Relationship between reduced heart rate variability and insulin resistance, serum cystatin C in type 2 diabetes patients

Objective To investigate the relationship between heart rate variability and insulin resistance (IR), serum cystatin C (Cys-C) in patients with type 2 diabetes mellitus (T2DM). Methods A total of 95 T2DM patients hospitalized in the Department of Endocrinology of the First Affiliated Hospital of Zhengzhou University from January 2014 to August 2018 were selected. According to the standard deviation (SDNN) of RR interval of all sinus beats in dynamic electrocardiogram, the patients were divided into normal heart rate variability group (n=56) and reduced heart rate variability group (n=39). The levels of serum Cys-C, fasting insulin and fasting blood glucose were observed and the level of insulin resistance index (HOMA-IR) was calculated. Results The HOMA-IR and serum Cys-C levels in patients with reduced heart rate variability were higher than those in patients with normal heart rate variability (P<0.01). After correcting the duration of diabetes mellitus, partial correlation analysis showed that HOMA-IR and Cys-C were negatively correlated with SDNN (P<0.05). Conclusions Reduced heart rate variability in type 2 diabetes mellitus is closely correlated with insulin resistance and serum Cys-C levels, suggesting that the high levels of Cys-C and insulin resistance are correlated with diabetic cardiac autonomic neuropathy. Key words: Type 2 diabetic mellitus; Heart rate variability; Insulin resistance; Cystatin C; Cardiac autonomic neuropathy