Geriatric Medicine: diabetes mellitus


Diabetes mellitus (diabetes) is a disease that occurs most often in cats older than seven. It develops when an absolute or relative deficiency of the pancreatic hormone insulin occurs, interfering with the normal transport and utilization of glucose (blood sugar).

Diabetes mellitus in cats is identical to the disease that occurs in people and in dogs, sometimes called “sugar diabetes.” Signs of diabetes mellitus include increased drinking and urination and increased appetite. As the disease progresses weight loss occurs despite the increased appetite. Eventually, lethargy, vomiting, diarrhea, rapid respiration, weakness, and complete collapse will occur in untreated cats.

A veterinarian can confirm the diagnosis of diabetes mellitus by a combination of blood and urine glucose tests.


Treatment includes controlled feeding of special reduced calorie or high fiber diets and the administration of insulin. Oral drugs used to lower blood sugar in humans are occasionally used in treatment of cats.

Traditionally insulin has been given by injection, but other methods of administration such as implantable insulin pumps or permeable insulin administration units may be available when the cost is not prohibitive. Veterinarians train owners of cats who require ongoing insulin administration to control blood sugar levels to give the injections at home.


Diabetes has been shown to be more prevalent in obese cats and in neutered male cats (who are often allowed to become obese). It is also more prevalent in cats who have been given certain drugs such as adrenocorticosteroids or progesterone-like drugs that are sometimes used to treat certain behavioral problems or skin diseases.

Cats weighing more than 15 pounds (6.8 kg) are twice as likely to become diabetic than those weighing less, and many diabetic cats blood sugar levels return to normal when they are treated with diet restriction and weight reduction alone. Help prevent diabetes in your older cat by avoiding unnecessary drug administration and by maintaining a normal weight. (For information on weight reduction.)