Correlations between serum bilirubin levels and diabetic nephropathy progression among Japanese type 2 diabetic patients: a prospective cohort study (Diabetes Distress and Care Registry at Tenri [DDCRT 5])

Association of Serum Total Bilirubin to Cholesterol Ratio With Progression of Chronic Kidney Disease in Patients With Type 2 Diabetes: A Retrospective Cohort Study

AIM

To explore the influence of the serum total bilirubin to total cholesterol (TBIL/TC) ratio on the progression of chronic kidney disease (CKD) in people with type 2 diabetes.

MATERIALS AND METHODS

The present retrospective discovery cohort investigated 4282 patients. The exposure was baseline TBIL/TC ratio. The outcome was the first time to progressing CKD, defined by a drop in the estimated glomerular filtration rate (eGFR) category, along with a reduction in eGFR of at least 25% compared to the baseline value. Hazard ratios (HRs) for CKD progression were evaluated based on the Cox proportional hazards approach. Dose-response relationships were conducted using Restricted Cubic Splines (RCS). Additionally, 758 patients were enrolled as an independent validation cohort.

RESULTS

During a median observation period of 2.4 years (interquartile range 1.3-3.8 years) within the discovery cohort, 522 individuals showed progression in CKD. The analysis revealed a negative association between the TBIL/TC ratio and the risk of CKD progression, with an adjusted HR of 0.17 and a 95% CI ranging from 0.07 to 0.41. After adjusting for confounding variables, the HRs for the second, third, and fourth quartiles of the TBIL/TC ratio were recorded at 0.61 (95% CI 0.48, 0.78), 0.55 (95% CI 0.42, 0.72), and 0.55 (95% CI 0.41, 0.74), respectively. Analysis with RCS indicated an optimal TBIL/TC ratio threshold of 0.25%. Similar results were also observed in the validation cohort.

CONCLUSIONS

A higher TBIL/TC ratio was significantly associated with a reduced risk of CKD progression in patients with type 2 diabetes.

Low Levels of Metrnl are Linked to the Deterioration of Diabetic Kidney Disease

Objective

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease. Metrnl is a secreted protein that plays an important role in kidney disease. The aim of this study was to investigate DKD-related factors and the correlation between serum Metrnl levels and the severity of DKD.

Methods

Ninety-six type 2 diabetes mellitus (T2DM) patients and 45 DKD patients were included in the study. A range of parameters were measured simultaneously, including waist-to-hip ratio (WHR), body mass index (BMI), urinary albumin/creatinine ratio (UACR), monocyte-lymphocyte ratio (MLR), albumin/globulin (A/G), liver and kidney function, blood lipid profile, islet function, and others. Subsequently, the related factors and predictive significance of DKD were identified. The correlation between the relevant factors of DKD and serum Metrnl levels with DKD was evaluated.

Results

The duration of the disease (OR: 1.12, 95% CI: 1.01-1.24, P=0.031), hypertension (OR: 4.86, 95% CI: 1.16-20.49, P=0.031), fasting blood glucose (OR: 1.23, 95% CI: 1.03-1.48, P=0.025), WHR (OR: 2.53, 95% CI: 1.03-6.22, P=0.044), and MLR (OR: 1.91, 95% CI: 1.18-3.08, P=0.008) are independent risk factors for DKD (P < 0.05). Conversely, A/G (OR: 0.13, 95% CI: 0.02-0.76, P=0.024) and Metrnl (OR: 0.99, 95% CI: 0.98-1.00, P=0.001) have been identified as protective factors against DKD. Furthermore, the level of Metrnl was negatively correlated with the severity of DKD (rs=-0.447, P<0.001). The area under receiver operating characteristic (ROC) curves for the diagnostic accuracy of Metrnl for DKD is 0.765 (95% CI: 0.686-0.844).

Conclusion

The duration of the disease, hypertension, fasting blood glucose, WHR, and MLR are major risk factors for DKD. Metrnl and A/G are protective factors for DKD. Serum Metrnl concentrations are inversely correlated with DKD severity.

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.

Clinical impact of serum bilirubin levels on kidney transplant outcomes

Serum bilirubin, a potent endogenous antioxidant, has been associated with decreased risks of cardiovascular disease, diabetes, and kidney disease. However, the effects of serum bilirubin on kidney transplant outcomes remain undetermined. We analyzed 1628 patients who underwent kidney transplantations between 2003 and 2017. Patients were grouped into sex-specific quartiles according to mean serum bilirubin levels, 3–12 months post-transplantation. Median bilirubin levels were 0.66 mg/dL in males and 0.60 mg/dL in females. The intra-individual variability of serum bilirubin levels was low (9%). Serum bilirubin levels were inversely associated with graft loss, death-censored graft failure, and all-cause mortality, independent of renal function, donor status, and transplant characteristics. Multivariable analysis revealed that the lowest serum bilirubin quartile was associated with increased risk of graft loss (HR 2.64, 95% CI 1.67–4.18, P < 0.001), death-censored graft failure (HR 2.97, 95% CI 1.63–5.42, P < 0.001), and all-cause mortality (HR 2.07, 95% CI 1.01–4.22, P = 0.046). Patients with lower serum bilirubin were also at greater risk of rejection and exhibited consistently lower glomerular filtration rates than those with higher serum bilirubin. Serum bilirubin levels were significantly associated with transplantation outcomes, suggesting that bilirubin could represent a therapeutic target for improving long-term transplant outcomes.

Serum Total Bilirubin and Progression of Chronic Kidney Disease and Mortality: A Systematic Review and Meta-Analysis

Background: Previous studies have suggested that serum total bilirubin (STB) levels are associated with heightened chronic kidney disease (CKD) and mortality in both the general population and nephropathy patients. However, these results remain inconsistent. The aim of our study was to investigate whether STB was a predictor for progression of CKD and mortality by meta-analysis.

Methods: We performed a systematic literature search in PubMed, Web of Science, MEDLINE, EMBASE, Google Scholar, and Cochrane Library's database up to June 30, 2019. Pooled risk ratios (RR) and corresponding 95% confidence intervals (CI) were extracted for the highest vs. lowest category STB levels within the physiological range, and a random-effects model was applied to calculate the dose–response relationships. A pooled hazard ratio (HR) was used to investigate the association between STB levels and mortality in dialysis patients.

Results: A total of 16 studies, wherein participants were followed from 21 months to 7 years, were eligible for inclusion in the study. For the categorized STB, 11 studies with 41,188 participants were identified and analyzed. Patients with the highest STB levels were associated with a lower risk of CKD (RR = 0.64; 95% CI 0.55–0.73) compared to those with the lowest STB levels. Furthermore, based on seven studies, a pooled RR of 0.89, 95% CI (0.80–0.99) was observed for the continuous STB levels (per 0.2 mg/dL increase). Four studies that included 51,764 participants illustrated that there was no association between STB levels and all-cause mortality (HR = 0.77; 95% CI 0.42–1.41). A prominent negative linear relationship (X² = 14.70; P = 0.0001) was found between STB levels and risk of CKD. Subgroup analyses showed that there were no significant differences in the subgroup adjustment factor except for sample size.

