzymes that allow your cat to digest food. The other is to produce a hormone (insulin) that regulates how your cat’s body utilizes sugar (glucose). Glucose is the main fuel of all animal cells. Most of it is manufactured in the pet’s liver or released from recent carbohydrate meals.

The process by which the pancreas regulates your cat’s blood sugar level is actually much more complicated than my explanation and not yet fully understood. But my explanation should do for this article. Should you wish to know more, go here .

Many types of cells form the pancreas. The ones that are important in understanding diabetes occur in small islands scattered throughout the pancreas (islets of Langerhans). These particular insulin-secreting cells are called ß (beta) cells.

What Is Occurring In Diabetic Cats?

There are several forms of diabetes. But the one affecting your cat is almost certainly the one known as diabetes mellitus, also called Type 2 (Type II, DM) diabetes. In this form of diabetes, your cats cells have lost some of their ability to respond to the insulin your cat’s pancreas is still producing. In some cases, less insulin is also being produced than should be. When this occurs, blood sugar can not move out of the cats blood and into all of it’s body cells that rely on the sugar for energy.

When this occurs, a number of things happen. The cat’s blood sugar level skyrockets up (hyperglycemia) , some of the excess sugar spills out the kidneys and into the urine (glycosuria) and the cat’s body shifts to alternative sources of energy (it metabolizes fat and protein).

Veterinarians really do not know how much of the problem is due to decreased effectiveness of insulin in the cat’s body and how much is due to decreased production of insulin by its pancreas. As a species, cats produce less insulin and respond to it less dramatically than other species do. (read here) To determine the relative amount of either would require a procedure (glucose clamp technique) that is not performed in clinical veterinary practice.

As the frequency of Type 2 diabetes has risen in people, it has also risen in cats. In 1970, eight cases were diagnosed per 10,000 cat-visits to the veterinary teaching hospital at Purdue University. By 1999, that number had risen to 124 per 10,000 cat-visits. (read here)

What Happened In My Cat That Caused It To Develop Diabetes?

There are many genetic and life style factors that increase your cat’s risk of developing diabetes. Far and away, the greatest risks that are under your control are allowing your cat to become fat and feeding it commercial high-carbohydrate foods. The two go hand-in-hand. Cats are true carnivores. Over the eons, their bodies have lost their ability to process the sugar that carbohydrates in food generate. There was no need for them to retain that ability that you and I possess.

But we know that diabetes occurs more frequently in male cats. The risk of developing diabetes is several fold greater for male cats than for female cats – neutered and un-neutered alike. (read here) We do not know why.

Just as in humans families, some families of cats are more prone to diabetes than others.
We know that at least one breed of cat, the Burmese, develops more than its fare share of diabetes. (read here) In Australia, Burmese cats are 3.7 times more likely to develop DM than non-pedigree cats. In the case of Burmese cats, their post-dining blood triglyceride levels remain higher than they should be. (ref)

Obesity – Is My Cat Too Chubby?

Most cats that develop diabetes are, or were, overweight. These “Garfield” cats develop a condition quite similar to the metabolic syndrome of people, although cats are blessed in not developing the heart and vascular disease that accompanies MS in us humans.

Obese cats aren’t just rolly-poley, they have much higher fatty compounds ( plasma triglycerides, non-esterified fatty acids and VLDL lipoproteins) in their blood. (read here) More importantly, many of us do not realize that fat is not just blubber; it is a living organ that secretes compounds called adipokines that directly affect your cat’s pancreas and health. 

Fat cats are indoor, inactive cats. They are all consuming more calories that they need. In addition, many are consuming the wrong calories, in the form of carbohydrates – foods they were not designed to consume. (read here)

Adrenal Gland Disease Probably Underlies Some Cases of Diabetes In Cats

Some cats are prone to over-active adrenal glands (Hyperadrenocorticism – Cushing’s Disease). It is not nearly as common in cats as it is in dogs, but it does occur ( read here, here & here)

Although not nearly as common in cats as it is in dogs, these glands can become over-active due to glandular tumors or over-stimulation by the cat’s pituitary gland. In either case, they begin to produce steroid hormones (cortisol) in excessive amounts. One function of this cortisol is to elevate blood sugar another is to increase appetite and body weight. That is probably the mechanism by which it encourages diabetes. (read here)

A similar problem can happen when your cat is given steroids (prednisolone, dexamethasone, methylprednisolone, etc.) over extended periods of time. In this case, these cortisol-like drugs are not produced by the cat’s adrenal glands, but they have the same effect. It is possible that dexamethasone causes higher sugar elevations and insulin resistance than prednisolone – but further studies need to be done. (read here)

Medications like megesterol and Depopovera, given to cats for various reasons, occasionally cause diabetes in cats through the same mechanism.

Pancreatic Amyloidosis

Amyloids are  proteins that  form in the pancreas of cats as the result of chronic inflammation. Cats, as a species, seem to be particularly susceptible to oxidative damage to their cells and chronic, low grade, inflammations of many types. You can read about chronic pancreatic inflammation (pancreatitis) here. With time, the processes involved in amyloid formation can also destroy the ß beta cells of the cat’s pancreas. (read here)

There are other theories as to why amyloid accumulates in the cat’s pancreas, some associate it with a compound called IAPP which the pancreatic ß cells secrete in the process of producing insulin. (read here)

Acromegaly – Too Much Growth Hormone

Acromegaly occurs when the adult body produces growth hormone in excess. One of the effects of this hormone in adulthood is to decrease the effectiveness of insulin. Cats develop acromegaly when their pituitary glands develop tumors. Almost all of these cats are male. It is a condition to consider when cats do not respond to insulin injections as dramatically as they should (insulin resistance). (read here, here,& here)

Chronic Pancreatitis , Triad Disease And Similar Chronic Inflammatory Conditions

Cats not only suffer from pancreatic island inflammation – the portion of their pancreas that produces insulin. Some also suffer from chronic inflammation to the entire pancreas and surrounding organs. This is called triad disease. You can read more about pancreatitis and triad disease in my cat pancreatitis article. Some veterinarians, me included, suspect that all or some of these conditions result from oxidative stress. (read here & here), possibly the result of (or made worse by) some of the ingredients in commercial cat foods. I am particularly concerned with cat foods that contain fish ingredients. Cooked fresh fish is an excellent food ingredient for cats. But the fish ingredients in cat foods tend to be from fish that spent too long on the dock. Quality fish products end up as human food, fish products unfit for human consumption end up in cat food. Fish oils, and some poultry fats are highly unsaturated. That makes them very susceptible to rancidity and free-radical generation when they become stale. That is why I suggest to my clients that they not feed anything to their cats that they would not readily consume themselves.

