Abnormal 1-hour post-load glycemia during pregnancy impairs post-partum metabolic status: a single-center experience

Purpose: Recent evidence indicates that people with normal glucose tolerance (NGT) but 1-h post-load plasma glucose (1-h OGTT) ≥ 155 mg/dl have an increased risk for developing Type 2 diabetes mellitus (T2DM), determining a new risk category with deeper metabolic impairment. The aim of this study was to identify, among women with gestational diabetes (GDM), which alterations at OGTT during pregnancy are more frequently associated with 1-h OGTT ≥ 155 mg/dl at post-partum examination. Methods: Among 297 women affected by GDM, we retrospectively evaluated 244 resulted NGT after delivery. Based on post-partum glucose levels at 1-h OGTT, these people were divided into 188 cases (77.0%) with 1-h OGTT < 155 mg/dl (L-NGT) and 56 (23.0%) with 1-h OGTT ≥ 155 mg/dl (H-NGT). Results: Abnormal glucose levels at 1-h OGTT during pregnancy (≥ 180 mg/dl) were more frequent in H-NGT than in L-NGT (39.3 vs. 24.6%, odds ratio 3.7 [95% CI 1.4–9.6]; p = 0.016). Moreover, H-NGT showed more frequently the simultaneous alteration of all three OGTT plasma glucose values during pregnancy (10.7 vs. 2.1%, odds ratio 4.5 [95% CI 1.5–20.3]; p = 0.038) and less frequently the alteration of fasting plasma glucose alone (14.3 vs. 30.8%, odds ratio 0.4 [95% CI 0.1–0.7]; p = 0.028). Conclusions: Abnormal 1-h OGTT during pregnancy predicts an increased risk for post-partum 1-h OGTT ≥ 155 mg/dl in women with previous GDM. Even if NGT after delivery, these women may require a closer long-term post-partum follow-up, being at higher risk to develop future glucose intolerance.