In 2025, Seyed Mohammad Mousavi and team from Harvard T.H. Chan School of Public Health analyzed data from three large US studies with over 205,000 health professionals followed for nearly 40 years. They tracked potato intake—French fries vs. boiled, baked, or mashed—and diabetes cases, adjusting for lifestyle factors like smoking and exercise. 22,299 people developed type 2 diabetes during the study.