Nutrition and the diabetic pet


Help clients offer their diabetic pets better veterinary nutrition to improve their health.

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.

Diabetes mellitus is caused by insufficient insulin production or by the failure of the body's cells to respond to insulin. Insulin is a hormone produced by the beta cells in the pancreas. Glucose from food is absorbed into the bloodstream and carried to all the cells in the body. Insulin is responsible for moving glucose across cell membranes for use by insulin-dependent tissues (e.g., skeletal muscle, cardiac muscle, brain).

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.

Clinical signs

Among the first clinical signs of diabetes mellitus that an animal may exhibit at home are polyuria, polydipsia, and weight loss, despite a voracious appetite. As the disease progresses, owners may report decreased appetite, lethargy, weakness, vomiting, sweet or chemical-smelling breath, sudden blindness caused by cataracts (in dogs), seizure, coma, or death.


Nutrition is an important part of managing a diabetic patient. Proper nutrition, along with medical management, plays a role in maintaining glucose concentrations within an acceptable range.

The goals of nutritional management in diabetic patients are:

1. Provide proper balance of nutrition and maintain adequate caloric intake.

2. Minimize the risk of potential complications of diabetes.

3. Help reduce or eliminate the clinical signs of diabetes.

4. Maintain healthy body weight, body condition score (BCS), and muscle condition score (MCS).

Choosing a diet for a diabetic patient largely depends on the individual. The patient's current body weight and concurrent health concerns are important factors. A diabetic animal may present with a BCS indicating excessive weight or obesity, or it may be at a lean or healthy weight.

A complete nutritional assessment of the animal's diet should be performed. This includes obtaining a complete diet history and assigning a BCS and an MCS. If the current diet is not appropriate for the diabetic patient, then a different diet may be recommended. Sending patients home with samples of selected diets is a good way to determine what they will eat in the comfort of their own homes. The hospital setting is usually not the best environment to initiate a diet change.

What to feed

When it comes to nutritional support of a diabetic patient, there are several common approaches, which aim to correct obesity, maintain consistent timing and caloric content of meals, and minimize postprandial increases in blood glucose. Fiber-enriched diets are often used. Certain types of fiber slow the digestion and absorption of carbohydrates, reducing peaks in blood sugar after meals. In people, soluble fibers are often recommended. This type of fiber forms a gel on the surface of the intestine, which impairs glucose and water transfer to the blood, slowing glucose absorption.

On the other hand, a study completed in 2000 at the University of Pennsylvania concluded that consuming a diet containing increased amounts of insoluble fiber (less viscous) improved glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus.1 Therefore, the amount and exact type of fiber that should be used to improve glycemic control is currently unknown, and further clinical trials are needed to give more specific recommendations.

High-protein, low-carbohydrate diets are being used successfully to manage diabetic cats. Cats, being obligate carnivores, are designed for diets high in protein and fat.

Consistency of nutrients is critical to diabetes management. The type and quality of protein, fat, and carbohydrate as well as total caloric intake must be maintained from day to day to achieve good glycemic control. It is important to choose a manufacturer that uses fixed food formulations, ensuring that the nutrient profile remains consistent from batch to batch. Some pet food manufacturers will change ingredients based on availability and cost.

For these reasons, home-cooked diets are discouraged for use in diabetics, as it is often difficult to maintain nutrient consistency.

And while the goals of diet in treating diabetic patients include achieving an optimal body condition, maintaining feeding consistency, and providing a diet that minimizes spikes in blood glucose, it is important to also consider the specific ingredients. Some sources of carbohydrates are better for glycemic control than others. Look for diets using carbohydrates with a lower glycemic index (e.g., sorghum, barley, or oats, as opposed to white rice).

Semi-moist foods are not an optimal choice for diabetic patients. The higher levels of simple sugars in semi-moist diets cause postprandial spikes in blood glucose concentrations. This is because they require minimal digestion and are absorbed rapidly into the bloodstream.

Feeding methods

Choosing a consistent feeding method for a diabetic patient is extremely important. Insulin is usually administered with food to help control blood glucose concentrations. Twice-daily feedings work well for most diabetic dogs. By allowing nutrients to be absorbed slowly, when insulin levels are adequate, postprandial fluctuations in blood glucose concentrations can be avoided.

Dogs are easily transitioned to twice-a-day feedings. Cats, especially those accustomed to free feeding, may take some time to adapt to a new routine. To begin this transition, offer food for one hour and then remove it. The animal will soon realize that if it doesn't finish that meal when it is offered, it will no longer be available. Cats are very resistant to change, but if this transition is done slowly over the course of several weeks, they should adjust to their new feeding routine.

High-fiber diets, as discussed earlier, work well for many diabetic patients. These diets are usually low-calorie weight loss diets and should not be considered for those patients that are already in a negative energy balance. An animal with a history of weight loss and decreased appetite would have difficulty meeting its daily energy requirements with a low-calorie food.

High-protein, high-fat, and low-carbohydrate foods have also been used successfully to control diabetes in patients, especially cats. The dry versions of these foods are extremely palatable and high in calories. However, the decreased amount of food that the animal is allowed to consume per day may not be acceptable to an animal—or an owner. One way around this is finding an appropriate commercial canned diet designed for managing diabetics and for weight loss. The addition of water to these foods often means that higher volumes may be fed without increasing the caloric intake.

A few pointers to keep in mind when it comes to feeding and insulin administration:

  • Administer the exogenous insulin along with half of the pet's caloric requirements in the morning, and the other half later in the day.

  • Coordinate the feeding and insulin administration to minimize postprandial hyperglycemia and maximize food usage.

  • Feed animals with poor glycemic control more frequent meals throughout the day.

  • Be as consistent as possible once glycemic control is achieved. Insulin administration and meals should be given at the same time every day.

  • Discourage pet owners from offering between-meal treats.


There is no ideal diet for diabetic patients. You may need to try several to see what is most palatable and works best for each patient. The most important nutritional considerations remain nutrient consistency and a diet that the animal will eat reliably day after day.

Charlotte Higgins, AS, CVT, is a nurse practitioner in nutrition at the MJ Ryan Veterinary Hospital of the University of Pennsylvania in Philadelphia. She's also a charter member of the Academy of Veterinary Nutrition Technicians.


1. Kimmel SE, Michel KE, Hess RS, et al. Effects of insoluble and soluble dietary fiber on glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus. J Am Vet Med Assoc 2000;216(7):1076-1081.

Related Videos
dvm360 Live! with Dr. Adam Christman
dvm360 Live! with Dr. Adam Christman
dvm360 Live! with Dr. Adam Christman
dvm360 Live! with Dr. Adam Christman
dvm360 Live! with Dr. Adam Christman
dvm360 Live! with Dr. Adam Christman
© 2023 MJH Life Sciences

All rights reserved.