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Reference:Lancet 2013 Dec 19 early online (level 2 [mid-level] evidence)
Lifestyle modifications have been shown to reduce the rate of progression to type 2 diabetes in patients with impaired glucose tolerance (BMJ 2007 Feb 10;334(7588):299 full-text). In fact, the Diabetes Prevention Program trial demonstrated that lifestyle changes can reduce the incidence of diabetes more effectively than metformin (N Engl J Med 2002 Feb 7;346(6):393 full-text), and a secondary analysis showed that such changes are cost-effective for diabetes prevention across all age groups (Ann Intern Med 2005 Mar 1;142(5):323 full-text). However, the impact of lifestyle changes on cardiovascular outcomes in patients with impaired glucose metabolism has remained unclear. Now, a cohort analysis of data from a randomized trial evaluates the association between walking and the risk of cardiovascular events in a patient population at risk of developing cardiovascular disease.
A total of 9,018 patients with impaired glucose tolerance and increased risk of cardiovascular disease from the NAVIGATOR trial were included in the analysis. All patients had existing cardiovascular disease if ≥ 50 years old, or had at least 1 additional cardiovascular risk factor if ≥ 55 years old. Ambulatory activity was assessed using a pedometer at baseline and again at 12 months.
Overall, 531 patients had a cardiovascular event (defined as a composite of cardiovascular mortality, non-fatal stroke, or myocardial infarction) during 45,211 person-years of follow-up. Each increase in activity by 2,000 steps per day (about 20 minutes of walking at a moderate pace) was associated with a decrease in the risk of cardiovascular events, with a hazard ratio of 0.92 (95% CI 0.86-0.99) when evaluating the change in activity level from baseline to 12 months. Similarly, a higher baseline activity rate was also associated with decreased risk of cardiovascular events, with a hazard ratio of 0.9 (95% CI 0.84-0.96). These findings were consistent across additional analyses adjusted for all potential confounders evaluated, including treatment group and changes in body mass index. However, an important limitation of this study is the large proportion of patients with some missing data (25% at baseline and 45% at 12 months).
Previous studies evaluating interventions in patients with prediabetes have focused only on prevention of a diabetes diagnosis. There has been an absence of more patient-oriented outcomes. This study extends the previous findings by evaluating clinical complications among patients with prediabetes, specifically showing decreased cardiovascular events with increased activity levels. Further, it quantifies the relationship between activity and cardiovascular risk in a way that is easy to communicate to patients.
For more information, see the Prediabetes and Physical activity for cardiovascular disease prevention topics in DynaMed.