Ultra-processed food intake and risk of type 2 diabetes: a pooled analysis of three prospective cohorts of Korean adults and an updated meta-analysis.

Studies suggest a positive association between ultra-processed food (UPF) intake and type 2 diabetes risk. However, studies were primarily conducted in Western populations with diets and disease profiles different from populations living elsewhere. In addition, the dose-response relationship needs to be further elucidated. We conducted an individual-level pooled analysis of three Korean prospective cohorts (n = 72,776). UPF intake (in the percentage of g/d as the main UPF unit) was assessed using validated food frequency questionnaires and categorized according to Nova classification. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). We subsequently conducted a meta-analysis of prospective studies, including recent studies from both Western and non-Western populations, to assess the dose-response relationship. In a pooled analysis of Korean cohorts (up to 18 years of follow-up), the highest (vs. lowest) quartile of UPF intake was associated with an increased type 2 diabetes risk (pooled HR [95% CI] = 1.11 [1.02, 1.21] , p-trend = 0.03). The positive association persisted after additional adjustment for BMI, nutritional factors (fiber, sodium, and carbohydrate intakes), or diet quality score. Among individual UPF subgroups, processed meats, ready-to-eat/heat mixed dishes, and ice cream were positively associated with diabetes risk. In a meta-analysis of 17 prospective cohorts, every 10% (of g/d) increment in UPF intake was associated with a 10% (summary RR [95% CI] = 1.10 [1.08, 1.12] ) higher risk in a dose-response fashion. Our meta-evidence supports that higher UPF intake may monotonically increase type 2 diabetes risk.