Correlation between serum bilirubin and cystatin C in patients with type 2 diabetes mellitus / 中国医师进修杂志

ABSTRACT

Objective:To study the correlation between serum bilirubin and cystatin C in patients with type 2 diabetes mellitus.Methods:A retrospective cohort study was conducted on 750 patients who were in the Affiliated Hospital of Jining Medical University from June 2017 to May 2018. The clinical data were collected, and the correlation between serum total bilirubin, direct bilirubin, indirect bilirubin and cystatin C was analyzed.Results:According to the results of single factor analysis, after adjusting the related confounding factors, the smooth curve fitting showed that there was a U-shaped relationship between the total bilirubin, indirect bilirubin and cystatin C. When the total bilirubin was <15.9 μmol/L, for every increase of 1 μmol/L in total bilirubin, cystatin C decreased 0.008 mg/L ( β = - 0.008, 95% CI - 0.014 to - 0.002, P<0.01); when indirect bilirubin was <11.5 μmol/L, for every increase of 1 μmol/L in indirect bilirubin, cystatin C decreased 0.011 mg/L ( β = - 0.011, 95% CI - 0.018 to - 0.003, P<0.01). When cystatin C was grouped according to the normal range (cystatin C<1.25 mg/L), after adjusting the related confounding factors, the smooth curve fitting showed that there was a U-shaped relationship between the total bilirubin and indirect bilirubin with cystatin C; when total bilirubin was <15.5 mol/L, for every increase of 1 μmol/L in total bilirubin, the risk of cystatin C exceeding the normal value was reduced by 17% ( OR = 0.83, 95% CI 0.71 to 0.96, P<0.01); when total bilirubin was ≥15.5 μmol/L, for every increase of 1 μmol/L in total bilirubin, the risk of cystatin C exceeding the normal value was increased by 12% ( OR = 1.12, 95% CI 1.01 to 1.25, P<0.05); when indirect bilirubin was <11.8 μmol/L, every increase of 1 μmol/L in indirect bilirubin, the risk of cystatin C exceeding the normal value was reduced by 20% ( OR = 0.80, 95% CI 0.67 to 0.95, P<0.01). However there was no significant correlation between direct bilirubin and cystatin C. Conclusions:There is a U-shaped relationship between total bilirubin, indirect bilirubin and cystatin C. At physiological concentrations, the increase of total bilirubin and indirect bilirubin can reduce cystatin C.