TWO ABNORMALITIES OF GLUCOSE-INDUCED INSULIN SECRETION: DOSE-RESPONSE CHARACTERISTICS AND INSULIN SENSITIVITY

Abstract

To characterize the defect of insulin secretion in diabetes, the response to different i.v. glucose loads was studied in women who have had gestational diabetes and are, by definition, latent diabetic (LD). Women who had produced a large-for-date baby, but who were not known to have been diabetic (LFD), were investigated to determine if they had abnormal metabolism. Both groups had raised fasting plasma glucose concentrations. Only the LD had glucose intolerance, which was associated with a reduced 1st phase insulin response to all glucose loads with a decreased maximal secretory capacity (low Vmax). The LFD women appeared to include a distinct abnormality in which the .beta. cells had decreased sensitivity to glucose (high Km), with diminished secretory response to small but normal response to large loads. Whereas the LD probably have disordered .beta. cell function, some of the LFD women may represent the upper end of the normal range of the glucose set of .beta. cell function. Neither group had insulin resistance, as measured by the hypoglycemic response to an i.v. insulin bolus. A woman who has produced a LFD, but who was not known to be diabetic, does not necessarily have a diabetic tendency.