Insulin secretion in maturity-onset-diabetes. Function of isolated islets.

An impaired insulin response to glucose is a characteristic finding in maturity onset diabetes (MOD). To clarify whether the decreased insulin response in vivo is related to a primary defect of the beta-cells, isolated islets of MOD - obtained by intraoperative biopsy - were examined for their insulin content, biosynthesis and release. The in vitro experiments showed that despite a missing or significantly reduced insulin response in vivo the isolated beta-cells of the same patients had a normal insulin content, a normal or even high biosynthesis, and insulin release could be induced by glucose. These results suggest that the primary defect in MoD cannot be related to an intrinsic failure of the beta-cells to response to glucose; extrapancreatic factors seem to influence their reaction to glucose. These factors may be of a higher level in those patients or the reaction of the beta-cells is more inhibited by the same concentrations in diabetic patients.