Flat oral glucose tolerance test during pregnancy and risk for type 2 diabetes - a five-year cohort study.

Abstract

To evaluate the risk of type 2 diabetes mellitus (T2DM) in women with flat response in the 100-gram oral glucose tolerance test (OGTT) performed during pregnancy in a large cohort of women with up to 5 years of follow-up. A retrospective analysis of women with documented OGTT during pregnancy and T2DM data up to 5 years after pregnancy. Gestational diabetes (GDM) screening was done by two-step strategy. Glucose levels during pregnancy were extracted from the computerized laboratory system of Meuhedet HMO and cross-tabulated with the Israeli National Diabetes Registry. Flat OGTT was defined as fasting glucose < 95mg/dl and 3 postprandial values lower than 100mg/dl. The cohort was stratified by OGTT results to normal glucose values, flat OGTT, and GDM according to Carpenter & Coustan thresholds. Cumulative risk for T2DM was evaluated and compared between groups. Statistical analysis included univariate analysis followed by survival analysis. 14,122 parturients entered analysis. Of them, 965(6.8%) had flat OGTT, 11,427(80.9%) had normal OGTT, and 1,730(12.3%) had GDM. Women with flat OGTT were younger, had lower BMI, and lower rates of hypertension. Their glucose values throughout pregnancy were lower compared to the other groups (p<0.001 for all). During the study period and following adjustment to maternal age, obesity, and hypertension, women with flat OGTT had a low incidence of T2DM, even when compared to women with normal OGTT (aHR 0.212, 95% CI 0.052-0.856). Parturients with flat OGTT during pregnancy are at low risk of developing T2DM up to 5 years following pregnancy.