Ultra-processed food consumption and risk of type 2 diabetes: three large prospective U.S. cohort studies.

Objective: We examined the relationship between ultra-processed food (UPF) intake and type 2 diabetes (T2D) risk among 3 large U.S. cohorts, conducted a meta-analysis of prospective cohort studies, and assessed meta-evidence quality.

Research design and methods: We included 71,871 women from Nurses’ Health Study (NHS), 87,918 women from NHSII, and 38,847 men from Health Professional Follow-Up Study. Diet was assessed using food frequency questionnaires and UPF were categorized per the Nova classification. Associations of total and subgroups of UPF with T2D were assessed using Cox proportional hazards models. We subsequently conducted a meta-analysis of prospective cohort studies on total UPF and T2D risk, and assessed meta-evidence quality using NutriGrade.

Results: Among the U.S. cohorts (5,187,678 person-years; 19,503 T2D cases), the hazard ratio for T2D comparing extreme quintiles of total UPF intake (percent of grams/day) was 1.46 (95% CI: 1.39, 1.54). Among subgroups, refined breads; sauces, spreads and condiments; artificially-and sugar-sweetened beverages; animal-based products; and ready-to-eat mixed dishes were associated with higher risk. Cereals; dark and whole-grain breads; packaged sweet and savory snacks; fruit-based products; and yogurt and dairy-based desserts were associated with lower risk. In the meta-analysis (415,554 participants; 21,932 T2D cases), each 10% increment in total UPF was associated with a 12% (95% CI: 10%, 13%) higher risk. Per NutriGrade, high quality evidence supports this relationship.

Conclusion: High quality meta-evidence shows that total UPF consumption is associated with higher T2D risk. However, some UPF subgroups were associated with lower risk in the U.S. cohorts.