Effectiveness of lifestyle interventions to promote physical activity on glycated hemoglobin and physical activity in type 2 diabetes patients - Systematic review with meta-analysis
Authors: Hohberg Vivien , Lichtenstein Eric , Kreppke Jan-Niklas , Zanitti Cedrine , Streckmann Fiona , Gerber Markus , Faude Oliver 
Published: February 2024

Introduction
An increase in Type 2 diabetes (T2D) cases worldwide can be attributed to the prevalence of an unhealthy lifestyle. Engaging in regular exercise can significantly benefit individuals with T2D (Colberg et al., 2016). A multitude of studies have explored this impact through controlled exercise interventions (Hou et al., 2023). Nevertheless, our understanding of how lifestyle interventions can effectively promote physical activity (PA) and positively influence the progression of T2D in practical, real-world scenarios remains limited. The objective of this systematic review with meta-analysis is to investigate the impact of lifestyle interventions targeting the promotion of PA on glycated hemoglobin (HbA1c) levels and PA outcomes. Furthermore, the aim is to examine whether lifestyle interventions influence PA and therefore HbA1c.
Methods
We searched three databases (MEDLINE via PubMed, PsycINFO, and SPORTdiscus) using the expanded search strategy of “Type 2 diabetes” AND “lifestyle intervention” AND “randomized controlled trial” AND “physical activity” AND “HEMOGLOBIN A1C”. In order to provide a comprehensive overview, we examine the design of the studies and the structure of the lifestyle interventions. To address the aim of this study, we conducted a meta-analysis with the outcomes PA and HbA1c. Moreover, we performed a multivariate meta-regression analysis to explore the impact of the moderator variable, PA, on the study effect sizes of HbA1c.
Results
This review incorporated 12 studies (n = 2513 patients), exploring multiple lifestyle interventions with heterogeneity in design, components, and duration. Regarding PA outcomes, we found an increase in PA (g = 0.33, 95% CI = 0.21,0.45), with no disparity between objective and self-reported measurements of PA. For HbA1c, the effect size was g = -0.07 (95% CI -0.17,0.04). In multivariate meta-regression, the intercept was 0.004 (SE = 0.06, 95% CI -0.11,0.12), and the PA coefficient as a moderator was -0.05 (SE = 0.06, 95% CI -0.18,0.07). These findings suggest that physical activity does not act as a moderator for changes in HbA1c in the examined studies.
Discussion/Conclusion
The studies showed a small effect in increasing PA. Lifestyle interventions had no relevant impact on HbA1c compared to control conditions, and the role of PA as a moderator was inconclusive. Further research is required to determine if structured exercise programs, known for positively affecting HbA1c, could be a better alternative to lifestyle interventions for individuals with T2D. Additionally, there is a need to investigate ways to enhance the efficacy of lifestyle interventions in influencing PA and HbA1c levels.
References
Colberg, S. R., Sigal, R. J., Yardley, J. E., Riddell, M. C., Dunstan, D. W., Dempsey, P. C., Horton, E. S., Castorino, K., & Tate, D. F. (2016). Physical activity/exercise and diabetes: A position statement of the American Diabetes Association. Diabetes Care, 39(11), 2065-2079. https://doi.org/10.2337/dc16-1728
Hou, L., Wang, Q., Pan, B., Li, R., Li, Y., He, J., Qin, T., Cao, L., Zhang, N., & Cao, C. (2023). Exercise modalities for type 2 diabetes: A systematic review and network meta‐analysis of randomized trials. Diabetes/Metabolism Research and Reviews, 39(1), Article e3591. https://doi.org/10.1002/dmrr.3591