Diabetes mellitus is one of the most common endocrine diseases in cats, occurring in approximately 1 in 200 cats. The disease is more common in cats than dogs and the incidence is on the rise due to an increase in obesity and an ageing cat population. It is important to alert pet parents to the signs of diabetes in cats and the importance of maintaining a good body weight in their cat to reduce the risk of this nasty disease.

What is diabetes mellitus?

The hormone insulin is produced to control the level of sugar, or glucose, in the blood. Failure of insulin to control blood glucose leads to diabetes mellitus. Type I diabetes mellitus causes an absolute insulin deficiency while type II diabetes mellitus leads to reduced insulin production. Type II occurs most commonly in cats.

Causes of type II diabetes mellitus:

Obesity causes insulin resistance, decreasing tissue sensitivity by up to half! Reduced physical activity coupled with high energy foods has led to more obese cats. Other predisposing factors for insulin resistance include disease, drugs, genetic factors, the male gender and age over 8 years. Excessive blood glucose further increases insulin resistance.

Signs of type II diabetes mellitus:

The most common clinical signs are excessive drinking, urination and hunger. These clinical signs become apparent when the ability for the kidneys to reabsorb glucose is exceeded, and glucose is excreted in the urine. Glucose acts as a diuretic, drawing water out and leading to excessive drinking and urination. Dehydration can occur if the cat is unable to replace this water. Excessive hunger results from the inability of glucose to reach the satiety centre in the brain, meaning animals feel constantly hungry.


Cats should be taken to their nearest veterinary clinic if any of these clinical signs are present. Diagnosis is usually made on clinical signs, along with a persistent elevated glucose level and glucose in the urine. A urinary tract infection may be revealed through urine analysis, due to the diuretic effect of glucose in the urine which makes conditions in the urinary tract suited to bacterial proliferation. Subclinical diabetes, with an abnormally elevated glucose level but no clinical signs is often diagnosed incidentally when performing routine blood tests.

Treatment and management of type II diabetes mellitus:

Early intervention and treatment is vital as this decreases the damage and makes the return to normal glucose levels more achievable. Short-acting insulin is most commonly used in hospital for initial intensive blood glucose stabilisation following diagnosis. Long acting insulin is preferred for home use. Obese animals will need to be placed on a complete and balanced diet that achieves weight loss and ideal body condition. High fibre or high protein and low carbohydrate diets are preferred, upon recommendation from your Veterinarian. Animals should have their water intake monitored constantly for early signs of uncontrolled diabetes mellitus, and blood glucose levels should be checked regularly.

Article from Bayer Animal Health 

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