In a large study of nearly 200,000 US adults, those eating whole grains most frequently had a 29% lower risk of developing type 2 diabetes across the approximately 30-year study period than those rarely or never eating whole grains, even after adjusting for other lifestyle factors.
When looking at specific whole grain foods, common foods like whole grain breakfast cereal, oatmeal, whole grain bread, and brown rice were all linked with a lower risk of type 2 diabetes. The exception was popcorn, which was linked with a higher risk of type 2 diabetes when eaten more than once per day, perhaps because popcorn is often prepared with butter sauces and/or sugary toppings.
