Author Affiliations: Departments of Cardiovascular and Respiratory Sciences (Dr Armstrong) and Medicine (Dr Sigal) (email@example.com), University of Calgary, Calgary, Alberta, Canada; and Faculty of Physical Education and Recreation, University of Alberta, Edmonton (Dr Boulé).
To the Editor: The meta-analysis of exercise interventions in type 2 diabetes by Mr Umpierre and colleagues1 concluded that “aerobic, resistance, and combined training are each associated with HbA1c decreases.” However, we are not convinced that “the magnitude of this reduction is similar across the 3 exercise modalities.”
Key factors likely to influence the magnitude of hemoglobin A1c (HbA1c) reduction achieved by a glucose-lowering intervention include baseline HbA1c and use of an intention-to-treat analysis. When baseline HbA1c is higher, greater reductions are likely to be achieved. Six of the 20 aerobic exercise trials had baseline HbA1c greater than 8.5% vs none of the trials evaluating combined aerobic and resistance training. Six of the 20 aerobic exercise trials included more than 3 weekly exercise sessions vs none of the resistance exercise studies and only 1 combined exercise study.
Armstrong MJ, Boulé NG, Sigal RJ. Exercise Interventions and Glycemic Control in Patients With Diabetes. JAMA. 2011;306(6):607-610. doi:10.1001/jama.2011.1103