Heart rate variability in adolescents and adults with type 1 diabetes

Background: Limited data are available regarding the onset or trajectory of cardiovascular autonomic deterioration in persons with type 1 diabetes. Objective: To describe differences in heart rate variability among adolescents with type 1 diabetes, adults with type 1 diabetes who have coexisting renal failure, and adolescent and adult controls. Research Design and Methods: A correlational design was used to compare the status of heart rate variability in adults with type 1 diabetes and renal failure (n = 62); healthy adult controls (n = 67); adolescents with type 1 diabetes (n = 55); and healthy adolescent controls (n = 28). Convenience samples of adult patients with diabetes awaiting kidney or pancreas and kidney transplantation, and adolescents with diabetes were recruited from local university-based clinics. Volunteers served as healthy controls. The short-term R-R variability measures included in this study were changes in heart rate with deep breathing and with the Valsalva maneuver. Twenty-four hour ambulatory heart rate monitoring with power spectral analysis was also obtained to assess longterm R-R variability. Results: Adult patients with type 1 diabetes awaiting transplantation had significantly poorer heart rate variability measures than any of the other three populations studied (p < .0001). Adult control values also were significantly lower than either teenage controls or youths with diabetes (p < .05). Although most long-term R-R variability measures were lower in adolescents with diabetes versus controls, only one measure of parasympathetic modulation (i.e., pNN50) was significantly lower (p = .042). There were significant negative associations between HbA(1c) and sympathetic modulation (i.e., low hertz) in both the adult group (r = -.406, p = .029) and the adolescent group (r = -.324, p = .025) with diabetes. Conclusions: Type 1 diabetes is associated with decreased heart rate variability, with the extent of the decrease related to the age of the individual and the severity of the disease.