Oral Glucose Tolerance Test in Pregnancy and Subsequent Maternal Hypertension

Objective The aim of the study is to evaluate whether values and the shape of the glucose curve during the oral glucose tolerance test (OGTT) in pregnancy identify women at risk of developing hypertension (HTN) later in life. Methods This category includes the secondary analysis of a follow-up from a mild gestational diabetes mellitus (GDM) study that included a treatment trial for mild GDM (n = 458) and an observational cohort of participants with abnormal 1-hour glucose loading test only (normal OGTT, n = 430). Participants were assessed at a median of 7 (IQR 6-8) years after their index pregnancy, and trained staff measured their blood pressure (systolic blood pressure [SBP]; diastolic blood pressure [DBP]). The association between values and the shape of the glucose curve during OGTT in the index pregnancy and the primary outcome defined as elevated BP (SBP ≥120, DBP ≥80 mm Hg, or receiving anti-HTN medications), and secondary outcome defined as stage 1 or higher (SBP ≥130, DBP ≥80 mm Hg, or receiving anti-HTN medications) at follow-up were evaluated using multivariable regression, adjusting for maternal age, body mass index, and pregnancy-associated hypertension during the index pregnancy. Results There was no association between fasting, 1-hour OGTT, and the outcomes. However, the 2-hour OGTT value was positively associated (adjusted odds ratio [aRR] per 10-unit increase 1.04, 95% CI 1.01-1.08), and the 3-hour was inversely associated (aRR per 10-unit increase 0.96, 95% CI 0.93-0.99) with the primary outcome. When the shape of the OGTT curve was evaluated, a monophasic OGTT response (peak at 1 hour followed by a decline in glucose) was associated with increased risk of elevated BP (41.3vs. 23.5%, aRR 1.66, 95% CI 1.17-2.35) and stage 1 HTN or higher (28.5 vs. 14.7%, aRR 1.83, 95% CI 1.15-2.92), compared with a biphasic OGTT response. Conclusion Among persons with mild GDM or lesser degrees of glucose intolerance, the shape of the OGTT curve during pregnancy may help identify women who are at risk of HTN later in life, with biphasic shape to be associated with lower risk. Key Points The shape of the Oral Glucose Tolerance Test curve may help identify patients who are at risk of having elevated BP or HTN 5 to 10 years following pregnancy. The 2-hour Oral Glucose Tolerance Test values is positively associated with elevated BP 5 to 10 years following pregnancy. This supports the concept of pregnancy as a window to future health and represents a potential novel biomarker for maternal cardiovascular health screening.