• A new study suggests that dark chocolate consumption is associated with a significant reduction in type 2 diabetes risk.
• Milk chocolate was not linked to type 2 diabetes risk but was instead associated with excessive long-term weight gain.
• Swapping dark chocolate for milk chocolate could benefit health, but experts say moderation is key.
• The best way to reduce the risk of type 2 diabetes is by following a healthy eating pattern low in refined carbohydrates and sugar and getting regular exercise.

Dark chocolate is considered a healthy indulgence, with plenty of research supporting the benefits of this nutritional powerhouse, even for those with type 2 diabetes.

Some studies have explored the positive effects of cocoa antioxidants on type 2 diabetes risk, but the findings have been inconsistent. Fewer studies have compared the effects of dark chocolate to those of milk chocolate.

An observational study published online on December 4 in The BMJ suggests that dark chocolate, not milk chocolate, may help lower the risk of type 2 diabetes (T2D). Participants who consumed five or more weekly servings of dark chocolate had a 21% lower risk of developing type 2 diabetes.

The researchers also found that milk chocolate had a minimal effect on diabetes risk. Instead, it was linked to excessive long-term weight gain, a known risk factor for type 2 diabetes.

“Our findings suggest that not all chocolate is created equal,” lead author Binkai Liu, a doctoral student in the Department of Nutrition at Harvard T.H. Chan School of Public Health, said in a statement.

“For anyone who loves chocolate, this is a reminder that making small choices, like choosing dark chocolate over milk chocolate, can make a positive difference to their health.”

How dark vs. milk chocolate affects diabetes risk

Harvard researchers used data from 192,000 adults in the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study.

Participants reported their diabetes status, body weight, and food habits, including chocolate consumption, over a 30-year period. All subjects did not have diabetes at the start of the study.

By the end of the study, almost 19,000 people were diagnosed with type 2 diabetes. Of the nearly 112,000 people who reported chocolate intake, 5,000 developed the condition.

Compared to subjects who rarely consumed chocolate, those who consumed at least 5 ounces of chocolate per week had a 10% reduced risk of developing type 2 diabetes.

However, those who consumed dark chocolate experienced the greatest risk reduction. For every serving of dark chocolate consumed each week, there was a 3% reduced risk of developing type 2 diabetes. Overall, those who consumed dark chocolate had a 21% lower risk of developing the condition.

However, milk chocolate consumption contributed to long-term weight gain, likely due to higher levels of lactose and added sugar.

“We were most surprised by the stark contrast in the impact of dark and milk chocolate on diabetes risk and long-term weight management,” Binkai told Healthline.

“Despite having similar energy and saturated fat levels, dark chocolate appears to offer protective effects, likely due to its rich polyphenol content. This intriguing difference highlights the potential role of polyphenols in shaping health outcomes and warrants further exploration,” she added.

The authors say choosing dark chocolate over milk chocolate could positively impact health. However, they note that participants’ chocolate intake was relatively low compared to the national average. These findings, therefore, may not apply to those who consume a lot of chocolate.

Additionally, Binkai noted the researchers did not have data on specific percentages of cocoa in chocolate or on specific brands or quality of chocolate consumed (i.e., whether it was organic or conventional).

“To confirm these findings, further research should focus on conducting randomized controlled trials among middle-aged participants, ideally with longer durations. Such studies would help establish causality and provide deeper insights into the underlying mechanisms driving these associations,” she said.

Why is dark chocolate so healthy?

Dark chocolate is a rich source of antioxidants, which could help lower inflammation and reduce insulin resistance in type 2 diabetes.

Dark chocolate contains at least 50% cocoa, while milk chocolate contains less cocoa and often more added sugar. The higher the cocoa and lower the sugar content, the greater the health benefits.

“Cocoa is rich in bioactive compounds such as flavan-3-ols, which have been shown to improve insulin sensitivity and exhibit antioxidant and anti-inflammatory properties. These polyphenol compounds likely play a key role in the observed reduction in type 2 diabetes risk,” Binkai explained.

“While dark and milk chocolate contain similar levels of saturated fat and sugar, we observed a clear difference in their associations with weight gain. The exact mechanism remains unclear, but it is possible that the polyphenols in dark chocolate counteract the negative effects of saturated fat and sugar on weight gain and other cardiometabolic outcomes. This protective factor may be less present or absent in milk chocolate due to its lower cocoa content,” she said.

