Exogenous Somatostatin Raises Plasma Insulin Levels in Patients with Insulin-Dependent Diabetes Mellitus

Summary The effect of cyclic somatostatin on circulating insulin levels was studied in eight patients with insulin-dependent diabetes mellitus (IDDM). The study was performed after an overnight fast when their subcutaneous depots of insulin had been depleted during i. v. insulin substitution for 18 hours. A constant rate i. v. insulin infusion (0.4 mU/kg/min) was given for 240 min and somatostatin was co-infused between 60-120 min (100 μg/h) and 180-240 min (250 μg/h) respectively. Plasma insulin, blood glucose and hematocrit were measured at 15 min intervals. Hematocrit fell from 41.7 to 38.3% during the study period. Somatostatin increased the plasma insulin levels, corrected for the changes of hematocrit, by approximately 8% in the low dose (P < 0.05) as well as in the high dose (P < 0.05) period. It is concluded that somatostatin interferes with the clearance of insulin thereby increasing the circulating plasma insulin levels in IDDM patients without residual insulin secretion.