Diabetes in Cats

I am currently managing several feline patients with diabetes so I thought that would be an appropriate topic to write about this week.  Much of this information can also apply to dogs, but I will focus on the disease in cats. So what is diabetes?  There are technically two types, diabetes insipidus and diabetes mellitus. Diabetes insipudus is a disease where the animal is unable to concentrate urine and not the topic of today.  I am going to discuss diabetes mellitus.

Diabetes mellitus is a disease where the body is unable to regulate blood sugar.  First of all it is important to understand how a normal cat regulates their glucose. Glucose is the energy source for all cells in the body.  When a cat eats a meal it is digested in the GI tract and the food broken down into it's basic parts of amino acids, fats, and sugars.  The liver then plays a further role in breaking down fats into usable glucose.  As glucose levels increase in the blood this triggers the pancreas to release insulin.  Insulin is the "key" that opens the cell door to allow glucose in.  Without this key the glucose can not enter the cell and the cell will not get any energy.  It is like being in the middle of the ocean, but not having any water to drink.  Most cat's suffer from Type II diabetes where the body may produce enough insulin, but no longer knows how to use it properly.
Because cats are not pack animals, they will hide illness until they are no longer able to.  This makes early detection difficult, even with the most astute owner.  Diabetes occurs in 1 out of 400 cats, but is becoming more common due to rampant obesity in companion animals.  Neutered male cats are twice as likely to develop diabetes than females, but cats weighing over 15 lbs and over the age of 10 are at  the greatest risk of developing diabetes.  Many experts also believe that a high carbohydrate diet predisposes cats to diabetes.  All dry foods and a majority of canned food contain a much higher percent of carbohydrate than cats need.  Once a cat develops diabetes this definitely plays a role in controlling the disease.
Regular check-ups every six months as well as screening bloodwork can be a very good way to detect the disease early.  The earlier the disease is diagnosed the more easily it is controlled.  Common signs that people first notice in a diabetic cat are increased drinking, increased urination, and weight loss despite a good appetite.  In more advanced stages weakness, wobbly gate, vomiting, anorexia are the common signs.
Diabetes is actually fairly easy to diagnose.  A small drop of blood to check glucose level will rule diabetes out if it is normal.  A blood glucose level above 200 mg/dl is a strong indication that the cat is diabetic.  Stress or a recent meal can falsely elevate glucose so a urinalysis or fructosamine level will need to be done to confirm the diagnosis.
If the diagnosis is made early enough many cats can be controlled by feeding a low carb diet.  Eventually about 70% of cats will need insulin to control the diabetes.  There are oral medications for humans to control diabetes, but most cat owners find it much more difficult to give a cat a pill than an injection.  Also the oral medications tend to be much less effective in controlling the diabetes and may promote further pancreatic cell damage.

Diets that are low in carbs, meaning less than 7% carbs, are difficult to find.  Purina DM canned is the only prescription diet that is available that has <7% carbs.  Janet& Binky'sCat Food Nutritional Information Page is a good resource for over the counter diets that are low carb.  You can't go by what the guaranteed analysis of a can says because they count water content so I recommend picking something off the list or calling the company and asking what percent of carbs are in the food on a dry matter basis.  Water intake is also a critical component to feline health, especially in sick cats.  For the last 10-15 years veterinarians have been preaching how important it is to feed your cat dry food for dental health, when in fact there are only a very few dry foods that actually do any cleaning of their teeth.  Dry foods are very high in carbs and low in water content.  We are now seeing other health issues such as renal disease, urinary tract disease, and diabetes that may be due to these dry diets.  So should all cats be fed canned food?  I honestly don't know, but more and more research is coming out to support the belief that they should.
OK back to the subject of diabetes.  Switching your cat to a low carb diet is a very important part of managing diabetes.  If your cat is already on insulin it is VERY important to note that he may suddenly no longer require as much insulin or any at all once switched.  Many cats can go into an insulin seizure or coma from getting the same dose of insulin they have been getting for months or years once switched to a low carb diet.  Careful glucose monitoring is critical to prevent this.  If your cat is newly diagnosed then many vets will start them on a low carb diet before insulin is started to see if the disease can be managed that way.  Regular insulin checks and close monitoring of water intake and urinary output are necessary to be able to quickly realize when diet control are no longer adequate and insulin will be needed.
Insulin therapy is often instantly rejected by many clients as an option.  People fear to give their cat injections once or twice a day and are afraid they will stress out or hurt their cat too much.  In fact I find it much easier to give a cat a subcutaneous injection than to pop pills down their throat.  With proper instruction most people can learn to administer these tiny injections.  Especially of done while the cat is eating or relaxed they often don't even seem to notice the shot.  Don't reject insulin therapy out of hand.  Worst case scenario is you try it and you can't do it.  Don't euthanize your diabetic cat without at least giving it an honest try.
Monitoring a diabetic is very important.  Once you are good at giving your cat insulin injections, learning how to prick their ear for a small blood sample to check glucose levels is an easy step.  This is the best way to monitor glucose.  A glucose curve is a very important test to see how your cat's body responds to the insulin injections.  This is a test where blood glucose levels are checked every 2 hours for a 12-16 hour period.  Taking your cat to the vet hospital to stay the day for this test is unlikely to give very accurate results due to the stress involved.  Being able to perform this test at home give a much better indication of the true effectiveness of the treatment.
Diabetes is a manageable disease that does not have to shorten your cat's life expectancy or overtly affect his quality of life.  Diabetes left untreated is a completely different story.  Uncontrolled high blood glucose levels lead to repeated urinary tract infections, kidney damage, neurological effects (weakness, dementia, seizures, coma), cataracts (more common in dogs), liver damage, dehydration, infection, and eventually death.