A priori‐defined Diet Quality Indexes, Biomarkers, and Risk of Type 2 diabetes in Five Ethnic Groups: The Multiethnic Cohort

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ObjectiveDiet quality has been related to the risk of type 2 diabetes (T2D) predominantly in white populations. Underlying biological mechanisms of this association may include chronic inflammation, dyslipidemia, and adipokines. This study evaluated the association of four a priori diet quality scores with HOMA‐IR and T2D risk and examined biomarkers indicating potential pathways for this relation in the Multiethnic Cohort (MEC).MethodsThe analysis included 166,550 white, African American, Native Hawaiian, Japanese American, and Latino participants with 9,200 incident T2D cases based on three self‐reports and confirmed by administrative data. Dietary intake was assessed at baseline with a validated quantitative food frequency questionnaire. Biomarkers, i.e., leptin, adiponectin, HDL‐cholesterol, triglycerides, C‐reactive protein (CRP), glucose, and insulin, were measured using standard assays on average 10 years later. The Homeostatic Model Assessment Insulin Resistance (HOMA‐IR) was calculated based on glucose and insulin. Cox regression was applied to estimate T2D risk for the Healthy Eating Index‐2010 (HEI‐2010), alternative HEI‐2010 (AHEI‐2010), alternate Mediterranean diet score (aMED), and Dietary Approaches to Stop Hypertension (DASH) and adjusted for known confounders. In a subset of participants, adjusted means of biomarkers were computed across tertiles of dietary scores using general linear models.ResultsThe AHEI‐2010, aMED (in men only), and DASH were related to a significant 10–20% lower T2D risk with the strongest associations for the DASH and in whites. After stratification by ethnicity, the direction of the relations was consistent across ethnic groups with few exceptions. In the biomarker subcohort (N=10,032; approximately 6% of cohort members), the four index scores were related to lower HOMA‐IR values (although not always significant) and to lower triglycerides and CRP in men. In women, the HEI‐2010, AHEI‐2010, and DASH were inversely associated with triglycerides, the AHEI‐2010 and DASH to higher HDL‐cholesterol, and the aMED and DASH to lower CRP. Only the DASH was associated with higher adiponectin and leptin was not associated with any diet quality score.ConclusionsAs one of the first prospective analyses relating a priori dietary patterns to T2D‐related biomarkers, the current findings suggest that an optimal lipid profile, low inflammation as assessed by CRP, and high adiponectin levels may translate high diet quality into a lower T2D risk in this cohort composed of five ethnic groups.Support or Funding InformationThe Multiethnic Cohort has been supported by NCI grant R37 CA54281 (PI: Dr. L.N. Kolonel) and by U01CA164973 (PI: Drs. L. Le Marchand/B.E. Henderson/L.W. Wilkens). The diabetes project was funded by R21 DK073816 (PI: Dr. G. Maskarinec). SJ was supported by a postdoctoral fellowship from the German Research Foundation (DFG, JA 2564/1‐1).