Effects of exercise training on arterial function in type 2 diabetes mellitus: a systematic review and meta-analysis

Controversy exists among trials assessing whether exercise can improve arterial function in type 2 diabetes mellitus (T2DM) subjects. Therefore the aim of this study was to systematically review and quantify the effects of exercise on arterial function in T2DM subjects.

MEDLINE, Cochrane, Scopus and Web of Science were searched up until January 2013 for randomized controlled trials evaluating the effects of exercise interventions lasting 4 weeks or more on arterial function in T2DM subjects. Flow-mediated dilation (FMD) and nitrate-mediated dilation (NMD) of the brachial conduit artery were considered for assessment of arterial endothelial function and smooth muscle function, respectively.

Five randomized trials comparing exercise and control groups (overall n = 217) met the inclusion criteria. The mean exercise characteristics were as follows: 3.6 sessions per week, 67.5 min per session, intensity at 74.4 % of the maximum heart rate (HR(max)), for 14 weeks. The post-intervention mean difference in FMD favoured the exercise groups over the control groups (2.23 %; P < 0.0001). No significant post-intervention mean difference in NMD (1.22 %; P = 0.29) was found between the groups. Neither heterogeneity nor publication bias was detected among the trials.

Exercise training alone improved FMD, showing its capacity to restore arterial endothelial function in T2DM subjects. However, further research is needed to determine whether longer and/or more intense exercise interventions could enhance arterial smooth muscle function in this population.