Background: Though decreased baroreceptor refl ex sensitivity (BRS) promotes cardiovascular (CV) morbidity and CV risks are reported in the fi rst-degree relatives (FDR) of Type 2 diabetics, the pathophysiological mechanisms contributing to CV risks in these subjects are not yet elucidated. Methods and Results: Body mass index (BMI), CV parameters such as heart rate (HR), blood pressure (BP), rate-pressure product (RPP), stroke volume (SV), left-ventricular ejection time (LVET), cardiac output, total peripheral resistance (TPR) and BRS, spectral-indices of heart rate variability (HRV), autonomic function tests (AFT) and fasting blood glucose (FBG) were measured and analyzed in subjects of the study group (FDR of Type 2 diabetics, n = 79) and control group (subjects with no family history of diabetes, n = 115). BMI, HR, BP, RPP, SV, LVET, cardiac output, TPR, low-frequency to the high-frequency ratio (ratio of LF-HF power of HRV) and FBG were increased (P < 0.0001), and BRS was decreased (P < 0.0001) in the study group compared to the control group. AFT and HRV parameters demonstrated sympathovagal imbalance (SVI) in the study group, which was due to concomitant sympathetic activation and vagal inhibition. There was a signifi cant correlation of BRS with BMI, CV parameters and LF-HF ratio, a sensitive marker of SVI. Multiple-regression analysis demonstrated independent contribution LF-HF ratio and hypertension status to BRS in the study group. Bivariate-logistic regression revealed signifi cant prediction (odds ratio: 2.15; confi dence interval: 1.1112-6.856, P = 0.008) of BRS to increased RPP, the marker of CV risk, in the study group. Conclusion: Decreased BRS in FDR of Type 2 diabetics predisposes them to CV dysfunction. BRS is linked to SVI and CV risks in these high-risk subjects.
Key words: Autonomic derangement, baroreceptor refl ex sensitivity, cardiovascular risk, fi rst-degree relatives of Type 2 diabetics, heart rate variability, sympathovagal imbalance.