Insulin response patterns contribute to different perinatal risks in gestational diabetes

The aim of this study was to evaluate the insulin dynamics of patients with gestational diabetes mellitus (GDM) and to compare perinatal outcomes acco rding to the insulin response patterns. Twenty-two out of 925 consecutive w omen examined were diagnosed as having GDM. One hundred and ten women who e xperienced a normal pregnancy were used as controls. Plasma glucose levels and insulin responses were evaluated by a 2-hour 75-gram oral glucose toler ance test (OGTT). Immunoreactive insulin (IRI), the area under the curve (A UC) of glucose (AUCg) and insulin (AUCi), and the insulinogenic index (II = Delta IRI 30 min/Delta BS 30 min) were measured. The GDM patients were div ided into three subgroups, consisting of hyper-, normo- and hypoinsulinemic groups, according to the mean +/- 2 SD of the AUCi obtained from the contr ols. Clinical and laboratory findings were compared among the GDM subgroups and controls. The GDM patients showed impaired insulin secretion to glucos e stimuli, with low plasma insulin levels (at 30 min) and reduced insulin/g lucose ratios (at 30 and 60 min) early in the 75-gram OGTT. The II and AUCi /AUCg values of GDM patients were reduced as compared with those of control s. These reduced insulin responses were remarkable in hypo- and normoinsuli nemic GDM patients, but were not detected in hyperinsulinemic GDM patients. The number of babies large for their gestational age in normo- and hypoins ulinemic GDM patients was significantly higher than that in hyperinsulinemi c GDM patients or controls. Hyperinsulinemic GDM patients had a high freque ncy of pregnancy-induced hypertension (40%). The body mass index prior to p regnancy of hyperinsulinemic GDM patients was significantly higher than tha t of normoinsulinemic GDM patients or controls. It was demonstrated that no t only insulin secretion, but also perinatal clinical characteristics, diff ered among the GDM subgroups. The heterogeneity of the disease was thus con firmed. Copyright (C) 2001 S. Karger AG. Basel.