Kelsey Costa, MS, RDN, a registered dietitian nutritionist and founder of Dietitian Insights, explained further that, unlike milk chocolate, dark chocolate is rich in flavonoids like epicatechin and catechin. Costa wasn’t involved in the study.

“While the mechanisms aren’t entirely clear, flavonoids appear to improve insulin sensitivity by enhancing endothelial (blood vessel cell) function, reducing oxidative stress, and regulating glucose metabolism,” Costa told Healthline.

“Dark chocolate flavonoids may also inhibit certain enzymes, like alpha-glucosidase, which breaks down carbohydrates into glucose in our small intestine. Inhibiting this enzyme may slow glucose absorption and help prevent post-meal blood sugar spikes,” she noted.

“These potential effects contribute to dark chocolate’s role in reducing the risk of type 2 diabetes and promoting metabolic health, unlike milk chocolate, which usually contains far more added sugar and fewer of these beneficial compounds,” she said.

Costa explained that true dark chocolate with at least 70% cocoa content is higher in antioxidants and lower in sugar compared to other forms of chocolate.

“Dark chocolate (70%) has a lower glycemic index than milk chocolate, leading to a slower, more gradual rise in blood sugar levels. This is likely due to its unique composition, which includes healthy fats like cocoa butter, powerful flavonoid antioxidants, and a lower sugar content,” she said.

Everything in moderation, even dark chocolate

Dark chocolate comes in many forms and varies in cocoa percentages, quality, manufacturing processes, etc. Some brands may contain unhealthy hidden ingredients and higher amounts of sugar.

Despite the known benefits, dark chocolate is often high in sugar and fat and may not be the best recommendation for lowering diabetes risk, according to Pouya Shafipour, MD, board certified family and obesity medicine physician at Providence Saint John’s Health Center in Santa Monica, CA. Shafipour was not involved in the study.

“It’s not really standardized like a drug or a specific supplement,” Shafipour told Healthline. “Is it something that I would recommend as a treatment modality for diabetes? Probably not. It would be an alternative healthy snack for people to have 4 to 5 ounces a week as a treat in place of milk chocolate, candy, or other sweets,” he said.

For those at risk for prediabetes and type 2 diabetes, Shafipour recommended capping your dark chocolate intake at 5 ounces per week.

“Insulin resistance and higher fasting glucose are not uncommon. Everything in moderation,” he said.

Costa agreed but said most healthy individuals can safely consume 1 to 2 ounces of 70% dark chocolate daily.

“Be mindful of calorie intake when adding dark chocolate to your diet, and choose options with minimal added sugar. If it fits your budget, choose organic, fair trade varieties for a healthier and more ethical option,” she said. “Dark chocolate will offer the most benefits when enjoyed in moderation as part of a balanced, plant-rich diet.”

Other ways to reduce diabetes risk

Swapping dark for milk chocolate may not be enough to reduce the risk of type 2 diabetes, especially if you have a genetic predisposition or other risk factors like high body mass index (BMI).

Shafipour recommended individuals at risk follow a low- or no-carbohydrate diet and adhere to a healthy eating pattern like the Mediterranean diet. He also recommended practicing intermittent fasting (IF) and getting enough dietary fiber.

A few servings of dark chocolate a week may be OK for most people. Other ideas for antioxidant-rich snacks include:

• apples
• berries
• melons
• grapefruit
• cucumber
• black or green tea

Diet aside, lifestyle choices can make a big impact on diabetes risk. To stay healthy long term, experts generally recommend the following:

• regular physical activity
• non-exercise physical activity (i.e., taking the stairs)
• limit or avoid alcohol
• quit smoking (if you smoke)
• getting 7–8 hours of quality sleep

Takeaway

Dark chocolate, in moderation, can be a healthy indulgence for people with type 2 diabetes, a condition that causes blood sugar levels to spike.

A new observational study concludes that dark chocolate, compared to milk chocolate, could help lower type 2 diabetes risk by 21%.

Experts say dark chocolate should be consumed in moderation alongside a healthy, balanced diet low in carbohydrates and sugar and rich in antioxidants. Healthy lifestyle habits, like regular exercise and adequate sleep, are also beneficial for maintaining overall health.