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Diabetologia. 2018 Nov 13. doi: 10.1007/s00125-018-4767-z. [Epub ahead of print]

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

Author information

1
Department of Physiology and Pharmacology, Section of Integrative Physiology, Karolinska Institutet, Solnavägen 9, Biomedicum (C4), 171 77, Stockholm, Sweden.
2
Faculty of Medicine, University of Oslo, Oslo, Norway.
3
Department of Molecular Medicine and Surgery, Section of Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.
4
Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden.
5
The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
6
Department of Physiology and Pharmacology, Section of Integrative Physiology, Karolinska Institutet, Solnavägen 9, Biomedicum (C4), 171 77, Stockholm, Sweden. Harriet.Wallberg@ki.se.

Abstract

AIMS/HYPOTHESIS:

Exercise 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.

METHODS:

Eleven 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.

RESULTS:

Morning 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/INTERPRETATION:

Afternoon 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.

KEYWORDS:

Blood glucose level; Circadian rhythm; Continuous glucose monitoring; Exercise; High-intensity interval training; Type 2 diabetes

PMID:
30426166
DOI:
10.1007/s00125-018-4767-z

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