Ultra-processed food indices and component food groups in relation to incident type 2 diabetes and cardiometabolic multimorbidity: a prospective cohort study

Broad ultra-processed food (UPF) measures combine product groups that may differ in cardiometabolic relevance. This study examined questionnaire-observable processing-related food groups, sweet-tasting beverage subtypes and dietary difference indices in relation to type 2 diabetes and cardiometabolic multimorbidity. This prospective cohort analysis included 188,405 UK Biobank participants with Oxford WebQ dietary data. A study-specific UPF-like food-group index comprised processed meat, sweet snacks, savoury snacks, sweet-tasting beverages and ready/fried foods. Cox models estimated hazard ratios (HRs) per 1-standard-deviation higher score for incident type 2 diabetes and cardiometabolic multimorbidity, with sequential adjustment for demographic factors, conventional nutrients, body mass index and a nuclear magnetic resonance (NMR) biomarker score. Median follow-up was 14.4 years for type 2 diabetes and 14.3 years for cardiometabolic multimorbidity. The total index was associated with type 2 diabetes in the base model (HR 1.20, 95% confidence interval [CI] 1.17–1.22) and cardiometabolic multimorbidity (HR 1.13, 95% CI 1.11–1.15). After nutrient adjustment, corresponding HRs were 1.18 (95% CI 1.15–1.20) and 1.11 (95% CI 1.09–1.13); after adding body mass index, 1.09 (95% CI 1.06–1.11) and 1.06 (95% CI 1.04–1.08). Additional NMR adjustment yielded HRs of 1.07 (95% CI 1.05–1.10) and 1.05 (95% CI 1.03–1.07). In nutrient- and body-mass-index-adjusted models, the sweet-tasting beverage subtype composite was associated with type 2 diabetes (HR 1.12, 95% CI 1.10–1.15) and cardiometabolic multimorbidity (HR 1.08, 95% CI 1.07–1.10). Savoury snacks showed smaller positive associations. The minimally processed plant-food minus UPF-like difference index was inversely associated with both outcomes (type 2 diabetes HR 0.92, 95% CI 0.90–0.94; cardiometabolic multimorbidity HR 0.95, 95% CI 0.93–0.96). Although the overall UPF-like dietary index was associated with incident type 2 diabetes and cardiometabolic multimorbidity, the observed associations appeared to be driven primarily by sweet-tasting beverages and, to a lesser extent, savoury snacks, with considerably weaker evidence for the remaining food groups. Reporting component food groups alongside UPF-related indices may distinguish food-specific associations from broader dietary patterns for understanding cardiometabolic risk.