• Diabetes Mellitus
• Prevention & Screening

Twenty-three years of follow-up data from the China Da Qing Diabetes Prevention Study (CDQPDS) show that lifestyle intervention to prevent diabetes can reduce all-cause and cardiovascular (CV) mortality among women with impaired glucose tolerance (IGT) but not among men. Findings from the study were reported by Guangwei Li, MD, Department of Endocrinology, China-Japan Friendship Hospital, Beijing, China.

In 1986, 577 adults with IGT from 33 clinics in Da Qing, China, were randomly assigned to a control group or 1 of 3 lifestyle intervention groups (diet, exercise, or diet plus exercise). Active intervention was carried out from 1986 to 1992. Participants who were assigned to the exercise group or diet-plus-exercise group were encouraged to increase the amount of their physical activity by at least 1 unit per day (as defined in Table 1) and by 2 units per day, if possible, for participants aged <50 years with no evidence of CV disease (Table 1) [Pan XR et al. Diabetes Care 1997].

A 20-year follow-up study showed that group-based combined lifestyle interventions over 6 years in people with IGT can prevent or delay diabetes for up to 14 years after the active intervention [Li G et al. Lancet 2008]. Lifestyle intervention for 6 years in IGT was also associated with a 47% decline in the incidence of severe, vision-threatening retinopathy over 20 years [Gong Q et al. Diabetologia 2011].

The aim of the current trial was to examine all-cause and CV mortality among those who participated in the 6-year lifestyle intervention that was implemented in the Da Qing Diabetes Prevention Study. In 2009, 23 years after randomization, participants were traced to determine the long-term impact of the interventions on mortality; 47 women and 127 men had died.

Mortality rates were compared between the control groups and the combined intervention groups (diet, exercise, and diet plus exercise). All-cause mortality was defined as death from any cause. CV mortality was defined as death from coronary heart disease, stroke, and sudden death.

In women, combined lifestyle intervention (diet, exercise, and diet plus exercise) reduced all-cause mortality by 53% (hazard rate ratio [HRR], 0.47; 95% CI, 0.25 to 0.86), with cumulative all-cause mortality of 16.2% (95% CI, 11.2 to 21.2) in the intervention group versus 29.3% (95% CI, 17.5 to 48.0) in the control group (p=0.02). Among men, there was no significant difference in cumulative all-cause mortality (p=0.41) between the combined intervention and control groups (41.1% versus 46.7%).

The reduction in all-cause mortality in women was mainly because of differences in CV mortality (heart disease and stroke; HRR, 0.30; 95% CI, 0.12 to 0.68), with 23-year cumulative mortality of 6.8% in the intervention group (95% CI, 3.4 to 10.2) versus 18.8% (95% CI, 8.8 to 28.8) in the control group (p=0.006). In men, there was also no significant difference in cumulative CV mortality (p=0.47) in the combined intervention and control groups (26.4%; 95% CI, 21.1 to 31.6 versus 27.4; 95% CI, 18.6 to 32.2).

Data from the intervention groups (diet, exercise, and diet plus exercise) suggest that combined lifestyle intervention significantly lowers all-cause and CV mortality among women with IGT but not among men. Reasons may include a large difference in baseline smoking rates between men and women.

Apart from diabetes, measures of risk factors for death (and CV disease) at baseline and during the trial were limited. In turn, the investigators were unable to identify or exclude possible confounding factors for the differences in outcomes between women and men. The reasons remain unclear.

Participants in the intervention group were, on average, 2 years younger than those in the control group, but there were no differences in baseline body mass index (BMI) in controls, 26.2±0.2 kg/m² versus BMI in the combined intervention group, 25.7±0.2 kg/m². The changes in body weight during the active-intervention period (1986 to 1992) and the entire follow-up period (1986 to 2006) did not differ significantly by group [Guangwei L et al. Lancet 2008].

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