Aim: The present study assesses the relation between cardiovascular autonomic function and some indexes of glycose variability, insulin resistance and oxidative stress in prediabetes.
Material and Methods: A total of 50 subjects - 12 males, mean age 55.6±9.7 years, mean BMI 28.4±6.4 kg/m2, divided into 2 groups according to glucose tolerance:32 subjects with prediabetes and18 subjects with normal glucose tolerance (NG) were included. Glucose tolerance was assessed by OGTT in accordance with WHO 2006 criteria. Plasma glucose was measured by hexokinase method and immunoreactive insulin - by immuno-chemiluminescence method at fasting, 120-minute and 180-minute during the test; and also oxLDL and 5-Nitrotyrosine - by ELISA method at fasting and 120-minute during the test. Indirect indexes of insulin resistance - HOMA-IR and insulin sensitivity - OGIS were calculated. HbA1c was assessed by immuno-turbidimetric, NGSP certified method. Continuous glucose monitoring was performed with blind sensor for professional use - FreeStyle Libre Pro - for a mean period of 13.6 ± 2.3 days.
Results: There was a significantly decreased parasympathetic tone during deep breathing test (p=0.009) and sympathetic tone at rest (p=0.021) and during Valsalva maneuver test (p=0.026) in prediabetes. Sympathetic activity was related to the standard deviation of glycemic excursions in prediabetes (F [1,31]=7.91, p=0.018); whilst parasympathetic activity was related to J-index and % time spent in glycemic range >7.8 mmol/l in prediabetes (F [1,31]=7.20, p=0.004) and with CONGA index in NGT (F [1,18]=6.75, p=0.025). No significant correlation between autonomic tone and the assessed markers of insulin resistance and oxidative stress was established.
Conclusions: The autonomic tone has been found to be declined in prediabetes. Glucose variability is probably an additional risk factor for autonomic dysfunction at these early stages of glucose intolerance.
R. Dimova: None. N. Chakarova: None. G. Kirilov: None. G. Grozeva: None. T. Tankova: Advisory Panel; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Merck Sharp & Dohme Corp., Sanofi. Speaker's Bureau; Self; Lilly Diabetes, Novo Nordisk A/S, Servier.