Higher Resting Heart Rate Linked to Diabetes and Mortality in Older Age

October 31, 2007 — Higher resting heart rate (HR) was associated with diabetes and mortality in older age, according to the results of a study reported in the October 24 Online First issue of Diabetes Care.
"Given that estimates of autonomic function and fitness are associated with the development of insulin resistance and hyperglycemia in population studies and that heart rate is correlated with these physiologic measures, it is biologically plausible that higher heart rate is associated with the development of diabetes," write Mercedes Carnethon, PhD, from the Feinberg School of Medicine, Northwestern University in Chicago, Illinois, and colleagues. "In a sample of young and middle-aged adults, we tested the hypothesis that a faster resting heart rate was associated with a greater likelihood of experiencing diabetes-related morbidity or mortality in older age (after age 65 years)."
In the Chicago Heart Association Detection Project in Industry Study, resting HR was measured at baseline, from 1967 to 1973. Using Medicare billing records for 14,992 participants aged 35 to 64 years who were free from diabetes at baseline, the investigators identified diabetes-related hospital claims and non–hospital-based diabetes expenses from 1992 through 2002. They also determined diabetes-related mortality from 1984 to 2002 using National Death Index codes 250.XX (International Classification of Diseases [ICD]-8 and -9) and E10–E14 (ICD-10).
Diabetes-related hospital claims occurred in 1877 participants after age 65 years, and 410 participants had some mention of diabetes on their death certificate. For every 12-bpm higher baseline HR, the odds of having a diabetes-related claim was approximately 10% higher (odds ratio [OR], 1.10; 95% confidence interval [CI], 1.05 - 1.16), after adjustment for demographic characteristics, cigarette smoking, and years of Medicare eligibility.
This association became nonsignificant after adjustment for body mass index (BMI) and postload glucose levels at baseline. In adults aged 35 to 49 years at baseline, higher HR was associated with diabetes-related mortality after adjustment for postload glucose levels and BMI (OR, 1.21; 95% CI, 1.03 - 1.41).
"Higher resting HR is associated with diabetes claims and mortality in older age, and is only due in part to BMI and concurrently-measured glucose," the study authors write.
Limitations of the study include measured glucose levels lower than would be obtained with current standard measurement techniques, possible underestimate of the number of participants with fasting glucose levels of more than 11.1 mmol/L who had undiagnosed diabetes, diagnosis of diabetes at follow-up based on Medicare claims data, findings only generalizable to adults who live to older age, reliance on hospital visit diagnosis codes to identify diabetes, inability to evaluate the role of changes in covariates with time on the association between HR and diabetes, and no measurement of physical activity available for statistical adjustment.
"In our study of a large sample of middle-aged adults, baseline heart rate (measured up to 35 years before) was associated with diabetes diagnoses and mortality in older age," the study authors conclude. "Our findings provide further evidence that higher heart rate is associated with adverse morbidity and mortality from a number of causes including diabetes."
The National Heart, Lung, and Blood Institute funded this study.
Diabetes Care. Published online October 24, 2007.