(If this particular theory interests you, you may want to read about the NF-kB theory of cell damage)

If you or your veterinarian suspect that your cat’s diabetes problem is only a part of the larger problem of Triad disease, a test has recently become available to confirm it. It measures the level of a specific enzyme in the cat’s blood that is associated with generalized pancreatitis. (read here) This test, the fPLI test, is patented and performed by Idexx laboratories.

There are other veterinarians who believe that the high blood sugar in diabetic or pre-diabetic cats cause generalized pancreatic inflammation and not the other way around. (read here

What Signs Might I See If My Cat Develops Diabetes?

Diabetes is a disease that usually develops very slowly and symptoms do not become obvious until the disease is quite advanced. So unless your cat gets periodic “wellness” screens, you are unlikely to know of the impending problem.

The most common reason diabetic cats are brought to my animal hospital is because of owner concern that the cat has begun to urinate too frequently and drink too much water (polyuria & polydipsia).

At that point, it is the veterinarians job to differentiate between kidney problems, urinary tract infection, and diabetes. There are other things that can cause polyuria and polydipsia. But those three are the most common causes.

In discussions, the owners often tell me that the cat has recently lost considerable weight. Yet they may tell me that their cat appears to always be hungry and eating.

These cats usually have unkempt hair coats. If the diabetes is quite advanced, the cats may be wobbly (ataxic) and a few show cataracts in excess of what is normal for their age.

Emergency Situations When Your Cat Has Had Unrecognized Diabetes For Some Time

If these cats are not eating and their condition is much worse. They are usually ketotic (= ketosis, ketoacidosis) . There is an explanation as to what that means, later in this article. These cat are also prone to have a liver problems called hepatic lipidosis that occurs in cats that stop eating for any reason.

They need to be immediately hospitalized and will likely need intravenous fluids to correct dehydration and adjust the acidity of their blood (pH) back to normal values. They will probably receive a short-acting insulin as well and have their blood sugar level monitored many times throughout the day.

Cats are generally not good patients. If at all possible, stay with your cat to reassure it. Inquire if the faculty offers 24-hour care – not all do. Be your cat’s advocate.

Many of these cats are vomiting or experiencing diarrhea that will require medications. Many have sub-normal body temperatures that require additional external heat.

How Will My Veterinarian Confirm That My Cat Has Diabetes – What Tests And Examinations Will My Vet Run?

In addition to the veterinarian’s physical examination of your cat and your description of the cat’s symptoms and history, your veterinarian will run a series of tests:

A Blood Glucose Tests

When your veterinarian suspects that your cat might be diabetic, the vet’s goal will be to document that your cat’s blood sugar level is persistently above normal.
This can be difficult because stresses of all kinds often cause cats to have high blood sugar levels. The normal fasting blood sugar level in cats is about 70-170 mg/dL of blood. Cats can easily exceed that for a number of reasons other than diabetes.

A Urine Test For the Presence of Sugar

Once their blood sugar level exceeds 240 mg/dL, their urine also becomes positive for sugar. A simple dip-stick, placed in a sample of your cat’s urine, will confirm or refute the presence of sugar. The same dip-stick tests for evidence of the urinary tract infections (nitrite + or -) that sometimes accompany diabetes.

A  Blood Chemistry  Profile And A CBC/ WBC Count

It is always wise to do a general health screen on cats that are suspected of having diabetes. That includes a series of blood chemistry tests and a red and white blood cell count and differential count (WBC).  It is not uncommon for diabetes to cause , or exist in tandem, with other body illnesses. It is also not uncommon for diseases other than diabetes to cause blood glucose elevation and other signs that could be confused with diabetes. So your veterinarians will want to send blood samples to the lab that screen for a large number of abnormalities and disease conditions. You can see what the normal blood values are for your cat here.

A Fructosamine Test

Blood glucose levels can have many sudden peaks and valleys. So blood sugar reading only tell us what the sugar level was at the instant the blood was withdrawn. However elevated fructosamine, a compound that forms in the blood as blood sugar and certain blood proteins combine, is an indicator of persistently high blood sugar. It forms slowly and is quite stable . So the amount of fructosamine is a good indicator of your cat’s average blood glucose levels over a more extended period of time (1-2 weeks). This test is particularly valuable when your cat’s blood sugar levels are not exceedingly high but are still above what they should be. The fructosamine test has become a standard procedure in cats since 1996. (read here)

This test is also quite helpful during treatment. It determines if your insulin injection plan has been successful in keeping your cat’s blood glucose level in its normal range (glycemic [blood sugar] control).

Preparing Your Cat’s Treatment Plan

A diagnosis of diabetes in your cat insures that you and your veterinarian must form a close working relationship. Diabetes is a lifelong challenge. For you to be successful in dealing with it, you must find a veterinarian whom you trust whose personal philosophy and practice style matches yours. I have an article on choosing the right veterinarian. You can read it here.

Not all veterinarians are good communicators. Some practices are too rushed or pass patients between multiple practitioners. If you don’t feel entirely comfortable with your veterinarian and the office staff, keep looking. Ask your friends and pet professions whom they recommend. Join support groups. There are plenty of wonderful, supportive veterinarians out there – but it is your job to find them.

Do not assume that because your cat appears stable, it does not need continuing checkups. Currently, the safest and most important test to monitor your diabetic cat’s health over time are periodic blood fructosamine assays (read here) performed twice a year in cat that appear well regulated; more frequently if they don’t. If you can not afford all these tests, you will need to be very scrupulous and frequent in the use of your glucometer.

Will Treating My Cat Take A Lot Of Time And Commitment On My Part?


Not every cat owner can, or wants to take on this responsibility. Yet many cat owners derive great satisfaction and personal growth from the experience. Cat owners often find that caring for their diabetic pet produces an intense bond and personal satisfaction that they had never, until then, experienced. 

