Diabetes in Cats: Diagnosis

Diagnosing your cat's diabetes is a straightforward process for the veterinarian. Diabetes may be suspected because you noticed that your cat was urinating, drinking and possibly eating excessively, and that your cat was losing weight.

To firm up the diagnosis, the veterinarian will
look at three factors:¹

Does the cat have the major clinical
symptoms of diabetes (excessive urination, drinking, hunger and weight loss)?

Is the cat’s blood glucose level too high?

Is there glucose in the cat’s urine?

Butter-Bean is a 10 year old Manx. He was recently diagnosed with diabetes - this is what he thinks of his insulin injections!!
Photo, courtesy of S. Brown
The veterinarian may run a lab test to measure the amount of fructosamine in your cat’s blood. Fructosamine is a chemical that forms when glucose molecules combine with certain proteins in the blood. The level of fructosamine indicates how high the cat’s blood glucose has been over the last one to two weeks.

Fructosamine cannot tell you how high the cat’s blood glucose is right now. However, if the cat has chronically high blood glucose, the fructosamine test will show it. The veterinarian may also measure the glycosylated hemoglobin level, which is similar to an A1c test in a human with diabetes. It indicates what the blood glucose level has been over the last two months.¹

The veterinarian cannot use blood glucose measurements alone to diagnose diabetes in a cat because under stress, even non-diabetic cats can have blood glucose levels as high as 300-400 mg/dL. This is why the urine and fructosamine or glycosylated hemoglobin tests are needed for a firm diagnosis. Temporary stress usually does not cause these tests to show an abnormal result.

The veterinarian may also suggest some additional tests, because many diabetic cats are older and may have other medical problems that need to be treated. Diabetic cats are more prone to have urinary tract infections, skin infections, and inflammation of the pancreas. They may also suffer from heart disease, kidney disease and anemia.

It is worthwhile to do some additional blood and urine tests at the time of diagnosis, along with a chest x-ray and an x-ray or ultrasound of the abdomen.²