One elevated oral glucose tolerance test value in pregnancy increases the risk for future diabetes mellitus type 2

Purpose: Women with only one elevated 100 g OGTT value are not considered as having gestational diabetes mellitus (GDM) and therefore there are no recommendations to address this population as a risk group for type 2 diabetes mellitus (T2DM). We aimed to elucidate whether one elevated OGTT value increases the risk for T2DM. Methods: A retrospective population-based cohort study of women with a first diagnosis of GDM who delivered between 1991 and 2011 was conducted. Women were divided according to GDM diagnosis criteria into three groups: (1) at least two elevated values of Carpenter and Coustan criteria (C&C; N = 209), (2) At least two elevated values of the National Diabetes Data Group (NDDG) criteria (NDDG2; N = 290) and (3) only one elevated value of the NDDG criteria (NDDG1; N = 226). A fourth group comprising women without GDM was included (control; N = 352). The primary outcome was the development of T2DM. Results: The mean follow-up was 12.4 ± 5.3 years and the mean age at follow-up was 43.0 ± 5.7 years. The rate of T2DM in the control, C&C, NDDG1 and NDDG2 groups were 5%, 18%, 19% and 31%, respectively. All GDM diagnoses were independent risk factors for T2DM in multivariable Cox regression when compared to controls, adjusted hazard ratio and 95% CI: C&C 7.8 [95% CI 3.7–16.4], NDDG1 5.5 [2.6–11.6], and NDDG2 10.5 [5.2–21.4]. Additional independent risk factors were parity, fasting and 1-h post-glucose load of the OGTT and insulin use. Conclusions: Women with one elevated OGTT value using the NDDG criteria are at increased risk for T2DM. Further studies are needed to decide whether those women should be considered a focus group for long-term surveillance and T2DM prevention interventions.