Context Exercise is widely perceived to be beneficial for glycemic control and
weight loss in patients with type 2 diabetes. However, clinical trials on
the effects of exercise in patients with type 2 diabetes have had small sample
sizes and conflicting results.
Objective To systematically review and quantify the effect of exercise on glycosylated
hemoglobin (HbA1c) and body mass in patients with type 2 diabetes.
Data Sources Database searches of MEDLINE, EMBASE, Sport Discuss, Health Star, Dissertation
Abstracts, and the Cochrane Controlled Trials Register for the period up to
and including December 2000. Additional data sources included bibliographies
of textbooks and articles identified by the database searches.
Study Selection We selected studies that evaluated the effects of exercise interventions
(duration ≥8 weeks) in adults with type 2 diabetes. Fourteen (11 randomized
and 3 nonrandomized) controlled trials were included. Studies that included
drug cointerventions were excluded.
Data Extraction Two reviewers independently extracted baseline and postintervention
means and SDs for the intervention and control groups. The characteristics
of the exercise interventions and the methodological quality of the trials
were also extracted.
Data Synthesis Twelve aerobic training studies (mean [SD], 3.4 [0.9] times/week for
18  weeks) and 2 resistance training studies (mean [SD], 10 [0.7] exercises,
2.5 [0.7] sets, 13 [0.7] repetitions, 2.5 [0.4] times/week for 15  weeks)
were included in the analyses. The weighted mean postintervention HbA1c was lower in the exercise groups compared with the control groups
(7.65% vs 8.31%; weighted mean difference, −0.66%; P<.001). The difference in postintervention body mass between exercise
groups and control groups was not significant (83.02 kg vs 82.48 kg; weighted
mean difference, 0.54; P = .76).
Conclusion Exercise training reduces HbA1c by an amount that should
decrease the risk of diabetic complications, but no significantly greater
change in body mass was found when exercise groups were compared with control