Aim: To examine the relation between meat intake and diabetes occurrence in adults. Methods: In a prospective cohort study we examined the relation between diet and incident diabetes recorded among 8,401 cohort members (ages 45–88 years) of the Adventist Mortality Study and Adventist Health Study (California, USA) who were non-diabetic at baseline. During the 17-year follow-up, we identified 543 incident diabetes cases. Results: (1) Subjects who were weekly consumers of all meats were 29% (OR = 1.29; 95% CI 1.08, 1.55) more likely (relative to zero meat intake) to develop diabetes. (2) Subjects who consumed any processed meats (salted fish and frankfurters) were 38% (OR = 1.38; 95% CI 1.05–1.82) more likely to develop diabetes. (3) Long-term adherence (over a 17-year interval) to a diet that included at least weekly meat intake was associated with a 74% increase (OR = 1.74; 95% CI 1.36–2.22) in odds of diabetes relative to long-term adherence to a vegetarian diet (zero meat intake). Further analyses indicated that some of this risk may be attributable to obesity and/or weight gain – both of which were strong risk factors in this cohort. It is noteworthy that even after control for weight and weight change, weekly meat intake remained an important risk factor (OR = 1.38; 95% CI 1.06–1.08) for diabetes. Conclusions: Our findings raise the possibility that meat intake, particularly processed meats, is a dietary risk factor for diabetes.