Diet, Lifestyle, and Genetic Risk Factors for Type 2 Diabetes: A Review from the Nurses’ Health Study, Nurses’ Health Study 2, and Health Professionals’ Follow-Up Study

The vast amount of epidemiological evidence from three large US cohorts (Nurses’ Health Study, Nurses’ Health Study 2, and Health Professionals’ Follow-Up Study) has yielded important information regarding the roles of overall diet, individual foods and nutrients, physical activity, and other lifestyle factors in the development of type 2 diabetes. Excess adiposity is a major risk factor for diabetes, and thus maintaining a healthy body weight and avoidance of excess weight gain during adulthood is the cornerstone of diabetes prevention. Independent of body weight, the quality or type of dietary fat and carbohydrates is more crucial than the quantity in determining diabetes risk. Higher consumption of coffee, whole grains, fruits, and nuts is associated with lower risk of diabetes, whereas regular consumption of refined grains, red and processed meats, and sugar-sweetened beverages including fruits juices is associated with increased risk. Dietary patterns rich in fruits and vegetables, whole grains, and nuts and legumes, but lower in red and processed meats, refined grains, and sugar-sweetened beverages are consistently associated with reduced diabetes risk, even after adjustment for body mass index. The genome-wide association studies conducted in these cohorts have contributed substantially to the discoveries of novel genetic loci for type 2 diabetes and other metabolic traits, although the identified common variants explain only a small proportion of overall diabetes predisposition. Taken together, these ongoing large cohort studies have provided convincing epidemiologic evidence that a healthy diet, together with regular physical activity, maintenance of a healthy weight, moderate alcohol consumption, and avoidance of prolonged sedentary behaviors and smoking would prevent the majority of type 2 diabetes cases.