Conclusions: Elevated STB levels within a physiological range are associated with lower risk of CKD regardless of the study characteristics and coincide with a liner dose–response relationship. However, whether high STB levels are a protective factor against mortality remains inconclusive. Large-scale randomized controlled trails are needed to target STB levels for predicting renal outcomes.

The joint association of diabetes distress and depressive symptoms with all-cause mortality in Japanese individuals with type 2 diabetes: a prospective cohort study (Diabetes Distress and Care Registry in Tenri [DDCRT 20])

AIMS/HYPOTHESIS

The independent association of depressive symptoms and diabetes distress with mortality risk in individuals with diabetes has not been evaluated. We examined the temporal joint association of diabetes distress and depressive symptoms at baseline and the subsequent risk of all-cause mortality.

METHODS

The longitudinal data of 3118 individuals with type 2 diabetes were obtained from a large Japanese diabetes registry. To assess the joint association of diabetes distress and depressive symptoms at baseline with the subsequent risk of all-cause mortality, the Cox proportional hazards model was used with adjustment for potential confounders.

RESULTS

The mean age, BMI and HbA_1c levels were 64.7 years, 24.6 kg/m² and 58.6 mmol/mol (7.5%), respectively, and 38.1% of the participants were women. In the multivariable-adjusted models evaluating the diabetes distress and depressive symptoms separately, the HRs for all-cause mortality were 1.67 (95% CI 1.14, 2.43; p = 0.008) and 1.40 (95% CI 1.05, 1.85; p = 0.020), respectively. In such models evaluating the joint association of diabetes distress and depressive symptoms, compared with individuals without diabetes distress or depressive symptoms (DD^-/DS^-), the HRs for all-cause mortality for the group without diabetes distress but with depressive symptoms (DD^-/DS⁺), with diabetes distress but without depressive symptoms (DD⁺/DS^-), and with diabetes distress and depressive symptoms (DD⁺/DS⁺) were 1.34 (95% CI 0.99, 1.86; p = 0.056), 1.96 (95% CI 1.10, 3.50; p = 0.023) and 1.71 (95% CI 1.06, 2.77; p = 0.029), respectively. We did not observe a significant interaction between diabetes distress and depressive symptoms with all-cause mortality risk (p = 0.2636). In the stratified analysis by sex, a significant joint association of diabetes distress and depressive symptoms with the risk of all-cause mortality was observed only in men.

CONCLUSIONS/INTERPRETATION

Diabetes distress and depressive symptoms were independently associated with all-cause mortality risk in male participants with type 2 diabetes, but we did not observe a significant interaction between diabetes distress and depressive symptoms in relation to all-cause mortality. Graphical abstract.

Relationship between Serum Indirect Bilirubin Level and Insulin Sensitivity: Results from Two Independent Cohorts of Obese Patients with Impaired Glucose Regulation and Type 2 Diabetes Mellitus in China

BACKGROUND

Serum bilirubin is an endogenous antioxidant that has protective effects against obesity-related metabolic diseases.

OBJECTIVES

This study aimed to evaluate the characteristics of total bilirubin (TBIL), direct bilirubin (DBIL), and indirect bilirubin (IBIL) and their relationships with insulin sensitivity in obese patients with impaired glucose regulation and type 2 diabetes mellitus (IGR/T2DM) in China. Patients and Methods. Cohort 1 comprised obese patients (n = 71) was divided into the IGR/T2DM group (n = 38, obesity with IGR/T2DM) and control group (n = 33, obesity without IGR/T2DM). Insulin sensitivity was evaluated using the hyperinsulinemic-euglycemic clamp technique (HEC) with glucose disposal rate (GDR, M value). Cohort 2 comprised obese patients with IGR/T2DM who underwent metabolic surgery (n = 109) as complementary to cohort 1. Insulin sensitivity was evaluated with the Matsuda Index and homeostatic model assessment of insulin sensitivity (HOMA-IS).

RESULTS

In cohort 1, TBIL, DBIL, and IBIL were higher within the physiological range in the IGR/T2DM group compared with the control group; IBIL was positively correlated with M value (r = 0.342, p=0.044) in the IGR/T2DM group, and multivariate logistic regression showed that IBIL might be independent protective factors against insulin resistance (odds ratio (OR) = 0.602; 95% confidence interval (CI): 0.413-0.878; p=0.008). In cohort 2, at 1 month after metabolic surgery, serum bilirubin levels (TBIL, DBIL, and IBIL) increased, and the percentage change in IBIL was positively correlated with the change of the Matsuda Index (r = 0.195, p=0.045).

CONCLUSIONS

The relationships between different types of bilirubin and insulin sensitivity varied. Serum indirect bilirubin might be a protective factor that enhances insulin sensitivity.

Associations between different bilirubin subtypes and diabetic microvascular complications in middle-aged and elderly individuals

AIMS

Some studies have reported associations between bilirubin and diabetic microvascular complications. However, these studies focused only on total bilirubin (TBIL) without distinguishing different bilirubin subtypes. In this study, we aimed to investigate the associations of TBIL, direct bilirubin (DBIL) and indirect bilirubin (IBIL) levels with albuminuria/creatinine ratio (ACR) and the prevalence of diabetic retinopathy (DR) among diabetic adults.

METHODS

We analyzed 4368 individuals out of 4813 diabetic participants enrolled from seven communities in 2018 in a cross-sectional study. Participants underwent several checkups, including the measurement of anthropometric parameters, blood pressure, glucose, lipid profile, TBIL, DBIL, IBIL and ACR. DR was detected by high-quality fundus photographs and was remotely read by ophthalmologists.

RESULTS

Compared with the first quartile of DBIL, participants in the fourth quartile had a lower prevalence of high ACR (odds ratio (OR) 0.76; 95% confidence interval (CI) 0.59, 0.99) (p for trend < 0.05). Neither TBIL nor IBIL was associated with the prevalence of high ACR. In DR, higher DBIL and TBIL by one standard deviation was associated with a 19% (OR 0.81; 95% CI 0.69, 0.94) and a 12% (OR 0.88; 95% CI 0.78, 0.99) lower frequency of DR, respectively (both p for trend < 0.05). However, IBIL was not associated with the prevalence of DR. These associations were adjusted for potential confounding factors.

CONCLUSION

DBIL had a stronger association with high ACR and DR than TBIL or IBIL did in diabetic adults. The effect of DBIL on diabetic complications should be noted and investigated in further studies.

Association of circulating total bilirubin level with ischemic stroke: a systemic review and meta-analysis of observational evidence

Background

Circulating total bilirubin is a biomarker of ischemic stroke and may serve as a potential prognostic factor. It is imperative to systemically evaluate the correlation between circulating total bilirubin and risk for stroke. This systematic review and meta-analysis investigated the relationship between total serum bilirubin and risk for stroke.

Methods

Studies published before 30 June 2017 were searched in four databases (PubMed, EMBASE, Web of Science and Cochrane Central). Additional studies were searched by reviewing references and contacting authors. Cohort, cross-sectional and case-control studies in adults that examined the association between serum total bilirubin and stroke were included irrespective of language and date of publication. The primary outcome of this study was ischemic stroke, and the secondary outcome was stroke. Abstract and full-text were reviewed by two independent reviewers, and disagreement was resolved by consulting a third reviewer. Data were extracted by two independent reviewers using a pre-designed data collection form.

