Previous studies in nondiabetic patients have shown that exercise reduces hypertension, dyslipidemia, insulin resistance, and hyperglycemia (38, 42 - 45).

In diabetics a number of small studies have been published, however, apart from lacking statistical power, their results were not uniform, and no large-scale studies have been performed so far. A meta-analysis of 14 trials, extracted from a total of 2700 potential articles, included 504 participants.

Selection of the studies was based on a predetermined program of physical exercise lasting for a minimum of 8 weeks, supervision of exercise, and presence of type 2 diabetic control group (46). Of the 14 trials, 11 were randomized controlled trials, and 3 were case-control trials.

The mean age of the participants was 55.0 -  7 years, duration of diabetes was 4.3 -  4.6 years; 50% of the participants were women.

The exercise interventions consisted of three workouts per week lasting for a mean of 53 -  17 min. Exercise consisted of walking or cycling of light to moderate intensity.

Postintervention HbA_1C was reduced by 0.66% in the intervention groups as compared to the nonexercise groups; in contrast body mass index remained unchanged.

The magnitude of this reduction is comparable to the results of the U.K. Prospective Diabetes study (47), where patients received intensive treatment with insulin or sulfonylureas. 

In this study HbA_1C decreased from 7.9% to 7.0% (p < .001), and was associated with a reduction in clinical endpoints from 46 events to 40.9 events per 1000 patient years (p < .03).

A more recent meta-analysis of interventional studies using exercise was published in the Cochrane Database (48); 14 studies were included in the analysis comprising 377 patients.

There is considerable overlap with the analysis published by Boulë in 2001, and not surprisingly the results and the conclusions are not dissimilar.

It is common to all studies that although the benefit of any form of exercise has been proven beyond doubt, adherence to these programs is short and haphazard.

The therapeutic benefit offered by this form of treatment is utilized only to a very small degree rendering its efficiency in daily practice insignificant.

Gerhard Schuler and Axel Linke
Department of Internal Medicine/Cardiology, University of Leipzig, Leipzig, Germany

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