The decision needs to be a family decision because it will affect every member of your family, your spouse, your children, your co-workers, your other pets. Not only will you have to decide if you will treat your cat. You will have to decide on the level of treatment. These are things that veterinarians are not taught in school to help you with . Some intuitively understand it; others do not.

The most worrisome factors for you are likely to be the difficulty of finding pet-sitters and boarding facilities when you travel, some loss of control in your life due to the added responsibility, more difficult interacting with family and friends, more worry, less time for social life, added costs and interference with your work life. 

Probably the least important fact for you to worry about is your ability to perform the procedures that will be involved. None of these procedures are that difficult to master and there are plenty of cat owners and veterinary staff willing to instruct you. If you live in an isolated area, the Internet is full of instructional videos.

“No Man Is An Island” . People do not thrive in isolation, particularly when they are confronted by illness in those they love. So go find your support network – the people that care about you and your cat. The Web will lead you to many support sites, your veterinarian can tell you of other cat owners facing the same situation with their cat.

Try not to be motivated by guilty feeling that you were in some way responsible for your cat’s diabetes. Dr. Vicki Rackner wrote an excellent article on caregiver support. You can read it here.

There are no referees or policemen on the Web. As you educate yourself on the Internet, you will read many conflicting opinions as to what you should or should not do for your cat. You will see advertisements of miraculous diabetes cures and owners who swear that this or that cured their cat. You will find veterinarians hyping mystical procedures and extracts of rare plants that only grow in isolated valleys of the Himalayas, etc.

I know how much you love this cat and how much you want this problem to go away. But please, do not believe the claims of folks trying to sell you this stuff. Get your advice from people who do not wish to sell you anything. If you cannot find a reference to a product or procedure in the ncbi index, it will probably be of no value to your cat.

A group of veterinarians at the Royal Veterinary College of London wrote a good article on the challenges faced by the owners of diabetic cats. To read it in its entirety ask me for Niessen2010 pdf. 

What Are The Treatment Options For My Diabetic Cat?

Your pet will need medications to lower its blood sugar level, dietary modification, exercise encouragement and treatment for any secondary health problems that might arise. Your pet is unlikely to thrive unless all four of these things are attended to. Arranging a low-stress lifestyle with a minimum of changes and interruptions is also very important for diabetic cats.

Insulin To Control Your Cat’s Blood Sugar Level

Insulin injection is the underpinning of almost all successful treatment of diabetes. A few cases can be controlled with oral products, but most will require insulin injections now, or later.

Every species of animal produces an insulin that is slightly different in structure from all others. Over the years, veterinarians have been plagued by having to rely on insulins that were designed for use in humans, not cats. An additional major problem has been the withdrawal of insulin products from the market just when veterinarians and owners were becoming comfortable with their use (ref) as well as frequent product recalls.(ref)

The veterinary insulin market has been chaotic for many years. As I write this article, the product I relied on most, Idexx PZI insulin (protamine zinc insulin), is being phased out by the primary Company than manufactures it. Idexx is no longer able to obtain enough beef and pork pancreas – the raw materials for the product.

The plants that collected cow and pig pancreas sold most of it to extract human-use insulin. With the switch in human medicine from animal-origin insulin to bio-engineered human insulin, the plants became unprofitable. There just wasn’t enough demand for their products from the veterinary community alone.

However, Merck Animal Health’s Vetsulin®, a pig pancreas product, has now been approved for use in cats and BCP Pharmaceuticals still plans to manufacture their version of PZI cow-derived insulin. BCP is a small niche pharmaceutical company in Houston, TX. Small companies tend to have more difficulty in maintaining product consistency. Idexx is currently searching for alternative insulin product they might market for cats.

Adequate control of your cat’s diabetes requires that one of these long-acting insulins be injected once or, more likely, twice a day. How frequently and in what amount can only be determined on an individual basis. Your veterinarian will begin this titration process at his/her animal hospital. But you will have to fine-tune it at home, based on your cat’s individual glucose curve chart.

Some veterinarians and pet owners rely on glargine insulin (Lantus®), the type of insulin sold in drugstores for human use. It seems to work fairly well in most cats. (read here) And some veterinarians report even better success with that product than with PZI insulins. (read here & here)

A disadvantage is that glargine insulin is sold in a quite concentrated solution, which must not be diluted. That means that you will be injecting a very small, difficult to measure, amount through your syringe. The advantages are its lower cost and easy availability. Glargine insulin is also available in more expensive pen injectors that minimize the measurement problem. Do not attempt to switch insulin products without your veterinarian being fully informed of what you are doing and be ultra-cautious in any changes you attempt. I do not want your cat to go into hypoglycemic shock. Read the product label and instructions thoroughly as to storage guidelines and do not use products past their expiration dates.

Determining Your Cat’s Correct Insulin Dose:

There are veterinarians and cat owners who feel that one can begin initial insulin injections at home (as an outpatient) if a cat is alert, well hydrated and eating and drinking normally. I am not one of them. Most cat owners are inexperienced in the techniques required, insulin is a very powerful medication and the cat’s responses to it are always somewhat unpredictable. Perhaps I am just a nanny veterinarian who likes to hover over my patients, but I just do not feel comfortable sending inexperienced clients out with a bottle of insulin ,a pack of syringes and advice.

On the flip side, the advantages of beginning insulin injections in your own home are the lack of hospitalization costs, the fact that some cats really detest being hospitalized and the likelihood that a calm cat at home will give a truer indication of its insulin needs than a stressed cat in a hospital setting.

Insulin injections are generally started at twice-a-day intervals, often at 1-2 units per injection. Let your attending veterinarian make that decision.

Changes in your cat’s insulin dose always need to be made very slowly and very cautiously. Always make them at the same time of day, at the same time after meals and under the same conditions. Do not make changes near weekends or when your vet is unavailable.

As Important As The Insulin You Give Is How You Give It

The biggest pitfall in administering insulin is inadvertently giving too much, due to distractions, a new formula or bottle size, or incorrect syringe size. Your veterinarian or his/her technician will demonstrate how and where the injections should be given.

Do not attempt to use syringes designed for one insulin product with a different insulin product until you are absolutely certain the gradations (numbers) on the syringes are accurate for the product. If you are in doubt, have a pharmacist (not a pharmacy technician) confirm that the syringe and the insulin product are compatible.

