Diabetes mellitus strikes 1 in 400 cats, though recent veterinary studies indicate that the disease is becoming more common in cats, perhaps because of increased obesity rates. Diabetes develops when the pancreas fails to produce adequate amounts of insulin or when the body’s cells have an inadequate response to insulin. Insulin enables glucose to enter the cells, where it is metabolized for energy. Without insulin, the body can’t utilize glucose and blood sugar levels rise (hyperglycemia). In hyperglycemic cats, the ability of the kidneys to reabsorb glucose from the urine is overwhelmed, resulting in glucose in the urine (glycosuria). Glycosuria increases the volume of urine, which in turn, causes frequent urination. To compensate for the increased urination, cats drink unusually large amounts of water.
Obesity is a predisposing risk factor for diabetes for all cats, and Burmese cats may have a genetic predisposition. Male cats have twice the risk of females. At greatest risk are neutered male cats older than 10 years and heavier than 15 pounds.
Diabetes is suspected when a urine glucose test comes back positive. Stress causes some cats to show high glucose levels in urine and blood, however, so a repeat test may be needed to verify the results. Defects in kidney tubule function, such as those seen with antifreeze poisoning, may also cause high glucose levels in blood and urine.
Ketones (the end product of rapid or excessive fatty-acid breakdown) are formed in the blood of animals and people with diabetes because of their inability to metabolize glucose. High levels lead to ketoacidosis, a condition characterized by acetone-smelling breath (acetone has a sweet odor like nail polish remover); rapid, labored breathing; and, eventually, diabetic coma.
Dietary management and daily injections of insulin under the skin (subcutaneous) can regulate diabetes in most cats, enabling them to lead normal lives. Because the amount of insulin needed cannot be predicted based on the cat’s weight, most cats must be hospitalized to determine their daily insulin requirement. Most cats with diabetes need one or two injections a day, and your veterinarian will show you how to give them. Luckily, the amounts are very small, the needles are tiny and very sharp and most cats tolerate the subcutaneous injections with no problem.
Even cats that are on oral diabetes medications may eventually need insulin injections. Oral drugs include glipizide, which enhances insulin production but may cause side effects, such as vomiting; acarbose, which blocks glucose absorption from the intestines; and troglitazone, vanadium and chromium, which make the cat’s body more sensitive to its own insulin.
In the past, cats with diabetes were placed on a high-fiber diet, which was thought to slow the absorption of nutrients and help stabilize blood glucose levels. However, recent research, some funded by Morris Animal Foundation, has shown that this is not the ideal diet for cats with diabetes. Because cats are true carnivores, they primarily metabolize protein not carbohydrates for glucose; thus, high-protein, low-carbohydrate diets have proven to be more efficiently metabolized and are of great help in controlling diabetes. These diets also help a cat lose weight while maintaining muscle. Consult your veterinarian for specific guidelines for your cat. Occasionally, an obese cat with diabetes will respond to dietary management alone and will not require insulin to keep blood glucose well controlled.
With proper dietary management and hyperglycemia control, diabetes mellitus can be successfully managed. Some cats with diabetes may reach a point where they no longer need insulin, even months or years after diagnosis. If diabetes has resulted from obesity, it is likely to improve a great deal—or even completely resolve—once the cat’s weight is under control. The serious chronic complications that afflict people with diabetes mellitus (such as kidney disease, circulatory disorders and coronary artery disease) are uncommon in cats with diabetes. Once control is attained with proper treatment and home care, a cat with diabetes can live many healthy years. Nonetheless, successfully managing your cat’s care requires much dedication and communication between you and your veterinarian.
Click here to find out about Morris Animal Foundation–funded research into feline diabetes.
Morris Animal Foundation (MAF) urges pet owners not to implement any suggestions on animal health treatments without prior consultation with a licensed veterinarian. If your pet is experiencing health issues, contact your veterinarian. MAF does not endorse any of the medical treatments described in these articles. The Foundation funds research to enhance medical options available to veterinary professionals and their patients.