A large study of over 4,600 people found that the time of day you exercise may be just as important as how much you exercise. Researchers tracked people’s daily activity for 8 years and discovered that those who moved around more in the afternoon and evening had a lower chance of developing type 2 diabetes compared to those who exercised mainly in the morning. Interestingly, exercising late at night appeared to increase diabetes risk. This suggests that shifting your workout time from morning to afternoon could be a simple way to help protect your health.

The Quick Take

  • What they studied: Whether the time of day you exercise affects your chances of developing type 2 diabetes, and what happens if you move your workouts from morning to afternoon or evening
  • Who participated: 4,615 adults from the Netherlands, averaging 59 years old, with no diabetes at the start. About 56% were women. Researchers tracked their daily movement for a full week using special activity monitors
  • Key finding: People who did light or moderate exercise in the afternoon had about 15-18% lower diabetes risk for every extra 10 minutes of activity. Moving a 10-minute workout from morning to afternoon cut diabetes risk by about 29%. However, exercising late at night was linked to higher diabetes risk
  • What it means for you: If you currently exercise in the morning, shifting some activity to the afternoon may offer extra protection against type 2 diabetes. However, this is one study and more research is needed before making major changes to your routine. Talk to your doctor before significantly changing your exercise schedule

The Research Details

This was a long-term tracking study where researchers followed the same group of people over 8 years. At the beginning, none of the 4,615 participants had diabetes. Researchers gave each person a special device called an activPAL monitor to wear for a full week. This device tracked every movement they made, 24 hours a day, and recorded whether the activity was light (like casual walking) or moderate-to-vigorous (like jogging or sports). The researchers then divided the day into four time periods: morning (6 AM to noon), afternoon (noon to 6 PM), evening (6 PM to midnight), and night (midnight to 6 AM). Over the next 8 years, they checked which participants developed type 2 diabetes and compared their activity patterns to those who stayed healthy.

The researchers used advanced statistical methods to account for other factors that affect diabetes risk, including diet, sleep duration, job type, age, and gender. They also used a special technique called ‘isotemporal substitution’ which allowed them to see what would happen if someone moved 10 minutes of activity from one time of day to another—like shifting a morning walk to the afternoon.

This approach is stronger than simply asking people to remember their exercise habits, because the activity monitor objectively recorded every movement without relying on memory.

Understanding when to exercise is important because our bodies follow natural daily rhythms called circadian rhythms. These rhythms affect how our bodies process sugar and manage insulin. By studying real-world activity patterns over many years, this research helps us understand whether timing matters for diabetes prevention. This is more practical than short-term studies because it shows what actually happens to people’s health over time

This study is fairly reliable because it tracked a large number of people (4,615) for a long time (8 years), used objective activity monitors instead of relying on memory, and carefully controlled for other health factors. However, the study only included people from one region in the Netherlands, so results might differ in other populations. Also, only 168 people developed diabetes during the study, which is a relatively small number for drawing strong conclusions about timing effects

What the Results Show

The main finding was that afternoon activity showed the strongest protection against diabetes. For every extra 10 minutes of light activity in the afternoon, diabetes risk dropped by about 18%. For every extra 10 minutes of moderate-to-vigorous activity in the afternoon, risk dropped by about 15%. Evening moderate-to-vigorous activity also helped, cutting risk by about 35% for every 10 minutes.

When researchers looked at what would happen if people shifted their exercise time, the benefits became clearer. Moving 10 minutes of morning light activity to afternoon light activity reduced diabetes risk by 29%. Moving 10 minutes of morning moderate-to-vigorous activity to evening moderate-to-vigorous activity reduced risk by 36%. These are meaningful reductions that suggest timing really does matter.

Surprisingly, morning exercise showed no protective effect against diabetes in this study. This doesn’t mean morning exercise is bad—it just didn’t show the same diabetes-prevention benefits as afternoon or evening activity. The most concerning finding was that moderate-to-vigorous activity done late at night (midnight to 6 AM) was linked to higher diabetes risk, though this was based on very few people doing late-night exercise.