Many communities regulate how used syringes can be disposed of. If this is a potential problem, call your local sanitation department and ask what is allowed in your area.

How Best To Give The Insulin Injection

Injections should always be give shortly after your cat eats and at the same time every day. Giving insulin to fasting cats is more likely to cause dangerous drops in their blood sugar level. (Have your vet demonstrate how and watch videos on the subject on )

Feed your cat and give it a few minutes to groom itself.

Meanwhile, let the insulin bottle warm up to room temperature.

Swirl the bottle around to be sure it is well mixed. Don’t shake the bottle violently.

Withdraw the insulin into the syringe to the proper gradation- being careful not to draw in air bubbles. If bubbles appear – gently force the product back into the bottle and try again or tap the syringe with your finger until the bubble rises high enough to be expelled.You may have been holding the bottle at the wrong level or the product may be foamy from excessive agitation.

Place the syringe on a clean surface and get your cat.

Be sure its claws are not sharp enough to scratch you.

Lift up a fold of skin along the cat’s side.

Insert the needle almost parallel to the surface of the cat but angular enough to be certain you are under the skin and not in it.

If you are in the skin, rather than under it, there will be resistance in the syringe when you inject and the cat will tell you the injection hurts.

Part the cat’s fur to be sure the needle has actually penetrated into the cat.

If you give the injection properly, the cat will probably not fuss or be aware that the injection was given.

Reward your cat by petting and cooing to it. Give it a tiny food treat.

Do not reuse syringes. The needles become dulled, burred and painful and the plungers often leak.

Alternate your injection sites. If you inject on the right in the morning, inject on the left side in the afternoon.

Cats can be uncooperative. You will need to tweak and customize these suggestions to your cat’s unique disposition. Sneaking up on cats, tricking them or seizing them suddenly in order to give them their injections, is counter productive in the long run. It doesn’t take cats long to learn what you are up to. It is much more productive to use petting, praise and small pungent treats to gain your cat’s cooperation and trust.

What If The Insulin Does Not Keep My Cat’s Blood Sugar Level Reliably In Its Normal Range ?

The blood sugar level of some cats is harder to control than others. This is called insulin resistance. The first thing to do is to be sure you are really giving the amount of insulin suggested by your veterinarian. The biggest cause of unexpected or poor results is giving the insulin product incorrectly.

Be sure your bottle of insulin is not expired and that it has been properly stored.
The next thing to do is to verify that your glucometer is accurate and that you are making your glucose level determinations correctly. The best way to do this is to check your cats blood sugar level on two different meters. Blood glucose levels are constantly changing. You will need to do the two tests simultaneously or one right after the other.

If neither of the above problems are occurring, your veterinarian will probably increase or lower your cat’s insulin dose. Generally, veterinarians begin cats on a low or moderate dose of insulin. That leaves room to adjust the dose upward if need be.

If changing your cat’s insulin dose still does not solve the problem, your veterinarian may try your pet on another brand or formulation of insulin.
Trying alternative subcutaneous injection sites; have another experienced person administer the injection to see if the results are the same; and changing the hour of the injection(s) and feeding schedule may also solve the problem.

Insulin Resistance

Calling a cat “insulin resistant” can mean several different things. Using the term in the traditional way means that one believes that the particular cat’s fat, liver and muscle cells no longer respond to circulating insulin as dramatically as they should. (ref). But as frequently, the term is used to mean that a particular cat just requires a larger dose of insulin than one might expect. As a species, cats tend to be insulin resistant in this second way – possibly because they were designed to live on a high protein diet of small prey.

If that still does not solve the problem, or perhaps earlier in this process, your veterinarian will look for health problems that could be contributing to its insulin resistance. These could be concurrent illnesses, infections, chronic stress, or malnutrition.

Occasionally, what appears to be insulin resistance is due to receiving too large a dose of insulin. This is called rebound hyperglycemia (Somogyi Overswing effect). When it occurs, the cats blood sugar level drops drastically and rapidly after receiving too large a dose of insulin. But the cat’s body quickly releases its own cortisone and adrenalin that cause its blood sugar to soon rise to abnormally high levels again. Careful examination of your cat’s blood glucose curve will detect this phenomenon. The treatment is smaller and possibly longer acting insulin doses.

Medications (such as steroids) that your cat is receiving can make it resistant to the effects of insulin. (Even topical anti-itch and anti-inflammatory spays and creams might have this effect.)

Occasional cats just do not absorb insulin well from their injection sites. Others appear to metabolize the insulin too rapidly. Some of these cats respond better to combinations of insulin products (long and short acting). Not all insulins are safe to combine in the same syringe.

There is one study I have on the problem of insulin resistance in cats. Ask me for Scott-Moncrieff.pdf

Checking Your Cat’s Blood Glucose Level At Home

Keeping a close watch on your cat’s blood sugar level at home is the key to keeping your diabetic cat healthy. The best way to do this is for you to purchase and learn to use a hand held glucometer.

Not all cats will allow you to use the sharp lancets this apparatus requires – but most will. Those that don’t will have to rely on periodic glucose testing at their veterinarian’s office, the services of a house-call veterinarian or periodic fructosamine tests.

Testing your cat’s urine for sugar spillover is a much less accurate way to keep track of your cats condition because sugar does not enter its urine until its blood sugar level is quite high. But it is a better test than none at all. There are also a cat litter dressings that will show a color change when sugar is present in your cat’s urine. (Purina ”Glucotest” Feline Urinary Glucose Detection System)

Most owners obtain their blood sample by nicking the marginal vein on one of their cat’s ears with a sharp lancet. After repeated testing, your cat may come to resent this. But there are other locations from which you can obtain the blood, often with less discomfort to the pet. Your cat’s front metacarpal foot pad (the one that does not touch the ground) is a good alternative. 

Your Glucometer

At one time, more cat owners used human glucometers to test their pets blood sugar levels than the meters designed specifically for cats and dogs. That was primarily due to the difference in their cost. What should concern you more than the price of the unit is the price of the test strips. Over time, the strips represent most of your true cost. Cheap strips are also often short-dated.

