Diabetes in Birds

My very first pet cockatiel, a lutino female named Buzzy was a diabetic, so I hope I have more insight that I can share with you, being both an avian vet and an owner of a diabetic bird. Diabetes mellitus is a disease involving the pancreas. To understand treatment, we must first have at least a rudimentary understanding of diabetes and the hormones produced by the pancreas. So, let's start there.

With mammals, diabetes mellitus is caused by the pancreas no longer producing enough insulin, a hormone involved with sugar metabolism and regulation. This is called Type 1 (or juvenile) diabetes. In mammals, Type 2 diabetes occurs when the body no longer responds correctly to insulin. There are two different pancreatic hormones that are involved with blood glucose metabolism. The other hormone is called glucagon. Insulin forces many different body cells to absorb and use glucose, thereby decreasing blood sugar levels. Glucagon assists in keeping blood sugar in the normal range, and its action is opposite that of insulin. Glucagon forces many different body cells to release (or produce) glucose, with the end result of increasing blood sugar levels.

There are also three other hormones produced by the endocrine pancreas. All of these hormones are released directly into the bloodstream. The pancreas also produces enzymes that are involved with digestion. These are not involved with diabetes mellitus.

Many people have some knowledge about diabetes mellitus. There is also another disease called diabetes insipidus, and that is a completely different disease. So, for the rest of this article, I will be referring to diabetes mellitus only when I use the term diabetes.

Type 1 diabetes is also called juvenile diabetes, and with this form, the pancreas malfunctions and not enough insulin is produced. Injections of insulin are usually required for this form, and the diet must be strictly regulated to control carbohydrate intake. Type 2 diabetes usually occurs in overweight adults, and is often called adult onset diabetes. With this form, either the body does not produce enough insulin, or the body becomes resistant to insulin. In both forms, the blood glucose level rises, often to dangerous levels, and the body is not able to adequately utilize glucose for many necessary body functions.

Now, let's talk about psittacine birds. Most parrots with diabetes also have elevated blood glucose levels, BUT the cause is different. While in mammals, diabetes is caused by problems with not enough insulin, but, with avian species, the problem is that too much glucagon is produced. Glucagon overproduction will cause the blood sugar level to rise, just as when insulin is not properly utilized, which also results in high blood sugar levels. So, the end result in both cases is high blood sugar levels. I have often thought that we should come up with another name for psittacine diabetes, since the cause is so different, even though the result is the same. Raptors are the only species of birds that appear to develop diabetes as a result of insulin problems and not glucagon.

Glucagon stimulates the liver to produce and release glucose into the bloodstream by stimulating hepatic glycogenolysis. Glucagon is usually secreted when the glucose levels drop in the bloodstream. For some reason, with avian diabetes, glucagon production increases, and overwhelms the results of insulin, and this causes elevated blood glucose. Got it? It is confusing, isn't it?

The symptoms of avian diabetes are similar to those found in other species. High blood sugar levels cause sugar to spill over into the urine. Urinalysis will show elevated sugar levels in the urine. Birds with diabetes often drink excessive amounts of water, and will also urinate excessively. Increased urine in the droppings must be differentiated from diarrhea, which is an increased volume of fluid in the feces. Some birds with diabetes may start out overweight, but many will become thin from not properly utilizing glucose. Animals with diabetes are more susceptible to infections.

It must be remembered that an elevated blood sugar level, called hyperglycemia, is just a symptom, and NOT a disease in itself. There can be many causes of hyperglycemia in birds. Stress can cause this. Corticosteroids can also elevate blood glucose levels, either when produced by the adrenal glands of the bird, or if administered orally, topically or injectably. Some vets who are not that familiar with avian medicine may use a topical cream or ointment containing a steroid, usually for feather picking, which can end up mimicking the signs of diabetes. Certain liver diseases and infectious diseases can also cause hyperglycemia and the signs of diabetes.

