A LONGITUDINAL-STUDY OF PLASMA-INSULIN AND GLUCAGON IN WOMEN WITH PREVIOUS GESTATIONAL DIABETES

OBJECTIVE- To investigate whether plasma insulin or glucagon predicts later development of diabetes in women with gestational diabetes melli tus (GDM). RESEARCH DESIGN AND METHODS- The subjects studied were 91 w omen with diet-treated GDM and 33 healthy women. Plasma insulin and gl ucagon during a 50-g oral glucose tolerance test (OGTT) were measured during pregnancy, postpartum, and at follow-up 5-11 years later. At fo llow-up, the women were also examined with a 75-g OGTT or an intraveno us glucagon test. RESULTS- Twenty-seven (30%) of the women with previo us GDM had abnormal glucose tolerance at follow-up (2 had insulin-depe ndent diabetes mellitus, 13 had non-insulin-dependent diabetes mellitu s, and 12 had impaired glucose tolerance). Compared with the control s ubjects, women with previous GDM had relatively impaired insulin secre tion (decreased insulinogenic index and delayed peak insulin response) at all time points investigated; this was also found when only nonobe se glucose-tolerant women were examined. Low insulin secretion during pregnancy together with a high fasting plasma glucose level at the dia gnostic OGTT in pregnancy and hyperglycemia during the postpartum OGTT were predictive for subsequent development of overt diabetes (logisti c regression analysis). CONCLUSIONS- Women who develop GDM have a rela tive insulin secretion deficiency, the severity of which is predictive for later development of diabetes. Furthermore, our data indicate tha t their relatively reduced beta-cell function may be a significant pat hogenic factor in relation to the high incidence of subsequent diabete s in women with GDM. This could be important in the design of follow-u p programs for women with previous GDM.