Researchers in Finland followed over 1,100 adults for 22 years to find the best ways to predict who might develop diabetes. They tested five different body measurements, including the familiar BMI (body mass index) and newer options like waist-to-hip ratio and relative fat mass. The study found that different measurements work better for men versus women, and using multiple measurements together gives the most accurate predictions. These findings could help doctors identify people at risk for diabetes earlier, allowing for better prevention and treatment strategies tailored to each person’s needs.

The Quick Take

  • What they studied: Which body measurements are best at predicting who will develop diabetes or pre-diabetes over time
  • Who participated: 1,168 adults aged 50 and older from a town in Finland, tracked for 22 years with health check-ups at the start, 10 years, and 22 years
  • Key finding: Waist-to-hip ratio worked best for men (70% accuracy), while relative fat mass and waist-to-height ratio worked equally well for women (68% accuracy). Using multiple measurements together improved predictions for everyone
  • What it means for you: If you’re concerned about diabetes risk, doctors may soon have better tools than just BMI to assess your personal risk. This could lead to earlier detection and more personalized prevention plans, though these findings need to be tested in other populations before becoming standard practice

The Research Details

This was a long-term observational study, meaning researchers followed the same group of people over 22 years without randomly assigning them to different treatments. They collected body measurements and blood tests at three time points: at the beginning, after 10 years, and after 22 years. The researchers measured five different body indicators: BMI (weight divided by height squared), waist-to-hip ratio (waist size compared to hip size), waist-to-height ratio (waist size compared to height), waist circumference (how wide the waist is), and relative fat mass (an estimate of body fat percentage). They also tracked who developed diabetes or intermediate hyperglycaemia (a pre-diabetes condition) using blood sugar tests and medical records.

BMI has been the standard measurement for decades, but it doesn’t account for where fat is stored on the body. Some people carry more fat around their belly, which is riskier for diabetes than fat stored elsewhere. By testing alternative measurements over a very long period, this study provides real-world evidence about which measurements actually predict diabetes development best. The 22-year timeframe is particularly valuable because it shows long-term predictive power rather than just short-term associations.

This study has several strengths: it followed people for 22 years (providing strong evidence), used actual diabetes diagnoses rather than just predictions, and included both men and women. However, all participants were from one Finnish town and were at least 50 years old, so results may not apply equally to younger people or different ethnic groups. The study also relied on people attending follow-up appointments, which could have introduced bias if certain types of people were more likely to drop out

What the Results Show

For men, waist-to-hip ratio was the most accurate predictor of diabetes development, correctly identifying risk about 70% of the time. For women, two measurements tied for best performance: relative fat mass and waist-to-height ratio, each correctly identifying risk about 68% of the time. These accuracy rates were similar to or slightly better than BMI alone. For intermediate hyperglycaemia (pre-diabetes), relative fat mass and waist-to-hip ratio worked best in men, while waist-to-height ratio was most accurate in women. The differences between measurements were relatively small, suggesting that several different approaches could work well. When researchers combined multiple measurements together, they could identify people at risk more reliably than using any single measurement alone.

The study found that sex differences were important—the best measurement for men wasn’t necessarily the best for women. This suggests that future screening programs should use different cutoff values and possibly different measurements for men versus women. The fact that combining multiple measurements improved predictions suggests that a personalized approach using several indicators together might be more effective than relying on one number. The study also confirmed that all these measurements were better predictors than age alone, indicating that body composition matters significantly for diabetes risk.

Previous research has questioned whether BMI alone is sufficient for diabetes prediction because it doesn’t distinguish between muscle and fat, and doesn’t account for where fat is stored. This study supports those concerns by showing that alternative measurements can perform equally well or better. The finding that waist-related measurements (waist-to-hip and waist-to-height ratios) are particularly predictive aligns with earlier research suggesting that belly fat is especially risky for diabetes. However, the relatively modest accuracy rates (around 68-70%) suggest that body measurements alone cannot perfectly predict who will develop diabetes—other factors like genetics, diet, and physical activity also play important roles.

The study only included people aged 50 and older from Finland, so results may not apply to younger adults or people from different ethnic backgrounds. All participants were relatively healthy enough to attend follow-up appointments, which may have excluded people at highest risk. The study measured body composition at only three time points over 22 years, so changes in body shape between measurements weren’t captured. Additionally, the accuracy rates, while useful, still mean that many people would be incorrectly classified as high or low risk using these measurements alone. The study is observational, so it shows associations but cannot prove that body measurements directly cause diabetes

The Bottom Line

If you’re 50 or older, ask your doctor about using multiple body measurements (not just BMI) to assess your diabetes risk. This is particularly relevant if you have a family history of diabetes or other risk factors. The evidence suggests moderate confidence in using these measurements for risk assessment, but they should be combined with other health information like blood sugar levels, family history, and lifestyle factors. These measurements may be especially useful for identifying people who need lifestyle changes or closer monitoring

Adults aged 50 and older should pay attention to these findings, particularly those with risk factors for diabetes. Healthcare providers and public health officials should consider implementing multi-measurement screening approaches. People with normal BMI but high waist circumference may particularly benefit from this research, as they might be at higher risk than BMI alone suggests. However, these findings are most directly applicable to people of European descent and may need adjustment for other populations

Diabetes typically develops gradually over years, so these measurements predict risk over a long timeframe (the study tracked people for 22 years). If you make lifestyle changes based on these measurements, you might see improvements in body composition within 3-6 months, though the full benefit for diabetes prevention may take longer. Regular monitoring every 1-2 years would be reasonable for tracking changes in these measurements

Want to Apply This Research?

  • Track waist circumference (measured at the narrowest point) and hip circumference monthly, then calculate your waist-to-hip ratio by dividing waist by hip measurement. For women, also track waist-to-height ratio by dividing waist circumference by height. Record these alongside your weight to see which measurements change most with lifestyle modifications
  • Use the app to set a specific waist circumference goal based on your height and sex (your doctor can help determine a healthy target). Create reminders to measure yourself monthly and log the results. If your measurements aren’t improving, use the app to adjust your activity level or nutrition tracking, focusing on the behaviors most likely to reduce belly fat, such as increasing physical activity and reducing processed foods
  • Set up quarterly reviews comparing your measurements to baseline. Create alerts if waist-to-hip ratio or waist-to-height ratio increases beyond your target range. Combine this with periodic blood sugar testing (as recommended by your doctor) to track actual diabetes risk, not just measurements. Use trend analysis in the app to identify patterns—for example, whether your measurements increase during certain seasons or after lifestyle changes

This research provides evidence about body measurements and diabetes risk, but should not be used for self-diagnosis. If you’re concerned about diabetes risk, consult with your healthcare provider who can evaluate your individual risk factors, perform appropriate blood tests, and recommend personalized prevention strategies. These findings are based on a study of adults aged 50+ in Finland and may not apply equally to all populations. Body measurements are one tool among many for assessing diabetes risk; they should be combined with blood sugar testing, family history, and lifestyle assessment for comprehensive risk evaluation. Always seek professional medical advice before making significant health decisions based on research findings.