The ability of exercise to meaningfully improve glucose tolerance in people living with prediabetes: A meta-analysis.

Background: Individuals with prediabetes are likely to progress to Type 2 diabetes. Although exercise training is an established method to improve glycemic control, the degree to which this translates into meaningful improvements, particularly in individuals with prediabetes, is unclear. The purpose of this meta-analysis was to investigate the ability of exercise training to improve 2-hour glucose tolerance beyond the smallest worthwhile difference in individuals with prediabetes. It was hypothesized that the majority of implemented exercise programs designed for individuals with prediabetes would not result in meaningful improvements in glucose tolerance.

Methods: Searches were performed in MEDLINE, The Cumulative Index to Nursing and Allied Health Literature, SPORTDiscus, and the Cochrane Library. Included studies reported glucose tolerance using a 2-hour oral glucose tolerance test at baseline and post-intervention; implemented an exercise program lasting at least 12 weeks; and included adults living with prediabetes. Mean effect summaries were determined using random-effects models. Magnitude-based inference statistic was used to estimate the likelihood that observed changes in glucose tolerance were meaningful to patients.

Results: Nine articles were included in the meta-analysis, producing 12 independent exercise interventions. The interventions led to an average improvement in glucose tolerance of 5.9% (95% confidence interval: 3.7%-8.0%). Seven (58%) exercise interventions were deemed likely to benefit patients, whereas five (42%) had trivial or unclear findings.

Conclusion: While exercise intervention led to statistically significant improvements in 2-hour glucose tolerance, the benefit for individuals living with prediabetes remains unclear. Further research is needed to delineate optimal prescription parameters for generating meaningful benefits in glucose tolerance.