Diabetes mellitus is caused by an inherited or an acquired deficiency in insulin production by the pancreas, by the ineffectiveness of the insulin produced on target tissues, or by glucagon excess. A hallmark of Diabetes mellitus is hyperglycemia (high blood sugar) which is suspected when glucose levels exceed 350mg/dL and confirmed at over 500mg/dL or 800mg/dL. Diabetes mellitus can occur secondary to pancreatitis. Macaws, toucans, cockatiels, and budgerigars seem to be more susceptible, and it is more common in adults. Risk factors include female birds in reproductive phase or birds on an inappropriate diet.
Increased urination, increased drinking, increased appetite, weight loss, poor body condition. Lethargy and abnormal behavior have also been reported.
Hyperglycemia can be caused by stress and pain, corticosteroids, female reproductive activity/disease, obesity, inappropriate diet. Increased thirst and urination can occur from kidney disease and heavy metal poisoning but it may also be seen in healthy animals during breeding season, high water content foods, and a condition known as psychogenic polydipsia. Conditions with clinical signs similar to pancreatitis include bacterial infection (Chlamydia, Gram-negative), viral infection (paramyxovirus 3, herpesvirus, polyomavirus, adenovirus, poxvirus), inflammatory, hemosiderosis, amyloidosis, hypervitaminosis A, secondary to egg-yolk coelomitis, and cancer.
Patients where Diabetes mellitus is a concern should have a full workup with a complete blood count, blood chemistry panel, and blood gas analysis to check for diabetic ketoacidosis. A fructosamine test can be used to determine if the high blood sugar as been going on for awhile. Analysis of the urine may reveal glucose and ketones. A PCR for Chlamydia psittaci and avian polyomavirus should be performed as well as both can cause pancreatitis. Radiography may be recommended to rule out other causes.
Supportive care in the hospital is important for those patients with diabetic ketoacidosis or who are otherwise sick. This should include fluid therapy, heat support, and assist feeding. Insulin is the mainstay of treatment for Diabetes mellitus. Initial monitoring of blood sugar is extremely important. Insulin dose should be adjusted according to clinical signs and glucose curves. Oral Glipizide has also been used in birds. Diet should be changed to a low carbohydrate and low fat, high fiber diet.
Daily monitoring of clinical signs and body weight at home is important. Blood glucose curves should be done starting 1 week after insulin treatment started and then repeated every 2-3 months after well controlled.
Prognosis is highly dependent on how sick the patient is at the time of diagnosis with diabetic ketoacidosis carrying a guarded prognosis.
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