The problem with using a glucometer designed for human on a cat or a dog is that blood glucose is distributed differently in the blood of humans versus the blood of cats and dogs. In humans, about 58% of the glucose is free in the blood plasma and 42% is tied up in the red blood cells. In cats about 93% of the glucose sugar is in plasma, 7% in the red blood cells (dogs ~ 87.5% of the glucose free in the plasma and only 12.5% in the red blood cells). The way human glucometers are calibrated at the factory, that means that they will likely read a lower blood sugar level than actually exists in your cat. I suggest you purchase a glucometer designed for cat and dog use – although formulas exist that allow approximate conversion of human meter readings into cat and dog readings.

No matter what brand you buy, check your unit and your strips periodically against the one used by your veterinarian as well against your test solutions. Remember that blood serum and plasma glucose levels run at a lab are often 10-15% higher than results obtained on meters. The most important attributes to look for in a meter are accuracy and repeatability of results. A very small amount of required blood sample is also important. Another important meter feature is that its test strips be very absorbent in drawing up blood from your test prick site (“sipping”). Unless you are uploading your cat’s results to a graph on your computer, additional features, that are added to many meters, are really an unnecessary complication and expense.

Be aware that meters marketed to the US give their glucose reading in milligrams/deciliter (mg/dL). In the rest of the World, the meters usually display in millimoles/liter (mmol/L). There are websites that will do automatic conversions.

Factors That Affect Your Meter Readings

Cats that are anemic may appear to have higher blood glucose levels than they really have. Cats that are not consuming enough water or are dehydrated will also test higher. Testing after your cat eats a fatty meal can also influence the meter reading as can vitamin C supplements.

Other things that commonly cause inaccurate readings are low batteries, expired test strips, insufficient or too much blood on the strip, dirty meters and failure to regularly check your meter’s calibration against the test solutions.

Preparing A Glucose Curve Chart For Your Cat

Enlarge the image above. Persistently high glucose levels take time to do their damage. Occasional spikes are not that important, what is important is that your treatment plan keeps glucose at as close to normal as possible over the majority of time.

Basically, you will use this graph to adjust your cats insulin dose, insulin type, injection interval, diet, exercise plan and lifestyle in a way that keeps your cat’s blood glucose level as stable and close to normal as possible with the fewest dramatic peaks and valleys (nadirs). That was the job of your cat’s pancreas. It is your job now.

Recommendations vary as to how to prepare glucose curve charts. I prefer clients prepare the curve at home, although it can also be done at the animal hospital. I tell clients to obtain their first glucose reading one hour prior to their cat’s morning insulin injection, one hour after the injection and then every hour until the reading has reached its lowest point and begun to rise again. From then on, the sampling can be done every two hours.

You should always allow your cat to become accustomed to a particular insulin dose and treatment plan for a few days before attempting to prepare a full glucose curve.
You also should be aware that the test is really not very accurate – it is hard to get reproducible curves on consecutive days (ref), and that there is considerable day-to-day variability.

Sometimes the curve you obtain will not mesh with your cat’s clinical picture. Occasionally, the curve may show you cat’s glucose is under good control when it isn’t. If your cat is continuing to drink and urinate excessively, experiences periods of weakness, or fails to normalize its weight, go with your intuition that something is wrong.

I prepare graphs similar to the one in my illustration using Graph 4.3. You can also use the Vetsulin insulin curve generator found on their website.

There is no one firm figure as to what your cats “normal” blood sugar level is because it is constantly fluctuating. But a value that I often used is about 70 – 170mg/dL, with the average being around 80 mg/dL.

Do not attempt to maintain your cat near 80 mg/dL. That would leave too little down space between what is normal and what might lead to hypoglycemic shock. Instead, consider an 100 mg/dL – 185 mg/dL average or so as your ideal goal. Some owners of easy-to-regulate cats succeed in keeping their cat’s average blood sugar level lower. But it is not something you should attempt until you are thoroughly comfortable with how your cat responds to its injections. Many cats cannot achieve my goal levels and must be satisfied with spike levels of 280 mg/dL.

If your cat’s blood sugar reading reach peaks over 180 – 270 mg/dL, sugar will begin to appear in its urine.

Cats with persistent readings over 300 mg/dL are at risk of developing health complications. These cats often have ketone-positive urine.

When contemplating your cat’s insulin curve, look for trends – not specific points. 


Many owners follow the ten percent rule – never changing their cat’s insulin dose by more than 10% in 4 days.

Every cat is different. Some cats require more than the typical twice-a-day procedure.

Insulin dose and frequency adjustment is more of an art than a science. There is quite a bit of variation in blood glucose from day to day in the same cat. (ref) That is
why there is so little agreement on exact figures and procedures. I am sure that many seasoned owners of diabetic cats have discovered schedules and procedures different from mine that work great for them. If you are new to diabetes care, you can be overwhelmed by these conflicting opinions. At some point you will just have to choose a protocol that appears reasonable to you and is offered by a person you trust. There is one thing I do not want you to do. I do not want you to base the treatment of your diabetic cat on this article. You need a hands-on veterinarian coaching you, not a provider of Internet advice. Online veterinary advice can be an important aid, but it is not a substitute. It is somewhat like online airplane flight instruction – if you rely solely on it , you are more likely to crash.

What If My Cat Is Not Eating Normally?

Cats that are not eating adequately will react differently to insulin than those that are. If your cat’s food consumption or weight has fallen off recently, let your veterinarian know immediately. Cats are not good at fasting. Unlike you, they have very poorly developed mechanisms for shifting from regularly-ingested food calories to calories stored within their body (glycogen reserves). Two problems that develop rapidly in non-eating cats are hepatic lipidosis and ketosis – both very serious problems.

In these situations, eating anything is better than eating nothing. These cats are usually not drinking enough either – so soups and broths come in handy. Try to remove any factors or changes that may have led to the problem and contact your veterinarian immediately for advice. If soups, hand or syringe feedings do not rapidly get the cat back to eating normally or if significant weight loss occurs, the cat needs to be hospitalized. It is mid 2018. Elura® (The same ingredient that is in Entyce®) is often an  effective appetite stimulant. If you have experience giving your cat Elura® let me know.

Are There Oral Medicines That Might Substitute For Insulin Injections?

Some cats in the early stages of diabetes can be maintained without insulin injections if they are given oral medications that lower their blood sugar, combined with special diets, weight loss and an exercise program.

