What—and when—you feed pets makes a big difference to their well-being. This is especially true for pets with diabetes. Here, we examine the disease and how diet can make a difference in the pet's health.

The disease

Diabetes mellitus is one of the most frequently diagnosed endocrinopathies in dogs and cats. Older obese neutered male cats and middle-aged or older female dogs are disproportionately affected, although younger animals of either sex may also develop the disease. There may be a genetic predisposition, and the disease is diagnosed more frequently in certain dog breeds—miniature schnauzers, poodles, Samoyeds, keeshonds, and daschunds, to name a few.

The result of insufficient insulin or an inability to use insulin is that cells cannot use glucose as an energy source. Glucose concentrations build up in the blood (hyperglycemia) and are eventually excreted in the urine (glycosuria).

Left untreated, a serious, life-threatening condition called diabetic ketoacidosis can develop. The animal's body is essentially starving, and fats are metabolized for energy because sugar is unavailable. Ketones, a byproduct of the breakdown of fat, can build up in the body. One of the ketones that cats produce is acetone, a primary ingredient used in manufacturing nail polish and responsible for a distinctive smell often reported by cat owners. Signs of ketoacidosis include anorexia, depression, weakness, and vomiting. The animal is likely to be dehydrated and will develop electrolyte imbalances. Immediate insulin, fluid, and electrolyte therapy as well as close monitoring in a hospital are essential to the patient's recovery.

Patients are classified as having either Type I, insulin-dependent diabetes mellitus, or Type II, noninsulin-dependent diabetes mellitus. In Type I—the most common form of diabetes in dogs—the beta cells of the pancreas are unable to produce or secrete insulin. To achieve glycemic control, the animal must receive exogenous insulin. Type II diabetes occurs when there is a relative deficiency of insulin. The pancreatic beta cells are still able to produce insulin, but peripheral tissues are insensitive to its effects. Type II diabetes is seen more commonly in cats than in dogs and is often associated with obesity. Diabetes mellitus treatment in cats requires initial insulin therapy, along with dietary management and weight loss. Some cats are able to achieve remission of their diabetes signs and can discontinue insulin therapy.

Concurrent problems

Diagnosing and treating a diabetic patient can be complicated by concurrent conditions, such as obesity, chronic pancreatitis, amyloidosis (in cats; effectively clogs the pancreas with accumulated protein), or hyperadrenocorticism (Cushing's disease), which may lead to insulin resistance.

In Cushing's disease, the adrenal glands—the two small glands located near the kidneys—produce excess amounts of certain hormones, including cortisol. The signs of Cushing's disease are similar to those of diabetes—increased appetite, drinking, and urination as well as elevated blood glucose concentrations and the development of insulin resistance.

Pancreatitis can also result in hyperglycemia (elevated blood glucose concentrations), and diabetic pets are at higher risk for developing this condition. Changing to a low-fat, high-fiber diet may be especially helpful in these patients.

Diabetic patients may also be more susceptible to bacterial infections, including urinary, pulmonary, or skin infections.

Obesity has been identified as a risk factor for developing diabetes mellitus in cats. Although the same correlation has not been proven in dogs, it is undoubtedly more difficult to maintain overweight diabetic dogs' and cats' blood glucose concentrations within a healthy range. So, in addition to gaining good glycemic control with insulin therapy and dietary management, a comprehensive weight loss program should be instituted. Because cats develop noninsulin-dependent diabetes mellitus, some cats may achieve remission of their diabetes signs with weight loss. In some cases, the same high-fiber diet used to control diabetes can also be used as part of a safe weight loss program. Close monitoring by the veterinarian is required, because as the patient loses weight, its need for exogenous insulin will also decrease. If the insulin dose is not properly adjusted, the patient will become hypoglycemic. In some cases, failure to recognize this change in an animal's insulin requirements can result in death.