Desserts, candies, and sugary baked goods are known to raise blood sugar levels and are often avoided by people concerned with their glycemic health.^1–4 However, chocolate intake for metabolic health has been a controversy, with observational studies showing inconsistent results. A large prospective cohort study published in December 2024 by The BMJ sheds a new light to this controversy, finding that regular consumption of dark chocolate may lower the risk of type 2 diabetes mellitus (T2DM).⁵

Data from three large prospective cohorts were analyzed in the study: the Nurses’ Health Study (NHS) 1976, NHSII 1989, and the Health Professionals Follow-Up Study (HPFS) 1986. A total of 111,654 participants were included and data on frequency of milk and dark chocolate intake, self-reported T2DM diagnosis, and changes in bodyweight were collected and analyzed.

After adjusting for personal, lifestyle, and dietary factors, the study found that consuming at least five servings of any type of chocolate every week was associated with a 10% lower risk of developing T2DM when compared to never or rarely consuming any chocolate. In a sub-analysis, this effect was even more pronounced for dark chocolate. Consuming >5 servings of dark chocolate/week was associated with a 21% lower risk of T2DM. Milk chocolate consumption did not affect T2DM risk but was associated with long-term weight gain.

This study is observational in nature and therefore a causal relationship between dark chocolate intake and reduced T2DM risk cannot be drawn. However, this calls for rigorous randomized controlled trials to be conducted to assess the effect of dark chocolates on the risk of T2DM. The authors of the study hypothesize that the high contents of flavanol in chocolate, known to be associated with decreased risk of T2DM, may explain the results of this study. Flavonoids are known to have anti-inflammatory, antioxidant, and vasodilatory effects that have cardiometabolic benefits. Additionally, dark chocolates are lowers in sugar and milk content when compared to milk chocolates and may explain why regular consumption of milk chocolate was associated with weight gain but without benefits to T2DM risk.