From the Guidelines
Exercise near bedtime generally improves blood sugar control for most people, though individual responses may vary, as supported by the most recent guidelines from 2024 1. When considering the impact of exercise on blood sugar control, it's essential to differentiate between the effects of moderate-intensity versus high-intensity exercise. Moderate-intensity exercise, such as walking, cycling, or light resistance training, tends to enhance insulin sensitivity and glucose uptake by muscles, thereby helping to lower blood sugar levels overnight 1. However, high-intensity exercise right before bed (within 1 hour) might temporarily raise blood sugar in some individuals due to the release of stress hormones like adrenaline and cortisol 1. Key considerations for individuals with diabetes include:
- Monitoring blood sugar before and after evening exercise to prevent potential nighttime hypoglycemia (low blood sugar) 1
- Possibly adjusting medication timing or having a small snack before bed to mitigate risks 1
- Understanding that muscle contractions during physical activity stimulate glucose uptake through non-insulin-dependent pathways, which can enhance the body's ability to regulate blood sugar even while sleeping 1 Given the most recent evidence from 2024, the recommendation is to encourage physical activity, including exercise, as part of a diabetes management plan, with an emphasis on finding a balance that works for each individual, considering factors like exercise intensity, timing, and individual health status 1.
From the Research
Effects of Exercise Timing on Blood Sugar Control
- The timing of exercise can have varying effects on blood sugar control, with some studies suggesting that afternoon exercise may be more beneficial than morning exercise for individuals with type 2 diabetes 2.
- A study found that afternoon high-intensity interval training (HIIT) reduced continuous glucose monitor (CGM)-based glucose concentration, whereas morning HIIT increased it 2.
- Another study discovered that moderate-intensity aerobic exercise before breakfast reduced the morning rise of blood glucose in type 2 diabetic patients and improved blood glucose control throughout the day 3.
- However, a study on young healthy men found that glucose fluctuation was slightly less stable when exercise was performed in the afternoon than in the morning, indicated by higher continuous overall net glycemic action (CONGA) and detrended fluctuation analysis (DFA) values 4.
Postprandial Exercise and Glucose Control
- Postprandial exercise, which is exercise performed after a meal, can reduce postprandial hyperglycemia by increasing contraction-mediated glucose uptake 5.
- A systematic review found that postprandial aerobic exercise decreased short-term glucose area under the curve by 3.4-26.6% and 24-h prevalence of hyperglycemia by 11.9-65% in individuals with type 2 diabetes 5.
- Resistance exercise also appears to be an effective modality for improving glucose control, with one study finding that it decreased the short-term glucose area under the curve by 30% and 24-h prevalence of hyperglycemia by 35% 5.
Comparison of Exercise Types and Glycemic Control
- A randomized controlled study found that yoga was superior to exercise alone in improving glycemic control, anxiety, depression, and quality of life, as well as exercise self-efficacy, in individuals with type 2 diabetes 6.
- The study suggested that yoga may be a useful adjunct to traditional exercise programs for improving glycemic control and psychosocial parameters in type 2 diabetes mellitus 6.