Ultra-Processed Food Consumption and Risk of Type 2 Diabetes in the Melbourne Collaborative Cohort Study

BACKGROUND: Prospective evidence on the association between ultra-processed food (UPF) consumption and type 2 diabetes, and the potential mediator role of body mass index (BMI; calculated as kg / m²), is lacking in Australia. OBJECTIVE: The aim of this study was to investigate the association between UPF consumption and incident type 2 diabetes in Australian adults, and to further examine the mediating role of BMI in this association. DESIGN: This was a prospective study using the Melbourne Collaborative Cohort Study data. PARTICIPANTS/SETTING: Participants were recruited from the Melbourne metropolitan area between 1990 and 1994 (baseline), with follow-up conducted in 1995-2002 and 2003-2007. A total of 25 214 participants aged 40-69 years, without diabetes at baseline, and who provided baseline dietary and follow-up diabetes data were included. MAIN OUTCOME MEASURES: Incidence of type 2 diabetes was assessed at follow-up 1 (self-report) and follow-up 2 (self-report, elevated plasma glucose ≥126 mg/dL fasting or ≥200 mg/dL nonfasting [to convert to mmol/L, multiply by 0.0555], or medication use). STATISTICAL ANALYSES PERFORMED: Adjusted Poisson regression models estimated incidence rate ratios (IRRs) and 95% CIs for the risk of type 2 diabetes per 10% increase and by quartiles of UPF consumption (% total g/d), using age as the time metric. Regression-based mediation analyses were used to assess the mediation role of BMI. RESULTS: During follow-up (mean [SD], 11.6 [1.7] years), 1734 cases of type 2 diabetes occurred. The direct association between each 10% increase in UPF consumption and type 2 diabetes was statistically significant (IRR, 1.16; 95% CI, 1.11-1.21), yet spline analyses indicated evidence of nonlinearity. Participants in the highest quartile of UPF consumption had a 40% higher risk of type 2 diabetes (IRRhigh×low category, 1.40; 95% CI, 1.22-1.60; P < .001). BMI significantly mediated 18% of the association. CONCLUSIONS: In this large cohort of Australian adults, higher UPF consumption was associated with an increased risk of type 2 diabetes, with BMI as an important mediator.