Abstract P214: Adherence to Dietary Patterns after Gestational Diabetes Mellitus and Risk of Subsequent Type 2 Diabetes

Background: Adherence to healthful dietary patterns is associated with lower risk of type 2 diabetes (T2DM) in the general population. Women with a history of gestational diabetes mellitus (GDM) are at particularly high risk for future type 2 diabetes (T2DM), though relations of dietary patterns with incident T2DM in this population are unknown. Hypothesis: We hypothesize that adherence to healthful dietary patterns among women with prior GDM is inversely associated with incident T2DM. Methods: We evaluated 4,413 participants from the Nurses' Health Study II longitudinal cohort with a history of GDM in one or more pregnancies. GDM was ascertained by self-report of a physician's diagnosis and has been previously validated in a subsample with confirmation of over 90% by medical record review. Participants were free of chronic disease at baseline and followed from 1991 through 2007. Dietary pattern adherence scores were derived for the alternate Mediterranean Diet (aMED), Dietary Approaches to Stop Hypertension (DASH), and the alternate Healthy Eating Index (aHEI) based on validated food frequency questionnaires assessed after GDM and updated every 4 years thereafter. Incident T2DM was assessed every 2 years through previously validated questionnaire responses. Multivariable Cox proportional hazards models estimated the relationship of each dietary pattern with incident T2DM, adjusting for age, total energy intake, parity, age at first birth, race/ethnicity, parental history of T2DM, oral contraceptive use, menopausal status, and smoking status. Body mass index (BMI) was included in a subsequent model. Results: There were 491 cases of incident T2DM over 52,743 person-years of observation. In multivariable analyses, the aMED, DASH, and aHEI dietary patterns were each inversely associated with incident T2DM. For each 1 standard deviation increase in score, the aMED pattern was associated with a 24% lower risk (HR=0.76 [95% CI: 0.67, 0.86] p<0.0001), DASH with an 18% lower risk (HR=0.86 [95% CI: 0.73, 0.92] p=0.0005), and aHEI with a 30% lower risk (HR=0.70 [95% CI: 0.61, 0.79] p<0.0001). Further adjustment for BMI moderately but not completely attenuated these findings: (aMED: HR=0.85 [95% CI: 0.75, 0.97] p=0.014; DASH: HR=0.91 [95% CI: 0.80, 1.02] p=0.11; aHEI: HR=0.84 [95% CI: 0.73, 0.96] p=0.009). Conclusions: Adherence to healthful dietary patterns is associated with a lower incidence of T2DM among women following a diagnosis of GDM, and may be partially mediated by BMI. These findings have implications for prevention efforts in this high-risk population.