Background

Physical activity is widely perceived to be beneficial for preventing type 2 diabetes mellitus and for controlling glycaemic levels in patients with type 2 diabetes, but evidence supporting a positive effect in the control of glycaemic levels in healthy people is rather weak. The aim of this review was to estimate the effect of physical activity on glycaemic control measured by glycosylated haemoglobin (HbA 1c ) levels in non-diabetic populations, and to determine which type of physical activity has a greater influence on glycaemic control.

Methods

We systematically searched the MEDLINE, EMBASE, Cochrane Library and Web of Science databases, from inception to May 2017, for experimental studies addressing the effect of physical activity on glycaemic control measured by HbA 1c levels in non-diabetic populations. The DerSimonian and Laird method was used to compute pooled estimates of effect size (ES) and respective 95% confidence intervals (CIs). The effect of physical activity on HbA 1c levels was estimated in two ways: (1) physical activity intervention versus control; and (2) physical activity pre–post intervention. Additionally, subgroup analyses were performed based on age of participants and different aspects of the intervention.

Results

Fifteen published studies were included in the meta-analysis. In analyses comparing physical activity intervention and control, we found a decrease of HbA 1c levels in favour of the intervention group (ES = 0.32; 95% CI 0.01–0.62) with substantial heterogeneity (I2 = 63.2%; p = 0.008). In the pre–post analysis, there was a decrease in HbA 1c levels post physical activity intervention (ES = 0.17; 95% CI 0.01–0.33) with low heterogeneity (I2 = 25.8%; p = 0.164). Additionally, for physical activity intervention versus control, a decrease in HbA 1c levels was observed in resistance exercise and in intervention length below 12 weeks. Furthermore, for pre–post effect analyses, a decrease in HbA 1c levels was observed in the supervised physical activity programme, other type of exercises, intervention length below 12 weeks and exercise intervention week duration above 150 min subgroups.

Conclusions

This systematic review and meta-analysis provides an overview of the evidence supporting physical activity as a suitable intervention for glycaemic control as measured by HbA 1c levels in non-diabetic populations.

Trial Registration

PROSPERO CRD42016050991.