Diabetes mellitus in dogs and cats is characterized by a high level of glucose in the blood.  Glucose is a sugar that the cells in the body use for energy.  The level of glucose in the blood and its absorption by cells are regulated by a hormone called insulin, which is produced in the pancreas.  If there isn't enough insulin, or if the cells can't use it effectively, then glucose levels in the blood increase, resulting in diabetes.

Diabetes often begins in middle age.  In dogs, it is more common in females and in certain breeds, including the Keeshond, Puli, Miniature Pinscher, and Cairn Terrier.  Male and female cats of all breeds can be affected and seem to be equally at risk.

Signs often develop gradually and most commonly include drinking a lot of water, urinating more often than usual, an increased appetite, and weight loss.  Because diabetes also interferes with the body's ability to heal, there may be sores or skin infections that take a long time to heal or are resistant to treatment. 

If diabetes is not treated, metabolic byproducts of fat breakdown, called ketones, can build up in the blood, leading to fatigue, poor appetite, and vomiting.  When ketones accumulate in the body, your pet's breath may have a faint chemical odor.

Diabetes is diagnosed by measuring increased levels of glucose in the blood.  If the level of glucose in the blood is high enough, it will "spill over" into the urine and can be detected there as well.

Very mild cases of diabetes can sometimes by managed by diet, exercise, and weight loss.  However, in most cases, insulin injections are needed to keep the level of blood glucose in the normal range.  Your pet may need to stay in the veterinary hospital for a few days until its condition is stabilized and your veterinarian can determine an appropriate initial dosage of insulin.  Treatment can then be continued at home.  Your vet will teach you how to give the insulin injections using small syringes and very tiny needles.  Once pets become used to the daily routine, they usually don't mind the shots.

Managing a pet with diabetes requires you to make a commitment and to stick to the same routine every day.  You will need to feed a fixed amount of a balanced diet, divided into equal morning and evening portions.  Table food and other snacks should not be given because they will interfere with the proper regulation of your pet's glucose level.  Exercise also needs to be consistent for the same reason.  Your vet may ask you to check your pet's urine glucose on a daily basis and to return regularly for a blood glucose test.  Your vet will also instruct you on possible emergency situations (such as giving too much insulin by accident) and how to respond to them.

Once you establish a routine and your pet is used to it, checking a urine glucose level, keeping meals and exercise consistent, and administering insulin (if needed) takes very little time.  Fortunately, with proper management, pets with diabetes can live healthy lives for many years.

 Q&A

What is diabetes?

Diabetes mellitus is a condition where the cells of the body cannot consume the glucose from the blood, so that blood sugar levels rise.  The cause is either lack of insulin or an inability of the cells to effectively respond to it.

What pets are likely to develop diabetes?

Diabetes often begins in middle age.  In dogs, it is more common in females and in certain breeds, including the keeshond, puli, miniature pinscher, and Cairn terrier.  Male and female cats of all breeds seem to be equally at risk.

How can I tell if my pet has diabetes?

Signs often develop gradually and most commonly include drinking a lot of water, urinating more often than usual, increased appetite, weight loss, and skin sores that take a long time to heal.  Definitive diagnosis is based on finding elevated levels of glucose in blood and/or urine tests.  

How is diabetes treated?  

Very mild cases can sometimes by managed by diet, exercise, and weight loss, but most cases require daily insulin injections.  Managing a pet with diabetes also requires a commitment to a strict regimen of diet and exercise, as well as regular visits to your veterinarian.

Written and reviewed by John A. Bukowski, DVM, MPH, PhD
and Susan E. Aiello, DVM, ELS