Association between Serum Bilirubin and Estimated Glomerular Filtration Rate among Diabetic Patients

Association of Serum Bilirubin Levels with Macro- and Microvascular Complications in Chinese People with Type 2 Diabetes Mellitus: New Insight on Gender Differences

BACKGROUND

Previous studies suggested protective effects of bilirubin against cardiovascular disease, with a possible gender difference. However, the relationship between serum total bilirubin (TBIL) with diabetic macro- and microvascular complications remains unknown. We aimed to examine the association of macro- and microvascular complications with serum TBIL levels.

METHODS

Serum TBIL was measured in 648 patients with T2DM. Demographic and clinical data were obtained from the inpatient medical record system. Serum TBIL was measured with an automatic biochemistry analyzer according to routine protocols. Parameters of vascular complications, including ankle-brachial index, carotid intima-media thickness, estimated glomerular filtration rate and the urinary albumin to creatinine ratio, were measured and calculated. The association between TBIL and diabetic macro- and microvascular complications was analyzed.

RESULTS

In multivariable logistic regression, after adjustment for age, sex, body mass index and diabetic duration, higher serum TBIL levels were significantly associated with decreased odds of microalbuminuria (OR = 0.31, [95% CI] 0.16-0.61, P = 0.003) and chronic kidney disease (OR = 0.19, [95% CI] 0.09-0.41, P < 0.001). These associations were only found in male but not in female patients. However, no significant relationship was found between TBIL and peripheral arterial disease or carotid hypertrophy.

CONCLUSION

Our findings suggest that physiological higher TBIL level might be a protective factor for diabetic microvascular complications.

Association of Serum Total Bilirubin and Uric Acid with Low Glomerular Filtration Rate Diabetic Kidney Disease in Type 2 Diabetic Patients

BACKGROUND

Diabetic kidney disease (DKD) is one of the major complications of Type 2 diabetes, clinically characterized by a progressive increase in albuminuria and/or a subsequent decline in glomerular filtration rate. Identification of novel risk factors contributes to reduction in the risk of diabetic kidney disease. Bilirubin, as an antioxidant and anti-inflammatory molecule, is believed to have a protective role in kidney disease. On the other hand, uric acid is implicated in the pathogenesis of DKD due to its pro-oxidant and pro-inflammatory property in vascular tissues.

METHODS

A hospital based comparative cross-sectional study was conducted from October 2020 to March 2021 on 200 eligible Type 2 diabetic patients (58 with DKD and 142 without DKD) to assess the association of serum total bilirubin and serum uric acid levels with low GFR diabetic kidney disease using consecutive sampling technique.

RESULTS

The serum total bilirubin level was significantly decreased (0.15±2.29, mean±SD) in the DKD group compared to the non-DKD group (0.19±2.26), whereas the mean±SD serum uric acid was significantly increased in the DKD group (7.13±2.21) compared to the non-DKD group (5.24±1.92). A low serum total bilirubin level was significantly associated with increased risk of DKD in multivariate analysis (AOR=2.23, 95% CI=1.55-4.13) also to high serum uric acid levels (AOR=2.09, 95% CI=1.06-4.12). Moreover, a low serum total bilirubin level was significantly associated with increased risk of DKD among patients with high serum uric acid (AOR=2.55, 95% CI=1.05-6.19). Similarly, high serum uric acid was significantly associated with increased risk of DKD among patients with low serum total bilirubin (AOR=3.49, 95% CI=1.29-9.42).

CONCLUSION

Co-presence of low serum total bilirubin and high serum uric acid may be useful for stratification of DKD risk among patients with Type 2 diabetes mellitus.

Association between serum bilirubin levels and progression of albuminuria in Taiwanese with type 2 diabetes mellitus

BACKGROUND

To investigate the association between serum bilirubin (BIL) levels and the progression of albuminuria in type 2 diabetic Taiwanese.

METHODS

Longitudinal data from January 2001 to June 2015 were retrospectively reviewed from Chang Gung Memorial Hospital in Taiwan. A total of 2877 type 2 diabetic patients with normal total BIL levels were divided into 4 groups according to BIL, with the highest BIL in the fourth group. The urinary albumin/creatinine ratio (UACR) trend and progression, as well as other laboratory measurements, were evaluated among the four groups. The cumulative incidence and Cox proportional hazard model analysis were performed to examine the relationship between BIL and the risk of albuminuria progression (AUPr).

RESULTS

The mean duration of follow-up was 1.5 years (±1.37 years). The mean patient age, glycosylated hemoglobin level, and duration of diabetes were 62.52 years, 7.9%, and 3.94 years, respectively. A significant correlation was observed between BIL and both the UACR at baseline (P < 0.001) and the cumulative incidence of AUPr (log-rank test, P = 0.031). Hazard ratio (HR) analysis revealed that patients in the fourth BIL quartile had the lowest HR risk of AUPr among the four groups (adjusted HR = 0.70; 95% Confidence Interval = 0.56-0.89, P < 0.05).

CONCLUSIONS

Higher serum BIL levels are associated with a lower risk of AUPr in type 2 diabetes patients in Taiwan.

Elevated bilirubin levels and risk of developing chronic kidney disease: a dose-response meta-analysis and systematic review of cohort studies

AIMS

Previous studies have indicated the link of bilirubin levels and risk of developing chronic kidney disease (CKD); however, the findings were inconsistent.

METHODS

We searched for cohort studies examining bilirubin as an exposure and CKD as an outcome in the Medline, EMBASE, and Web of Science databases from inception through November 31, 2016. A generalized least-squares approach was applied to assess the dose-response relationship between them by pooling rate ratios with 95% confidence intervals. Subgroup analyses, sensitivity analysis, meta-regression, and publication bias were also conducted.

RESULTS

Seven cohort studies with 1316 cases and 21,076 participants were identified for inclusion in the meta-analysis. The combined RR for the highest versus lowest bilirubin level was 0.36 (95% CI 0.19-0.68; P _{heterogeneity} = 0.001; Power = 0.72; n = 6). In the linear dose-response analysis, each 1-μmol/L increase in bilirubin was associated with a 5% reduced risk of CKD (RR = 0.95; 95% CI 0.92-0.97; P for trend test = 0.113; P _{heterogeneity} = 0.001; Power = 0.99; n = 7). The subgroup analyses and sensitivity analyses showed consistent results, and publication bias may exist.

CONCLUSION

This meta-analysis suggests that elevated bilirubin level may be associated with decreased risk of developing CKD.