Results

Eleven observational studies (5 prospective and 6 cross-sectional studies) involving 131,450 subjects were included for analysis. In four studies with 83,380 subjects, the relationship between circulating total bilirubin and ischemic stroke was investigated, ischemic stroke was found in 2,496 patients, and the total odds ratio (OR) of the highest bilirubin and the lowest bilirubin for the occurrence of ischemic stroke was 0.66 (95% CI: 0.58-0.74). Eleven studies with 131,450 subjects explored the correlation between bilirubin and stroke, stroke was reported in 5,060 patients, and the total OR of the highest bilirubin and the lowest bilirubin for the occurrence of stroke was 0.73 (95% CI: 0.68-0.79). A stratified analysis based on the gender showed that the total bilirubin level in males correlated with ischemic stroke or stroke, which was not noted in females.

Conclusions

The available studies support an inverse association between circulating total bilirubin and risk for ischemic stroke and stroke in males. Prospective studies with large sample size are needed to establish the role of circulating bilirubin in the prevention of stroke.

Association between serum total bilirubin levels and the risk of type 2 diabetes mellitus

AIM

To confirm whether serum bilirubin is an independent risk factor of type 2 diabetes mellitus (T2DM) onset in patients with impaired fasting glycemia (IFG) and impaired glucose tolerance (IGT).

METHODS

This was a prospective cohort study carried out at the Diabetic Identification Center of Tianjin Metabolic Diseases Hospital. Serum total bilirubin (TBIL) was measured at baseline and the patients were grouped according to baseline bilirubin quartiles. The outcome was the confirmation of T2DM by oral glucose tolerance test (OGTT) during the 3-year follow-up. Logistic regression was used to determine the risk factors for T2DM development and whether bilirubin levels are independently associated with T2DM development.

RESULTS

Finally, 523 patients were analyzed. After 3 years, 310 participants were diagnosed with diabetes based on OGTT. Baseline quartiles of total bilirubin were inversely associated with diabetes risk, even after multivariable adjustment. The adjusted ORs for diabetes were 1.0 (reference), 0.83 (95% CI 0.74-0.96), 0.78 (95% CI 0.68-0.90), 0.74 (95% CI 0.64-0.87) for the 1st, 2nd, 3rd, and 4th quartiles of baseline serum total bilirubin, respectively (P < 0.001).

CONCLUSION

In patients with IFG or IGT, low levels of serum total bilirubin were associated with a significantly increased risk of T2DM.

THE ASSOCIATION OF SERUM BILIRUBIN ON KIDNEY CLINICOPATHOLOGIC FEATURES AND RENAL OUTCOME IN PATIENTS WITH DIABETIC NEPHROPATHY: A BIOPSY-BASED STUDY

Objective: To explore the relationship between serum bilirubin concentration and clinicopathologic features and renal outcome in biopsy-diagnosed diabetic nephropathy (DN) in patients with type 2 diabetes mellitus. Methods: In this retrospective study, 118 patients with DN were enrolled. Participants were divided into two groups according to their median baseline serum bilirubin concentration: Group 1 (serum bilirubin ≤7.5 μmol /L); Group 2 (serum bilirubin >7.5 μmol /L). Basic clinical parameters were measured at the time of renal biopsy, and the relationships between serum bilirubin and the clinicopathologic features and renal outcome were analyzed. Results: Patients in Group 1 often had inferior renal function. Compared with Group 2, the glomerular classification and interstitial inflammation were more severe in subjects of Group 1, while arteriolar hyalinosis and interstitial fibrosis and tubular atrophy (IFTA) were comparable between the groups. Serum bilirubin was negatively correlated with the severity of the glomerular classification, interstitial inflammation, and IFTA. In the prognostic analysis, higher serum bilirubin level was associated with a lower risk of progression to end-stage renal disease, which was independent of the effects of age, gender, duration of diabetes, anemia, serum glucose, and hypertension but not of estimated glomerular filtration rate (hazard ratio, 0.406; 95% confidence interval, 0.074 to 2.225; P = .299). Conclusion: Our study showed a negative correlation between serum bilirubin level and renal pathologic lesions in patients with DN; serum bilirubin showed an inverse association with DN progression, but this was not independent. Abbreviations: CI = confidence interval; CKD = chronic kidney disease; DM = diabetes mellitus; DN = diabetic nephropathy; DR = diabetic retinopathy; eGFR = estimated glomerular filtration rate; ESRD = end-stage renal disease; HbA1c = glycated hemoglobin; HO-1 = heme oxygenase 1; HR = hazard ratio; IFTA = interstitial fibrosis and tubular atrophy; log-BIL = log-transformed baseline serum bilirubin; T2DM = type 2 diabetes mellitus.

Association of Hepatitis C and B Virus Infection with CKD and Impact of Hepatitis C Treatment on CKD

Hepatitis C virus (HCV) infection greatly increases the risk of nephropathy. In this observational study, we aimed to explore the relationship between viral hepatitis infection and chronic kidney disease (CKD), identify risk factors, and determine the effect of antiviral treatment on CKD in Chinese patients with chronic HCV infection. A total of 2,435 study subjects were enrolled and divided into four groups: the HCV infection, HBV infection, HBV and HCV co-infection, and uninfected control groups. Of these, 207 patients with chronic hepatitis C (CHC) were given standard dual therapy [subcutaneous injection of recombinant interferon (IFN)-α2b and oral ribavirin (RBV)] for 48 weeks. We found that the prevalence of CKD gradually increased with age in all groups and was significantly increased in patients 60 years or older. Multivariate logistic regression analyses showed that persistent HCV infection was significantly associated with CKD [odds ratio (OR), 1.33; 95% confidence interval (CI), 1.06–1.66; P = 0.013], whereas there was no significant link between CKD and spontaneous HCV clearance (OR, 1.23; 95% CI, 0.79–1.90; P = 0.364), HBV infection (OR, 0.73; 95% CI, 0.44–1.19; P = 0.201), or HBV/HCV co-infection (OR, 1.40; 95% CI, 0.81–2.40; P = 0.234). Notably, after anti-HCV therapy, the serum creatinine concentration was significantly decreased (76.0, 75.5–79.4 μmol/L) from the pretreatment level (95.0, 93.0–97.2 μmol/L), both in patients who showed an end of treatment virological response (ETVR) and those who did not (P < 0.001). Also, in both the ETVR and non-ETVR groups, the percentages of patients with an estimated glomerular filtration rate (eGFR) ≥90 ml/min/1.73 m² increased significantly (P < 0.001), whereas the percentages of those with an eGFR <60 ml/min/1.73 m² significantly decreased (P < 0.001). In conclusion, persistent HCV infection was independently associated with CKD, and antiviral treatment with IFN plus RBV can improve renal function and reverse CKD in HCV-infected patients.

Bilirubin and its changes were negatively associated with diabetic kidney disease incidence and progression: A five-year's cohort study based on 5323 Chinese male diabetic patients

AIMS

This study aimed to evaluate the association between baseline bilirubin (TBiL) and follow-up TBiL changes for diabetic kidney disease (DKD) incidence and progression based on a 5 years' cohort study.

METHODS

This cohort study was conducted in Beijing between 2009 and 2013. The subjects were consisted of 5342male diabetic patients with baseline retinopathy. Cox proportional risk model was used to calculate hazards ratio (HR).

