Improvement of glycemic control after a 3-5 day insulin infusion in type 2-diabetic patients with insulin resistance can be maintained with glitazone therapy.

INTRODUCTION

Insulin resistance is a common problem in obese patients with type 2 diabetes. In a prospective randomized study, we investigated the improvement of metabolic control after a 3-5 day period of intravenous insulin infusion in poorly insulin-treated, overweight type 2-diabetic patients with and without additional glitazone therapy.

METHODS

Twenty-eight overweight patients (BMI > 28) with poorly insulin-treated type 2 diabetes (HbA1c > 8%) requiring > 80 IU insulin/day received a continuous insulin infusion for 3-5 days (initially 4-6 IU insulin/hour). Thereafter, 14 of the patients also received pioglitazone (15 mg/day). The two groups were compared for HbA1c, mean blood glucose (MBG), body weight, cholesterol, triglycerides and insulin requirement (IU/day) three months before insulin infusion, during infusion, and at three and six months after the infusion.

RESULTS

Glycemic control was immediately improved under insulin infusion in both groups: MBG was reduced from 188 +/- 32 mg/dl at baseline to 142 +/- 28 mg/dl at the end of insulin infusion (p < 0.05). In the group receiving pioglitazone, the mean HbA1c three months after the insulin infusion was 16% lower and after six months 17% lower than baseline values (p < 0.02). Concomitantly, the required insulin dose decreased significantly by 15% after three months and 18% after six months (p < 0.02). Two patients (14%) were non-responders (< 10% reduction of required insulin dose). In the group without pioglitazone the mean HbA1c level three months after insulin infusion was 10% lower (p < 0.05) than at baseline; at six months the HbA1c value was the same as that before the infusion. The required insulin dose was 10% lower after three months and only 3% lower after six months (NS). Four patients (28%) were non-responders.

DISCUSSION

Short-term insulin infusion therapy is effective in improving metabolic control and, concomitantly, in reducing insulin requirement in poorly insulin-treated type 2-diabetic patients; however, these effects are mostly limited to three months. With additional glitazone treatment after the insulin infusion, the improvement in metabolic control and the reduced insulin requirement can be maintained for more than six months.