Diabetes Mellitus in Cats
Diabetes is an endocrine disorder caused by an absolute or relative insulin deficiency. Metabolism refers to how the body digests and uses food for growth and energy; this process is largely dependent on a sufficient amount of insulin in the body.
Insulin is a hormone that is produced in the pancreas, releasing into the cells in response to the digestive conversion of carbohydrates into glucose in the bloodstream. Much of the food that is ingested is broken down into glucose, a type of sugar in the blood and one of the body's main sources of energy. Appropriate insulin function will trigger the liver and muscles to take up glucose from the blood cells, converting it to energy.
In diabetes, there might be an absolute shortage of insulin (Type I), or the cells may not be responding appropriately to the insulin, a condition termed insulin resistance (Type II). Both of these conditions will prevent the muscles and organs from converting glucose to energy and will result in excessive amounts of glucose in the blood. Excessive blood sugar is also referred to as hyperglycemia.
Diabetes, a common condition for humans, is also relatively common in domestic animals like cats. Type I diabetes (insulin dependent diabetes mellitus – IDDM) occurs when the body is completely unable to manufacture insulin. While it is less commonly diagnosed than Type II diabetes in the cat, a poorly controlled diabetic can progress from Type II to Type I diabetes.
Type II diabetes, also referred to as non-insulin dependent diabetes mellitus (NIDDM), happens when the body can produce insulin but the body does not respond to it normally. While it is the more common form in the cat, many Type II diabetes still require insulin to maintain normal blood glucose levels. An estimated one in 1,200 cats will develop diabetes during its life-span.
At heightened risk are obese cats and male cats. Most cases are seen in cats middle aged and older, but it can occur at any age.
Symptoms and Types
- Excessive thirst
- Excessive urination (increase in both frequency and amount of urine)
- Poor appetite
- Weight loss
- Wasting of back muscles
- Weakness in back legs
- Oily coat with dandruff
- Enlarged liver
- Ketoacidosis – metabolic acidosis caused by the breakdown of fat and proteins in the liver in response to insulin deficiency
- Inflammation of the pancreas (pancreatitis)
- Occurs concurrently with certain diseases:
- Cushing's Disease
- Use of certain drugs
Your veterinarian will take detailed medical history from you of your cat's health leading up to the onset of symptoms and details of the exact symptoms. Standard tests will include a complete blood count, chemical profile, and urinalysis. These tests should be sufficient for diagnosis and initial treatment.
Typically, with diabetes, an unusually high concentration of glucose will be found in the blood and urine. Abnormally high levels of liver enzymes and electrolytes imbalances are also common. Urine test results may also show evidence of abnormally high levels of ketone bodies — water-soluble compounds produced as a by-product of fatty acid metabolism in the liver and kidney. Diabetic ketoacidosis is a medical emergency and pets are often extremely ill by the time they present to the hospital. A numbers of other abnormalities may also be found.
Radiographic studies, including x-rays and ultrasonography, can be helpful for the diagnosis of concurrent diseases and complications due to diabetes. Abdominal x-rays and ultrasound will help to determine the presence of kidney stones and/or inflammation of the pancreas and liver as well as other associated abnormalities. In the case of liver disease, should it appear suspect, your veterinarian may decide to take a sample of liver tissue for further diagnostic evaluation.