The most commonly used medication in this class is glipizide (Glucotrol®). Glipizide is not specifically intended for use in pets. It is a rather safe medication although a few cats will vomit and loose their appetite when taking the medicine. Cats taking glipizide should also have their Liver enzymes monitored. If your cat’s blood glucose level has not returned to an acceptable range after taking the medication for six weeks, it will probably be of no benefit to your cat. Unlike humans, the majority of cats cannot be maintained on any of these sulfonylurea medications and do need to receive insulin injections. But they may be worth a try. Generally, it is easier to give pet cats insulin injections than to get them to take medications like glipizide orally.

Alternatives to Glipizide are glimepiride, glyburide and acarbose. (read here)

Both the EveryCat Health Foundation and the Morris Animal Foundation have funded studies to see if the human anti-diabetic drug, pioglitazone, might help control (or perhaps, even prevent) the progression of diabetes in cats as it apparently does in humans. (This drug has the potential for very serious side effects. At this time, I would not experiment with it outside of a very controlled research study).

Why Is Dietary Therapy In Addition To Insulin So Important?

Diet, exercise, weight control and insulin are the four pillars of successful diabetes treatment. Whenever you make diet changes, do so cautiously and slowly. Expect some diarrhea and colic when transitions are made to fast. Cats are also much more likely to do well when their food is changes so slowly that the change is not noticeable to them. When you lower the amount of carbohydrate in your cat’s diet, expect its insulin dose to decrease. Never feed these pets dry cat foods of any kind. Consider preparing an all-meat diet for your pet at home using a commercial vitamin-mineral supplement. You can read about your choices here.

It usually takes quite a bit more than just offering a low-cal diet to get your cat to loose weight. No mater if you prepare the weight loss diet yourself or purchase it from your vet; it requires a strict feeding and lifestyle plan as well. It’s going to have to be a joint effort that you can read about here  and here.

When dieting, do not allow your cat to loose more than 1% of its body weight
per week. (A 15 pound cat should not loose more than a half a pound per month) until it reaches it’s optimum weight.

I usually suggest that a cat be fed an equal portion of its daily diet just after each of its insulin injections, but there are diabetic cats that do just fine when they receive their insulin shortly after eating. Only plotting your cats glucose curve will tell you what is best for your cat. There is no harm in giving them a small treat just before their insulin injection. The reward of that treat often makes getting them to come and accept their injections a bit easier.

Your cat’s foods and eating habits were probably the major cause of its diabetic problem, so food and eating habits are also a major part of its solution.

When diabetes is advanced, many cats are underweight. But most were overweight while the disease was developing.

There are several factors that come into interplay when considering why so many cats are overweight and why so many of the overweight ones go on to develop diabetes or other health problems.

The first is the composition of traditional cat foods. Although everyone knew that cats prefer meat and eat solely meat in their wild lives, feed manufacturers decided to include grain carbohydrates as a major ingredient in traditional cat foods. Why? The main reason was that grain is considerably cheaper than meat. A second reason is that cat foods were an outgrowth of the animal livestock feed industry. Livestock do quite well when they consume grain carbohydrates – God designed them that way – but not cats. (read here) Diets rich in carbohydrates and sugars just make their blood sugar control worse. Another reason was technical; it is grain gluten that is the binder in dry cat kibble. The extrusion process did not work well when this material or plant starches were lacking.

So limit carbohydrates in your cats diet to 15% of its energy needs. If you exclude grain, starchy vegetables and organ meats such as liver from a home-cooked cat’s diet, you will accomplish that. It is less clear how added fiber affects cats. Many cats can tolerate up to 8% fiber in their diets without developing loose stools.

[That carbohydrates are not good for cats and that drastically lowering the carbohydrate content of your cat’s diet helps in the treatment of diabetes is widely accepted in the United States. However, a 2010 study coming out of the U. of Ghent shows that things are rarely as simple as they first appear. 

Although we knew that cats in the wild, and over the majority of their human domestication, consumed wet or moist food (not the semi-moist foods sold in pouches!), we decided to feed them dry foods. Why? Dry foods were easy to store. Cat owners preferred them because they smelled less and were so convenient. And owners and veterinarians thought that the chewing action these chows required would keep the pet’s teeth cleaner. The problem is that cats, fed dry kibble rarely if ever drink sufficient water to keep their bodies well hydrated.

I do not suggest any of the commercially available dry formulas for diabetic cats as a first-choice diet. If you are hesitant about your abilities to prepare a nutritionally balanced , home-cooked, diet for your cat, there are veterinary services that will design one for you. You can also find suggestions on a webpage that I have posted on this site. 

Another factor that I believe is involved is the poor quality of the fats that find their way into commercial cat foods – canned or dry. Fats, particularly unsaturated fats, are unstable. When they oxidize, those oxidation products are unhealthy for your cat’s body. I believe that that is why so many cats feed canned or dry foods that contain fish have chronic health problems later in life. Pet food manufacturers try to prevent oxidation (spoilage, rancidity) by adding antioxidants and stabilizers to their diets (ethoxyquin, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tocopherols (vitamin E), ascorbic acid (vitamin C), citric acid, and rosemary, etc. ). A more natural and safer way is to just feed your cat a balanced diet of refrigerated fresh human-grade foods. That is something no pet food maker wants to hear.

So I suggest you do several things concerning what you feed your cat:

1) Limit your cat’s food intake to only that amount that maintains it at a trim, optimal weight.

2) Feed your cat a diet that is low in carbohydrate and high in protein.

3) Feed your cat only naturally moist (wet) foods. Adding additional water (up to 40%) is another way to help your cat loose weight.

4) Do not feed your cat products that contain pet-food grade fish or fish products. There is no problem in feeding you cat some fish. Just be sure it is human grade, fresh fish obtained from your supermarket.

Healthy cat foods are available commercially, but I prefer that owners prepare them at home. As I mentioned earlier, recipes and suggestions are given here. (If you do not have the capacity to plan a balanced diet for your cat, you are safer purchasing a diet ready- made.)

Some folks suggest feeding canned gluten-free cat foods like Fancy Feast. I have not recommended canned cat food ever since reading an article that pointed out the statistical relationship between cats eating canned food and their development of hyperthyroidism (read here). That, plus the constant recalls of commercial pet foods are reasons enough to cook for your cat. If you wouldn’t eat it, they oughtn’t either.

