Adherence to a Mediterranean-style eating pattern and risk of diabetes in a U.S. prospective cohort study

Abstract

Background: A Mediterranean-style eating pattern is consistently associated with a decreased diabetes risk in Mediterranean and European populations. However, results in U.S. populations are inconsistent. The objective of this study was to assess whether a Mediterranean-style eating pattern would be associated with diabetes risk in a large, nationally representative U.S. cohort of black and white men and women.

Methods: Participants from the Atherosclerosis Risk in Communities study prospective cohort without diabetes, cardiovascular disease, or cancer at baseline (visit 1, 1987-1989; n = 11,991) were included (mean age 54 years, 56% female, 75% white). Alternate Mediterranean Diet scores (aMed) were calculated using the mean dietary intake self-reported at visit 1 and visit 3 (1993-1995) or visit 1 only for participants censored before visit 3. Participants were followed from visit 1 through 31 December 2016 for incident diabetes. We used Cox regression models to characterize associations of aMed (quintiles as well as per 1-point higher) with incident diabetes adjusted for energy intake, age, sex, race and study center, and education (Model 1) for all participants then stratified by race and body mass index (BMI). Model 2 included potential mediating behavioral and clinical measures associated with diabetes. Results are presented as hazard ratios and 95% confidence intervals.

Results: Over a median follow-up of 22 years, there were 4024 incident cases of diabetes. Higher aMed scores were associated with lower diabetes risk [Model 1: 0.83 (0.73-0.94) for Q5 vs Q1 (p-trend < 0.001) and 0.96 (0.95-0.98) for 1-point higher]. Associations were stronger for black vs white participants (interaction p < 0.001) and weaker for obese vs normal BMI (interaction p < 0.01). Associations were attenuated but statistically significant in Model 2.

Conclusions: An eating pattern high in fruits, vegetables, whole grains, legumes, nuts, and fish, and moderate in alcohol was associated with a lower risk of diabetes in a community-based U.S.

Fig. 1. Adjusted hazard ratios for Alternate Mediterranean Diet (aMed) scores and incident diabetes for the overall population and according to race and BMI categories in the Atherosclerosis Risk in Communities study.

Results are represented as hazard ratios and 95% confidence intervals from Cox regression models adjusted for total energy intake, age, sex, race and study center (center only for the race-specific analyses), and education level. The first point estimate within each subgroup represents the risk of incident diabetes per 1-point higher in aMed scores. The second point estimate within each subgroup represents the risk of incident diabetes for those in the fifth quintile vs the first quintile (reference group). P-values for trend were calculated from Wald tests modeling aMed quintiles as an ordinal variable.

Fig. 2. Alternate Mediterranean Diet (aMed) score distribution and adjusted hazard ratios for incident diabetes in the Atherosclerosis Risk in Communities study.

The solid line indicates the hazard ratio for incident diabetes estimated via a Cox regression model with Alternate Mediterranean Diet scores modeled continuously as a linear spline with a knot at a score of 2 points, adjusted for total energy intake, age, sex, race and study center, and education level. The dashed lines indicate the 95% confidence interval. The grey bars represent the number of participants with each alternate Mediterranean diet score.