Relations of a Mediterranean dietary score to baseline glucose and insulin levels and 6-year incidence of Type 2 Diabetes: The Multi-Ethnic Study of Atherosclerosis (MESA)

Background Type 2 diabetes is a highly prevalent but preventable disorder. We assessed the association between an a priori Mediterranean diet score (MeDiet) and fasting glucose and insulin at baseline and 6-year follow-up for incident type 2 diabetes in MESA. Methods Dietary intake was measured at baseline by a 120-item food frequency questionnaire in 5,390 men and women aged 45-84 years free of prevalent diabetes and clinical CVD. A MeDiet score was created based on intake of 10 food groups. Multivariable linear and proportional hazard models were used to estimate the association of MeDiet, categorized in quintiles, with baseline insulin and glucose, and incident diabetes, respectively. Models adjusted for age, gender, race/ethnicity, study site, education level, income, smoking status, physical activity, total caloric intake, and waist circumference. Results After multivariable adjustment, individuals with a higher MeDiet score had lower baseline insulin levels (mean Q5 (MeDiet score>6) =4.8 umol/l; mean Q1 (MeDiet score<4) = 5.8umol/l; ptrend= 0.0002). No association, however, was found between MeDiet score and blood glucose in multivariable models (mean Q5=89.3 mg/dl and mean Q1=89.9 mg/dl; ptrend=0.24). During follow-up, 412 incident diabetes events were identified. In multivariable analysis, MeDiet was not statistically significantly related to risk of incident diabetes. Hazard ratio (95% CI) of diabetes in those in Q5 was 1.14 (0.83-1.54) compared to Q1 (ptrend=0.91). Conclusion Greater consistency with a Mediterranean-style diet, reflected by a higher a priori Mediterranean diet score, was cross-sectionally associated with lower insulin levels among non-diabetics, but not with lower blood glucose or the incidence of diabetes.