May 13 (HealthDay News) -- Obese workers with diabetes are less productive than their normal-weight co-workers, says a U.S. study.

Researchers surveyed 7,338 working adults about missed work time, reduced work effectiveness and impairment of daily activities. The results showed that people who were obese and had type 2 diabetes lost 11 percent to 15 percent of work time (about 5.9 hours a week) because of health problems, compared with 9 percent of work time (about 3.6 hours a week) lost by normal-weight people.

The survey also found that obese people with type 2 diabetes reported impairment during 20 percent to 34 percent of their daily activities, such as taking care of children, shopping and exercising.

The findings are in the May/June issue of the American Journal of Health Promotion.

"From an employer's perspective, this study provides evidence that workplace wellness programs that include weight loss and weight management would be beneficial for obese employees with or at risk for diabetes," Kathleen Fox, president of Strategic Healthcare Solutions and a co-author of the study, said in a news release from the Center for the Advancement of Health.

The study supports previously published research that found "the heavier people are, the most lost productivity at work," Anne Wolf, an instructor at the University of Virginia School of Medicine, who specializes in researching the economic effects of obesity, said in the news release. This study was different, she said, in that it found an independent effect of diabetes on worker productivity.

"Employers who spend money in a lifestyle intervention will find their investment returned to them in the form of increased productivity and reduced absenteeism," Wolf said.

SOURCE: Center for the Advancement of Health, news release, April 30, 2009