Pathophysiological Characteristics and Effects of Obesity in Women With Early and Late Manifestation of Gestational Diabetes Diagnosed by the International Association of Diabetes and Pregnancy Study Groups Criteria

Context: Appropriate risk stratification is essential in gestational diabetes (GDM) diagnosis to optimize therapeutic strategies during pregnancy. However, there are sparse data related to the newly recommended International Association of Diabetes and Pregnancy Study Groups criteria and their use in early pregnancy. Objective: This study sought to evaluate clinical and pathophysiological characteristics less up to gestational week (GW) 21 in women with early and late GDM onset. Design and Setting: This was a prospective study conducted at the Medical University of Vienna. Patients and Interventions: Pregnant women (n = 211) underwent an oral glucose tolerance test at 16 GW (interquartile range, 14-18 wk) with multiple measurements of glucose, insulin, and C-peptide for evaluation of insulin sensitivity and beta-cell function in addition to detailed obstetrical risk assessment. Clinical followups were performed until end of pregnancy. Main outcome measure: We performed a metabolic characterization of early-onset GDM. Results: Of 81 women, 49 (23%) showed early (GDM(Early) <= 21GW) and 32 (15%) later manifestation (GDM(Late) >= 24 GW) whereas 130 (62%) remained normal-glucose-tolerant (NGT). In contrast with GDM(Late), GDM(Early) were affected by decreased insulin sensitivity (GDM(Early) vs NGT, P < .001; GDM(Early)vs GDM(Late), P < .001; GDM(Late) vs NGT, P = .410). However, both early and late manifested subjects showed impairments in beta-cell function. GDM(Early) showed highest levels of preconceptional and actual body mass index (BMI), which was related to fasting glucose (r = 0.42, P < .001) and particularly insulin sensitivity (r = -0.51, P < .001). Differences in glucose disposal between the subgroups remained constant in multivariable analysis including the strongest risk factors for GDM, ie, age, history of GDM, and BMI in our population. Conclusions: Early manifestation of GDM is affected by insulin resistance that is partly explained by higher degree in obesity. However, beta-cell dysfunction was also detectable in GDM(Late), indicating defective compensatory mechanisms emerging already in early pregnancy.