Typical Symptoms of Diabetes in Cats

80% of cats suffering from diabetes mellitus suffer from type 2 diabetes. This type of diabetes is characterized by increasing the destruction of the insulin-producing beta cells in the pancreas and by decreasing the sensitivity of the insulin receptors in the body cells to insulin (insulin resistance). Insulin synthesis and secretion decrease while the release of the insulin antagonist glucagon increases. As a result, body mass is lost and blood sugar levels rise.

The typical cat patient with diabetes mellitus is older than nine years, male, neutered, overweight, and is kept as an apartment cat. Owners of these cats usually come to the practice because they need to clean the litter box more often. Many also come because the cat suddenly becomes unclean and urinates in undesirable places ( periuria ). Some notice the changed gait pattern or the lack of jumping power of their cat. The weight loss is usually not noticed or seen as positive, as the owner was advised during previous visits to the practice to have his overweight animal lose weight. The same applies to increased drinking, which is often equated with health. Also, constant hunger ( polyphagy) is not perceived as pathological, since the cat eats well from the point of view of the owner.

A major symptom of uncomplicated diabetes is increased thirst ( polydipsia ) and the associated increased urine output ( polyuria ). This in turn can lead to uncleanliness, as many cats are reluctant to go back to a litter box that has already been used. In addition, many cats with diabetes mellitus also have a urinary tract infection, which can also lead to periuria due to pain or increased urine output.

The lack of insulin leads to an increased release of the insulin antagonist glucagon. Glucagon promotes glycogenolysis, i. H. the breakdown of glycogen from the liver cells to glucose. Furthermore, glucagon increases gluconeogenesis, i. H. the formation of new glucose from e.g. B. Amino acids. Both mechanisms increase blood sugar levels and, together with the decreased uptake of glucose into the cell, lead to elevated blood sugar levels, and hyperglycemia.

If blood sugar rises above 250 mg/dl (14 mmol/l), glucose is excreted in the urine and can be detected in the urine with a test strip. Glucose has a strong osmotically active effect and leads to increased water loss via the urinary tract. The cat tries to compensate for this by drinking more. Since the excreted urine contains glucose and is highly diluted, the body’s natural defense mechanisms fail, opening the door to a urinary tract infection. Some infectious agents (e.g. E. coli) produce toxins that block water reabsorption in the kidneys. There is further loss of fluids, which further increases the feeling of thirst and thus water intake. The loss of liquid through the urine can be so high that the cat cannot compensate for it by drinking more. These patients are markedly dehydrated, which is clinically reflected in reduced skin turgor. Depending on the fluid deficit, a raised skin fold disappears slowly or stays put.

Diabetic cats have elevated blood glucose levels, but these can also occur in healthy, stressed cats! Only increased long-term blood sugar (fructosamine) in cats is evidence of diabetes mellitus. The fructosamine value reflects the average blood sugar over the past ten days.

In the course of uncomplicated diabetes mellitus, affected cats show cravings ( polyphagia ). The owners feed as before or significantly more since the cat is constantly hungry and yet there is an increasing weight loss.

The absence of insulin prevents the uptake of glucose into the cell and the storage of glucose in the form of glycogen in the liver. At the same time, glucose is lost through the urine. The body loses important energy reserves. The increased release of glucagon also increases the breakdown of proteins to provide amino acids for the formation of new glucose ( gluconeogenesis ). The main source of protein is the muscles. There is a loss of muscle mass and, due to protein breakdown, an impairment of the immune system and wound healing disorders. Fat metabolism is also increased under the influence of glucagon. There is a hasty breakdown of fat ( lipolysis ) which leads to an increase in the blood fat level (lipemia) causes. Released fats are stored in the liver, resulting in a fatty liver. The fatty liver causes reversible damage to liver cells and an increase in the liver enzymes AP (alkaline phosphatase), ALT (alanine aminotransferase), and cholesterol in the blood serum. Hyperlipidemia can be detected in the blood as an increase in triglycerides.

Some of the patients are presented because of abnormalities in the gait pattern. Unlike bears, who land with their entire foot, cats are toe-walkers because they only touch down with the tips of their toes. Some diabetic cats, on the other hand, walk on the entire sole of their hind paws and have problems jumping onto high places. This “plantigrade” gait is the result of nerve damage caused by hyperglycemia ( diabetic neuropathy ). This hindquarter weakness must not be misinterpreted as an orthopedic problem. It disappears when the diabetes is treated.

If diabetes is not recognized or left untreated, uncomplicated diabetes can develop into complicated diabetes. The fat metabolism derails and in the course of the hasty breakdown of fat, masses of ketone bodies are formed. The ketone bodies can be detected in both blood and urine. The blood pH shifts into the acidic range (acidosis), and the patient develops ketoacidosis. These patients stop eating (lack of appetite), become increasingly apathetic and their lives are acutely threatened. They need to be hospitalized and given intensive care. Mortality is high.

Many cats suffering from diabetes mellitus have comorbidities such as B. urinary tract infections or diseases of the teeth, which make treatment of diabetes difficult or impossible. Therefore, diagnosing diabetes always includes a thorough examination of the oral cavity and urinary status. In addition, it is advisable to check feline-specific pancreatic lipase, as some patients suffer from pancreatic inflammation. In older patients, the T4 value should also be determined to rule out hyperthyroidism (overactive thyroid).