Maternal diabetes following gestational diabetes: Does multiple gestation multiply the risk?

Objective: To assess whether the risk for future diabetes is higher among women diagnosed with gestational diabetes (GD) during twin versus singleton gestations.Method: A retrospective cohort study was performed including all women who delivered at a tertiary medical center between the years 1991 and 2021 and had at least one GD diagnosis. The first GD diagnosis per women was defined as the index pregnancy. Women diagnosed with GD during multiple gestations were compared with women diagnosed with GD during singleton gestations. The outcomes included first hemoglobin A1C (Hba1C) level > 6.4 mg/dL post partum, and the highest level measured during the follow-up period of up to 30 years. Multivariable logistic and Cox proportional analysis were used to compare the risk between the two groups while adjusting for confounding variables.Results: The current study included 13 770 mothers, with 458 patients (3.3%) diagnosed with GD during twin gestations and 13 312 (96.7%) during singleton gestations. The mean follow-up was 12.25 +/- 9.3 years. Mothers of both groups did not differ in age at index pregnancy; however, mothers of twins were more likely to conceive following fertility treatments. Incidence of diabetes and prediabetes (defined as Hba1C > 6.4 and >5.7, respectively) were lower among the twin-gestation group, both during the 6-month postpartum period (for diabetes: 15.5% vs 22.1%; odds ratio [OR], 0.65 [95% confidence interval (CI), 0.46-0.91]) and during the long-term follow-up (for diabetes: 31.8% vs 40.7%; OR, 0.68 [95% CI, 0.52-0.88]). These results remained significant in the multivariable analysis, while accounting for age, ethnicity, and fertility treatments.Conclusion: GD diagnosis during multiple versus singleton gestations is associated with a lower risk for future diabetes.