Abstract
Background: Autonomic imbalance has been described in first-degree relatives of diabetic patients, and dyslipidemia has been reported to induce sympathovagal imbalance (SVI).

Aims and Objective: To assess the contribution of dyslipidemia to SVI in adults with positive family history of type 2 diabetes mellitus (T2DM).

Materials and Methods: This is a cross-sectional study involving 150 male Saudi adults aged 19–30 years, recruited from students of College of Applied Medical Sciences in Taif University, Taif, Saudi Arabia. Lipid profile, atherogenic index (AI), body mass index (BMI), waist circumference (WC), basal heart rate (BHR), blood pressure (BP), spectral indices of heart rate variability (HRV), and homeostatic model of insulin resistance (HOMA-IR) were measured and analyzed in study groups (control subjects with no family history of T2DM, n = 50; positive family history of T2DM, nondyslipidemic subjects, n = 50 and dyslipidemic subjects n = 50).

Result: In the dyslipidemic group, lipid profile, LF-HF (ratio of low-frequency to high-frequency power of HRV, a precise indicator of SVI) was significantly increased (P˂ 0.05) when compared with non dyslipidemic and the control groups. Increased SVI was owing to simultaneous sympathetic motivation and vagal inhibition. LF-HF ratio was positively correlated with the WC, SBP, DBP, BHR, total cholesterol (TC), low-density lipoprotein (LDL) and AI. Significant contribution of WC, DBP, BHR, TC, and AI to the LF-HF ratio in the dyslipidemic group was observed by multiple regression analysis.

Conclusion: SVI in dyslipidemic subjects with family history of T2DM occurs owing to sympathetic activation and vagal depression. Dyslipidemia contributes to the SVI in these subjects.