Diabetes mellitus (DM) is a chronic condition in which a deficiency of the hormone insulin impairs the body's ability to metabolize sugar. It is one of the most common endocrine (hormonal) diseases of cats.

There are two types of diabetes mellitus. Type I DM occurs when the body does not produce enough insulin. This can be the result of destruction of the cells in the pancreas that normally produce insulin. This form is identified in approximately 50 to 70 % of cats diagnosed with diabetes mellitus. This form does not produce enough insulin and requires insulin injections to control the disease. Type II DM occurs when enough insulin is produced but something interferes with its ability to be utilized by the body. This form is identified in approximately 30% of cats with diabetes mellitus. This type of diabetes is treated with dietary management, weight control and oral drugs.

Approximately 20% of cats can be "transient" diabetics. This means that after diagnosis with diabetes mellitus, they can have total resolution of their diabetic state months to years after diagnosis. This does not happen in dogs.

DM usually affects middle-aged to older cats of either sex however it is most common in neutered male cats. The peak age seen in cats is 9 to 11 years. Juvenile-onset diabetes may occur in cats less than 1 year of age. Any breed can be affected.

DM leads to an inability of the tissue to utilize glucose. Disease occurs from high blood sugar levels, inadequate delivery of sugar to the tissues and changes in body metabolism.

Risk factors for diabetes mellitus include obesity, recurring pancreatitis, Cushing's disease, and drugs such as glucocorticoids and progestagens that antagonize insulin.

What to Watch For

Increased thirst

Increased frequency of urination

Weight loss despite a good appetite

Lethargy

Poor body condition/poor haircoat

Weakness – especially in rear legs and can be associated with plantigrade stance (where hocks are lower to the floor than normal)

Diagnosis

Veterinary care should include diagnostic tests to determine the underlying cause of the elevated blood sugar and help guide subsequent treatment recommendations. Some of these tests include:

Complete medical history and thorough physical examination

Analysis of the urine to check for glucose and for signs of urinary tract infection

A serum biochemical analysis to determine the blood glucose concentration and to exclude other potential causes of the same symptoms

A complete blood count (CBC).

Other tests such as abdominal X-rays or abdominal ultrasound if complications or concurrent diseases, such as pancreatitis (inflammation of the pancreas), are suspected.

Treatment

Many cats will eventually require one or two daily injections of insulin to control blood glucose. These injections are given under the skin using a small needle. Most cats become readily accustomed to the treatments. Your veterinarian's office will train you in the proper use of insulin and injection techniques.

Most oral hypoglycemic agents only work if the pancreas is still producing some insulin. These drugs can initially be used in cats but after time, the cat will likely need injectable insulin.

Proper weight management diet and regular exercise can aid in control of DM. The recommended diet for cats with diabetes is a high protein low carbohydrate diet.

Ovariohysterectomy (spaying) is indicated in female diabetic animals to reduce the effects of estrogen on diabetes and insulin.

Complications such as urinary tract infections may require additional medications, but certain drugs, including steroids (such as prednisone), should be avoided in diabetic cats.

Prepare for frequent adjustments to therapy early in the course of treatment. Veterinarians prefer to start with a low dose of insulin initially and adjust upwards slowly to avoid overdosing. Your veterinarian may recommend hospitalization to measure the blood glucose every few hours (mapping a 24-hour glucose curve).

Home Care and Prevention

At home care involves administering prescribed medications, including insulin, as recommended. If the insulin is prescribed twice daily, try to give it 12 hours apart and at the same time each day. You should also work with your veterinarian to develop a weight management and feeding plan. Stick to regular feeding times.

Feeding a special diet (such as Purina's DM or Hill's m/d diet) can significantly help some cats, even to the point that the cat may no longer need insulin injections.

Observe your cat's thirst and frequency of urination. If these remain increased, your veterinarian may need to adjust the insulin dosage.

Insulin overdose may cause low blood glucose, potentially resulting in disorientation, weakness or seizures (convulsions). If you notice any of these symptoms in an otherwise responsive cat, offer food immediately. If the cat is unconscious, Karo® syrup can be applied to the gums. In either case, call your veterinarian as soon as possible.

Familiarize yourself with insulin, insulin syringes, insulin storage, and insulin handling; your veterinarian or pharmacist can help.

While there is no way known to prevent type I DM, proper weight management can reduce the likelihood of developing type II DM.