A higher resting heart rate in adulthood means a higher risk of diabetes—and diabetes-related death—after age 65, finds a study by researchers at the Feinberg School of Medicine at Northwestern University.

The finding is consistent with previous studies, but according to researchers it comes from the longest ever follow-up study investigating heart rate and diabetes.

Researchers used data from the Chicago Heart Association Detection Project (1967 to 1973), which measured the resting heart rate of nearly 15,000 men and women ages 35 to 64. Thirty-five years later, the Northwestern researchers followed up to determine the rate of development of diabetes as well as the incidence of diabetes-related deaths in that group. They checked participants’ Medicare billing records to determine who had filed diabetes-related hospital claims, indicating that they’d developed diabetes. Though records did not distinguish between type 1 and type 2, the age of the participants evaluated at follow-up (older than 65 years) indicates that most cases of diabetes were type 2.

After accounting for demographics, smoking, and other factors, the odds of having a diabetes-related claim were 10 percent higher for every 12 beats per minute higher a person’s heart rate had been 35 years earlier.

The researchers were not surprised by the findings because a higher heart rate indicates reduced fitness of the cardiac, respiratory, and nervous systems—and a possibly increased risk of diabetes. In particular, a chronically high heart rate can compromise nerve fibers that help secrete and release insulin, the researchers explain.

“Resting heart rate is a measure of both autonomic nervous system function and fitness, both of which we know are related to the development of diabetes,” says Mercedes Carnethon, PhD, lead author of the research. And what people do affects that measure, she emphasizes, adding that “regular physical activity … may be an effective means to prevent diabetes.”

The study was published in the February 2008 issue of Diabetes Care.