Lifestyle changes made by people at high risk of diabetes appear to reduce their chance of developing the disease over the next two decades, according to a study from China.

The lifestyle changes, which included diet modifications and exercise, also helped lower death rates, especially among women.

The data are based on the six-year Da Qing Diabetes Prevention Study. Participants began the study with higher-than-normal blood sugar levels, but not high enough to be diagnosed with diabetes. Researchers wanted to see if they could help prevent or delay a diagnosis of full-on diabetes.

“Diabetes is strongly associated with the increased risk of cardiovascular disease event and mortality,” Dr. Guangwei Li told Reuters Health in an email.

Li, from the China-Japan Friendship Hospital in Beijing, said the prevalence of diabetes will increase with rapid economic development in China and all over the world.

“We have to do something active to delay the development of diabetes in high risk populations,” Li said.

For the new report, Li and colleagues followed up with 568 participants of the original study that began in 1986 in Da Qing, China.

Those people had been randomly placed into one of three intervention groups (diet, exercise or diet plus exercise) or a comparison group.

The diet intervention was meant to help heavy people lose weight and normal-weight people reduce the amount of simple carbohydrates they ate and the amount of alcohol they drank. The goal of the exercise program was to increase the amount of leisure time participants spent being active.

The original study indicated that all three intervention groups had a reduced risk of developing type 2 diabetes when the study ended in 1992.

The current researchers wanted to see if the lifestyle changes made in the original study still had an impact on the development of diabetes and death rates many years later. They compared medical records and death certificates of 430 participants in the intervention groups and 138 members of the comparison group.

By the end of 2009, 28 percent of participants in the intervention groups had died, compared to 38 percent of the controls.

When they looked specifically at heart disease, the researchers found that 12 percent of the intervention group participants had died of heart-related conditions, compared to 20 percent of the controls.

Almost all of the benefit was found in women - there was very little difference in death rates among men based on whether they went through one of the lifestyle programs.

The researchers also compared diabetes diagnoses and found that 73 percent of the intervention group had developed diabetes through 2009, compared to 90 percent of the control group. Those findings were similar for men and women, they report in The Lancet Diabetes and Endocrinology.

“The group based lifestyle interventions over a six-year period have long-term effects on prevention of diabetes beyond the period of active intervention,” Li said. “It is worth taking active action to prevent diabetes to reduce the risk of cardiovascular disease and mortality.”

“The intervention seemed to have a disproportionately large effect in women,” writes Nicholas Wareham in an editorial published with the study.

Wareham, from the University of Cambridge in the UK, did not respond to an interview request. It’s possible that differences between men and women were a result of how participants responded to the interventions, he writes. But because there are no data on people’s lifestyle habits during the study period, that’s impossible to say.

“However, this point should not detract from the main finding: that interventions aimed at changing diet and physical activity were effective for reduction of long-term health risks,” Wareham concludes.

SOURCE: The Lancet Diabetes and Endocrinology, online April 3, 2014.

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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

Methods
The study was a cluster randomised trial in which 33 clinics in Da Qing, China—serving 577 adults with impaired glucose tolerance—were randomised (1:1:1:1) to a control group or lifestyle intervention groups (diet or exercise or both). Patients were enrolled in 1986 and the intervention phase lasted for 6 years. In 2009, we followed up participants to assess the primary outcomes of cardiovascular mortality, all-cause mortality, and incidence of diabetes in the intention-to-treat population.
Findings
Of the 577 patients, 439 were assigned to the intervention group and 138 were assigned to the control group (one refused baseline examination). 542 (94%) of 576 participants had complete data for mortality and 568 (99%) contributed data to the analysis. 174 participants died during the 23 years of follow-up (121 in the intervention group vs 53 in the control group). Cumulative incidence of cardiovascular disease mortality was 11·9% (95% CI 8·8—15·0) in the intervention group versus 19·6% (12·9—26·3) in the control group (hazard ratio [HR] 0·59, 95% CI 0·36—0·96; p=0·033). All-cause mortality was 28·1% (95% CI 23·9—32·4) versus 38·4% (30·3—46·5; HR 0·71, 95% CI 0·51—0·99; p=0·049). Incidence of diabetes was 72·6% (68·4—76·8) versus 89·9% (84·9—94·9; HR 0·55, 95% CI 0·40—0·76; p=0·001).
Interpretation
A 6-year lifestyle intervention programme for Chinese people with impaired glucose tolerance can reduce incidence of cardiovascular and all-cause mortality and diabetes. These findings emphasise the long-term clinical benefits of lifestyle intervention for patients with impaired glucose tolerance and provide further justification for adoption of lifestyle interventions as public health measures to control the consequences of diabetes.
Funding
Centers for Disease Control and Prevention, WHO, the China-Japan Friendship Hospital, Da Qing First Hospital.

Prof Guangwei Li MD,Dr Ping Zhang PhD,Jinping Wang MD,Yali An MD,Qiuhong Gong MD,Edward W Gregg PhD,Wenying Yang MD,Bo Zhang MD,Ying Shuai BD,Jing Hong MD,Michael M Engelgau MD,Hui Li MD,Gojka Roglic MD,Yinghua Hu MD,Peter H Bennett FRCP
The Lancet Diabetes & Endocrinology - 3 April 2014
DOI: 10.1016/S2213-8587(14)70057-9