Dark Chocolate, but Not Milk Chocolate, Tracked With Lower Type 2 Diabetes Risk

CATEGORY: METABOLIC & BLOOD SUGAR

Five or more servings of dark chocolate a week tracked with 21% lower risk of developing type 2 diabetes than rarely or never eating it, across three long-running studies of US health professionals.¹ Type 2 diabetes is the condition in which the body loses its grip on blood sugar. Milk chocolate showed nothing of the kind.

192,208 People, 18,862 Cases, and One Smaller Subgroup

The starting group was 192,208 people free of diabetes, heart disease and cancer, drawn from the Nurses’ Health Study, its sequel, and the Health Professionals Follow-Up Study. They reported how often they ate chocolate on food questionnaires repeated over the years. New cases of type 2 diabetes came from follow-up surveys and were confirmed with a validated questionnaire. Across more than 4.8 million combined person-years, 18,862 people developed the condition. The dark chocolate result rests on a smaller slice. It covers the 111,654 participants who reported dark and milk chocolate separately, among whom 4,771 developed type 2 diabetes.¹

Dark and Milk Chocolate Parted Ways

Chocolate of any kind, eaten five or more times a week, went with a 10% lower rate of type 2 diabetes. The pattern was strongest for dark chocolate, which carries more cocoa flavanols, plant compounds thought to influence how the body handles sugar. Each extra weekly serving of dark chocolate was associated with 3% lower risk. Milk chocolate showed no such link. Higher milk chocolate intake went with long-term weight gain instead.

Where the Benefit Peaks Is Still Unsettled

This was observation, not assignment. People ate what they liked and researchers tracked what followed, so other habits of dark chocolate eaters may be doing some of the work. The authors said plainly that randomized trials are still needed. An earlier pooling of five studies covering about 133,000 people also linked chocolate to lower diabetes risk, 18% lower at the highest intakes against the lowest. In that analysis the benefit peaked near two servings a week, about 25% lower risk, with nothing further gained above it.² That work did not separate dark from milk chocolate. Where the peak sits for dark chocolate alone is unknown.

Key Takeaways

• Across three large cohorts, eating dark chocolate at least five times a week went with 21% lower risk of type 2 diabetes.
• Milk chocolate carried no similar association and went with weight gain over time.
• These cohorts watched what people chose to eat, so the finding is a link rather than a demonstrated cause.

References

1. Liu B, Zong G, Zhu L, et al. Chocolate intake and risk of type 2 diabetes: prospective cohort studies. BMJ. 2024;387:e078386. link.
2. Yuan S, Li X, Jin Y, et al. Chocolate consumption and risk of coronary heart disease, stroke, and diabetes: a meta-analysis of prospective studies. Nutrients. 2017;9(7):688. link.