Association of adherence to a Mediterranean diet with glycemic control and cardiovascular risk factors in youth with type 1 diabetes: The SEARCH Nutrition Ancillary Study

BACKGROUND/OBJECTIVES: This study aimed to determine the association between a Mediterranean diet and glycemic control and other cardiovascular risk factors among youth with type 1 diabetes (T1D). SUBJECTS/METHODS: Incident T1D cases aged <20 years at diagnosis between 2002 and 2005 were included. Participants were seen at baseline (N=793), 1-year (N=512) and 5-year follow-up visits (N=501). Mediterranean diet score was assessed using a modified KIDMED index (mKIDMED). Multivariate linear regression and longitudinal mixed model were applied to determine the association between mKIDMED score and log-HbA1c, lipids, blood pressure (BP), and obesity. RESULTS: In cross-sectional analyses using baseline data, for individuals with an HbA1c of 7.5%, a two-point higher mKIDMED score (one standard deviation) was associated with 0.15% lower HbA1c (P=0.02). A two-point higher mKIDMED score was associated with 4.0 mg/dL lower total cholesterol (TC) (P=0.006), 3.4 mg/dL lower low-density lipoprotein (LDL)-C (P=0.004), 3.9 mg/dL lower non-high-density lipoprotein (non-HDL)-C (P=0.004), and 0.07 lower LDL-C/HDL-C ratio (P=0.02). Using longitudinal data, a two-point increase in mKIDMED score was associated with 0.01% lower log-HbA1c (P=0.07), 1.8 mg/dL lower TC (P=0.05), 1.6 mg/dL lower LDL-C (P=0.03), and 1.8 mg/dL lower non-HDL-C (P=0.03) than would otherwise have been expected. HbA1c mediated about 20% of the association for lipids in both cross-sectional and longitudinal models. An unexpected positive association between mKIDMED score and systolic BP was found among non-Hispanic white youth in cross-sectional analyses (P=0.009). Mediterranean diet was not associated with obesity. CONCLUSIONS: Mediterranean diet may improve glycemic control and cardiovascular health in T1D youth.