Researchers followed nearly 13,300 people with type 2 diabetes for almost 12 years to see how diet and biological aging affected serious health problems. They found that people who ate healthier diets had slower biological aging (meaning their bodies functioned younger than their actual age) and were significantly less likely to develop three major diabetes complications: eye disease, kidney disease, and nerve damage. The study suggests that eating well doesn’t just help you feel better today—it may actually slow down how fast your body ages at a cellular level, which protects you from serious diabetes-related problems.

The Quick Take

  • What they studied: Whether eating a healthy diet and having a younger biological age (body functioning younger than actual age) could prevent serious complications from type 2 diabetes, like eye problems, kidney damage, and nerve damage.
  • Who participated: 13,294 people with type 2 diabetes who didn’t have these complications at the start of the study. Researchers tracked them for an average of almost 12 years.
  • Key finding: People with the healthiest diets had about 15-23% lower risk of developing diabetes complications. When people had both a healthy diet AND slower biological aging, their risk dropped by 30-54% depending on the type of complication.
  • What it means for you: If you have type 2 diabetes, eating a healthier diet may help protect you from serious complications and may actually slow down how your body ages. This suggests diet is one of the most powerful tools you have to prevent these problems, though you should work with your doctor on a plan that’s right for you.

The Research Details

This was a long-term follow-up study where researchers tracked the same group of people over time. They measured how well each person followed a healthy diet using a 10-point scoring system (higher scores meant healthier eating). They also calculated each person’s “biological age” using nine different measurements from blood tests and other health markers, comparing it to their actual age. Some people’s bodies were functioning younger than their actual age (slower aging), while others’ bodies were functioning older (faster aging).

Over nearly 12 years, researchers watched to see who developed three types of diabetes complications: diabetic retinopathy (eye disease), diabetic nephropathy (kidney disease), and diabetic neuropathy (nerve damage). They used statistical methods to figure out which factors—diet, biological age, or both together—were most protective.

This study design is powerful because it follows real people over many years in their normal lives, rather than testing them in a lab. This makes the results more realistic and applicable to everyday people. By measuring biological age (how old your body actually functions) rather than just calendar age, researchers could see whether diet actually slows down aging at a cellular level, not just whether it prevents disease.

This study has several strengths: it included a large number of participants (over 13,000), followed them for a long time (almost 12 years), and used validated methods to measure diet and biological age. The researchers also used advanced statistical methods to separate the effects of diet from biological aging. However, the study was observational, meaning researchers watched what people naturally did rather than randomly assigning them to different diets, so we can’t be 100% certain diet caused the benefits.

What the Results Show

People who scored highest on the healthy diet scale (scores of 6-10 out of 10) had significantly lower risks of developing diabetes complications compared to those with lower diet scores. Specifically, they had about 15% lower risk of overall complications, 20% lower risk of eye disease, and 23% lower risk of kidney disease. Interestingly, diet didn’t seem to protect against nerve damage as much as it did for the other two complications.

When researchers looked at biological aging separately, people whose bodies were aging slower (biological age younger than actual age) also had lower complication risks. But the most impressive finding was when both factors came together: people who ate healthy AND had slower biological aging had the biggest protection. For example, they had 39% lower risk of overall complications, 31% lower risk of eye disease, 54% lower risk of kidney disease, and 42% lower risk of nerve damage.

The mediation analysis revealed something important: about 43% of the protective benefit from eating a healthy diet came through slowing biological aging. In other words, eating well partly works by making your body age more slowly, which then protects you from complications. This suggests that diet affects aging at a deep biological level, not just surface-level health.

The study found that the protective effects were strongest for kidney disease (53.6% risk reduction with both healthy diet and slower aging) compared to eye disease (30.8% reduction) and nerve damage (41.9% reduction). This suggests that diet and biological aging may be especially important for kidney health in people with diabetes. The fact that diet showed less protection against nerve damage suggests that nerve complications may be influenced by different factors that diet alone can’t address.

Previous research has shown that healthy diets help people with diabetes, but this study adds an important new piece: it shows that diet works partly by slowing biological aging. Earlier studies focused mainly on preventing disease, but this research suggests the mechanism is deeper—diet actually affects how fast your body ages at a cellular level. This aligns with growing evidence that biological aging is a key factor in many age-related diseases.

The study was observational, meaning people chose their own diets rather than being randomly assigned to eat differently, so we can’t prove diet directly caused the benefits. The study also measured diet at one point in time, so it didn’t track whether people’s eating habits changed over the 12 years. Additionally, the study population may not represent all people with diabetes (participants were likely from specific healthcare systems), so results might differ in other populations. Finally, the study measured biological age using specific biomarkers, and other ways of measuring biological age might give different results.

The Bottom Line

If you have type 2 diabetes, focus on eating a healthier diet as one of your most important tools for preventing serious complications. The evidence suggests aiming for a diet score of 6-10 out of 10 on healthy eating scales (typically meaning plenty of vegetables, fruits, whole grains, and lean proteins while limiting processed foods and added sugars). This recommendation has moderate-to-strong evidence behind it. Work with your doctor or a diabetes educator to develop a specific eating plan that works for you. Also maintain other important diabetes management strategies like regular physical activity, medication adherence, and regular health check-ups.

This research is most relevant for people with type 2 diabetes who want to prevent serious complications. It’s also important for people at risk of developing type 2 diabetes, as eating a healthy diet may prevent diabetes in the first place. Healthcare providers treating diabetes should consider emphasizing diet as a key part of preventing complications. Family members of people with diabetes may also benefit from understanding how diet affects long-term health. However, this study doesn’t directly apply to people with type 1 diabetes or those without diabetes, though healthy eating is beneficial for everyone.

You likely won’t notice dramatic changes immediately, but research suggests that eating a healthier diet can start improving your biological aging markers within weeks to months. However, the major benefits in preventing serious complications typically develop over years. The people in this study were followed for almost 12 years, and that’s the timeframe over which significant protection became clear. This means you should think of healthy eating as a long-term investment in your health, not something that will fix problems overnight.

Want to Apply This Research?

  • Track your daily diet quality using a simple scoring system: assign points for eating vegetables (1 point per serving), fruits (1 point per serving), whole grains (1 point per serving), lean proteins (1 point per serving), and limit processed foods and added sugars (subtract points for these). Aim to accumulate 6-10 points daily and monitor your weekly average.
  • Set a specific, achievable goal like “add one extra vegetable serving to dinner three times this week” or “replace one sugary drink with water daily.” Use the app to log these changes and celebrate small wins. Start with one change rather than trying to overhaul your entire diet at once.
  • Review your diet quality score weekly and monthly to see trends. If possible, work with your healthcare provider to check biological aging markers (through blood tests) every 6-12 months to see if your healthier eating is actually slowing your biological aging. Track any changes in diabetes-related symptoms or complications with your doctor during regular check-ups.

This research suggests associations between healthy diet, biological aging, and reduced diabetes complications, but it does not prove that diet directly causes these benefits. This information is for educational purposes and should not replace professional medical advice. If you have type 2 diabetes, consult with your doctor or a registered dietitian before making significant dietary changes. The study followed people over many years, so individual results may vary. Always work with your healthcare team to develop a personalized diabetes management plan that includes diet, medication, exercise, and regular monitoring.