Light activity at night showed no significant association with diabetes risk, suggesting that the timing concern mainly applies to intense exercise. The study also confirmed that overall activity levels matter—people who were more active throughout the day had lower diabetes risk, regardless of when they exercised. This means that while timing appears important, total daily movement is still the foundation of diabetes prevention

Previous research has suggested that circadian rhythms (our body’s internal 24-hour clock) affect how we process sugar and respond to insulin. This study adds to that evidence by showing that afternoon activity may align better with our body’s natural rhythms. Some earlier studies hinted that morning exercise might be better, but this large, long-term study suggests the opposite. The findings about late-night activity increasing risk are new and need confirmation in other studies

The study only included people from one region in the Netherlands, mostly middle-aged and older adults, so results might not apply to younger people or different populations. Only 168 people developed diabetes during the study, which is a small number for analyzing timing effects—this means some of the findings (especially about night-time activity) are based on very few cases. The study couldn’t prove that timing causes lower diabetes risk, only that it’s associated with it. People’s activity patterns can change over time, but the study only measured activity once at the beginning. Finally, the study couldn’t account for all possible factors affecting diabetes risk, such as family history or stress levels

The Bottom Line

If you currently exercise mainly in the morning, consider shifting some activity to the afternoon or early evening. This may provide extra diabetes protection beyond what morning exercise offers. However, this is based on one study, so don’t make drastic changes without talking to your doctor first. The most important thing is still to stay active throughout the day—the timing benefit appears to be an additional advantage, not a replacement for regular exercise. Avoid intense exercise late at night (after midnight) until more research clarifies whether this timing is truly problematic

This research is most relevant to middle-aged and older adults (50+) who want to prevent type 2 diabetes. If you have a family history of diabetes, are overweight, or have been told you have prediabetes, this timing strategy may be especially worth trying. People who currently exercise mainly in the morning could benefit from shifting some activity to afternoon. However, if you’re already very active and healthy, the timing benefit may be less important than just maintaining your current routine. This research doesn’t apply to people who already have diabetes, as they may need different exercise recommendations

Don’t expect immediate results. The protective effect of afternoon activity builds up over months and years. Based on this study’s 8-year timeframe, you’d need to maintain afternoon activity consistently for several years to see meaningful reductions in diabetes risk. However, exercise provides many other health benefits (better mood, stronger muscles, better sleep) that appear much faster—within weeks to months

Want to Apply This Research?

  • Log the time of day for each exercise session and track it separately by time period (morning, afternoon, evening). Set a goal to gradually shift 30-50% of your weekly activity to the afternoon (12 PM-6 PM) and early evening (6 PM-9 PM) over the next month. Monitor whether you notice changes in energy levels or blood sugar readings if you have a glucose monitor
  • If you currently exercise at 7 AM, try moving one or two workouts per week to 2-4 PM instead. Start small—even moving one 20-minute walk from morning to afternoon counts. Use app reminders to prompt afternoon activity during typical lunch break or late afternoon times. Track which time slots feel most sustainable for you, since the best exercise time is the one you’ll actually stick with
  • Over 3 months, track your activity distribution across time periods and note any changes in energy, sleep quality, or fasting blood sugar if available. Every 3 months, review whether you’ve successfully shifted activity to afternoon/early evening and adjust your goals. If you have access to continuous glucose monitoring or regular blood sugar tests, compare readings before and after shifting your exercise timing. Remember that other factors (diet, sleep, stress) also affect diabetes risk, so don’t attribute all changes to timing alone

This research suggests an association between afternoon exercise and lower diabetes risk, but cannot prove that changing your exercise time will prevent diabetes. Individual results vary based on genetics, diet, sleep, stress, and other factors. Before making significant changes to your exercise routine, especially if you have existing health conditions, prediabetes, or take medications, consult with your doctor or a certified fitness professional. This information is educational and should not replace personalized medical advice. If you have diabetes or symptoms of diabetes, work with your healthcare team on an appropriate exercise plan for your specific situation.