Unveiling the Roles of Immune Function and Inflammation in the Associations Between Dietary Patterns and Incident Type 2 Diabetes.

Objective: To investigate the associations between data-driven dietary patterns, immune function, and incident type 2 diabetes (T2D) and the mediating effects of immune function.

Methods: This study included 375,665 participants without diabetes at baseline in the UK Biobank study. Dietary patterns were derived through principal component analysis of food frequency questionnaire data. Immune function was assessed using 14 individual inflammatory markers and an integrated low-grade inflammation score (INFLA-score). Cox proportional hazard models were used to estimate the associations of dietary patterns or immune function with incident T2D. Linear regressions were used to estimate the associations of dietary patterns with immune function. Mediating effects of immune function were quantified.

Results: During a median 14.6-year follow-up, 13,932 participants developed T2D. Four dietary patterns were identified: prudent diet (high in whole grains, vegetables, fruits, fish), wheat/dairy/eggs restrictive diet (limiting these foods), meat-based diet (high in red/processed meat, salt), and full-cream dairy diet (preference for full cream milk or dairy products). The prudent diet was negatively (HR, 0.69 [95% CI, 0.65-0.72]), while the wheat/dairy/eggs restrictive diet (HR, 1.08 [95% CI, 1.03-1.13]), meat-based diet (HR, 1.12 [95% CI, 1.06-1.17]), and full-cream dairy diet (HR, 1.08 [95% CI, 1.03-1.12]) were positively associated with incident T2D (all for trend ≤0.04). The prudent diet was negatively and the full-cream dairy diet was positively associated with most inflammatory markers. Most inflammatory markers, especially INFLA-score (HR, 1.18 [95% CI, 1.16-1.20]), were positively associated with incident T2D. INFLA-score mediated 13% of the association with incident T2D for the prudent diet and 34% for the full-cream dairy diet.

Conclusions: This study identified four distinct dietary patterns and a range of inflammatory markers associated with incident T2D. A notable proportion of the associations between dietary patterns and T2D was mediated by immune function.