Afternoon exercise is more efficacious than morning exercise at improving blood glucose levels in individuals with type 2 diabetes: a randomised crossover trial

Abstract

Aims/hypothesisExercise is recommended for the treatment and prevention of type 2 diabetes. However, the most effective time of day to achieve beneficial effects on health remains unknown. We aimed to determine whether exercise training at two distinct times of day would have differing effects on 24 h blood glucose levels in men with type 2 diabetes.MethodsEleven men with type 2 diabetes underwent a randomised crossover trial. Inclusion criteria were 45–68 years of age and BMI between 23 and 33 kg/m2. Exclusion criteria were insulin treatment and presence of another systemic illness. Researchers were not blinded to the group assignment. The trial involved 2 weeks of either morning or afternoon high-intensity interval training (HIIT) (three sessions/week), followed by a 2 week wash-out period and a subsequent period of the opposite training regimen. Continuous glucose monitor (CGM)-based data were obtained.ResultsMorning HIIT increased CGM-based glucose concentration (6.9 ± 0.4 mmol/l; mean ± SEM for the exercise days during week 1) compared with either the pre-training period (6.4 ± 0.3 mmol/l) or afternoon HIIT (6.2 ± 0.3 mmol/l for the exercise days during week 1). Conversely, afternoon HIIT reduced the CGM-based glucose concentration compared with either the pre-training period or morning HIIT. Afternoon HIIT was associated with elevated thyroid-stimulating hormone (TSH; 1.9 ± 0.2 mU/l) and reduced T4 (15.8 ± 0.7 pmol/l) concentrations compared with pre-training (1.4 ± 0.2 mU/l for TSH; 16.8 ± 0.6 pmol/l for T4). TSH was also elevated after morning HIIT (1.7 ± 0.2 mU/l), whereas T4 concentrations were unaltered.Conclusions/interpretationAfternoon HIIT was more efficacious than morning HIIT at improving blood glucose in men with type 2 diabetes. Strikingly, morning HIIT had an acute, deleterious effect, increasing blood glucose. However, studies of longer training regimens are warranted to establish the persistence of this adverse effect. Our data highlight the importance of optimising the timing of exercise when prescribing it as treatment for type 2 diabetes.

Effects of Exercise on Blood Glucose and Glycemic Variability in Type 2 Diabetic Patients with Dawn Phenomenon

“…Exercise increases the concentration of GLUT-4 in the cell membrane and increases glucose uptake in skeletal muscles [22][23][24]. Acute exercise increases glucose tolerance and insulin sensitivity and blood glucose reduction within 20-72 h, depending on the exercise intensity, form, duration, and observation time [25][26][27][28][29][30][31][32][33]. Studies have shown that acute moderate-intensity endurance training leads to a reduction in blood glucose levels [25,30], whereas light and short resistance and endurance training shows no effect [30,31].…”

The importance of being rhythmic: Living in harmony with your body clocks

“…Beneficial effects of time-restricted feeding for weight loss and metabolic improvement have been recently established in rodents, 194,195 followed by emerging translational studies in humans. 203,204 Understanding the function of the human circadian timing system has a tremendous application in chronopharmacology. 202 Furthermore, recent evidence suggests that timed exercise has the potential to improve metabolic characteristics.…”

“…202 Furthermore, recent evidence suggests that timed exercise has the potential to improve metabolic characteristics. 203,204 Understanding the function of the human circadian timing system has a tremendous application in chronopharmacology. 205 Indeed, liver clocks have important impact on the response to numerous medications, which should certainly be F I G U R E 3 Clock in the dish: approaches for molecular in-vitro studies of human peripheral oscillators.…”

Relationship of Consistency in Timing of Exercise Performance and Exercise Levels Among Successful Weight Loss Maintainers

“…Future research should also examine potential biological benefits of performing PA at certain times of the day. For example, there are mixed findings about the time of day at which PA may optimally influence blood sugar control .…”