BOSTON—A recent study found even later in life, combined lifestyle factors are associated with a markedly lower incidence of new-onset diabetes mellitus (Arch Intern Med. 2009;169(8):798-807). Researchers prospectively examined associations of lifestyle factors, measured using repeated assessments later in life, with incident diabetes mellitus during a 10-year period (1989 to1998) among 4,883 men and women 65 years or older enrolled in the Cardiovascular Health Study. Low-risk lifestyle groups were defined by physical activity level (leisure-time activity and walking pace) above the median; dietary score (higher fiber intake and polyunsaturated to saturated fat ratio, lower trans-fat intake and lower mean glycemic index) in the top-two quintiles; never smoked or former smoker more than 20 years ago or for fewer than 5 pack-years; alcohol use (predominantly light or moderate); body mass index less than 25 (calculated as weight in kilograms divided by height in meters squared); and waist circumference of 88 cm for women or 92 cm for men. The main outcome measure was incident diabetes defined annually by new use of insulin or oral hypoglycemic medications.
During 34,539 person-years, 337 new cases of drug-treated diabetes mellitus occurred (9.8 per 1000 person-years). After adjustment for age, sex, race, educational level and annual income, each lifestyle factor was independently associated with incident diabetes. Overall, the rate of incident diabetes was 35 percent lower (relative risk, 0.65; 95% confidence interval, 0.59-0.71) for each one additional lifestyle factor in the low-risk group. Participants whose physical activity level and dietary, smoking and alcohol habits were all in the low-risk group had an 82 percent lower incidence of diabetes compared with all other participants. When absence of adiposity was added to the other four low-risk lifestyle factors, incidence of diabetes was 89 percent lower. Overall, nine of 10 new cases of diabetes appeared to be attributable to these five lifestyle factors. Associations were slightly attenuated, but still highly significant, for incident diabetes defined by medication use or glucose level.