Salakos E, Rabeony T, Courbebaisse M, et al. - Researchers examined the correlation of vitamin D status during the first trimester with the risk of gestational diabetes mellitus (GDM) via performing a nested case-control study from a multicenter prospective observational cohort of pregnant women assessed for 25-hydroxyvitamin D levels (25OHD). For this study, they matched 250 women with GDM (cases) with 941 women without GDM (controls) for parity, age, BMI before pregnancy, the season of conception, and phototype. Patients with 25OHD levels < 20 ng/mL had significantly greater GDM risk. However, no significant relationship was observed with other thresholds. Per observations, no linear relationship exist between GDM and 25OHD levels in the first trimester of pregnancy as no continuous decrease in GDM risk was observed with increase in 25OHD concentrations. The results most probably suggest that 25OHD levels do not associate with GDM risk.