RESULTS

The mean age of the 5342 diabetic patients was 78.68 ± 8.40 (65-102 yrs). The total five year incidence was 8.7% (95%CI: 7.9%-9.4%) for DKD and 10.5% (95%CI: 9.7%-11.3%) for eGFR decrease. The HR of baseline TBiL showed a decreasing trend for both DKD incidence and eGFR decrease. The HRs of baseline TBiL (per μmol/L increase) for DKD and eGFR decrease were 0.967(95%CI: 0.946-0.988) and 0.955(95%CI: 0.936-0.975) respectively. For follow-up TBiL changes, after adjusted for related co-variables and baseline TBiL levels (as continuous variable) in the model, the HRs (per μmol/L of follow-up TBiL changes) for DKD and eGFR decrease were 0.973(95%CI: 0.952-0.995) and 0.991(95%CI: 0.974-0.998) respectively. The results were similar when baseline TBiL and follow-up TBiL changes were used as tertiary variable.

CONCLUSION

Not only baseline TBiL, but also follow-up changes were significantly associated with DKD incidence and progression.

Serum bilirubin level and its impact on the progression of chronic kidney disease

PURPOSE

To examine whether an elevated serum total bilirubin level affects the decline in renal function or new-onset chronic kidney disease (CKD) in patients with type 2 diabetes mellitus (DM2).

METHODS

This was a longitudinal observational study in patients who presented at the University of Health Sciences Hospital in Kayseri. Five hundred twenty-nine patients with DM2 who had conserved renal function were enrolled (estimated glomerular filtration rate > 60 ml/min/1.73 m²). Arising CKD stage 3 was the outcome measure. The patients were separated into three groups based on the total serum bilirubin levels. The first group (G1) ranged from 0.1 to 0.3, the second (G2) 0.4-0.5, and the third (G3) 0.6-0.9 mg/dl. The effect of total serum bilirubin levels on CKD 3 development was assessed using Cox proportional hazards regression.

RESULTS

The risk of the CKD stage 3 development was highest in G1 who has the lowest serum total bilirubin levels (G1 vs. G3; hazard ratio [HR], 2.02; 95% confidence interval [CI] 1.21-3.36; p = 0.007). In addition, G2 had a significant risk of CKD stage 3 development (G2 vs. G3; hazard ratio [HR], 1.58; 95% confidence interval [CI] 1.08-2.32; p = 0.018). In the adjusted analysis, compared to G2 and G3, G1 had the highest risk (G1 vs. G3; hazard ratio [HR], 2.20; 95% confidence interval [CI] 1.29-3.77; p = 0.004). Similarly, G2 had a higher risk compared to G3 (hazard ratio [HR], 1.57; 95% confidence interval [CI] 1.05-2.34; p = 0.028).

CONCLUSIONS

Serum bilirubin may predict the progression of CKD in patients with type 2 diabetes and preserved kidney function.

Association of proton pump inhibitor use with the risk of the development or progression of albuminuria among Japanese patients with diabetes: A prospective cohort study [Diabetes Distress and Care Registry at Tenri (DDCRT 16)]

AIMS

We aimed to determine the prospective association between proton pump inhibitor (PPI) use and the subsequent risk of the development or progression of albuminuria or eGFR.

METHODS

Longitudinal data of patients with diabetes were obtained from a large Japanese diabetes registry. To assess the independent correlation between PPI use and the development or progression of urine microalbuminuria, the time-varying Cox proportional hazards model was used with adjustment for potential confounders.

RESULTS

The mean patient age, body-mass index (BMI), and hemoglobin A1c (HbA1c) levels were 65.7 y, 24.5 kg/m², and 7.5% (57.9 mmol/mol), respectively. In 1711 patients without albuminuria, we observed 599 cases with development of albuminuria over median follow-up of 4.0 years, and in 1279 patients with microalbuminuria, 290 cases with urinary albuminuria progression over 4.0 years, and 257 eGFR decline cases over 3.8 years. PPI use was not associated with the development of albuminuria (HR = 0.88; 95%CI, 0.77-1.01; p = .058), progression of albuminuria (HR = 1.24; 95%CI, 0.87-1.79; p = .236), nor eGFR decline (HR = 1.05; 95%CI, 0.81-1.34; p = .973) even in a propensity score-adjusted model with time-varyingly updating PPI use information.

CONCLUSIONS

In conclusion, PPI use was not associated with the subsequent risk of development or progression of albuminuria, or eGFR decline in patients with diabetes.

Real-life glycemic control in patients with type 2 diabetes treated with insulin therapy: A prospective, longitudinal cohort study (Diabetes Distress and Care Registry at Tenri [DDCRT 9])

AIMS/INTRODUCTION

We investigated the association between four insulin regimens, and increase in glycated hemoglobin (HbA1c) and insulin dose in a real-life clinical setting because there are no data about them among insulin regimens.

MATERIALS AND METHODS

Participants included 757 patients with type 2 diabetes having been treated with insulin therapy for more than 1 year. The four insulin regimens were regimen 1 (long-acting insulin, once daily), regimen 2 (biphasic insulin, twice daily), regimen 3 (biphasic insulin, three times daily) and regimen 4 (basal-bolus therapy). Main outcomes were increases in HbA1c levels >0.5% and increases in daily insulin units after 1 year. We carried out multivariable analyses to examine differences in glycemic control and insulin dose with adjustment for possible confounders.

RESULTS

Mean HbA1c level and duration of insulin therapy were 7.8% and 11.3 years, respectively. HbA1c levels increased by >0.5% at follow up in 22.8, 24.9, 20.7, and 29.3% of participants using regimen 1, 2, 3 and 4, respectively, with no significant differences between groups. Daily insulin doses increased in 62.3, 68.8, 65.3 and 38.6% of patients, respectively (P < 0.001). Multivariable regression analysis showed that patients who received regimen 4 had significantly lower odds of requiring future insulin dose increases than those who had received regimen 2 (adjusted odds ratio 0.24, 95% confidence interval 0.14-0.41; P < 0.001).

CONCLUSIONS

Many patients receiving insulin therapy showed increases in HbA1c levels and insulin doses 1 year later. The smallest increase in insulin dose was observed in the basal-bolus therapy group compared with other regimens.

Noninvasive Real-Time Characterization of Renal Clearance Kinetics in Diabetic Mice after Receiving Danshensu Treatment

Danshensu (DSS) is an active ingredient extracted from the root of the Danshen that could ameliorate oxidative stress via upregulation of heme oxygenase- (HO-) 1. Little is known about the treatment effects of DSS on kidney function in diabetic mice. Therefore, the primary aim of the present study was to characterize the renal clearance kinetics of IRdye800CW in db/db mice after DSS treatment. The secondary aim was to measure several biomarkers of renal function and oxidative stress (urinary F2-isoprostane, HO-1 in kidney and serum bilirubin). Fourteen db/db diabetic mice were randomly assigned into two groups and received either DSS treatment (DM + DSS) or vehicle treatment (DM). A third group that comprised of db/+ nondiabetic mice (non-DM control) received no DSS treatment and served as the nondiabetic control. At the end of a 3-week intervention period, serum and urinary biomarkers of renal function and oxidative stress were assessed and the renal clearance of IRdye800CW dye in all mice was determined noninvasively using Multispectral Optoacoustic Tomography. The major finding from this study suggested that DSS treatment in db/db mice improved renal clearance. Increased expression of HO-1 after DSS treatment also suggested that DSS might represent a potential therapeutic avenue for clinical intervention in diabetic nephropathy.

