HbA1c falls with structured exercise

A structured programme of aerobic and/or resistance exercise is associated with the greatest improvement in glycaemic control among people with type 2 diabetes, researchers found.

The systematic review and meta-analysis showed that greatest reductions in glycosylated haemoglobin (HbA1c) occurred in patients exercising for more than 150 minutes in total per week. Exercise intensity did not appear to matter.

The study authors analysed 47 randomised controlled trials into the effect of exercise on HbA1c, with a total of 8538 patients. In 23 of these RCTs, patients took part in structured exercise training, and in the other 24 they were simply given advice on physical activity.

Across all studies analysed, engaging in structured exercise was associated with decreased HbA1c levels compared with controls, whether this was structured resistance training (fall in HbA1c of 0.57%), structured aerobic exercise (fall of 0.75%), or a combination of both (0.51% fall).

A longer total time spent in structured exercise was associated with better glycaemic control. If total weekly time in structured exercise exceeded 150 minutes, the average drop in HbA1c was 0.89%, against 0.36% for a time of 150 minutes or less.

Physical activity advice was only associated with a decline in HbA1c if it was combined with dietary advice.

The authors said: “This systematic review and meta-analysis of RCTs demonstrates important findings regarding the prescription of structured exercise training. First, aerobic, resistance, and combined training are each associated with HbA1c decreases, and the magnitude of this reduction is similar across the three exercise modalities.

“Second … structured exercise of more than 150 minutes per week is associated with greater declines in HbA1c than structured exercise of 150 minutes or less per week in patients with type 2 diabetes. This finding is important because the current guideline-recommended exercise duration is at least 150 minutes per week.

They added: “Although high-intensity exercise has been previously shown to have an association with HbA1c reduction, our findings did not demonstrate that more intensive exercise was associated with greater declines in HbA1c.”

The author of an accompanying editorial argues that “the meta-analysis … and cumulative evidence from a large number of randomised controlled trials conducted over the past few decades in the area of physical activity and exercise provide solid evidence for public policy makers to consider structured exercise and physical activity programs as worthy of insurance reimbursement to promote health, especially in high-risk populations.”