Eating French Fries May Be Associated with 20 Percent Increased Risk of T2DM: Study - Video

A new study led by the Harvard T.H. Chan School of Public Health and published in the BMJ has found that consuming French fries three times a week is associated with a 20% increased risk of developing type 2 diabetes (T2D). In contrast, other forms of potatoes—such as baked, boiled, or mashed—did not show a significant link to diabetes risk. The study also found that replacing any type of potato with whole grains may reduce the risk of T2D.

The study, described as the most comprehensive of its kind on the relationship between potatoes and diabetes, followed the diets of 205,107 adults over several decades. It analyzed participants from the Nurses’ Health Study, Nurses’ Health Study II, and the Health Professionals Follow-up Study. Over 30 years, these individuals regularly completed dietary questionnaires and reported health conditions, including T2D diagnoses. During the study period, 22,299 participants developed type 2 diabetes.

The findings revealed that while French fries significantly raised T2D risk, baked, boiled, and mashed potatoes did not. Replacing any form of potatoes with whole grains like brown rice, whole grain pasta, or farro was linked to reduced diabetes risk. Notably, swapping French fries with whole grains cut the risk by 19%.

The researchers also used a meta-analytic approach based on 24 prior cohort studies to validate their findings, involving over 500,000 participants and 43,000 T2D cases globally.

“The public health message here is simple and powerful: Small changes in our daily diet can have an important impact on risk of type 2 diabetes. Limiting potatoes—especially limiting French fries—and choosing healthy, whole grain sources of carbohydrate could help lower the risk of type 2 diabetes across the population,” said corresponding author Walter Willett, professor of epidemiology and nutrition.

Reference: Mousavi S M, Gu X, Imamura F, AlEssa H B, Devinsky O, Sun Q et al. Total and specific potato intake and risk of type 2 diabetes: results from three US cohort studies and a substitution meta-analysis of prospective cohorts BMJ 2025; 390 :e082121 doi:10.1136/bmj-2024-082121