Gilbert syndrome in patients with type 1 diabetes-Prevalence, glycemic control, and microalbuminuria

BACKGROUND

Gilbert syndrome (GS) is a common hereditary condition, characterized by intermittent unconjugated hyperbilirubinemia. In adults with type 2 diabetes and GS, a markedly lower prevalence of nephropathy was documented, suggesting a beneficial effect of hyperbilirubinemia. We investigated the prevalence of GS among individuals with type 1 diabetes mellitus (T1DM), and the prevalence of microalbuminuria.

METHODS

The prevalence of GS was assessed in 401 (204 female) patients with T1DM, median age 21.0 years, (interquartile range [IQR], 15.7-27.9), median disease duration 10.8 years (IQR, 5.7-15.8); and was compared with GS prevalence in 181 children (control). The prevalence of microalbuminuria was assessed in patients with T1DM and GS (group I) and compared with that of patients with T1DM alone (group II), in a ratio of 1:2 matched by gender, age, and duration of diabetes.

RESULTS

The prevalence of GS in TIDM patients was significantly higher than in the control group (10.7% vs 3.3% respectively, p = .004), with no gender difference. Patients with T1DM and GS had significantly lower HbA1c levels than did those with T1DM alone 7.3 ± 1.2 vs 7.9 ± 1.3% respectively (56 ± 13 vs 63 ± 14 mmol/mol), p = .02. The rate of microalbuminuria was 14.0% vs 11.0% for patients with T1DM and GS, compared with those with T1DM alone (p = .6).

CONCLUSIONS

The occurrence of GS was 3-fold higher among individuals with T1DM than in a healthy control group. Despite better glycemic control, the rate of microalbuminuria was similar among young individuals with T1DM and GS, and those with T1DM alone, suggesting no protective value to elevated bilirubin.

Low serum bilirubin level predicts the development of chronic kidney disease in patients with type 2 diabetes mellitus

BACKGROUND/AIMS

We evaluated whether serum bilirubin levels can predict the development of chronic kidney disease (CKD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a retrospective observational longitudinal study of patients presenting at the Pusan National University Hospital. A total of 349 patients with T2DM and preserved kidney function (estimated glomerular filtration rate ≥ 60 mL/min/1.73 m²) were enrolled. The main outcome was the development of CKD stage 3 or greater. The patients were divided into four groups according to the quartiles of the total serum bilirubin levels at baseline.

RESULTS

The group with the lowest range of total serum bilirubin level (Q1) showed the highest cumulative incidence of CKD stage 3 or greater than that of the other lower quartiles (Q1 vs. Q4; hazard ratio [HR], 6.75; 95% confidence interval [CI], 1.54 to 29.47; p = 0.011). In multivariate analysis, the risk of developing CKD stage 3 or greater was higher in the second lowest quartile of the serum bilirubin level than that in the highest quartile of the serum bilirubin level (Q2 vs. Q4; HR, 9.36; 95% CI, 1.33 to 65.73; p = 0.024). In the normoalbuminuria subgroup (n = 236), multivariate analysis showed that the risk of developing CKD stage 3 or greater was higher in the lowest quartile of the serum bilirubin level than that in the highest quartile of the serum bilirubin level (Q1 vs. Q4; HR, 7.36; 95% CI, 1.24 to 35.82; p = 0.019).

CONCLUSIONS

Serum bilirubin might be an early clinical marker for predicting the progression of CKD in patients with T2DM and preserved renal function.

Association between dipstick hematuria and decline in estimated glomerular filtration rate among Japanese patients with type 2 diabetes: A prospective cohort study [Diabetes Distress and Care Registry at Tenri (DDCRT 14)]

AIMS

To assess the association between dipstick hematuria and estimated glomerular filtration rate (eGFR) decline in Japanese patients with type 2 diabetes.

METHODS

Longitudinal data were obtained from 3068 Japanese patients with type 2 diabetes. To assess the independent association between dipstick hematuria and eGFR decline, we used Cox proportional hazard model adjusted for potential confounders.

RESULTS

Median follow-up period was 699.7days. Mean age, body mass index (BMI), and HbA1c level were 65.7years, 24.6kg/m², and 7.5% (58.1mmol/mol), respectively. Positive dipstick hematuria was significantly associated with baseline eGFR and severity of albuminuria (p<0.001). The multivariable-adjusted hazard ratio for eGFR decline in patients with dipstick hematuria compared with those without dipstick hematuria was 2.19 [95% confidence interval (CI): 1.22-3.91]; this association remained significant even after the exclusion of patients who did not have diabetic retinopathy (hazard ratio: 2.39; 95% CI: 1.13-5.04).

CONCLUSION

Positive dipstick hematuria was associated with severity of albuminuria and renal function. A significant association was found between dipstick hematuria and increased risk of eGFR decline among patients with type 2 diabetes. Therefore, our results suggest that dipstick hematuria is perhaps indicative of more severe diabetic nephropathy.

Supplementation with Phycocyanobilin, Citrulline, Taurine, and Supranutritional Doses of Folic Acid and Biotin-Potential for Preventing or Slowing the Progression of Diabetic Complications

Oxidative stress, the resulting uncoupling of endothelial nitric oxide synthase (eNOS), and loss of nitric oxide (NO) bioactivity, are key mediators of the vascular and microvascular complications of diabetes. Much of this oxidative stress arises from up-regulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Phycocyanobilin (PhyCB), the light-harvesting chromophore in edible cyanobacteria such as spirulina, is a biliverdin derivative that shares the ability of free bilirubin to inhibit certain isoforms of NADPH oxidase. Epidemiological studies reveal that diabetics with relatively elevated serum bilirubin are less likely to develop coronary disease or microvascular complications; this may reflect the ability of bilirubin to ward off these complications via inhibition of NADPH oxidase. Oral PhyCB may likewise have potential in this regard, and has been shown to protect diabetic mice from glomerulosclerosis. With respect to oxidant-mediated uncoupling of eNOS, high-dose folate can help to reverse this by modulating the oxidation status of the eNOS cofactor tetrahydrobiopterin (BH4). Oxidation of BH4 yields dihydrobiopterin (BH2), which competes with BH4 for binding to eNOS and promotes its uncoupling. The reduced intracellular metabolites of folate have versatile oxidant-scavenging activity that can prevent oxidation of BH4; concurrently, these metabolites promote induction of dihydrofolate reductase, which functions to reconvert BH2 to BH4, and hence alleviate the uncoupling of eNOS. The arginine metabolite asymmetric dimethylarginine (ADMA), typically elevated in diabetics, also uncouples eNOS by competitively inhibiting binding of arginine to eNOS; this effect is exacerbated by the increased expression of arginase that accompanies diabetes. These effects can be countered via supplementation with citrulline, which efficiently enhances tissue levels of arginine. With respect to the loss of NO bioactivity that contributes to diabetic complications, high dose biotin has the potential to "pinch hit" for diminished NO by direct activation of soluble guanylate cyclase (sGC). High-dose biotin also may aid glycemic control via modulatory effects on enzyme induction in hepatocytes and pancreatic beta cells. Taurine, which suppresses diabetic complications in rodents, has the potential to reverse the inactivating impact of oxidative stress on sGC by boosting synthesis of hydrogen sulfide. Hence, it is proposed that concurrent administration of PhyCB, citrulline, taurine, and supranutritional doses of folate and biotin may have considerable potential for prevention and control of diabetic complications. Such a regimen could also be complemented with antioxidants such as lipoic acid, N-acetylcysteine, and melatonin-that boost cellular expression of antioxidant enzymes and glutathione-as well as astaxanthin, zinc, and glycine. The development of appropriate functional foods might make it feasible for patients to use complex nutraceutical regimens of the sort suggested here.