How do we diagnose diabetes in our avian patients then? If the blood glucose levels are persistently elevated above 500-600 mg/dl, this can indicate diabetes. Blood glucose levels may range from 600-2000 mg/dl, and a definitive diagnosis of diabetes can usually be made if the blood glucose level is persistently above 800 mg/dl. A thorough physical examination, complete blood count and plasma chemistry panel should be performed, including a urinalysis. Normal avian urine can contain a trace to moderate amounts of glucose. Unfortunately, there is not an easy way to test a bird for elevated levels of glucagon. There is a way to test insulin levels, but since this seems to be a problem with the overproduction of glucagon, this would not be helpful. So blood glucose levels, along with the bird's history, clinical signs and other test results are all used in diagnosing diabetes in birds.

Most people recognize that the classic treatment for Type 1 diabetes in humans involves injectable insulin. For Type 2 diabetes, injections of insulin may not be necessary, and instead oral medications may be used to help control blood sugar levels.

In all cases, it is very important that the diabetic patient consumes a low carbohydrate diet. Many carbohydrates break down into simple sugars during digestion, so carbohydrate metabolism is definitely involved in attempting to control diabetes in avian patients. It is also important to offer a diet low in sugar-containing foods. Some carbohydrates are necessary for life, so they should not be eliminated completely from the diet. It is also important that the amount of daily activity and exercise for a diabetic bird be regulated, in order to best maintain blood sugar levels within normal limits.

Injectable insulin used for humans often results in variable uptake, utilization and breakdown by avian patients. For some reason, birds tend to quickly eliminate insulin from their systems. Dosing is highly variable and some birds quickly develop insulin resistance. With diabetic birds, the goal of treatment is to provide enough insulin to overwhelm the overproduction of glucagon in the system, unlike normal Type 1 diabetes, where the goal is to provide enough insulin to bring the blood glucose levels back down to normal. But, the result is the same. Normalizing blood glucose levels is the goal. Unfortunately, injectable insulin has proved to be less than satisfactory in controlling blood glucose levels in avian patients. Even long-acting injectable insulin will usually only provide a few hours of normal glucose utilization by the tissues.

Because of the problems with injectable insulin, alternative therapies have been attempted. The medication that you mentioned, glipizide, has proved to be a more effective treatment for diabetes in birds than injectable insulin, in many cases. This medication is given orally, which is easier for some owners who might be afraid of needles. The dosage is either given once a day or twice a day, depending on what it takes to control the blood glucose levels.

A serious problem can occur with treatment of diabetes. If for some reason, the blood glucose level drops too low, this can result in seizures, coma or death. Low blood sugar, or hypoglycemia, can be dangerous or life-threatening. For this reason, the owner of a diabetic bird must always keep corn syrup, sugar-water or other simple-sugar containing liquids on hand, in case of a hypoglycemic crisis. While hyperglycemia is detrimental to the health of an animal, it cannot cause a life-threatening immediate situation, but hypoglycemia can. Low blood sugar can cause shaking, pale, cool skin, anxiety or may even progress to hypoglycemic seizures and death. At the first sign of hypoglycemia, something containing simple sugars should be administered (but not chocolate or caffeine containing products).

While in humans, we strive for very tight control of blood sugar levels, this is just not practical or possible in psittacine patients. So, we hope to keep the blood sugar within the normal range as best we can. This may require significant testing to establish a correct dosage of medication. Owners must realize the commitment necessary to care for a diabetic bird. One way to monitor the patient at home is by using urine dipsticks for sugar. We try to keep birds with a trace amount of sugar in the urine on a daily basis. But, the diabetic patient will need to be seen and evaluated by their avian vet periodically.

Since there is no cure for diabetes, treatment will most likely continue for the life of the bird. There have, however, been a few cases of hyperglycemia spontaneously disappearing, with a normal return to pancreatic function, but I wouldn't count on that occurring. Maybe those weren't true cases of diabetes.

Cadeusus
Copyright 2006 Margaret A. Wissman, D.V.M., D.A.B.V.P.
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