Peripheral plasma somatostatin-like immunoreactive responses to insulin hypoglycemia and a mixed meal in healthy subjects and in noninsulin-dependent maturity-onset diabetics.

We have measured peripheral plasma immunoreactive somatostatin (SRIF-LI) in 10 healthy subjects and 10 noninsulin-dependent maturity-onset diabetics (NIDDM). The mean (+/-SE) basal level of SRIF-LI in NIDDMs of 185 +/- 27 was similar to that of 174 +/- 23.5 pg/ml in age-, weight-, and sex-matched healthy subjects. Insulin hypoglycemia of equivalent magnitude induced a 113 +/- 15.8 pg/ml increase in SRIF-LI 40 min after injection in healthy subjects and no significant change in the NIDDMs. Ingestion of a mixed meal induced a biphasic rise with a mean peak of 75 +/- 30 pg/ml above basal at 15 min and a later peak of 130 +/- 35 pg/ml above basal at 120 min in healthy subjects. In NIDDM, there was no significant rise above basal, and the differences were significant at 15 and 120 min. Our findings are compatible with deficient SRIF release in these NIDDM in whom the deficient SRIF secretion may contribute to the hyperglycemia.