Higher levels of physical activity are independently associated with a lower incidence of diabetic retinopathy in Japanese patients with type 2 diabetes: A prospective cohort study, Diabetes Distress and Care Registry at Tenri (DDCRT15)

We assessed the prospective association between baseline levels of physical activity (PA) and the incidence of newly developed diabetic retinopathy (DR) in patients with type 2 diabetes. Data from 1,814 patients with type 2 diabetes without DR were obtained from a Japanese diabetes registry at Tenri Hospital, Nara, Japan. To assess the independent correlations between baseline PA levels and newly developed DR, the participants were divided into five categories based on their PA levels. A Cox proportional hazards model with time-varying exposure information was used and adjusted for potential confounders to assess the independent correlations. At baseline, the mean age, BMI, and hemoglobin A1c levels of the patients were 65.5 years, 24.5 kg/m2, and 7.2% (54 mmol/mol), respectively. After 2 years, newly developed DR was confirmed in 184 patients (10.1%). Patients with newly developed DR had longer duration of type 2 diabetes (14.7 versus 11.0 years, p < 0.0001), higher systolic blood pressure (139.2 versus 135.1 mmHg, p = 0.0012), lower estimated glomerular filtration rate (74.0 versus 77.1 mL/min/1.73 m2, p = 0.0382), greater urinary albumin-creatinine ratio (4.00 versus 2.45 mg/mmol, p < 0.0039), and higher HbA1c levels (7.5 versus 7.2%, p = 0.0006) than those without newly developed DR. The multivariable-adjusted hazard ratios for DR development were 0.87 (95% CI, 0.53-1.40; p = 0.557), 0.83 (95% CI, 0.52-1.31; p = 0.421), 0.58 (95% CI, 0.35-0.94; p = 0.027), and 0.63 (95% CI, 0.42-0.94; p = 0.025)for the second, third, fourth, and fifth PA categories, respectively, compared with the reference category of patients with a mean PA of 0 metabolic equivalent of task-hours/week). Higher PA levels are independently associated with a lower incidence of DR in Japanese patients with type 2 diabetes.

Effect of bilirubin concentration on the risk of diabetic complications: A meta-analysis of epidemiologic studies

Diabetes can affect many parts of the body and is associated with serious complications. Oxidative stress is a major contributor in the pathogenesis of diabetic complications and bilirubin has been shown to have antioxidant effects. The number of studies on the effect of bilirubin on the risk of diabetic complications has increased, but the results are inconsistent. Thus, we performed a meta-analysis to determine the relationship between bilirubin concentration and the risk of diabetic complications, and to investigate if there was a dose-response relationship. We carried out an extensive search in multiple databases. A fixed or random-effects model was used to calculate the pooled estimates. We conducted a dose-response meta-analysis to analyze the association between these estimates. A total of 132,240 subjects from 27 included studies were analyzed in our meta-analysis. A negative nonlinear association between bilirubin concentration and the risk of diabetic complications was identified (OR: 0.77, 95% CI: 0.73-0.81), with a nonlinear association. We also found that there was a negative association between bilirubin concentration and the risk of diabetic nephropathy, diabetic retinopathy and diabetic neuropathy. The results of our meta-analysis indicate that bilirubin may play a protective role in the occurrence of diabetic complications.

Total bilirubin level may be a biomarker of nephropathy in type 2 diabetes mellitus: A meta-analysis of observational studies based on MOOSE compliant

Recently, the number of the studies on the relationship between the total bilirubin level (TBL) and diabetic nephropathy (DN) is increasing, but their results were not consistent. Therefore, we performed a meta-analysis to analyze the relationship between TBL and the risk of DN.We searched 5 databases before October 31, 2016, and reviewed the reference list of relevant articles. The fixed or random-effects model was used to pool risk estimates. We conducted the dose-response meta-analysis to evaluate the relationship between TBL and the risk of DN.Our meta-analysis showed that TBL in the DN group was lower than that in diabetes without the kidney disease (NDN) group (standard mean difference [SMD]: -0.63, 95% CI: -0.80, -0.46). The result of each subgroup also showed that TBL in the DN group was lower than that in the NDN group. The result of meta-regression indicated that duration of diabetes mellitus might be the source of heterogeneity. Our meta-analysis also showed that there was a significant negative relationship between TBL and the risk of DN (OR: 0.86, 95%CI: 0.82, 0.90). The results of subgroup analysis were similar to those of SMD; no sources of heterogeneity were detected by meta-regression. Sensitivity analysis indicated that the results were robust. We observed a linear association between TBL and the risk of DN, and there was a negative dose-response association between TBL and the risk of DN.In conclusion, bilirubin may be used as a biomarker of DN. It helps early diagnosis and effective therapeutic strategies on DN.

Relationship between kidney function decline and initial risk factors for the progression of diabetic kidney disease: a retrospective analysis of 91 Japanese patients with type 2 diabetes

BACKGROUND

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD) in Japan. The clinical course and factors related to the progression of DKD to ESRD are important issues when treating patients with DKD.

METHODS

Ninety-one type 2 diabetic patients with DKD that had progressed from chronic kidney disease (CKD) stages G1-3 on their initial clinical visit to ESRD were enrolled. The decline in the estimated glomerular filtration rate (eGFR) was analyzed and the initial clinical factors that influenced the decline rate were explored.

RESULTS

There was a linear decline in eGFR before progression to ESRD, with a median annual decline rate (∆eGFR) of 9.2 mL/min/1.73 m2. In all patients, a history of coronary artery disease and increased levels of initial eGFR and high-density lipoprotein cholesterol (HDL-C) were positive predictors of log ∆eGFR, whereas age, history of cerebral infarction (CI), and an increased level of serum albumin were negative predictors of log ∆eGFR. In patients with CKD stages G1-2 on their first visit, male sex and increased diastolic blood pressure were positive predictors. In patients with CKD stage G3 on their first visit, an increased level of LDL-C was a positive predictor, whereas a history of CI and an increased level of serum total bilirubin (TBil) were negative predictors.

CONCLUSION

In addition to the common risk factors, initial eGFR, HDL-C, and TBil were identified as novel risk factors for ESRD. These risk factors may differ between patients with early and advanced stages of CKD.

Association of Diabetic Nephropathy and Liver Disorders

INTRODUCTION

Liver disorder is known to be a risk factor for Diabetes Mellitus (DM) and diabetic patients are at risk of developing liver disorders. Association of liver and renal disease is less explored in the field of research; hence, we conducted a retrospective study on this.

