Researchers studied 68 adults with prediabetes—a condition where blood sugar is higher than normal but not yet diabetic—to see what works best to reverse it. They split people into three groups: one did intense interval workouts plus ate fewer calories, one did just the workouts, and one just ate fewer calories. After 13 weeks, the group combining both exercise and dieting saw the biggest improvements in blood sugar levels, heart fitness, and blood pressure. This suggests that combining these two approaches might be more powerful than doing either one by itself.

The Quick Take

  • What they studied: Whether doing intense, short bursts of exercise combined with eating fewer calories works better than doing just one of these things to help people with prediabetes get healthier
  • Who participated: 68 adults (mostly women) with an average age of around 44 years who had prediabetes—meaning their blood sugar was higher than normal but they didn’t have diabetes yet
  • Key finding: People who combined intense interval workouts with a reduced-calorie diet saw their fasting blood sugar drop by about 18.5%, their heart fitness improve by nearly 13%, and their blood pressure decrease by 8.2%—much better results than the other two groups
  • What it means for you: If you have prediabetes, doing intense workouts while also watching your calorie intake may be your best bet to prevent developing diabetes. However, talk to your doctor before starting any new exercise program, especially if you have health concerns

The Research Details

This was a controlled study where researchers randomly assigned 68 people with prediabetes into three equal groups. One group did high-intensity interval training (HIIT)—short bursts of very hard exercise followed by recovery periods—plus ate fewer calories. Another group did only the HIIT workouts. The third group only reduced their calorie intake. Everyone followed their assigned plan for 13 weeks.

Before and after the 13 weeks, researchers measured several important health markers: blood sugar levels when fasting (before eating), how much oxygen people could use during exercise (a measure of heart fitness), blood pressure, and overall diabetes risk using a standard scoring system. They carefully tracked all these measurements to see which group improved the most.

The study was ‘single-blind,’ meaning the people being studied didn’t know which group was expected to do best, which helps prevent bias in how they reported their results.

This research design is strong because it randomly assigned people to groups, which helps ensure the groups were similar at the start. This makes it easier to tell if differences at the end were actually caused by the different treatments rather than by chance or differences between the groups. The 13-week timeframe is long enough to see real changes in the body but short enough to track people carefully.

The study had a reasonable sample size of 68 people, which is decent for this type of research. The researchers measured multiple important health markers, not just one thing. However, the study was relatively short (13 weeks), so we don’t know if these benefits last longer. Also, most participants were women, so results might be different for men. The study was published in a peer-reviewed journal, meaning other experts reviewed it before publication.

What the Results Show

The group that combined intense interval workouts with reduced calorie eating saw the most impressive improvements. Their fasting blood sugar dropped from about 112 to 91 mg/dL—a decrease of about 20 points, or roughly 18.5%. This is important because lower fasting blood sugar means their bodies are handling glucose better and they’re moving away from diabetes.

Their heart fitness also improved significantly. A measure called VO2max—which shows how much oxygen your body can use during exercise—increased by about 13%. This means their hearts and lungs became noticeably more efficient. Their systolic blood pressure (the top number) dropped by about 13 points, from 164 to 150 mmHg, which is a meaningful improvement for heart health.

The group doing only intense workouts saw some improvements, but not as much as the combined group. The group doing only reduced calorie eating saw the least improvement overall. This suggests that combining both strategies creates a more powerful effect than either one alone.

Interestingly, the study found no significant differences between groups in overall body weight or waist circumference, even though other health markers improved. This suggests that the benefits come from the exercise and dietary changes themselves, not just from losing weight.

The study also measured diabetes risk using a standard scoring system called FINDRISC. The combined group showed the greatest reduction in this risk score, meaning they were moving furthest away from developing type 2 diabetes. This is important because prediabetes is essentially a warning sign, and these improvements suggest the intervention is working to prevent the disease from developing.

Previous research has shown that both intense interval training and reduced calorie diets can help with prediabetes, but this study adds important evidence that doing them together appears to work better than either alone. This aligns with what many health experts recommend—a combination approach to managing prediabetes rather than relying on just one strategy.

The study only lasted 13 weeks, so we don’t know if these improvements continue over months or years. Most participants were women (73.5%), so the results might be different for men. The study didn’t include a control group that did nothing, so we can’t compare these results to what happens if people make no changes. Also, we don’t know how well people stuck to their assigned programs, which could affect the results. Finally, this was a relatively small study with only 68 people, so larger studies would help confirm these findings.

The Bottom Line

If you have prediabetes, combining intense interval workouts with eating fewer calories appears to be the most effective approach based on this research (moderate confidence level). Start with talking to your doctor about what’s safe for you. If approved, aim for regular intense interval training sessions combined with a modest reduction in calories. Even if you can’t do both, doing either one is better than doing nothing (high confidence level).

This research is most relevant for adults with prediabetes who want to prevent developing type 2 diabetes. It’s also useful for people with metabolic syndrome or those at high risk for diabetes. People with existing type 2 diabetes, heart disease, or other serious health conditions should consult their doctor before starting intense exercise. Pregnant women and people with certain joint or bone problems should also get medical clearance first.

Based on this study, you might expect to see meaningful improvements in blood sugar and heart fitness within 13 weeks if you stick with the combined approach. However, the biggest benefits likely come from maintaining these habits long-term. Don’t expect overnight results—give yourself at least 4-6 weeks to notice changes, and 8-13 weeks to see significant improvements.

Want to Apply This Research?

  • Track two key metrics weekly: (1) your fasting blood sugar if you can test it (aim to see it decrease over time), and (2) your exercise sessions completed and type (note when you do intense interval workouts). Also log your daily calorie intake to ensure you’re maintaining a modest reduction.
  • Set up reminders for 3-4 intense interval workout sessions per week (each 20-30 minutes), and use the app’s food logging feature to maintain a reduced-calorie diet. Create a simple goal: ‘This week I’ll do 3 HIIT sessions and stay within my calorie target.’ The app can celebrate these wins to keep you motivated.
  • Check in monthly with your health metrics: blood sugar levels (if testing at home), how you feel during exercise (energy levels, endurance), and any changes in blood pressure readings. Use the app to track trends over 3-6 months to see if you’re moving in the right direction. Share these trends with your doctor at regular checkups.

This research suggests that combining intense interval training with reduced calorie eating may help manage prediabetes, but it is not a substitute for medical advice. Always consult with your doctor or healthcare provider before starting any new exercise program or making significant dietary changes, especially if you have prediabetes, diabetes, heart disease, or other health conditions. Results may vary based on individual factors, and this study was conducted over 13 weeks—longer-term effects are not yet known. Do not use this information to replace professional medical diagnosis or treatment.