Ambulatory Heart Rate Variability Correlates with High-Sensitivity C - Reactive Protein in Type 2 Diabetes and Control Subjects

Type 2 diabetes mellitus has been associated with elevated high-sensitivity C-reactive protein (hsCRP), but the possible implication of ambulatory heart rate (HR) variability in enhancing chronic subclinical inflammation biomarkers remains to be elucidated. We aimed to evaluate the correlations between HR variability and coefficient of variance assessed during 24-hour ambulatory blood pressure monitoring (ABPM) and hsCRP in type 2 diabetes and control subjects. The observational study included type 2 diabetes (n=75) and control (n=11) subjects. HR variability was calculated as standard deviation of mean HR during daytime, nighttime and 24-hour periods. The coefficient of variation was calculated using standard deviation and mean HR. Nighttime HR dipping was calculated using daytime and nighttime HR variability. We found higher hsCRP in type 2 diabetes compared to controls. Also, we found that daytime, nighttime and 24-hour HR variability and coefficient of variance were lower in the type 2 diabetes group compared with the control group, while type 2 diabetes subjects receiving beta-blockers had even lower ambulatory HR variability and coefficient of variance. Subjects with diabetic neuropathy, retinopathy and atherosclerotic cardiovascular disease had lower HR variability and coefficient of variance compared to their peers without disease. We observed that daytime and 24-hour HR variability inversely correlated with hsCRP, while all HR variability parameters inversely correlated with hypertension duration in the study population. Nighttime HR dipping inversely correlated with duration of type 2 diabetes and hypertension. Our results suggest that 24-hour ambulatory HR variability and coefficient of variance are significantly correlated with chronic inflammation evaluated using hsCRP in type 2 diabetes and control subjects, and these findings deserve further investigations.