Reduced Heart Rate Variability Among Youth With Type 1 Diabetes

Abstract

OBJECTIVEThis study compared heart rate variability (HRV) parameters in youth with and without type 1 diabetes and explored potential contributors of altered HRV.RESEARCH DESIGN AND METHODSHRV parameters were measured among 354 youth with type 1 diabetes (mean age 18.8 years, diabetes duration 9.8 years, and mean A1C 8.9%) and 176 youth without diabetes (mean age 19.2 years) participating in the SEARCH CVD study. Multiple linear regression was used to assess the relationship between diabetes status and HRV parameters, adjusting for covariates.RESULTSCompared with control subjects, youth with type 1 diabetes had reduced overall HRV (10.09 ms lower SD of NN intervals [SDNN]) and markers of parasympathetic loss (13.5 ms reduced root mean square successive difference of NN intervals [RMSSD] and 5.2 normalized units (n.u.) reduced high frequency [HF] power) with sympathetic override (5.2 n.u. increased low frequency [LF] power), independent of demographic, anthropometric, and traditional cardiovascular risk factors. Older age, female sex, higher LDL cholesterol and triglyceride levels, and presence of microalbuminuria were independently associated with lower HRV but did not account for the observed differences between youth with and without diabetes. Youth with type 1 diabetes and A1C levels ≥7.5% had significantly worse HRV parameters than control subjects; however, in youth with optimal glycemic control (A1C <7.5%), HRV parameters did not differ significantly from control subjects.CONCLUSIONSYouth with type 1 diabetes have signs of early cardiac autonomic neuropathy: reduced overall HRV and parasympathetic loss with sympathetic override. The main driver of these subclinical abnormalities appears to be hyperglycemia.

Cardiac Autonomic Dysfunction Is Associated With High-Risk Albumin-to-Creatinine Ratio in Young Adolescents With Type 1 Diabetes in AdDIT (Adolescent Type 1 Diabetes Cardio-Renal Interventional Trial)

“…This is the first large-scale study examining heart rate variability in relation to risk of nephropathy in adolescents with type 1 diabetes who have not yet developed microalbuminuria. Reduced heart rate variability has been associated with microalbuminuria in older adolescents (4,9). In the SEARCH for Diabetes in Youth Study, lower SDNN (one measure of overall heart rate variability) was associated with microalbuminuria in older adolescents with type 1 diabetes (mean age 18.8 years, mean duration 9.8 years) (9).…”

“…Reduced heart rate variability has been associated with microalbuminuria in older adolescents (4,9). In the SEARCH for Diabetes in Youth Study, lower SDNN (one measure of overall heart rate variability) was associated with microalbuminuria in older adolescents with type 1 diabetes (mean age 18.8 years, mean duration 9.8 years) (9). In this current study, we found significantly lower SDNN and RMSSD (measures of overall heart rate variability) and faster heart rate in younger adolescents at risk for nephropathy (mean age 14.1 years, mean duration 6.4 years).…”

“…Power spectral analyses of heart rate variability allow more sensitive detection of cardiac autonomic changes than the conventional Ewing battery of tests based on dynamic cardiovascular maneuvers (5,7,8). Recent studies using these modern methods have demonstrated that adverse changes in heart rate variability may be detected during adolescence in people with type 1 diabetes and are primarily associated with poor glycemic control (1,9,10). However, there is a paucity of data on whether cardiac autonomic function is associated with early renal dysfunction before the onset of microalbuminuria.…”

Cardiovascular Disease Risk Factors in Youth With Diabetes Mellitus

“…131 However, 1 large study (n=354) found overall heart rate variability reduction, suggesting a more advanced state of cardiac autonomic neuropathy. 132 Predictors of abnormal heart rate variability in children with T1DM included higher HbA 1c 132 and low PA. 133 The few small studies of neurological function conducted in youth with T2DM showed lower cognitive function, 134 peripheral neuropathy, 135 and lower heart rate variability compared with control subjects. 136 These early changes in neurological function have implications for future CVD because autonomic dysfunction measured in childhood predicts increased arterial stiffness 18 years later.…”

‘SeXX’ matters: In the myocardium of patients with type 1 diabetes

“…Other studies have also demonstrated higher resting heart rates 16 and lower heart rate variability in patients with T1DM compared with controls. 17 However, heart rate and heart rate variability are influenced by many different inputs including parasympathetic tone, hormones, temperature, and levels of various ions and molecules. The lack of a difference in the norepinephrine analog tracer in the myocardium between the normal subjects and the patients with T1DM may simply mean that sympathetic stimuli/hormones are not the main influence on the heart rate difference between the 2 groups.…”