Diabetes: Diagnosis and Treatment

Diabetes is a chronic endocrine disorder that can occur in dogs and cats. It is characterized by high blood sugar (hyperglycemia), increased appetite with or without weight loss, increased thirst and increased urination. These signs occur when the pancreas is unable to produce enough insulin to meet the animal’s requirements.

Insulin is a hormone which is needed to transport glucose (blood sugar) as well as certain amino acids and minerals through the blood to energy producing cells. When there is a lack of insulin, glucose cannot move into the cells, and the glucose level in the blood rises to abnormally high levels. This rise in blood sugar causes increased thirst and increased urination. The increased appetite with weight loss is due to the lack of energy getting into the cells.

Other Signs of Diabetes

Symptoms of a bacterial urinary tract infection may or may not be present and are dependent on which part or parts of the urinary system are infected. The urinary bladder is most often infected, in which case one often observes signs of urgency and frequent urination (pollakiuria). Other symptoms may include blood in urine (hematuria), straining to urinate (stranguria), foul-smelling urine, urination in inappropriate places, inability to hold urine, and urinating small volumes or not passing any urine while posturing to urinate.


Diabetes in dogs and cats is caused by damage to the pancreas. Predisposing factors include chronic pancreatitis, obesity (greater than 15% over ideal body weight), genetic predisposition, poor quality diet, hormonal abnormalities, stress and certain drugs.

The sex of the animal can also be a predisposing factor. In dogs, females are affected twice as often as males whereas in cats diabetes is seen more often in males.


Your veterinarian will perform a thorough physical examination of your pet and ask you questions about your pet’s health history. Your pet’s diet history is also very important.

Blood work and urinalysis need to be done to confirm the presence of diabetes. Depending on the condition of your pet at this initial exam, hospitalization may be necessary to allow for correction of any metabolic problems and stabilization of the diabetes.

Diabetes is often complicated by urinary tract infections, other hormone disorders (Cushing’s disease, hyperthyroidism), infections, or a build-up of chemical compounds called ketones in the body.


Treatment requires a commitment of time and management from you, the owner. There is no cure for diabetes, but, as with humans, it can be controlled with insulin injections, diet and exercise. With such therapies, your pet can lead a happy, comfortable and prolonged life.

All dogs with diabetes are insulin–dependent and thereby require daily insulin injections. Although most cats are also insulin-dependent, some cats are non-insulin dependent, and their disease can be controlled by diet, weight loss (if obese) and oral hypoglycemic medications. Some cats with diabetes may lose their requirement for insulin for reasons that are not completely understood.

Upon diagnosis of diabetes mellitus, specific insulin requirements will need to be determined. Frequent phone contact may be required in order to mutually assess proper response to insulin therapy. Your pet’s insulin needs may change once going home because of diet changes, exercise levels and changes in environmental stresses. Therefore, periodic reevaluation of blood work is required until satisfactory control is achieved. Once reasonable diabetic control is achieved, evaluations should be done every three to six months.

If, at some point, there is a need to change the brand of insulin, treatment must start over as though insulin had never been given.

Home Care

Typically two daily injections of insulin will be required for the rest of your pet’s life. Though with some cats, once the blood sugar has been lowered, the dose of insulin may be reduced or eliminated. However, cats may become insulin-dependent again later in life.

Oral medication may be effective for some diabetic cats. It is also important that the injections are given at the same times each day, usually every 12 hours. In sporadic occasions if the 12-hour time frame cannot be met, insulin may be given 10-14 hours apart. The injection is given just under the skin (subcutaneous) and is not painful to your pet. Insulin should be given behind the region of the shoulder blades, along the back, changing the site of administration at each administration. 

The Insulin Dose

The type of insulin and the daily dose are tailored to meet the needs of each animal. Other medications may be prescribed, depending on any concurrent illnesses.

Your veterinarian will determine the initial dose of insulin while your pet is in the hospital. This dose will likely need adjustment once your pet has been home for 7-14 days because your pet’s food and exercise at home are different. Your veterinarian will continue to monitor your pet with blood testing to regulate insulin dose changes.

Handling Insulin and Insulin Syringes

The insulin needs to be kept cool and out of light; most people prefer to keep it in the refrigerator. The bottle should be mixed by rolling or swirling before withdrawal of the insulin into the syringe. The bottle should never be shaken to mix the insulin.

The syringe and needle should be stored in protective wrappers to keep them sterile. Syringes and needles have four parts consisting of the syringe barrel, the plunger, the needle and the needle guard.

Various syringes are available for injecting insulin. Ultralow dose (1/3 cc) insulin syringes are preferred because they are designed for ease in measuring small amounts of insulin.

These syringes and needles are disposable or “single use” only. They should not be reused!

After injecting your pet with insulin, place the needle and the needle guard in a suitable disposal container. DO NOT recap the needle, you could inadvertently stick the needle into your hand or finger. A convenient disposal container for insulin syringes is a plastic milk jug that has been rinsed out well and can be recapped between uses. For their safety, it is extremely important that children not have access to the syringes and needles.

Drawing Up the Insulin

Set out the syringe and needle, insulin bottle and have your pet ready.

  1. Remove the needle guard from the needle; draw back the plunger to the desired dose level.
  2. Insert the needle into the insulin bottle.
  3. Inject the air in the syringe into the bottle to prevent a vacuum from forming in the insulin bottle.
  4. Pull back on the plunger, filling the syringe with insulin to the correct level.

Before withdrawing the needle from the bottle check to see that there are no air bubbles in the syringe. If you see an air bubble, draw up slightly more insulin into the syringe and gently tap the barrel with your finger to move the air bubble to the nozzle of the syringe, then gently expel the bubble by pushing the plunger upwards towards the bottle.

