Review: exercise plus diet prevents type 2 diabetes
Dr D Mauricio, Hospital Universitari Arnau de Vilanova, Lleida, Spain;
Do exercise and diet interventions, alone or in combination, prevent type 2 diabetes mellitus?
Studies selected compared exercise plus diet or exercise alone with standard recommendations or no intervention, or exercise alone with diet alone, for ⩾6 months and reported incidence of diabetes in people at risk of developing type 2 diabetes. Studies of pharmacological agents were excluded. Outcomes included incidence of type 2 diabetes; glucose tolerance; fasting glucose, cholesterol, and triglyceride concentrations; blood pressure; body weight; body mass index; waist-to-hip ratio; and waist circumference.
Medline, CINAHL, EMBASE/Excerpta Medica, Cochrane Library (Issue 1, 2008), LILACS, SocioFile, Current Controlled Trials, and reference lists were searched to March 2008 for randomised controlled trials (RCTs). 8 RCTs (n = 5956, mean age 50 y) met the selection criteria. Duration of follow-up ranged from 1 to 7 years.
Meta-analysis showed that exercise plus diet decreased incidence of type 2 diabetes and improved fasting glucose and triglyceride concentrations, blood pressure, body weight, body mass index, and waist circumference compared with standard recommendations (table); groups did not differ for glucose tolerance, waist-to-hip ratio, or cholesterol concentrations. Exercise alone and standard recommendations, and exercise alone and diet alone, did not differ for incidence of type 2 diabetes.
Orozco LJ, Buchleitner AM, Gimenez-Perez G, et al. Exercise or exercise and diet for preventing type 2 diabetes mellitus. Cochrane Database Syst Rev 2008;(3):CD003054.
Clinical impact ratings: Endocrinology 5/7; Family/general practice 6/7; General/internal medicine 6/7; Health promotion 6/7; Special interest - obesity 6/7
Source of funding: Agència d’Avaluació de Tecnologia i Recerca Mèdiques, Spain.
The continuing increase in the incidence of type 2 diabetes and its detrimental effect on mortality and morbidity persists as a worldwide problem affecting both developing and developed countries.1 Prevalence of type 2 diabetes is predicted to continue to rise, with major contributing factors considered to be unhealthy diets, overweight and obesity, and sedentary lifestyles.1 The systematic review by Orozco et al adds further weight to the “prevention is better than cure” argument, concluding that combined diet and exercise programmes (lifestyle interventions) targeted at high-risk groups decrease the incidence of type 2 diabetes. Orozco et al also note that the potential for lifestyle modifications had previously been recognised in several prospective cohort studies; 2 meta-analyses also support this viewpoint.2 3
Participants included in the review were all considered to be at “high risk.” It is interesting to note, however, that although World Health Organisation criteria were used to identify patients with impaired glucose tolerance, American Diabetes Association (ADA) criteria were used to identify those with impaired fasting glycaemia. The lower cut point adopted by the ADA has been the subject of debate. Orozco et al also had to take into account the heterogeneity between studies relating to the overall outcomes.
Despite this, the review clearly showed that lifestyle interventions reduce incidence of type 2 diabetes in high-risk individuals. Although the authors stressed that they do not presently know how these interventions would perform outside of a trial setting, they recommend that they be considered by policy makers and practitioners when planning and implementing preventative programmes in clinical practice.