Diabetes in Cats
Important symptoms of DM include increased thirst (polydipsia) and increased urination (polyuria). These are often the most prominent symptoms of diabetes mellitus, also known as sugar diabetes. Frequently there is weight loss despite a good appetite. Several other diseases can also cause increased thirst and urination. These diseases include:
Kidney failure that results in an inability to concentrate the urine
Hormone disturbances, including excess or deficient steroid hormones (hyperadrenocorticism and hypoadrenocorticism), deficient anti-diuretic hormone (diabetes insipidus or water diabetes) and excess thyroid hormone
Liver failure and certain cancers that prevent the kidneys from concentrating urine
A urinary tract infection can lead to increased frequency of urination and uncontrollable urination in inappropriate locations. Urinary tract infections often accompany DM because bacteria live well in the sugary, diluted urine.
Weight loss while having a good appetite can be observed with intestinal disease, digestive enzyme failure, kidney disease, excess thyroid hormone or cancers.
Concurrent complications and conditions often found in diabetic patients include:
Urinary tract infection due to diluted, sugar-containing urine
Infections in other parts of the body, including the gums
Acidosis (low blood pH) due to the production of ketones as the body tries to provide energy for the tissues in the absence of appropriate glucose (sugar) metabolism. Ketones are formed from fatty acids when the body believes it is starving.
Diabetic ketoacidosis, the most severe form of DM, results in severe changes in blood chemicals, including imbalances in small, simple chemicals known as electrolytes.
Cataract formation because of the abnormal accumulation of sugars in the lens of the eye. Although treatment of DM will not reverse cataract formation, surgical therapies for cataracts are an option.
Pancreatitis, an inflammation of the pancreas, can occur in the same organ that makes insulin. Occasionally, severe, repeated bouts of pancreatitis can damage the organ and cause DM, but pancreatitis can also occur in animals that already have DM. Pancreatitis ranges from a mild “belly ache” to a life-threatening disorder, with anorexia being the most common clinical sign.
Hyperadrenocorticism, an excess of steroid hormones may accompany and complicate DM in older cats. It is not caused by DM, but left untreated it complicates the therapy of DM. This disease is very uncommon in cats.
Veterinary care should include diagnostic tests to determine the underlying cause of the diabetes and help guide subsequent treatment recommendations. Diagnostic tests are needed to recognize DM and exclude other diseases. These tests may include:
Complete medical history and physical examination. Particular attention will be given to your assessment of changes in eating and elimination activities. Changes in weight or general behavior will also be noted. The abdomen will be carefully palpated (probed by touch) to feel for changes in the size of the abdominal organs.
Analysis of the urine. This will allow your veterinarian to check for the presence of glucose or ketones (an acid produced by the body when insulin is absent), as well as for signs of urinary bladder infection, a common complication of DM.
Biochemical analysis of the blood. This test will allow confirmation of elevated blood glucose (sugar) concentrations. Elevated blood glucose is the hallmark of DM. In addition, these tests will allow some assessment of kidney and liver function and of the acidity (pH) of the blood. Results of biochemical analysis may reveal complications of DM and can often reveal the presence of concurrent diseases as well.
Blood glucose concentrations may be measured more than once. Stress, a recent meal or certain drugs may cause mild to moderate elevations in blood glucose in the absence of DM. Persistent elevations in blood glucose, particularly after a fast, often suggests DM.
Additional tests may be recommended on an individual basis. These tests include:
Glycosylated hemoglobin, the product of the cumulative effect of blood glucose on red blood cell hemoglobin, is measured by sending blood to a special laboratory. This test allows the veterinarian to get an idea of what the blood glucose concentrations are like over the course of several days instead of at one brief instant. The response of the patient to treatment must be followed.
Serum fructosamine measurements are used in the same way that glycosylated hemoglobin measurements are. Fructosamine, is the product of the effect of blood sugar on the blood protein albumin. This level is generally monitored every 3 to 6 months after diabetic control is attained.
Urine culture may confirm the presence of a urinary bladder infection, prove what type of bacteria is causing the infection and tell the veterinarian which antibiotics should be effective in treating it (and which ones will not).
Complete blood count (CBC) can discover anemias (too few oxygen-carrying red blood cells), abnormal platelet numbers (too few or too many blood clotting cells) and abnormal white blood cell counts (too few or too many infection-fighting cells). Infections are a common complication of DM.
Abdominal radiographs (X-rays) may be requested to rule out changes in size of organs like the liver or kidneys or to look for evidence of abdominal tumors. Kidney disease, intestinal disease, disease of the adrenal gland or certain abdominal tumors may be present and have signs very similar to DM.
Abdominal ultrasonography uses sound waves to evaluate the contents of the abdominal cavity. A specialist often performs the test in which the fur is shaved and a probe is held against the abdomen (this is the same test given to many pregnant women to visualize the fetus). This test can reveal many of the same things as abdominal radiographs, but provides a more detailed examination along with views of the inside of organs rather than just the shadow of the organ.
Specific endocrine tests including an ACTH stimulation test, low and/or high dose dexamethasone suppression test, or urine cortisol/creatinine ratios may be requested if hyperadrenocorticism is suspected (generally in older cats). Hyperadrenocorticism complicates both the diagnosis and treatment of DM.