Pregnancy thiamine and riboflavin intake and the risk of gestational diabetes mellitus: A prospective cohort study

Background: Thiamine and riboflavin deficiencies exist to varying degrees worldwide, especially in developing countries. Evidence regarding the association between thiamine and riboflavin intake and gestational diabetes mellitus (GDM) is scarce. Objectives: We aimed to evaluate the association of thiamine and riboflavin intake during pregnancy, including dietary source and supplementation, with GDM risk in a prospective cohort study. Methods: We included 3036 pregnant women (923 in the first trimester and 2113 in the second trimester) from the Tongji Birth Cohort. A validated semi-quantitative food frequency questionnaire and a lifestyle questionnaire were used to assess thiamine and riboflavin intake from dietary source and supplementation, respectively. GDM was diagnosed using the 75 g 2-h oral glucose tolerance test at 24-28 weeks of gestation. A modified Poisson regression or logistic regression model was used to evaluate the association between thiamine and riboflavin intake and GDM risk. Results: Dietary intake of thiamine and riboflavin was at low levels during pregnancy. In the fully adjusted model, compared with participants in quartile 1 (Q1), those who had more total thiamine and riboflavin intake had a lower risk of GDM during the first trimester [thiamine: Q2: RR: 0.58 (95% CI: 0.34, 0.98); Q3: RR: 0.45 (95% CI: 0.24, 0.84); Q4: RR: 0.35 (95% CI: 0.17, 0.72), P for trend = 0.002; riboflavin: Q2: RR: 0.63 (95% CI: 0.37, 1.09); Q3: RR: 0.45 (95% CI: 0.24, 0.87); Q4: RR: 0.39 (95% CI: 0.19, 0.79), P for trend = 0.006]. This association was also observed during the second trimester. Similar results were observed for the association between thiamine and riboflavin supplement use but not dietary intake and GDM risk. Conclusions: Higher intake of thiamine and riboflavin during pregnancy is associated with a lower incidence of GDM.