Dietary fiber intake, dietary glycemic load, and the risk for gestational diabetes mellitus.

OBJECTIVE: We aimed to examine whether pregravid dietary fiber consumptions from cereal, fruit, and vegetable sources and dietary glycemic load were related to gestational diabetes mellitus (GDM) risk. RESEARCH DESIGN AND METHODS: This study was a prospective cohort study among 13,110 eligible women in the Nurses’ Health Study II. GDM was self-reported and validated by medical record review in a subsample. RESULTS: We documented 758 incident GDM cases during 8 years of follow-up. After adjustment for age, parity, prepregnancy BMI, and other covariates, dietary total fiber and cereal and fruit fiber were strongly associated with GDM risk. Each 10-g/day increment in total fiber intake was associated with 26% (95% CI 9-49) reduction in risk; each 5-g/day increment in cereal or fruit fiber was associated with a 23% (9-36) or 26% (5-42) reduction, respectively. Dietary glycemic load was positively related to GDM risk. Multivariate relative risk for highest versus lowest quintiles was 1.61 (1.02-2.53) (P for trend 0.03). The combination of high-glycemic load and low-cereal fiber diet was associated with 2.15-fold (1.04-4.29) increased risk compared with the reciprocal diet. CONCLUSIONS: These findings suggested that prepregnancy diet might be associated with women’s GDM risk. In particular, diet with low fiber and high glycemic load was associated with an increased risk. Future clinical and metabolic studies are warranted to confirm these findings.