Healthful dietary patterns and type 2 diabetes mellitus risk among women with a history of gestational diabetes mellitus.

Background: Type 2 diabetes mellitus (T2DM) has reached epidemic proportions. Women with gestational diabetes mellitus (GDM) are at high risk for T2DM after pregnancy. Adherence to healthful dietary patterns has been inversely associated with T2DM in the general population; however, whether these dietary patterns are associated with progression to T2DM among a susceptible population is unknown.

Methods: Four thousand four hundred thirteen participants from the Nurses' Health Study II cohort with prior GDM were followed up from 1991 to 2005. We derived the alternate Mediterranean diet (aMED), Dietary Approaches to Stop Hypertension (DASH), and alternate Healthy Eating Index (aHEI) dietary pattern adherence scores from a post-GDM validated food-frequency questionnaire, with cumulative average updating every 4 years. Multivariable Cox proportional hazards models estimated the relative risk (hazard ratios) and 95% confidence intervals.

Results: We observed 491 cases of incident T2DM during 52 743 person-years. All 3 patterns were inversely associated with T2DM risk with adjustment for age, total calorie intake, age at first birth, parity, ethnicity, parental diabetes, oral contraceptive use, menopause, and smoking. When we compared participants with the highest adherence (quartile 4) vs lowest (quartile 1), the aMED pattern was associated with 40% lower risk of T2DM (hazard ratio, 0.60 [95% CI, 0.44-0.82; P=.002]); the DASH pattern, with 46% lower risk (0.54 [0.39-0.73; P.001]); and the aHEI pattern, with 57% lower risk (0.43 [0.31-0.59; P.001]). Adjustment for body mass index moderately attenuated these findings.

Conclusions: Adherence to healthful dietary patterns is associated with lower T2DM risk among women with a history of GDM. The inverse associations are partly mediated by body mass index.