[Pathogenesis of diabetes in adulthood. II. The nature of the insulin secretory defect].
Insulin secretion was studied during three successive stimulations: with tolbutamid, with tolbutamid +0.25 g glucose/kg body weight and with tolbutamid +0.50 g glucose/kg body weight in 30 patients with diabetes mellitus at a mature age, subdivided into two groups (SUP-sensitive and SUP-resistant). The rate of insulin secretion was found, in the first 10 minutes (early insulin secretion) to depend only on tolbutamid, remaining constant with blood sugar level fluctuations from 90 to 254 mg%. Later, insulinemia was higher in the test with combined loading, being most manifested with the most massive glucose loading. Similar correlation was not observed in the group of SUP resistant patients with diabetes. The results provide grounds to conclude that in SUP-sensitive diabetes, the ability of B-cells to synthesize and secrete insulin is being preserved but the sensitivity of glucose receptor versus the signal glucose information was declined. At the same time, the signal sensitivity versus other stimulations of insulin secretion, tolbutamid in this case, was still preserved. In this way, one of the possible pathogenic mechanisms of diabetes development at a mature age is elucidated.