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), is lacking in Australia. Objective 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 Prospective study using the Melbourne Collaborative Cohort Study (MCCS) data. Participants /Setting: Participants were recruited from the Melbourne metropolitan area between 1990-1994 (baseline), with follow-ups 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 non-fasting), or medication use). Statistical Analyses Performed Adjusted Poisson regression models estimated Incidence Rate Ratios (IRRs) and 95% confidence intervals (CIs) for the risk of type-2 diabetes per 10% increase and by quartiles of UPF consumption (% total grams/day), using age as the time metric. Regression-based mediation analyses were employed to assess the mediation role of BMI. Results During follow-up (mean: 11.6 ± 1.7 years), 1,734 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 non-linearity. Participants in the highest quartile of UPF consumption had a 40% higher risk of type-2 diabetes (IRR highxlow category = 1.40, 95%CI: 1.22, 1.60; p<0.001). 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.