I am not a fan of raw diets – I have seen too many cats become ill from the bacteria that sometimes contaminate raw meat.

Exercise Contributes To Success

Always begin exercise programs cautiously and slowly.

You are unlikely to lower your cat’s weight through exercise alone. You will need to control what the cat eats and how much it eats as well. But exercise will certainly help achieving its ideal weight and exercise has great benefits beyond weight reduction.

Toys, hanging strings, hand-held lasers, etc. are all good ways to encourage your cat to be active. Better yet is a fully-enclosed, outdoor play area (a cat run) or leashed walks with your cat. It takes cats some time to walk on a leash. But when they do, they love it as much as dogs do. Simply reducing your cats food intake will cause it to be more active and exploratory.

Exercise also changes the way cells react to insulin. (read here) And studies have found that indoor confinement and inactivity are major risk factors in cats developing diabetes. (read here)

Although outdoor, free-roaming cats rarely if ever develop diabetes, I don’t suggest a cat door or allowing your cat out-of-doors unattended. There are risks out there that are as great or greater than diabetes.

Dealing With Excessive Peeing Accidents In Your House

One of the most annoying signs of unregulated diabetes in cats is their distressing need to urinate excessively. Not only do they have to void huge amounts of urine, they are more prone to urinary tract infections, possibly due to the increased sugar in their urine. (read here)

Here are some things you can do:

1) Have your veterinarian examine a fresh sample of your cat’s urine for evidence of an infection. if one is present, the cat needs antibiotic treatment. If other urine abnormalities are found, the vet will treat those as well.

2) Confirm that your cat’s blood sugar is not overly elevated. If it is, direct your attention to reducing its blood sugar and the problem should correct itself.

3) If the problem persists, follow the advice given in another article which you can read  here.

Never withhold water from your cat in an attempt to deal with this problem.

Can My Cat’s Diabetes Be Cured?

Occasional cats, caught early in their diabetic syndrome, will revert to normal with only a program of weight loss, dietary modification and exercise. Others no longer require insulin after a period of time. These are more likely remissions than complete cures – I think that these cats will probably always be at a higher risk of the problem returning.

Cats most likely to go into remission and no longer require insulin injections are those that are older when their diabetes first begins, those that have not yet become underweight, those with only moderated elevated blood glucose levels and those whose cholesterol levels were not markedly elevated. (read here & here) In a small Australian study, it appeared that more cats receiving glargine insulin went into remission than those receiving PZI or lente insulin. (read here)

A bright spot is that it appears that humans, at least, are capable of some regeneration of lost pancreatic beta cells – the source of insulin. (read here  & here) Perhaps that explains the occasion “cured” cats or offers future therapies veterinarians do not yet have.

What Are Ketones And Why Are They So Important To Avoid?

When your cat lacks insulin and can no longer fuel its body’s cells with blood sugar, it switches its metabolism to fuel those cells with the fatty acid portion of its stored body fat and portions of its own muscle protein. This metabolic switchover leads to excess formation of ketone (ketone bodies ). Some are always formed in your cat’s body. But when the process accelerates in cats starved for energy due to diabetes or fasting from a lack of food or appetite, the excess ketone acidifies its blood to dangerous levels. This condition is called ketoacidosis.

Signs of ketoacidosis in cats include, vomiting, diarrhea, weakness, dehydration and rapid shallow breathing. The body can only operate in a narrow range of acidity (pH). Blood glucose levels in these cats are usually sky high and ketones are present in the urine. Untreated, severe ketoacidosis is rapidly fatal. (read here)

When cats are presented to veterinarians in this condition, they require immediate IV fluid administration to correct dehydration, rapidly acting, short-term insulin to bring high blood sugar levels down, often additional intravenous potassium, continuous monitoring and intensive care. Some cats become deficient in blood phosphorus as well and many require intravenous buffers (bicarbonate) to bring their blood pH back into normal range.

It is quite common for veterinarians make their first acquaintance with a diabetic client during a ketoacidosis crisis. That is the first occasion that many cat owners realize that something is seriously wrong with kitty.

You can monitor your cat’s ketone levels at home. The procedure is simple. It only requires urine dipsticks (Ketostix®) available online (Ebay) or at the pharmacy with no prescription. Check your cat’s first urine of the morning. Do not panic if it is occasionally weakly positive. If it remains so for three or more days in a row, consult your vet.

What Are Some Warning Signs I Need To Watch For In My Diabetic Cat?

Diabetes in cats is a disease in which successful treatment relies more on the nursing skills, dedication and perceptiveness of the owner than the skills of the veterinarian. It is very important that you faithfully stay with your cat’s daily treatment plan and monitor your pet day by day for warning signs that its diabetes is no longer in control. That, and periodic testing, are the way your veterinarian becomes aware of secondary health problems that occur down the road.

Observe your cat frequently. Has its appetite, appearance or water consumption changed? Is it gaining or loosing weight? How about its activity level? Is it spending more time in the litter box? Has its urine consistency, odor or color changed? Is it steady on its feet? Is the cat coughing or sneezing? What is the color and consistency of its stools?

Hypoglycemia – Low Blood Sugar

If your cat’s blood sugar drops too low (less than 45 mg/dL [2.5 mmol/L] ) its body cells will be dangerously starved of the energy they need to function. That is what causes hypoglycemic shock.

Diabetic cats become hypoglycemic when they receive a dose of insulin that is too large for their current needs (dose too large or, perhaps, did not eat as much as usual). The signs to expect are weakness, drunken motion, and, in severe cases, convulsions and coma. The problem can begin as no more than restlessness, shivering, disorientation and meowing. Some cats react to mild hypoglycemia with ravenous hunger. In mild cases, it may progress no further than that.

Hypoglycemia can progress to a life-threatening condition that advances very rapidly. The cure is to raise the cat’s blood sugar level rapidly.

1) If time permits, check your cats blood glucose level with your glucometer.

2) Cats facing this condition should eat if they are willing to or can be coaxed to.

3) Contact your veterinarian, describe the situation and ask for advice. If the situation is already serious, just put the cat in the car and go there now. (The vet’s phone number and that of your nearest emergency clinic should always hang from your refrigerator)

4) Provide oral glucose to your cat.

