I get lots of questions about diabetes in dogs. Here’s a recent one.

My Miniature Schnauzer has diabetes, but he is 170s one week and then 330s the next. Any feedback on what is going on? We are giving him four units of insulin now, which was increased from three units.

Cheryl

Diabetes mellitus, commonly known simply as diabetes, is a disease of blood sugar regulation. Dogs with diabetes suffer from chronically high blood sugar, which can lead to increased thirst, increased urination, weight loss, immune system compromise, and a host of other issues. In dogs, diabetes usually occurs when the pancreas produces insufficient insulin. Diabetes therefore usually is treated with synthetic insulin. There are many types of insulin available for dogs.

Diabetes is a famously frustrating condition. Because every dog responds differently to insulin, an initial dose is calculated. The dog’s response is measured, and the dose is adjusted as necessary. Several rounds of adjustment can be necessary before stability (known as regulation) occurs.

But some dogs, such as Cheryl’s, are especially hard to regulate. Their blood sugars can vary significantly from day to day despite no changes in insulin protocols (a blood sugar of 170 is basically normal; 330 is unacceptably high). Several steps are recommended in such situations.

• Be regular in your administration of insulin. Confirm with your vet that your injection technique is good, and then administer it at exactly the same time every day. Improper insulin administration is a leading cause of difficulties in regulating diabetes.
• Check for a concurrent disease that might be interfering with insulin treatment. For instance, bladder infections are common among diabetics, and they also interfere with regulation of the disease. Schnauzers are prone to pancreatitis, and active pancreatitis also can interfere with regulation of diabetes. Similarly, infections or inflammation elsewhere in the body, and certain glandular problems such as Cushing’s disease, can also contribute to wild swings in blood sugar. Talk to your vet about blood and urine tests to screen for these issues.
• Follow an appropriate diet. Current recommendations focus on low-carbohydrate content, but high protein and high soluble-fiber levels also are purported to help. The most important thing is to be consistent. If you frequently switch your dog’s diet (or feed a variety of treats), it will be hard to regulate his blood sugar because his needs will change with his diet.
• Check the type of insulin and frequency of administration. You don’t mention what type of insulin you’re using or how often you’re giving it, but switching to a different type or frequency might help this problem. This should be done only under the very careful supervision of a veterinarian. Whenever insulin is switched, low blood sugar (a potentially fatal side effect of insulin) can occur.
• Consider a different type of blood sugar testing. If your dog’s blood sugar is being checked only once during the day, consider running full blood sugar curves on him instead. These curves involve checking blood sugar levels serially throughout the day, and they provide a more comprehensive assessment of the effects of insulin than do solitary measurements.

I’m sorry to say it, but in some dogs, all of these steps fail. That’s because in some dogs the pancreas produces insulin in an unpredictable fashion. Some days the pancreas produces more insulin, and thus the dog needs less to be administered. On others the dog produces less insulin, and thus needs more to be administered. These dogs are best managed through regular home glucose measurements prior to insulin administration, but these cases are complicated and, unless the owner is extremely well-informed, there is a very high potential for complications.