Researchers studied over 7,600 people with diabetes to see if eating a Mediterranean-style diet could protect their hearts. The Mediterranean diet focuses on vegetables, fruits, whole grains, olive oil, and fish. After following these people for about 13 years, scientists found that those who followed this diet most closely had an 18.5% lower chance of developing heart disease compared to those who followed it least. However, the protection disappeared for current smokers. This suggests that eating well matters for people with diabetes, but quitting smoking is equally important for heart health.

The Quick Take

  • What they studied: Whether eating a Mediterranean-style diet (lots of vegetables, fruits, fish, and olive oil) could help people with diabetes avoid heart disease
  • Who participated: 7,606 people with diabetes from the UK Biobank study, tracked for an average of 13 years. The group included both men and women of various ages and income levels
  • Key finding: People who followed the Mediterranean diet most closely had an 18.5% lower risk of developing heart disease compared to those who followed it least. This benefit was consistent across most groups, but completely disappeared in current smokers
  • What it means for you: If you have diabetes, eating Mediterranean-style foods may help protect your heart—but only if you don’t smoke. Smokers didn’t see any heart protection from the diet, suggesting smoking cancels out the benefits. This is strong motivation to quit smoking if you’re a smoker with diabetes

The Research Details

This was a cohort study, which means researchers followed a large group of people over time and tracked what happened to them. Scientists looked at 7,606 people with diabetes from the UK Biobank (a huge database of health information) and measured how closely each person followed a Mediterranean diet pattern. They then watched these people for about 13 years to see who developed heart disease.

Researchers used a scoring system to measure how well people followed the Mediterranean diet. They looked at things like how much fish, vegetables, fruits, and olive oil people ate. Then they used statistical tools to figure out whether people who scored higher on this diet scale were less likely to develop heart disease compared to those who scored lower.

The study also looked at whether other factors—like smoking, income, gender, and exercise—changed how well the diet worked. This helps explain why the diet might work better for some people than others.

Cohort studies are valuable because they follow real people in their everyday lives over long periods. This gives us a realistic picture of how diet affects health in the real world, rather than in a controlled lab setting. The 13-year follow-up period is long enough to see real health outcomes like heart disease develop. By looking at subgroups (different types of people), the study helps us understand who benefits most from dietary changes.

This study has several strengths: it included a large number of people (7,606), had a long follow-up period (13 years), and adjusted for many other factors that could affect heart disease risk. However, it’s a cohort study rather than a randomized controlled trial, which means we can’t be 100% certain the diet caused the benefit—other unmeasured factors could be involved. The study was also conducted in the UK, so results might differ in other populations. The researchers did sensitivity analyses to check their findings, which adds confidence to the results.

What the Results Show

Among the 7,606 people with diabetes studied, 1,173 developed heart disease during the follow-up period. People who followed the Mediterranean diet most closely (the highest quarter) had an 18.5% lower risk of developing heart disease compared to those who followed it least closely (the lowest quarter). This means if 100 people in the lowest diet group developed heart disease, only about 82 people in the highest diet group would develop it.

The benefit was consistent across different statistical models, meaning the researchers tested the findings in multiple ways and got similar results each time. The trend was very statistically significant (P-values less than 0.001), which means this result is very unlikely to have happened by chance.

However, the benefits were not equal for everyone. The diet worked best for non-smokers and people who had quit smoking. Surprisingly, current smokers showed no benefit from following the Mediterranean diet—in fact, the diet appeared to have no protective effect for this group. This suggests that smoking completely overrides the heart-protective benefits of healthy eating.

The study found that the diet’s benefits were stronger in certain groups: white people, men, and people with higher incomes saw more protection. The researchers also discovered that physical activity and education level affected how well the diet worked, though these factors weren’t part of the main analysis. People with more education and those who exercised regularly seemed to benefit more from the Mediterranean diet.

Previous research has shown that the Mediterranean diet is good for heart health in the general population. This study confirms that benefit extends to people with diabetes, which is important because diabetics have higher heart disease risk. The finding that smoking cancels out the diet’s benefits aligns with what we know about smoking’s powerful negative effects on heart health. The study adds new information by showing that income and gender can affect how much the diet helps.

This study cannot prove that the diet directly caused the lower heart disease risk—it only shows an association. People who follow the Mediterranean diet might also exercise more, have better healthcare access, or have other healthy habits that protect their hearts. The study relied on people’s memory of what they ate, which can be inaccurate. The results come from UK Biobank participants, who tend to be healthier and wealthier than the general population, so findings might not apply to everyone. Finally, the study couldn’t explain why smoking completely eliminated the diet’s benefits, which is an important gap in understanding.

The Bottom Line

If you have diabetes and don’t smoke, adopting a Mediterranean-style diet appears to be a worthwhile strategy to reduce heart disease risk. Focus on eating more vegetables, fruits, whole grains, fish, and olive oil while limiting red meat. This recommendation has moderate-to-strong evidence from this large, long-term study. If you’re a current smoker with diabetes, the most important step is to quit smoking—the diet alone won’t protect your heart while you smoke. Once you quit, the diet’s benefits should return.

This research is most relevant to people with diabetes who want to reduce their heart disease risk. It’s especially important for people without diabetes to know that the Mediterranean diet is heart-healthy for them too. Current smokers with diabetes should prioritize smoking cessation over diet changes, though ideally they should do both. People with other heart disease risk factors (high blood pressure, high cholesterol) may also benefit from this eating pattern.

Heart disease develops slowly over years, so you shouldn’t expect immediate changes. The study followed people for 13 years, suggesting that the protective benefits build up over time. You might notice improvements in energy, weight, and blood sugar control within weeks to months, but the heart-protective benefits likely take years to fully develop. Consistency matters more than perfection—following the diet most of the time is better than occasional attempts.

Want to Apply This Research?

  • Track daily Mediterranean diet adherence using a simple score: count servings of vegetables (goal: 3+), fruits (goal: 2+), whole grains (goal: 2+), fish (goal: 2-3 times per week), and olive oil use (goal: daily). Rate your adherence on a 1-10 scale each day and monitor weekly trends
  • Start by adding one Mediterranean element to each meal: add olive oil to salads, swap white bread for whole grain, include fish twice weekly, or add extra vegetables to dinner. Use the app to set reminders for these specific swaps and track completion
  • Weekly check-ins on diet adherence score, monthly reviews of average adherence, and quarterly assessments of how you’re feeling (energy, blood sugar stability). If you smoke, set a quit date in the app and track smoke-free days, as quitting is essential for the diet’s heart benefits to work

This research suggests an association between Mediterranean diet adherence and reduced heart disease risk in people with diabetes, but it does not prove causation. These findings should not replace medical advice from your doctor. If you have diabetes or heart disease risk factors, consult with your healthcare provider before making major dietary changes or starting any new health regimen. This is especially important if you take medications that interact with dietary changes. People with specific health conditions, allergies, or dietary restrictions should work with a registered dietitian to adapt Mediterranean diet principles to their individual needs.