INSULIN RESISTANCE IN 3 DOGS WITH HYPOTHYROIDISM AND DIABETES-MELLITUS

Insulin resistance resolved in 3 dogs with hypothyroidism and diabetes mellitus after treatment with sodium levothyroxine. A thorough diagno stic evaluation failed to identify any other cause of insulin resistan ce in these dogs. Hypothyroidism was diagnosed in each dog on the basi s of clinical signs, physical findings, hyperlipidemia, and results of thyrotropin or thyrotropin-releasing hormone stimulation test. Hypogl ycemia was documented in each dog within 2 weeks of starting sodium le vothyroxine administration. The insulin dosage was decreased by 60 to 62% during the ensuing months and good glycemic control was obtained a t these lower insulin dosages in all dogs. These findings would sugges t hypothyroidism-induced insulin resistance in these dogs.