Intensive control of blood sugar (glucose) in patients with type 1 diabetes is associated with a lower resting heart rate, according to a report in Diabetes Care.

"This effect may partially explain why the intensive insulin treatment has been shown to reduce the risk of heart disease in those with type 1 diabetes," Dr. Andrew D. Paterson of the University of Toronto, Canada told Reuters Health.

"(High) resting heart rate is a risk factor for cardiovascular disease in the general population, and case-control studies have reported a higher resting heart rate in individuals with type 1 diabetes," Paterson and colleagues note.

As part of the Diabetes Control and Complications Trial, 1,441 type 1 diabetic patients had their resting heart rate measured every 2 years, for up to 8 years. In the follow-up study -- the Epidemiology of Diabetes Intervention and Complications study -- resting heart rate was measured annually for 10 years.

An analysis of data from the two trials "support and extend the association of diabetes with faster resting heart rate and of higher levels of glycemia with resting heart rate previously demonstrated in cross-sectional studies," the researchers report.

During the Diabetes Control and Complications Trial, intensive treatment was associated with lower resting heart rate than was conventional treatment in both adolescents and adults. During the follow-up study of the Epidemiology trial, the difference in resting heart rate favoring intensive diabetes treatment remained.

Summing up, Paterson said, "In this study, patients with type 1 diabetes who controlled their blood glucose within the normal range had a lower heart rate than those whose blood glucose control was not as good."

Furthermore, "This effect occurred within 2 years after the start of the intensive insulin treatment ... and persisted for at least 10 years after the end of the treatment," he added.