Abstract
Objectives
Hypoglycaemia is a serious complication of exercise in patients with type 2 diabetes mellitus (T2DM). The aim of this study was to test energy expenditure and the degree of the glucose-lowering effect of different exercise modalities.
Design
Cross-sectional study
Participants
This study included 44 patients {35 women and nine men, mean age 51 [standard deviation (SD) 5] years} with T2DM [mean HbA1c 7% (SD 1%)].
Main outcome measures
Standardised exercise tests for walking, running and cycling were performed using the 6-minute walk test (6MWT), incremental shuttle walk test (ISWT), and symptom-limited maximal cycle exercise test, respectively. Energy expenditure was assessed with a multisensory accelerometer. Change in capillary glucose levels (∆glucose) was measured before and after each exercise modality.
Results
∆Glucose was lower in the 6MWT {median 14 [interquartile range (IQR) 22] mg/dl} than in the ISWT [median 18 (IQR 23) mg/dl; median difference 7 mg/dl, 95% confidence interval (CI) of the difference 3–11] and the cycle test [median 18 (IQR 24) mg/dl; median difference 7 mg/dl, 95% CI 0–16]. Energy expenditure was lower during the 6MWT [median 41 (IQR 18) Kcal] compared with the ISWT [median 51 (IQR 23) Kcal; median difference 11 Kcal, 95% CI 6–16] and the cycle test [median 44 (IQR 25) Kcal; median difference 6 Kcal, 95% CI 0–13].
Conclusions
Energy expenditure and corresponding glucose-lowering effect during exercise in patients with T2DM can be predicted from the results of an exercise test. The type of exercise is related to the risk of hypoglycaemia. Walking is associated with the lowest energy expenditure and risk of hypoglycaemia, while cycling and running/jogging cause higher energy expenditure and greater reductions in glucose in patients with T2DM.
Contribution of the paper
- Energy expenditure and risk of hypoglycaemia during exercise can be predicted by exercise tests.
- The intensity and type of exercise are related to the risk of hypoglycaemia.
- The change in glucose level was greater for running and cycling than for walking.