June 11, 1012 (Philadelphia, Pennsylvania) — Long-term lifestyle intervention (diet, exercise, or both) helps women with impaired glucose tolerance live longer, according to the results of a study presented here at the American Diabetes Association 72nd Scientific Sessions. The same cannot be said for men, the researchers reported.
“The reasons for the difference in the effect of lifestyle intervention in men and women are not clear,” Guangwei Li, MD, from the Department of Endocrinology at the China-Japan Friendship Hospital in Beijing, China, told conference attendees.
The findings come from 23 years of follow-up data on participants in the Da Qing Diabetes Prevention Study.
In 1986, 576 adults (mean age, 45 years), from 33 clinics, with impaired glucose tolerance were randomly assigned to a control group or to 1 of 3 lifestyle intervention groups (diet, exercise, and diet plus exercise). The intervention took place from 1986 to 1992.
In 2009, 23 years after randomization, the long-term effects of the intervention on all-cause and cardiovascular (coronary heart disease, stroke, and sudden death) mortality were determined.
“We compared mortality rates in women and men in the control group with those in the combined intervention groups using intent-to-treat analyses,” Dr. Li explained.
Over the 23-year follow-up period, 47 women and 127 men died.
In women, lifestyle intervention reduced all-cause mortality by 53% (hazard rate ratio [HRR], 0.47; 95% confidence interval [CI], 0.25 to 0.86); cumulative all-cause mortality was 16.2% (95% CI, 11.2 to 21.2) in the intervention group and was 29.3% (95% CI, 17.5 to 48.0) in the control group (P = .02)
The reduction in all-cause mortality in women was mainly due to differences in cardiovascular mortality (heart disease and stroke; HRR, 0.30; 95% CI, 0.12 to 0.68); 23-year cumulative mortality was 6.8% (95% CI, 3.4 to 10.2) in the intervention group and was 18.8% (95% CI, 8.8 to 28.8) in the control group (P = .006).
In men, however, the story was different. There was no significant difference in cumulative all-cause mortality (P = .41) between the intervention groups (41.1%; 95% CI, 34.7 to 47.5) and the control group (46.7%; 95% CI, 35.4 to 58.0).
There was also no significant difference in cumulative cardiovascular mortality between men (P = .47) in the intervention groups (26.4%; 95% CI, 21.1 to 31.6) and the control group (27.4%; 95% CI, 18.6 to 32.2).
Dr. Li noted that for patients with impaired glucose tolerance, lifestyle interventions are known to reduce the incidence of diabetes. However, it remains unclear whether lifestyle intervention will reduce mortality.
The 23-year follow-up data from the Da Qing Diabetes Prevention Study hints that lifestyle intervention does, in fact, lead to a “significantly lower all-cause and cardiovascular mortality among women with impaired glucose tolerance, but not among men,” he said.
Dr. Li said it is possible that the women stuck more closely to the intervention after the active intervention period ended. It is also possible that the higher mean blood pressure and higher rates of smoking in the men are partly responsible.
Linda S. Werner, MD, a diabetes, metabolism, and endocrinology specialist from Endocrine Associates in Bridgeport, Connecticut, who was not involved in the study, agrees.
“My sense,” she told Medscape Medical News, “is that the men probably didn’t follow the lifestyle modification as well as their female counterparts. I think it’s hard to compare apples to apples when looking at lifestyle modification, especially if you throw smoking into the equation.”
“If the men smoked but exercised and dieted, that would cancel out their diet and exercising — kind of like eating well 6 days a week but then eating 10 days worth of food on the seventh day at an all-you-can-eat buffet,” Dr. Werner said.
Dr. Werner explained that “it’s significant — and expected — that the women’s group showed a decrease in cardiovascular events and cardiovascular mortality. It’s not so much a difference between men and women as it is between what the men in that group did that countered their increased risk by other things, [with] smoking being a huge factor.”
The study authors and Dr. Werner have disclosed no relevant financial relationships.
American Diabetes Association (ADA) 72nd Scientific Sessions: Abstract 147-OR. Presented June 9, 2012.
— Megan Brooks0