Clinical assessment of insulin action during late pregnancy in women at risk for gestational diabetes: Association of maternal glycemia with perinatal outcome

ObjectiveWe prospectively evaluated differences in fasting- and oral glucose tolerance test (OGTT)-derived indices of insulin action in Caucasian (Cau) and African-American (AA) pregnant women and compared them with obstetric outcomes.Study designIRB-approved prospective study in 171 pregnant women undergoing a 3-h OGTT. Mathematical modeling was used to evaluate insulin response, insulin activity and glucose tolerance in fasting and postglucose ingestion state. Insulin sensitivity indices derived from fasting (HOMA-IR) and glucose-stimulated values (SIOGTT) were compared. An insulin sensitivity-secretion index (IS-SI) was calculated from the product of the SIOGTT and early-phase insulin secretion.ResultsForty-nine patients had gestational diabetes (GDM), 28 had gestational impaired glucose tolerance (GIGT) and 94 had normal glucose tolerance after an abnormal glucose challenge test (NGT-abnGCT). Insulin sensitivity was lowest in women with GDM. In all groups, pregnant AA women were significantly more insulin resistant than Cau women, based on both HOMA-IR and SIOGTT, but had enhanced insulin secretion compared to their Cau counterparts. The mean IS-SI progressively improved for all women from GDM to GIGT to NGT-abnGCT. Women with NGT-abnGCT had a higher prevalence of large-for-gestational age (LGA) newborns and significantly higher cesarean section rate.DiscussionInsulin measures along with glucose determinations during OGTT testing in pregnant women at risk for diabetes provide valuable information that varies according to race. We observed that pregnant women with a lesser degree of glucose tolerance abnormality during pregnancy who receive no intervention have a higher risk for LGA infants and significantly increased C-section rate (ClinicalTrials.gov number, NCT006874791).