Traveling to and from work can reduce cardiovascular disease in people with type 2 diabetes

Jul 26 2004

Research published in the current issue of the Journal of the American Heart Association shows that moderate exercise can reduce cardiovascular disease deaths in people with type 2 diabetes, even if that activity comes from work or traveling to and from work.

The protective effects of exercise are not limited to leisure-time activities, said senior author Jaakko Tuomilehto, M.D., Ph.D., professor, Diabetes and Genetic Epidemiology Unit in the National Public Health Institute in Helsinki, Finland.

Diabetes increases the risk of heart disease and stroke. It is a condition where the body can no longer control its blood sugar level. Without adequate control the level tends to rise dramatically and remains high. Over time, these high levels can result in damage to blood vessels leading to heart disease, stroke, blindness, kidney failure, impotence, circulatory problems and nerve damage.

“Regular physical activity should be part of standard treatment for diabetic patients. People with diabetes need to look for ways to build activity into their work, their commuting to and from work and also their leisure time,” Tuomilehto said. “Physical activity during commuting is one of the easiest, least-time consuming ways to promote health.”

“We know that type 2 diabetes can be prevented or at least postponed by physical activity and a healthy diet, but too often people think only of leisure-time physical training or other aerobic activities,” Tuomilehto said.

Diabetes is caused by an alteration in the metabolism of carbohydrates due to a deficiency in production of the hormone insulin by the pancreas. Insulin helps cells use sugar as a fuel and also transforms it into energy.

There are two forms of diabetes: Type 1, or insulin-dependent diabetes, in which a person has to keep track of insulin levels with daily injections, and Type 2, which is not dependent on insulin.

Ninety percent of diabetics suffer from Type 2 diabetes, which is also known as "silent diabetes." It usually develops in people over 40, with limited or no symptoms. However, increasing levels of obesity in the population have resulted in Type 2 diabetes appearing more frequently in adolescents and in young adults.

Although occupational, commuting and leisure-time physical activity has been associated with reductions in cardiovascular disease (CVD) deaths in the general population, this is the first large, long-term prospective study among people with type 2 diabetes, said lead researcher Gang Hu, M.D., Ph.D., M.P.H.

Researchers reviewed data on 3,316 people ages 25 to 74 who had type 2 diabetes and participated in national surveys of randomly selected samples in the Finnish population between 1972 and 1997. The data included results from questionnaires on heart disease risk factors such as smoking, medical history and the level of physical activity on the job, on the way to and from work, and during leisure time.

Work activity was divided into three exercise levels: light (easy physical work and sitting, e.g., office work); moderate (walking and lifting light objects, e.g., store clerk) and active (walking and lifting, heavy manual labor).

Light commuting was defined as using motorized transportation; moderate was walking or bicycling up to 29 minutes daily; active commuting was walking or cycling 30 minutes or more per day. Light leisure activity was almost completely inactive, such as reading or watching TV. Moderate was more than four hours each week of walking, cycling or light gardening and active was more than three hours of vigorous activity per week such as swimming, running or jogging.

During an average follow-up of 18.4 years, 1,410 of the subjects had died, including 903 (64 percent) from cardiovascular disease. After adjusting for age, gender, body mass index, systolic blood pressure, total cholesterol and smoking, the researchers found that moderately active work was associated with a 9 percent reduction in cardiovascular death and active work was associated with a 40 percent reduction in CVD death.

An analysis of leisure-time activity found that high leisure-time physical activity was associated with a 33-percent drop in CVD death and moderate activity was linked to a 17 percent drop in CVD death compared to the most sedentary group.

“If this finding represents a causal relation, increasing exercise could be highly important to the improvement of health and the lengthening of life among working-aged patients,” Hu said.

“Since the increase in computerization and mechanization has resulted in ever-increasing numbers of people being sedentary for most of their working time, adding short time exercise during working breaks, or adding walking activity during work time are recommended. We believe that it would be cost-efficient for employers.”

Regular physical activity may reduce CVD and death among patients with diabetes several ways. For instance, regular exercise is associated with improvements in insulin sensitivity, blood sugar control and other heart disease risk factors.

Commuting to work is a major source of physical activity in some populations and it can be implemented at little expense, the researchers said. More than 90 percent of workers walk or cycle to and from work each day in urban China, as did more than 40 percent of those in this study.

Co-authors include: Johan Eriksson, M.D.; Noël C. Barengo, M.D.; Timo A. Lakka, M.D.; Timo Valle, M.D.; Aulikki Nissinen, M.D.; and Pekka Jousilahti, M.D.

Statements and conclusions of study authors that are published in the American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect Association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.