PracticeUpdate Diabetes June 2019

EDITOR’S PICKS 4

Morbidity and Mortality After Lifestyle Intervention for People With Impaired Glucose Tolerance The Lancet Diabetes & Endocrinology Take-home message • In this longitudinal study of patients with impaired glucose intolerance (n=577), the authors evaluated the long-termeffects of lifestyle interventions on diabetes incidence, complications, and overall mortality. Over a 30-year follow-up after initial implementation of lifestyle interventions, the authors determined that themedian delay in diabetes onset compared with controls was 3.96 years. Also, patients in the initial treatment group experienced fewer cardiovascular disease events, fewer microvascular complications, as well as fewer cardiovascular disease-specific and overall deaths. • Lifestyle interventions for patients with impaired glucose tolerance improved overall morbidity and mortality risk and increased life expectancy by an average of 1.44 years. Lifestyle interventions should remain a strong focus in the treatment of glucose intolerance and type 2 diabetes. COMMENT By Deborah Wexler MD, MSc

I n 1986, in Da Qing, China, 577 adults with impaired glucose tolerance (of 110,660 screened) enrolled in a cluster randomized trial of lifestyle intervention. Clinics were assigned to no intervention or to deliver one of three lifestyle interventions: • dietary intervention aimed at increasing vegetable intake and decreasing alcohol and sugar intake; • exercise intervention aimed at increasing leisure time activity; or • both. All lifestyle intervention groups empha- sized the importance of weight loss and reduced caloric intake for patients who were overweight (BMI >25 kg/m 2 , which was close to the mean BMI in this popu- lation). Active intervention was carried out over 6 years and showed a reduced risk of diabetes in all intervention arms com- pared with control. Gong et al report the 30-year (!) outcomes of this cohort. For the 30-year analysis, intervention participants were combined (n=438) and compared with control partici- pants (n=138) in intention-to-treat analyses adjusting for clinic site, with over 90% out- come ascertainment (most participants still live in Da Qing, and the majority receive their secondary and tertiary care at a sin- gle regional hospital).

and treating clinics may have continued after the study ended (indeed, sustained behavior change on the part of both patients and providers may be considered a goal of lifestyle intervention). Finally, it is possible that the benefit observed was not due to the lifestyle intervention itself, but to something else, possibly a stronger therapeutic alliance between patients and providers that was engendered by life- style intervention, which, if true, could also count as a plus for lifestyle intervention. What is incontrovertible is that lifestyle intervention focused on dietary modi- fication, exercise, or both, coupled with weight loss among those who are over- weight, sustained over time, yields myriad health benefits, at relatively low cost. Although not all participants are willing to engage in lifestyle change, for those who do, new habits may be lasting and even, as Da Qing illustrates and multiple observational trials suggest, prolong both lifespan and health span. Taken together with other trials showing benefit (Diabetes Prevention Program, Look AHEAD, Finn- ish Diabetes Prevention Study), lifestyle intervention should be the foundation of management of people with impaired glucose tolerance and cardiometabolic disease.

The authors extend earlier reports of the benefit of lifestyle intervention based on more accumulated events, reporting significant reductions of 26% in cardio- vascular events, including stroke, 35% in microvascular complications, 33% in car- diovascular deaths, and 26% in all-cause mortality among lifestyle compared with control participants, corresponding to an increase of 4.82 years in median sur- vival and a mean increase of 1.44 years in life expectancy. The number needed to treat (over the 6 years of the interven- tion, measured at 30 years) to prevent diabetes, CVD death, or the composite microvascular disease outcome was 10 for each outcome. Results this strong have not been seen in other lifestyle intervention studies, even with relatively long follow-up. What is different about the Da Qing Diabetes Prevention Study? Da Qing has the long- est duration of follow-up, and differences in non-diabetes event rates began to emerge only 12 years after randomiza- tion. Background medical therapy or risk factors, such as smoking, may have been less favorable in Da Qing than those in other contexts, allowing the benefit of life- style intervention to become evident in this cohort. Also, the lifestyle intervention was long – 6 years – and both participants

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