Insulin overdose causing low blood sugar in dogs and cats

Abstract

OBJECTIVE: To characterize the frequency, medical history, clinical signs, methods of treatment, and outcome of insulin-induced hypoglycemia and to identify predisposing factors. DESIGN: Retrospective study. ANIMALS: 8 dogs and 20 cats with diabetes mellitus that developed hypoglycemia because of insulin overdose. PROCEDURE: Medical records of dogs and cats receiving insulin for treatment of diabetes mellitus were reviewed. Medical records of dogs and cats that had an episode of hypoglycemia were reviewed in detail. RESULTS: Overdosing of insulin was more common in cats than in dogs. Median weight of diabetic cats that became hypoglycemic was significantly greater than that of the hospital population of diabetic cats at diagnosis. Eighty percent of cats that became hypoglycemic were receiving insulin doses > 6 U/injection, administered once or twice daily. Dose and type of insulin did not correlate with duration or severity of hypoglycemia. In 7 of 8 dogs and 10 of 20 cats, management factors or concurrent medical problems were considered to be predisposing causes for insulin overdose. Two dogs and 2 cats did not have clinical signs of hypoglycemia, despite documented low concentrations of glucose in their blood. CLINICAL IMPLICATIONS: Diabetic cats, especially if obese, are at greater risk of insulin overdose than are diabetic dogs. The reason for overdose may not be evident. Diabetic dogs and cats may become hypoglycemic without developing autonomic warning signs of hypoglycemia, or these signs may not be recognized (hypoglycemia unawareness).