Now check to see that you have the correct amount of insulin in the syringe. The correct dose of insulin is measured from the needle end, or “0” on the syringe barrel, to the end of the plunger closest to the needle.

How to Give an Injection
  1. Hold the syringe in your right hand (or your left, if left-handed). There are many ways to hold the syringe. With time you will
  2. develop the one easiest for you. You may find it helpful to begin practicing with a syringe filled with water and injecting it into an orange.
  3. Have a friend or member of your family hold your pet as you pick up a fold of skin along the back with your free hand. Be sure to pick a different spot for each injection. Insulin injections should not be given between the shoulder blades because insulin absorption is erratic or unpredictable in this area.
  4. Push the very sharp, very thin needle through the animal’s skin quickly. This should be easy and painless using the insulin needle. Take care to push the needle through only one fold of the skin, not into your finger, your pet’s underlying muscle or through both layers of skin.
  5. Pull back gently on the plunger (aspirate) to make sure that no blood fills the syringe. If this happens, remove the syringe from this site, and proceed in another location. You may have just hit a skin blood vessel.
  6. With your thumb on the plunger, push the plunger further into the syringe until it will not go in any farther.
  7. Withdraw the needle from the pet’s skin and immediately dispose of the syringe and needle guard.
  8. Pat your pet to reward it for sitting quietly for the injection.

“Sterilizing” the skin with alcohol is not necessary and may be counterproductive if it stings and causes your pet to avoid the injections.

Dietary Restrictions

When you feed your pet is as important as what you feed your pet. Your pet must be fed the recommended diet in the correct quantity at a regular time each day in conjunction with the insulin injection.

Correct dietary management is a critical part of the successful management of the diabetic animal. As a general rule of thumb, the diabetic animal should be fed two to three times daily. Ensure that your pet is eating well before giving each insulin injection.

If the insulin is given first and the animal refuses to eat, this could lead to hypoglycemia. Cats that are fed free-choice (i.e., food available all time) require no changes in their lifestyle as long as you are certain that they are eating normally.

What to Feed

Table scraps, treats or any other foods not approved by your veterinarian should not be allowed. Do not allow access to the food of other pets in the house if your diabetic pet requires a special diet.

It is important that the food your pet eats is constant with respect to ingredient content and nutrient source. Diabetic control is difficult to obtain if the composition of the food varies. Many commercial pet foods, especially grocery store brands, are produced from “open” formulas, and ingredients can vary from batch to batch depending on the ingredients’ cost and availability.

The semi-moist diets and treats such as Tender Vittles® and Gaines Burger® should not be fed at any time. These foods have a sugar coating to preserve their freshness and greatly complicate diabetic control.

Studies have indicated that dogs fed low fat fixed formula diets with moderately fermentable fiber, soluble non-digestible fiber (carboxymethylcellulose), and complex carbohydrates have lower insulin requirements and slower absorption of sugars following each meal.

These types of foods delay the emptying of food from the stomach and slow the release of the glucose from food within the digestive tract into the blood stream. This results in a less abrupt rise in blood sugar following a meal. High protein diets are recommended in feline patients with diabetes mellitus.

The amount of food to be fed daily will be determined by your pet’s caloric requirements. This amount should NOT be varied, as it will have a direct impact on insulin needs.

If your pet is overweight, weight reduction is essential. Obesity decreases the body’s tissue responsiveness to insulin (both natural and injected) and can cause dangerous increases in blood sugar levels. Follow the diet program laid out by your veterinarian or veterinary technician. Changes in weight will affect the insulin dose that is required.


There are no restrictions on your pet’s normal activity. However, it is important that your pet’s exercise be moderately regulated and consistent in order to keep the insulin needs as consistent as possible. Dogs undergoing periods of extreme activity (i.e., hunting dogs, herding dogs) will require a slightly lower dose of insulin during periods of extreme activity.

Home Glucose Monitoring

We do not find it is ordinarily essential to monitor your pet’s blood or urine glucose levels at home. Any changes in insulin dosage will be done by your veterinarian after blood work has been done in the hospital. Insulin dosage does not need to be adjusted with each injection, and, in fact, should remain unchanged.

Blood Monitoring

We have found that the most effective way to monitor diabetic control is through the use of two blood tests. These are serum fructosamine and serum glucose tests.

Both of these should be done together at your veterinarian’s office and will need to be sent out to a laboratory for evaluation. There is no requirement for fasting or to stop insulin injections prior to the tests.

The doctor will use these tests to monitor your pet’s response to the insulin that you are giving at home. An elevated serum fructosamine shows that your pet has elevated blood glucose over a longer period than desired throughout the day, and suggests that the dose or type of insulin may need to be changed.

A low serum fructosamine indicates that too much insulin is being given and a dose adjustment is needed. If the serum fructosamine and serum glucose do not “agree” (i.e. one is low and one is high), than we need to evaluate the pet’s home care or any other problems that could affect diabetic control.

Things to Watch for at Home
Special Considerations

Although diabetes can be controlled with insulin and diet, diabetic animals are more susceptible to other health problems. Diabetes can cause an increased incidence of infections (especially bladder), slow wound healing, cataracts, gastrointestinal problems, pancreatitis and nervous system disorders.

An intact female diabetic should not be bred. Neutering is recommended, as it is extremely difficult to control diabetes during pregnancy, and it may cause life-threatening problems.


The cost for caring for a diabetic pet is an important consideration. Of course, the cost will vary somewhat depending on the size of your pet and any additional health problems that may occur. The cost of insulin, syringes and periodic blood work will need to be carefully planned.

Beyond the monetary cost, there is the time commitment required of owners of a diabetic pet. Such a commitment may not seem easy, but can be very rewarding for both the pet and the owner. Your commitment adds to the quality of your pet’s life and is paid back in years of companionship.