To analysis the relationship between urinary albumin creatinine ratio (UACR) and heart rate variability (HRV) in patients with type 2 diabetes mellitus (T2DM).

Patients with T2DM were divided into control group (patients with T2DM only) and treatment group (patients with T2DM and proteinuria) using the cohort method. The treatment group was further divided into a microalbuminuria subgroup (UACR 30 - 300 mg·g^-1) and a macroalbuminuria subgroup (UACR≥300 mg·g^-1). Collected general clinical data, biochemical indicators and 24-hour holter electrocardiogram reports from patients, recorded HRV-related indicators [including pairs of normal N-N Intervals differ by more than 50 ms (PNN50), standard deviation of normal-to-normal R-R intervals (SDNN), etc] of each group of patients, and calculated body mass index (BMI) and estimated glomerular filtration rate (eGFR). Compared the differences in clinical data and HRV parameters among groups, analyzed the impact of UACR on HRV and their interrelationships, and used the receiver operating characteristic curve (ROC) to predict the optimal cutoff point for the occurrence of proteinuria in T2DM patients.

The treatment group enrolled 190 cases, and the control group enrolled 184 cases; the microalbuminuria subgroup enrolled 120 cases, and the macroalbuminuria subgroup enrolled 70 cases. The levels of UACR in the treatment and control groups were 113.99 and 12.76 mg·mmol^-1 Cr, the levels of UAER were 74.81 and 10.92 μg·min^-1, the levels of UA were (353.83±96.41) and (326.17±81.64) μmol·L^-1, the levels of PNN50 were 2.25 and 3.95, the levels of SDNN were 102.83±38.10 and 114.14±31.23, the levels of HRV triangular index were 20.80 and 25.55, respectively; the differences of above results were statistically significant between two groups (all P<0.05). In the macroalbuminuria and microalbuminuria subgroups, the levels of UACR were 1 088.17 and 64.64 mg·mmol^-1 Cr, the levels of UAER were 878.65 and 44.26 μg·min^-1, the levels of UA were (375.88±97.58) and (340.97±93.74) μmol·L^-1, the levels of PNN50 were 1.50 and 2.70, the levels of SDNN were 88.00 and 108.00, the levels of HRV triangular index were 19.49±7.77 and 24.48±8.84, respectively; the differences of above results were statistically significant between two subgroups (all P<0.05). Logistic regression analysis showed that the duration of diabetes mellitus, fasting blood glucose (FPG) and HRV triangle index were the influencing factors for the occurrence of proteinuria in patients with type 2 diabetes mellitus. ROC showed that HRV triangle index had the largest area under ROC curve, with 66.10% sensitivity and 63.00% specificity.

UACR in T2DM patients is closely related to the duration of DM, FPG and HRV triangle index, with the increase of UACR in T2DM patients, the risk of cardiovascular autonomic neuropathy increases.