Lifestyle interventions reduced the long-term risk of diabetes in adults with impaired glucose tolerance

ED FROM Li G, Zhang P, Wang J, et al. The long-term effect of lifestyle interventions to prevent diabetes in the China Da Qing Diabetes Prevention Study: a 20-year follow-up study. Lancet 2008;371:1783–9. Correspondence to: Dr G Li, China-Japan Friendship Hospital, Beijing, China; guangwei_li@medmail.com. cn Source of funding: no external funding. c Clinical impact ratings: GP/FP/Primary care 6/7; Endocrine 6/7; Public health 6/7; IM/Ambulatory care 5/7 Lifestyle interventions (diet and/or exercise) v usual care in adults with impaired glucose tolerance* Outcomes at 20 years Lifestyle interventions{ Usual care RRR (95% CI) NNT (CI) Diabetes 80% 93% 16% (5 to 29) 7 (4 to 22) Cardiovascular disease event 41% 44% 1% (225 to 23) Not significant Cardiovascular disease mortality 13% 17% 16% (235 to 50) Not significant All-cause mortality 25% 29% 3% (232 to 31) Not significant *Abbreviations defined in glossary. RRR, NNT, and CI calculated from hazard ratios in article, adjusted for age and clustering by clinic. {3 groups pooled. C O M M EN TA R Y T hree large randomised trials, the China Da Qing Diabetes Prevention Study, the Finnish Diabetes Prevention Study, and the Diabetes Prevention Program trial, have shown that progression from impaired glucose tolerance to type 2 diabetes can be delayed or even prevented by diet and exercise. The study by Li et al shows for the first time that the benefit can be long-lasting. What is not clear is whether the participants continued their improved lifestyle for some years or the 6-year interventions were enough to have long-term benefit. Either scenario would justify translating this evidence into practice. The finding that both group-based interventions and intensive one-toone approaches can yield benefit is useful. Whereas we know that the Diabetes Prevention Program intervention was intensive, we are less informed about what levels of interventions were required in the Da Qing trial. Unfortunately, governments, healthcare funders, and clinicians are often still reluctant to invest time and resources into widespread implementation of these strategies. The trial by Li et al was not adequately powered to detect reductions in CVD events or mortality from lifestyle interventions. However, there were trends consistent with results from a previous trial, which showed that the slowing of progression from impaired glucose tolerance to type 2 diabetes can improve CVD outcomes, although this was achieved with medication rather than lifestyle. What we found most alarming from this study was that after 20 years, 93% of participants in the control group had diabetes. Even though 80% of the intervention groups eventually developed diabetes, there was a delay (mean 3.6 y). These findings stress the need for primary care physicians to systematically identify patients with impaired glucose tolerance and target intensive lifestyle change at this stage. C Raina Elley, MD Tim Kenealy, MD University of Auckland Auckland, New Zealand 1. Tuomilehto J, Lindström J, Eriksson JG, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. N Engl J Med 2001;344:1343–50. 2. Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002; 346:393–403. 3. Chiasson JL, Josse RG, Gomis R, et al. Acarbose treatment and the risk of cardiovascular disease and hypertension in patients with impaired glucose tolerance: the STOP-NIDDM trial. JAMA 2003;290: 486–94. Therapeutics EBM December 2008 Vol 13 No 6 173