RF02 | PMON308 Hyperglycemia Is the Main Determinant of Cardiac Autonomic Dysfunction in Youth With Obesity Across the Spectrum of Glycemic Regulation.

Heart Rate Variability (HRV) results from the autonomic nervous system activity, it is a non-invasive marker of cardiac autonomic function. Loss of parasympathetic function (PNS) and sympathetic (SNS) override, reflected in decreased HRV, is one of the earliest subclinical manifestations of cardiac autonomic dysfunction. Lower HRV is associated with increased risk of cardiac events in adults. We aimed to characterize HRV in normal weight and overweight children with and without dysglycemia and to investigate the determinants of HRV in these youth, including body composition, glycemia measures, beta-cell function and inflammatory markers. We evaluated 94 adolescents (50 males/44 females), age 15 ± 2.1 years; 21 normal weight with normal glucose tolerance (NW-NGT), 23 overweight with NGT (OW-NGT) and 50 overweight with impaired glucose regulation (OW-IGR) including prediabetes (n= 27) and type 2 diabetes (n= 23). They underwent assessment of anthropometrics, body composition (DXA scan), inflammatory markers (hs-CRP and TNF-α), fasting labs and 2-hour oral glucose tolerance test (OGTT) with determination of glucose and insulin concentration. EndoPat was used to measure HRV: frequency-domain indices [high-frequency (HF) reflecting PNS, low-frequency (LF) reflecting both PNS and SNS, and LF/HF (higher is worse) estimating the ratio between SNS and PNS] and time-domain indices [the inter-beat interval of normal sinus beats (NN) and the standard deviation of NN (SDNN) measuring overall HRV, the square root of the mean squared difference of successive NN (RMSSD) and the NN intervals differing by more than 50 milliseconds (NN50) measuring PNS activity]. LF/HF was higher in the OW-IGR group compared with NW and OW-NGT (p=0.005). After controlling for sex, race and Tanner stage, fasting glucose (FBG) negatively correlated with NN (r=-0.22,p=0.04), SDNN (r=-0.21,p=0.05), RMSSD (r=-0.3,p=0.004), NN50 (r=-0.27,p=0.01) and HF (r=-0.26,p=0.02). LF/HF was positively related to FBG (r=0.39,p<0.001), 2hr-glucose (r=0.31,p=0.004) and HbA1c (r=0.22,p=0.04), and negatively with the insulinogenic index (r=-0.27,p=0.02), but not fasting insulin or HOMA-IR; LF/HF also correlated with percent body fat (r=0.22,p=0.04), hs-CRP (r=0.33,p=0.002) and TNF-α (r=0.38,p=0.006). In a linear regression model with LnLF/HF as the dependent variable and percent body fat, hs-CRP, FBG and HOMA-IR as the independent variables, FBG (beta=0.39,p=0.003) and hs-CRP (beta=0.21,p=0.09) were the significant determinants of LnLF/HF independent of age, sex, race and Tanner stage as covariates (R(2)= 0.23,p=0.013). Youth with impaired glucose metabolism have evidence of early subclinical cardiac autonomic dysfunction with decreased HRV, loss of parasympathetic function and sympathetic overdrive as reflected by lower time-domain indices, lower HF and higher LF/HF, related to glycemia and systemic inflammation. Presentation: Saturday, June 11, 2022 1:00 p.m. - 2:00 p.m., Saturday, June 11, 2022 1:12 p.m. - 1:17 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.