AIM

To compare the renal and liver profiles of type II DM patients compared to healthy controls and find the association between the two profiles in diabetics.

MATERIALS AND METHODS

The renal and liver profiles of 68 type II DM patients and 58 controls were compared. Estimated Glomerular Filtration Rate (GFR) (eGFR) was calculated using Modification of Diet in Renal Disease (MDRD) formula and was taken as a tool to grade different stages of diabetic nephropathy. Comparison of liver profiles between different stages of diabetic nephropathy was done. Correlations and associations were studied between eGFR and liver enzymes and Bilirubin.

RESULTS

A significant elevation in Total Bilirubin (TB) (p< 0.15), Direct Bilirubin (DB) (p< 0.0035), Aspartate Amino Transferase (AST) and Alanine Amino Transferase (ALT) (p<0.0001) levels in diabetics was noted. An elevated eGFR and a significant correlation between eGFR and liver enzymes were observed. A significant association between liver and renal disease has been obtained in diabetics (p=0.0136).

CONCLUSION

Significantly, high liver function tests and low eGFR were observed in type II diabetics. A significant positive correlation between liver enzymes (AST and ALT) and eGFR suggest a possible association between liver and kidney functions in DM.

Association between serum bilirubin levels and decline in estimated glomerular filtration rate among patients with type 2 diabetes

AIMS

Studies indicate that elevated serum total bilirubin (TBil) levels are associated with lower risk of diabetic kidney disease (DKD). Few studies examined the associations of direct bilirubin (DBil) and indirect bilirubin (IBil) with the development of DKD.

METHODS

Type 2 diabetes patients (n=2,958) with estimated glomerular filtration (eGFR)≥60mlmin(-1) 1.73m(-2) from the Dongfeng-Tongji cohort were selected and followed up for 5years. Development of DKD was defined as decline in eGFR≥30% during follow-up. Generalize linear model was used to assess the associations of bilirubin levels with DKD development.

RESULTS

Compared with those in the first tertile of serum TBil, the relative risks (RRs) and 95% confidence intervals (CIs) of incident eGFR decline for tertile 2 to 3 were 0.83 (0.64-1.09) and 0.74 (0.56-0.98), Ptrend=0.04. The counterpart RRs (95% CIs) in IBil were 0.74 (0.57-0.97) and 0.75 (0.57-0.98), Ptrend=0.04. No significant associations were observed in DBil. Moreover, TBil and IBil interacted with smoking, the bilirubin-DKD associations were evident in ever smokers.

CONCLUSIONS

Our findings suggest that elevation of serum TBil or IBil levels are independent protective factors for development of DKD, particularly in smokers.

Association of serum uric acid levels with the risk of development or progression of albuminuria among Japanese patients with type 2 diabetes: a prospective cohort study [Diabetes Distress and Care Registry at Tenri (DDCRT 10)]

AIMS

To assess the prospective association between baseline serum uric acid level and subsequent risk of development or progression in albuminuria.

METHODS

Longitudinal data were obtained from 2518 patients with type 2 diabetes in the development cohort and registered in a Japanese diabetes registry. To assess the independent correlations between baseline serum uric acid quartiles and either the development or progression of diabetic nephropathy for 2 years, the Cox proportional hazards model was used and adjusted for potential confounders.

RESULTS

The mean patient age, body mass index, and glycated hemoglobin (HbA1c) level were 66.1 years, 24.6 kg/m(2), and 7.5 % (57.6 mmol/mol), respectively. The baseline serum uric acid levels, with mean values of 3.6, 4.9, 5.8, and 7.3 mg/dL from the first to fourth quartiles, were significantly associated with the urinary albumin/creatinine ratio at baseline (p < 0.001). Baseline uric acid levels were not significantly associated with the development of nephropathy, but they were with the progression of nephropathy. The multivariable-adjusted hazards ratios for the progression from microalbuminuria to macroalbuminuria were 2.17 [95 % confidence interval (CI) 1.15-4.08; p = 0.016], 3.04 (95 % CI 1.67-5.53; p < 0.001), and 3.56 (95 % CI 1.83-6.93; p < 0.0011) for the first, third, and fourth quartiles of serum uric acid levels, respectively, as compared to that for the second quartile. We did not observe significant association between uric acid levels and change in estimated glomerular filtration rate.

CONCLUSIONS

Low and high serum uric levels, independent of possible confounders, were associated with a subsequent risk of progression, not development, in albuminuria in type 2 diabetes patients. Therefore, serum uric acid levels may be useful for predicting the future risk of progression of microalbuminuria.

Association of circulating total bilirubin with the metabolic syndrome and type 2 diabetes: A systematic review and meta-analysis of observational evidence

OBJECTIVE

Emerging evidence suggests that bilirubin levels might be associated with the metabolic syndrome (MetS) and type 2 diabetes (T2D), although the nature of the association remains unclear.

DESIGN

This systematic review and meta-analysis investigated the relationship between total plasma bilirubin and the risk of MetS and T2D.

DATA SOURCES

Relevant studies were identified using five databases (Embase, Medline [Ovid], Web of Science, PubMed, Cochrane Central and Google Scholar), with the last search done on 21 October 2015. Study references were checked and authors contacted to identify additional studies.

STUDY SELECTION

Randomized controlled trials, and cohort, case-control and cross-sectional studies of adults examining the association between blood bilirubin levels and MetS and T2D were included, irrespective of language and date of publication. Abstract and full-text selection was done by two independent reviewers, with a third reviewer available in case of disagreement.

DATA EXTRACTION

Data were extracted by two independent reviewers using a predesigned data collection form.

MAIN OUTCOMES AND MEASURES

MetS and T2D.

METHODS

Summary estimates were obtained by random-effects meta-analysis.

RESULTS

Of the 2313 searched references, 16 observational studies (11 cross-sectional, two prospective, one that was both cross-sectional and prospective, two retrospective and one national survey) met our inclusion criteria. Overall, data were available for 175,911 non-overlapping participants, including 7414 MetS cases and 9406 T2D cases. In the meta-analysis of seven cross-sectional studies, the pooled odds ratio (95% confidence interval) for MetS in a comparison of extreme tertiles of serum bilirubin levels was 0.70 (95% CI: 0.62, 0.78), whereas no significant association was found for the pooled estimated relative risk between two prospective studies (0.57, 95% CI: 0.11, 2.94). The corresponding estimate was 0.77 (95% CI: 0.67, 0.87) for T2D from four cross-sectional studies.

CONCLUSION

The available evidence, mainly from cross-sectional studies, supports an inverse association of bilirubin levels with adverse metabolic outcomes. Large-scale prospective studies are now needed to establish whether bilirubin levels may be useful in the prevention of MetS and T2D.

Serum uric acid levels are associated with a high risk of rapid chronic kidney disease progression among patients with type 2 diabetes: a prospective cohort study [Diabetes Distress and Care Registry at Tenri (DDCRT 12)]

Background

We assessed the prospective association between baseline serum uric acid (SUA) concentrations and consequent risk of chronic kidney disease (CKD) progression in type 2 diabetes patients.