All owners of diabetic cats should have a liquid glucose source readily available in their home. You can ask your veterinarian for a 10cc syringe of 50% Dextrose (5% dextrose (D5W) is too dilute). I make sure all my clients have some around – particularly when they are just beginning or changing insulin doses. You can also go to your pharmacy or Walmart, purchase some glucose tablets (Dextrosol, B-D glucose tabs, etc.) and dissolve them in warm water (a 1-2-gram/dose should be sufficient). Wait 15 minutes and check the cat’s blood sugar level again. Repeat the dose if need be. Keep unused sugar solutions refrigerated.

Some folks suggest Karo Syrup or anything sweet. That is better than nothing, but not as effective. Products containing table sugar contain sucrose, not glucose (aka dextrose). Sucrose is 50% glucose and 50% fructose. Karo Syrup is a form of high fructose corn syrup. It contains more glucose than generic corn syrups, but it also contains other sugars (maltose, maltotriose, maltotetraose). Generic Corn syrup is 55% fructose and 42% glucose. Although you cat’s liver can metabolize the fructose into glucose, that takes more time. (In humans at least, It is a particularly inefficient process when oral medications like acarbose are in use).

Your cat can metabolize fructose sugar, but it requires additional time and effort. (Intermediate glycolysis in its liver because there are no dedicated pathways to metabolize it)

The best way to give glucose solution to your cat is by wetting the lining of its lips, mouth and tongue with it. Be careful not to be bitten or use a toothbrush to “paint” it around the oral surface. Do not pour or squirt liquid into the cat’s mouth – it is libel to go down wrong. Never place food in the mouth of a cat that is not fully alert.

Small, periodic amounts of glucose are better than one large amount. Some folks say it can also be given through the other end with a rectal enema. Theoretically, that is possible. I have never tried it. I would prefer you just get a cat in that debilitated a condition to a veterinarian as rapidly as possible.

Many owners are hesitant about giving glucose to their cat – after all, they were under the impression that the whole point of diabetes treatment is to lower glucose sugar. Don’t worry about that in a hypoglycemic emergency. The short period of time your cat’s blood sugar level will be high will have no effect on its long term health.

As soon as the cat is willing to eat, allow it to. Keep close watch on the cat that the problem does not return – the glucose you gave will have only a short time effect and may need to be repeated.

After the incident has passed, re-evaluate your insulin dose, interval and any other factors that might have caused this crisis and correct them. Remember that the glucose curve graph you made for your cat may not have caught blood glucose at its lowest point between blood-draws. If the curve was headed in a downward slope, it may have dipped even lower sometime before the next time you drew blood. That may have been the point when hypoglycemia occurred.

Increased Susceptibility To Infections

It is not only urinary tract infections that are more common in diabetic cats. They are also somewhat more susceptible to other infections as well. It is probably not anything special about the diabetic condition that causes this; just the general debility that accompanies advanced or poorly-controlled diabetes. However, when diabetes accompanies generalized inflammatory problem, such as pancreatitis, it may be only one of many problems the cat is having to deal with. In those cases, running an fPL blood test would be prudent.

Eye Problems Associated With Diabetes

Eye problems and cataracts associated with diabetes are common in dogs and humans. They almost never occur in cats as the result of diabetes. (read here)

Nerve Problems Associated With Diabetes

Like eye problems, visible nerve problems associated with diabetes are rare in cats. Some vets have seen them; I have not. When this type of nerve damage occurs (diabetic neuropathy) the cats are described as walking on their hocks (plantigrade). There are reports that even cats with no visible evidence of this type of gait have microscopic evidence of nerve damage. (read here)

Heart Problems Associated With Diabetes

There is no denying that diabetes takes it toll on the body. It is true that the better you control it, the longer your cat will live. But in one English study, veterinarians found that cats with diabetes had a ten-fold increase in developing heart failure over non-diabetic cats during the period that they were observed. One small, subjective study like this does not prove anything, but it suggests a trend. 

 Hepatic Lipidosis 

Cats that feel poorly and will not eat have troubles drawing on their stored fat and protein reserves. I mentioned, hepatic lipidosis (aka an enlarged fatty liver = hepatomegaly) earlier in this article. It occurs in any condition that causes cats not to eat. You can read more about hepatic lipidosis and its many causes by following the above link.

How Long Is My Cat Likely To Live Now That We Know It Is Diabetic?

How long your cat is likely to live depends on how early the problem is discovered and how well you succeed in controlling your cats blood sugar level. It also depends on your cat’s temperament – some cats are more cooperative than others. 

The older your cat is when it first develops diabetes, the more likely it is to live to ripe old age. Mookey, the cat in the photo, lived to be 21 was diabetic for the third portion of its life. (read here)

Cases of feline diabetes do not occur in a vacuum. You also have physical, emotional and financial needs that come into play. But there are some things that most owners can do:

1) Keep your cat trim and scrupulously follow its nutritional, exercise and medication plan.

2) Keep your glucose curve chart current.

3) Have your cat examined once or twice a year by your veterinarian even if the cat appears stable – immediately if it is not. Include a fructosamine test in your yearly or biannual checkups.

4) Brush your cat’s teeth. Gum problems in cats are a constant source of bacteria that have the ability to enter the bloodstream.

5) To the best of your abilities, keep its lifestyle constant, stable, stress-free and monotonous.

6) Eliminate carbohydrates from your cat’s diet. (read here)

If My Cat Is Not Neutered Will Neutering Help In Its Treatment?

We know this can be helpful in regulating diabetic dogs. There are many good reasons for neutering your cat, but this isn’t one of them. You can read my thoughts on spay/neuter here if you wish. 

Are New Treatment Options On The Horizon?

There are some. One was the study that noted that pancreatic beta cells are sometimes capable of regeneration. With that point in mind, there are ongoing studies on how one might artificially encourage that regenerative process.

Regenerative medicine is the current “Manhattan Project of Medicine”. The US Defense Department funds it generously. And at the basic level of tissue regeneration, there is little difference between humans and cats. (read here) A study found that insulin, spayed into the nose of cats had possible potential as an alternative to insulin injections. (read here) Another study explored the possibility of growing pancreatic cells in the cats own bone marrow. (read here)

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