If people at a high risk for diabetes spend six years following an improved diet and exercise regimen, they can reduce their risk of developing the disease for up to 14 years, a new study says.

The study, conducted by Chinese and American researchers, was published Thursday in a special diabetes edition of the journal The Lancet.

The researchers analyzed data from almost 800 Chinese adults with impaired glucose tolerance, a pre-diabetes condition whereby blood sugar levels are higher then normal. This happens when the body does not produce enough insulin, or does not properly use insulin, which carries glucose into the body's cells to be used as energy.

Researchers began to follow the patients in 1986 by assigning them to one of three intervention groups. They were put on a diet program, an exercise program, or a regimen of both, which lasted until 1992.

When researchers followed up with the patients in 2006, they found that the combined diet and exercise program reduced the incidence of diabetes by 51 per cent during the six-year intervention period, compared to a control group. Over the entire 20-year span of the study, the diet and exercise regimen reduced the incidence of diabetes by 43 per cent.

While it is well known that a healthy lifestyle can reduce risk factors for a variety of health problems, including diabetes, this study shows that improved diet and exercise habits can stave off diabetes over a long-term period.

"This study has shown that, in Chinese people with impaired glucose tolerance, group-based interventions targeting lifestyle changes such as diet and exercise produce a durable and long-lasting reduction in incidence of type 2 diabetes," the authors concluded in their study.

"Since around three million excess deaths a year are attributable to diabetes worldwide, lifestyle interventions seem to be a justifiable public-health action both in developed and developing nations."

Abstract:

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

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.