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Lifestyle Changes during Prediabetes Can Reduce Mortality

Not only may an intensive program of diet, exercise, or both delay progression from prediabetes to diabetes, but among women, it may also lower CVD and all-cause mortality…. 

That information comes from a 23-year follow-up of the Da Qing Diabetes Prevention Study. From lead author Dr. Guangwei Li (China-Japan Friendship Hospital, Beijing, China), "The study showed that type 2 diabetes can be prevented and group-based lifestyle interventions over a six-year period have long-term effects on prevention of diabetes beyond the period of active intervention." "These results emphasize the long-term benefits of the intervention and reinforce the overall value and importance of lifestyle interventions as public-health strategies to prevent diabetes."

The mortality benefit may have been greater among women than among men because "the effect of more smoking in the men overwhelmed and masked a beneficial effect of the [lifestyle] intervention . . . and women in the lifestyle arm may have maintained their adherence to lifestyle intervention after the active intervention period [to a greater extent] than men," Li speculated.

Previous randomized controlled trials have established that people with impaired glucose tolerance who improve their diet and increase their physical activity can delay or prevent the development of diabetes and lower their other cardiovascular risk factors, Li and colleagues explain. However, it was unclear whether lifestyle changes could prevent death from cardiovascular disease, which is much higher among people with impaired glucose tolerance.

Previously, the researchers reported that 20-year follow-up data from the Da Qing Diabetes Prevention Study showed a statistically insignificant 17% reduction in cardiovascular disease mortality and a significantly lower incidence of severe diabetic retinopathy. Extending this work, they now looked at 23-year follow-up data.

In 1986, 577 individuals with impaired glucose tolerance who were living in Da Qing, China were randomized equally to a control group to receive standard medical care (138 participants) or to a six-year intervention of diet alone, exercise alone, or both (438 participants). In the current analysis, the data from the three interventions were combined to provide sufficient power.

For people who were overweight or obese, the diet intervention was designed to promote weight loss. For people of normal weight, the diet consisted of reducing simple carbohydrate and alcohol intake. The exercise intervention was designed to increase leisure time spent doing physical activity.

At study entry, the participants were on average about 46 years old and had a mean body-mass index (BMI) of about 26. A higher percentage of men than women were smokers (61% vs 16%). Just over 60% of the participants were overweight (BMI >25), and 13.7% were obese (BMI >30). The weight loss in the active intervention period was 0.9 kg for people in the control group and 1.9 kg for people in the intervention group. After 23 years of follow-up, 174 participants had died.

Overall, 73% of participants in the intervention group developed diabetes compared with 90% of participants in the control group. Similarly, overall, all-cause mortality and CVD mortality were significantly lower in the intervention arms than in the control arm (28.1% vs 38.4%, respectively, and 11.9% vs 19.6%, respectively).

The mortality benefits were significant in women only.

Effect of Lifestyle Intervention on Mortality and Diabetes Incidence in Women (23 yr follow-up)*

Cumulative Incidence

Control, n=59 (%)

Lifestyle Intervention, n=200 (%)

HR (95% CI)

p

All-cause mortality

28.8
15.0

0.46 (0.24–0.87)

0.02

CVD mortality

17.0
6.0

0.28 (0.11–0.71)

0.01
Diabetes
93.2
74.0

0.55 (0.35–0.87)

0.006

Effect of Lifestyle Intervention on Mortality and Diabetes Incidence in Men*

Cumulative Incidence

Control, n=79 (%)

Lifestyle Intervention, n=230 (%)

HR (95% CI)

p

All-cause mortality

45.6
39.6

0.97 (0.65-1.46)

0.9

CVD mortality

21.5
17.0

0.91 (0.50-1.65)

0.7
Diabetes
87.3
71.3

0.56 (0.39-0.81)

0.004
 
Published online April 3, 2014 in Lancet Diabetes & Endocrinology – Li G, Zhang P, Wang J, et al. Cardiovascular mortality, all-cause mortality, and diabetes incidence after lifestyle intervention for people with impaired glucose tolerance in the Da Qing Diabetes Prevention Study: a 23-year follow-up study. Lancet Diabetes Endocrinol 2014; DOI:10.1016/S2213-8587(14)70057-9.