Diabetes in Cats: Diagnosis and Testing

In our last blog on diabetes, we defined the illness and mentioned several symptoms that could indicate your cat has, or is developing, diabetes. In this blog, we will discuss the tests used to diagnose the disease as well as the short-term and long-term treatment and management.

Diagnosing:
Generally, the following screening tests are recommended when diabetes mellitus is suspected: a complete blood count (CBC), a serum biochemistry profile, and a urinalysis. While it would seem that simply checking for an elevated blood sugar would be enough, a thorough set of screening tests gives us much more information that will help to treat the disease. Cats present a unique challenge in diagnosing diabetes because their blood glucose levels can become elevated simply from stress. Additionally, because diabetes is often found in senior to geriatric cats, there may be unrelated conditions that may affect how your cat's diabetes is treated and may also need to be managed for your cat's optimal health and well-being.

The complete blood count (CBC) evaluates the red blood cells, the white blood cells, and the platelet components of a blood sample. With uncomplicated diabetes mellitus, these results are often within the normal range. Some problems we can see is an elevated white blood cell count if there is an infection, to which diabetic cats are more susceptible. Also the red blood cell count may be elevated if there is dehydration or decreased with anemia, which are common with severe diabetic states and other concurrent medical conditions.

The serum biochemistry profile evaluates substances in the serum component of the blood including glucose, enzymes, lipids (fats), proteins and metabolic waste products. The serum glucose level is usually very elevated in diabetic cats. We can also find changes in the electrolytes (potassium, sodium, etc.) and liver enzymes secondary to the diabetes. Chronic kidney disease is very common in older cats and often seen in diabetic cats.

Another blood test that is very valuable in a diabetic cat is a Serum Fructosamine. This test looks at how sugar levels have been over the previous week and not just at the moment of the blood draw. Therefore, it is not affected by the level of stress the cat experiences at the clinic. This test confirms the diagnosis of diabetes and aids in evaluating how well the diabetes is being managed with treatment.

Finally, a urinalysis is needed. Urine from healthy cats typically does not contain any glucose (sugar). A diabetic cat will have a large amount of glucose in the urine, which aids in the diagnosis. Urinary tract infections are also more common in diabetic cats as the presence of glucose in the urine makes conditions ideal for bacterial growth. By detecting white blood cells in the urinalysis, the infection can be detected and treated.

The presence or absence of ketones in the urine are also evaluated. Ketones are by-products of fat metabolism. Increased utilization of fat occurs in diabetic animals because their insulin deficiency results in poor utilization of carbohydrates as an energy source. The presence of ketones in the urine indicates a more severe or long-standing case of diabetes, which will require more intense treatment.

Treatment:
Once your cat has been diagnosed with diabetes, it's likely that your cat will be started on insulin treatment. Insulin is a very effective treatment for the regulation and management of diabetes. Fortunately, insulin from one mammal is biologically active in another, which means your cat's system will respond to the injected insulin as if it were its own insulin.

Here at Scottsdale Cat Clinic, we generally prescribe Glargine, frequently known by the brand name of Lantus, which can be purchased through a human pharmacy. This is a long-acting human recombinant insulin analog that forms microprecipitates at the site of injection from which insulin is slowly released. It generally starts to work within 2-4 hours, continues working for 24 hours, and does not have a peak effect. There are other insulin formulas available as well.

In addition to starting insulin, we also strongly recommend changing your cat's diet to a high-protein, low-carbohydrate formula, ideally in a canned formula. We do have several diabetic prescription diets available, and there are wonderful resources for finding other high-protein foods on our website.

At Scottsdale Cat Clinic, once a patient is diagnosed with diabetes and prescribed insulin, we follow up with daily phone calls to the owner for the first three or four days to monitor any changes in symptoms and to make sure the insulin administration is going well and without difficulties. Because it can take time to establish the correct insulin dosage for your cat, we recommend having a glucose curve every two weeks until the correct dosage is established. A glucose curve is a test that takes a glucose reading every two hours for 12 hours. Once the correct dosage is established, the glucose curve should be repeated one month later. If everything is still good, then the test can be repeated every 4-6 months.

The long-term goals of treatment are to remove all the symptoms of diabetes, maintain a healthy and appropriate weight and to regulate the cat's glucose levels. If insulin and a high-protein diet are begun fairly early in the course of the disease, many cases of diabetes can even resolve and go into remission. These cats still need a high-protein canned diet, but no longer require insulin injections.

It is very important to follow through on all treatments and diet changes recommended by your veterinarian to have the best outcome for your cat.