This disease occurs when the insulin-producing cells in the pancreas become impaired. Insulin is essential for glucose metabolism, promoting its absorption into muscle cells for energy and into the liver for storage. Reduction of insulin production can lead to increased levels of glucose in the blood. Cats younger than 6 years rarely develop diabetes mellitus which affects older males and females equally. There are many probable causes of diabetes mellitus in the cat. One common cause is long-term use of megestrol acetate, a progesterone drug sometimes used to treat cancer and allergies. Other risks of developing feline diabetes mellitus are being male, neutered, old, inactive, kept indoors, obese or treated with drugs such as corticosteroids.1
Affected cats may be overweight at the onset of the disease, but become emaciated as it progresses. The most common signs of diabetes mellitus are excessive thirst and urination, accompanied by an increased appetite and weight loss. Other signs include soreness and swelling of the gums and tongue and thinning of the coat. At an advanced stage of the disease, signs become more severe and include severe weakness of the hind legs (causing the cat walk with their hocks touching the ground), vomiting, even more severe weight loss, coma and death.
Diagnosis can be difficult. Although a cat with this condition has an abnormally high blood glucose level, many cats develop high blood glucose level when they are nervous or stressed. Even a routine visit to the veterinarian may bring this about. It may be necessary, therefore, to test not only the cat's blood several times, but also its urine before the diagnosis is made. Normal cat urine should not contain any glucose; it is found only when the blood glucose is at an abnormally high level.
Treatment varies with the severity of the diabetes, and how ill the cats is. Inevitably, this disease makes tremendous demands on the cat's owner. Schedules must be observed. A missed meal or delayed medication can have serious implications. Even in not-so-critical cases, once- or twice-daily injections of long-acting insulin may be prescribed. Many veterinarians also recommend a change in diet; often, cats will require less insulin if they are fed a high-fiber diet.
Food content must be checked carefully. Products with a high sugar content, semi-moist cat food, for example, should be avoided. Cats on insulin must also be monitored regularly to make sure they receive the proper dosage. To regulate this, many veterinarians recommend daily to weekly check of blood glucose. Once the dosage is regulated, the cat's blood glucose must be monitored every month or so. If the diabetes is well advanced and there is a risk the cat may die, the blood glucose may have to be monitored hourly.
Ordinarily, full recovery is possible, provided the disease is diagnose early, treatment is carried out consistently, and the cat is taken to the veterinarian for regular checkups.
- Prevalence and risk factors for the development of diabetes mellitus in Swedish cats. Marie Sallander et al.