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

CATEGORY: METABOLIC & BLOOD SUGAR

People who ate at least five servings of dark chocolate a week had a 21% lower risk of developing type 2 diabetes—a condition in which the body struggles to keep blood sugar (glucose) at healthy levels—than those who rarely or never ate it, according to a large analysis of three long-running studies of US health professionals.¹

192,208 Adults Followed, 18,862 Developed Diabetes

Researchers followed 192,208 people who were free of diabetes, heart disease, and cancer at the start, drawing on the Nurses’ Health Study, its follow-up, and the Health Professionals Follow-Up Study. Participants reported how often they ate chocolate on repeated food questionnaires, and new cases of type 2 diabetes were identified through follow-up surveys and confirmed with a validated questionnaire. Over more than 4.8 million combined person-years of follow-up, 18,862 people developed the condition. A smaller group of 111,654 participants reported dark and milk chocolate separately, which let the team compare the two. The dark chocolate finding rests on that smaller subgroup, in which 4,771 people developed type 2 diabetes.¹

Dark and Milk Chocolate Differed

Eating any type of chocolate five or more times a week was linked to a 10% lower rate of type 2 diabetes, but the pattern was strongest for dark chocolate, which is richer in cocoa flavanols—plant compounds thought to influence how the body handles sugar. Each additional weekly serving of dark chocolate was associated with a 3% lower risk. Milk chocolate showed no such link, and higher milk chocolate intake was instead associated with long-term weight gain.

Observational Design Cannot Prove Chocolate Lowers Risk

Because this was an observational study, it can show an association between dark chocolate and lower diabetes risk but cannot prove the chocolate itself is responsible; other habits of dark chocolate eaters may play a role. The researchers noted that randomized trials are still needed to confirm the effect.

Earlier Pooled Analysis Peaked Near Two Weekly Servings

An earlier analysis pooling five studies that tracked about 133,000 people over time also linked chocolate to lower diabetes risk, 18% lower for the highest intakes versus the lowest, but the benefit peaked near two servings a week—about 25% lower risk—with no further gain above that.² That pooled work did not separate dark from milk chocolate, so where the peak benefit sits for dark chocolate alone remains unsettled.

Key Takeaways

• In three large cohorts, eating dark chocolate at least five times a week was associated with a 21% lower risk of type 2 diabetes.
• Milk chocolate showed no similar benefit and was linked to weight gain over time.
• This is an association, not proof of cause and effect.

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.