Regulating diabetes mellitus in dogs and cats


Brush up on your clinical skills with this disease overview.

Many pets have diabetes mellitus and their owners don't even know it. The good news is that with the right insulin, patience and diligence on the owner's part, and your help, this disease can be effectively managed. More on diagnosis can be found by reading "Diabetes mellitus: What is it and how is it diagnosed?".

Managing diabetes

Diabetes is generally managed rather than treated. The exception is cats that still have enough functioning pancreatic beta cells. For these cats, diabetic remission is likely with aggressive diet and exercise changes along with insulin therapy. Dietary recommendations for diabetic dogs include feeding a dry food high in insoluble fiber and sticking to two equal meals a day given at regular intervals, preferably every 12 hours. For cats, feeding four times a day at regular six-hour intervals is ideal. Diets high in protein and low in carbohydrates are essential to help diabetic cats regain glycemic control. Uncomplicated diabetes can be well-managed long-term with diet, exercise, and insulin injections administered at home by owners.

Insulin basics

Insulin products are categorized based on their duration of action. Three general types of insulin are administered to dogs and cats: short-acting (regular or crystalline), intermediate-acting (NPH and lente), and long-acting (PZI and glargine). PZI (dogs and cats) and glargine (cats) are longer acting but still require initial twice daily dosing. Glargine insulin is slowly released from the subcutaneous tissues, so blood glucose values may take several days to begin adjusting downward when using this insulin. Owners may be apprehensive about giving their pets insulin injections. Having the owner practice an injection using a pinch technique and some sterile saline solution while you observe is a good idea. Owners should rotate injection sites with each injection to avoid the possibility of scarring, which can impair the absorption of the insulin administered at that site. Insulin products are either 40 U insulin or 100 U insulin, and they must be used with the correct corresponding syringe. Insulin should be given just after a meal, generally after the first meal of the day and again after the last. Owners should have detailed instructions on what to do if their pet misses a meal or eats only half of it.

Insulin will have different effects and durations for every individual. This is due to many factors including response to the individual insulin product, underlying medical conditions, and improvements in insulin resistance. Insulin therapy must be tailored to the individual patient. Owners should expect to do some adjusting of the dose or to change products along the way, either because a patient becomes unresponsive to the insulin originally prescribed or because of a Food and Drug Administration recommendation if a product was improperly produced. With persistence of hyperglycemia, owners will see a continuation or worsening of the clinical signs of diabetes. Owners should be looking out for signs of low blood sugar such as hunger, weakness, or ataxia and even seizures.

Blood glucose curves

In order to regulate a diabetic patient, its blood glucose is generally monitored, and a blood glucose curve, sometimes called an insulin-glucose-response curve, is generated. At-home monitoring may be more effective than generating curves in the hospital. Since glycemic control is highly dependent on sticking to a normal feeding and exercise routine (which is hard to do in a hospital setting), curves generated at home can provide better information about the animal's daily blood glucose concentrations. Today there are handheld glucometers that are accurate, easy to use, and require a small amount of blood. To generate this curve, the owner will measure the blood glucose concentration every one to two hours for an eight-to-24-hour period. In-hospital curves are common, especially if owners think that they are unable to perform one at home or if the patient is difficult to get blood from. For in-hospital curves, drawing the blood from the ears or medial saphenous veins to spare the commonly used intravenous catheter sites in case of crisis is recommended. While monitoring the patient's blood glucose, offer the patient plenty of water and frequent walks. (Click here to download a patient admission form for blood glucose curves.)

Multiple curves are often necessary to best regulate the insulin dose. If the dose changes because the pet's needs change, subsequent glucose curves are usually generated to access the change and regulation. Blood glucose curves should be generated one week after initiation of insulin therapy or anytime there is a dose or insulin product change. Keep in mind that a patient that is newly diagnosed or unregulated will probably need a longer curve to better track its response to the insulin.

Periodically, it is also important to evaluate fructosamine concentrations. As mentioned earlier, a fructosamine concentration can give an indication of the average blood glucose concentration over the previous one to two weeks.

Client instruction

Pet owners are crucial to the process of managing diabetes, and you should empower them to be a part of their pet's care. Since owners will be administering insulin at home, it is important that you teach them how to do it correctly. A good way is to demonstrate how to administer subcutaneous injections and then have owners practice in the exam room using a syringe filled with water and a stuffed animal. Then, help them give an injection of sterile saline solution to their own pets so they leave knowing they can tackle this task. Remember, it is also important to have the pet leave confident, so be sure to handle the pet safely and give lots of positive reinforcement after the injection. By practicing in the clinic, you can give immediate answers to owners' questions and provide further instruction if they are doing it incorrectly.

During this lesson, make sure to show owners the different syringe sizes (40 U vs. 100 U) to prevent any mix-ups. Nothing is too basic: Talk about refrigeration, expiration dates, and why they should roll the insulin bottle instead of shaking it, as agitation can damage the insulin molecule, rendering the hormone inactive.

Again, let clients know that, over time, a pet's overall health or condition may change, requiring a change in the insulin type or dose. Periodic treatment adjustments and monitoring will keep pets healthy and prevent serious and often expensive complications (weight changes are especially important). For cats in remission or for well-controlled patients, urine glucose dipsticks may be useful to detect a loss of control or recurrence of diabetes if clients observe clinical signs. (However, the use of urine glucose dipsticks cannot replace periodic blood glucose monitoring.) If the blood glucose level on the urine dipstick is elevated, owners should call the clinic. Hyperglycemia is rarely an emergency, but it does need to be evaluated to adjust the dose or to look for underlying conditions such as Cushing's disease and urinary tract infections that may be affecting the animal's regulation. Hypoglycemia can be the real emergency.

Final thought

Although diabetes mellitus is fairly common in pets, in most patients, it usually isn't difficult to manage if there is good cooperation between the medical team and pet owner. Since a big issue with unregulated diabetic patients is frustration among pet owners, a large part of your job is thoroughly explaining the process of achieving regulation to them and teaching them how to provide good home care. Technicians make a real difference in how effectively a patient's diabetes is managed.

Robin Sereno, BS, CVT, VTS (SAIM), is the nursing coordinator and supervisor for the Small Animal Internal Medicine Service at the University of Wisconsin Veterinary Medical Teaching Hospital in Madison, Wis.

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