Elsevier

The Lancet

Volume 371, Issue 9626, 24–30 May 2008, Pages 1783-1789
The Lancet

Articles
The long-term effect of lifestyle interventions to prevent diabetes in the China Da Qing Diabetes Prevention Study: a 20-year follow-up study

https://doi.org/10.1016/S0140-6736(08)60766-7Get rights and content

Summary

Background

Intensive lifestyle interventions can reduce the incidence of type 2 diabetes in people with impaired glucose tolerance, but how long these benefits extend beyond the period of active intervention, and whether such interventions reduce the risk of cardiovascular disease (CVD) and mortality, is unclear. We aimed to assess whether intensive lifestyle interventions have a long-term effect on the risk of diabetes, diabetes-related macrovascular and microvascular complications, and mortality.

Methods

In 1986, 577 adults with impaired glucose tolerance from 33 clinics in China were randomly assigned to either the control group or to one of three lifestyle intervention groups (diet, exercise, or diet plus exercise). Active intervention took place over 6 years until 1992. In 2006, study participants were followed-up to assess the long-term effect of the interventions. The primary outcomes were diabetes incidence, CVD incidence and mortality, and all-cause mortality.

Findings

Compared with control participants, those in the combined lifestyle intervention groups had a 51% lower incidence of diabetes (hazard rate ratio [HRR] 0·49; 95% CI 0·33–0·73) during the active intervention period and a 43% lower incidence (0·57; 0·41–0·81) over the 20 year period, controlled for age and clustering by clinic. The average annual incidence of diabetes was 7% for intervention participants versus 11% in control participants, with 20-year cumulative incidence of 80% in the intervention groups and 93% in the control group. Participants in the intervention group spent an average of 3·6 fewer years with diabetes than those in the control group. There was no significant difference between the intervention and control groups in the rate of first CVD events (HRR 0·98; 95% CI 0·71–1·37), CVD mortality (0·83; 0·48–1·40), and all-cause mortality (0·96; 0·65–1·41), but our study had limited statistical power to detect differences for these outcomes.

Interpretation

Group-based lifestyle interventions over 6 years can prevent or delay diabetes for up to 14 years after the active intervention. However, whether lifestyle intervention also leads to reduced CVD and mortality remains unclear.

Funding

Centers for Disease Control and Prevention, WHO, the China-Japan Friendship Hospital, and Da Qing First Hospital.

Introduction

Major clinical trials in the USA, China, India, Finland, and Japan1, 2, 3, 4, 5 have shown the effectiveness of lifestyle interventions to reduce the incidence of diabetes in people with impaired glucose tolerance. Interventions designed to achieve modest weight loss and enhance behavioural change were effective across sex, age, and race or ethnicity groups, and over different bodyweights. The interventions used group or individual counselling to reduce total dietary intake and saturated fat, increase dietary fibre, exercise, and self-monitoring of behaviours.

Despite these studies' importance as catalysts for new public health efforts, important questions remain. How long does the reduction in the incidence of diabetes persist? The Finnish Diabetes Prevention Study6 is known to have assessed this question, reporting that diabetes incidence was reduced for 3 years after the 4-year active intervention. Also unclear is how much the benefits of diabetes prevention extend to reducing the complications of diabetes, such as myocardial infarction, stroke, and mortality.

The China Da Qing Diabetes Prevention Study2 (CDQDPS) was the first of these large-scale trials and examined the effect of different lifestyle interventions in a group setting among Chinese people with impaired glucose tolerance. We report the results from a 20-year follow-up of the CDQDPS, in which 98% (568 of 577) of the participants were reassessed to establish the effect of lifestyle interventions on diabetes and other related health outcomes in people at high risk for diabetes.

Section snippets

Methods

Details of the design, methods, and population of the CDQDPS have been published previously.2 Briefly, the CDQDPS investigated the effect of dietary and exercise intervention, alone and in combination, on incidence of type 2 diabetes in people with impaired glucose tolerance. In 1986, 577 adults with impaired glucose tolerance at 33 clinics in Da Qing city, China, were recruited and randomised by clinic into either a control group or one of three lifestyle interventions: diet, exercise, or diet

Results

Of the original 577 CDQDPS participants, one could not be traced at the end of the active intervention in 1992. By 2006, 142 (25%) had died and 426 (74%) were alive on Dec 31, 2006 (figure 1). Eight could not be traced and were lost to follow-up. For 26, only data from the active intervention period or from medical records during the post-intervention period were obtained. For the remainder (400), 293 were interviewed and examined at the Da Qing First Hospital and 79 were interviewed at home,

Discussion

Our findings from the CDQDPOS indicate that the reduction in diabetes incidence seen during the 6-year period of active intervention persisted for two decades. Chinese participants with impaired glucose tolerance randomised to lifestyle intervention groups had a 43% lower diabetes incidence (age and clinic adjusted) for up to 14 years after the active intervention ceased, and diabetes onset was delayed an average of 3·6 years. These findings are consistent with those of the Finnish Diabetes

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