Methods

Longitudinal data from a Japanese diabetes registry including 3454 type 2 diabetes patients were obtained. To assess the independent correlations between SUA and rapid CKD progression [i.e., 30 % reduction in estimated glomerular filtration rate (eGFR) over 2 years], participants were divided into five groups based on SUA levels: <5.0, ≥5.0-6.0, ≥6.0-7.0, ≥7.0-8.0, and ≥8.0 mg/dl. Cox proportional hazards model adjusted for potential confounders was used for analysis.

Results

After 2 years, rapid CKD progression was recognized in 169 patients (4.89 %) who showed longer duration of type 2 diabetes (15.5 vs. 13.5 years, p = 0.005); higher systolic blood pressure (142.0 vs. 138.3 mmHg, p = 0.016), SUA (6.15 vs. 5.32 mg/dl, p < 0.001), and urinary albumin-creatinine ratio (1127.4 vs. 184.7 mg/gCr, p < 0.001); and lower diastolic blood pressure (69.7 vs. 72.8 mmHg, p = 0.003). Multivariate ratios for rapid CKD progression were 1.19 (p = 0.371), 1.02 (p = 0.937), 1.18 (p = 0.625), and 3.04 (p = 0.004), respectively, for the first, third, fourth, and fifth serum UA range groups; a second group was used as a reference.

Conclusions

Higher SUA levels, independent of possible confounders, were associated with rapid eGFR decline and CKD progression in type 2 diabetes patients. SUA may be a useful biomarker for predicting future risk of rapid diabetic CKD progression.

Serum bilirubin concentration is associated with eGFR and urinary albumin excretion in patients with type 1 diabetes mellitus

AIMS

Although relationships of serum bilirubin concentration with estimated glomerular filtration rate (eGFR) and urinary albumin excretion (UAE) in patients with type 2 diabetes have been reported, whether such relationships exist in patients with type 1 diabetes is unknown.

METHODS

A total of 123 patients with type 1 diabetes were investigated in this cross-sectional study. The relationship between bilirubin (total and indirect) concentrations and log(UAE) as well as eGFR was examined by Pearson's correlation analyses. Multivariate regression analyses were used to assess the association of bilirubin (total and indirect) with eGFR as well as log(UAE).

RESULTS

A positive correlation was found between serum bilirubin concentration and eGFR; total bilirubin (r=0.223, p=0.013), indirect bilirubin (r=0.244, p=0.007). A negative correlation was found between serum bilirubin concentration and log(UAE); total bilirubin (r=-0.258, p=0.005), indirect bilirubin (r=-0.271, p=0.003). Multivariate regression analyses showed that indirect bilirubin concentration was an independent determinant of eGFR and log(UAE).

CONCLUSIONS

Bilirubin concentration is associated with both eGFR and log(UAE) in patients with type 1 diabetes. Bilirubin might have a protective role in the progression of type 1 diabetic nephropathy.

Diabetes treatment-related quality of life is associated with levels of self-care activities in insulin injection among Japanese patients with type 2 diabetes: Diabetes Distress and Care Registry at Tenri (DDCRT 8)

AIMS

We investigated the association between diabetes treatment-related quality of life (QOL) and levels of self-care activities in insulin injection among Japanese patients with type 2 diabetes.

METHODS

Data from 1394 patients with type 2 diabetes on insulin therapy were obtained from a diabetes registry in Japan. We used the Diabetes Therapy-Related QOL (DTR-QOL) questionnaire and relative risk regression analysis to assess the independent association of high levels of self-care activities in insulin injection and DTR-QOL scores while adjusting for possible confounders.

RESULTS

The mean age, BMI and HbA1c level were 65.8 years, 24.8 kg/m(2) and 62 mmol/mol (7.8 %), respectively. The frequency of insulin injection omission was associated with DTR-QOL scores. In the multivariable-adjusted model, the relative risks for high levels of self-care activities in insulin injection was 1.15 (95 % confidence interval, 1.05-1.26) in the highest quintile compared with those in the lowest quintile of DTR-QOL scores. Subgroup analysis confirmed this association in patients <65 years.

CONCLUSIONS

DTR-QOL was associated with self-reported levels of self-care activities in insulin injection, particularly among Japanese patients <65 years with type 2 diabetes. DTR-QOL might be a useful tool to identify patients who consequently omit insulin. For patients with low DTR-QOL score, healthcare providers should discuss their treatment-related problems to prevent insulin injection omission.

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

The subjects comprised 230 men aged 77 ± 10 (range: 50-100) years and 279 women aged 81 ± 10 (50-101) years that visited the medical department. We examined the relationship between increased serum bilirubin and renal function evaluated by estimated glomerular filtration rate (eGFR) using CKD-EPI equations modified by a Japanese coefficient. Compared with the fourth quartile in serum bilirubin (1.01-1.97 mg/dL), the nonadjusted, age and gender-adjusted, and multivariate-adjusted odds ratios {95% confidence interval (CI)} of eGFR <60 mL/min/1.73 m(2) for the first quartile in serum bilirubin (0.13-0.50 mg/dL) were 2.08 (1.25-3.44), 1.82 (1.07-3.09), and 1.53 (0.83-2.81), respectively. Moreover, compared with the fourth quartile, nonadjusted, age and gender-adjusted, and multivariate-adjusted odds ratios (95% CI) of eGFR <45 mL/min/1.73 m(2) for the first quartile were 3.50 (1.95-6.23), 3.12 (1.72-5.65), and 3.53 (1.71-7.26), respectively. The data were further stratified by gender, age, medication (antihypertensive, antidyslipidemic, and antidiabetic agents), and prevalence of cardiovascular disease (CVD). The standardized coefficients for eGFR were significant in all the subgroups other than the prevalence of CVD, and there were significant interactions between the two groups regarding CVD. Our data demonstrated an independent positive association between serum bilirubin and eGFR among diabetic patients.

Bilirubin activates transcription of HIF-1α in human proximal tubular cells cultured in the physiologic oxygen content

The expression of hypoxia-inducible factor (HIF) is influenced by reactive oxygen species (ROS). Effect of bilirubin on HIF-1 expression in proximal tubular cells was investigated under physiological oxygen concentration, which is relative hypoxic condition mimicking oxygen content in the medulla of renal tissue. The human kidney (HK2) cells were cultured in 5% oxygen with or without bilirubin. HIF-1α protein expression was increased by bilirubin treatment at 0.01-0.2 mg/dL concentration. The messenger RNA expression of HIF-1α was increased by 1.69±0.05 folds in the cells cultured with 0.1 mg/dL bilirubin, compared to the control cells. The inhibitors of PI3K/mTOR, PI3K/AKT, and ERK 1/2 pathways did not attenuate increased HIF-1α expression by bilirubin. HIF-1α expression decreased by 10 µM exogenous hydrogen peroxide (H2O2); scavenger of ROS with or without bilirubin in the HK2 cells increased HIF-1α concentration more than that in the cells without bilirubin. Exogenous H2O2 decreased the phosphorylation of P70S6 kinase, which was completely reversed by bilirubin treatment. Knockdown of NOX4 gene by small interfering RNA (siRNA) increased HIF-1α mRNA expression. In coonclusion, bilirubin enhances HIF-1α transcription as well as the up-regulation of HIF-1α protein translation through the attenuation of ROS and subunits of NADPH oxidase.

Effect of bilirubin on triglyceride synthesis in streptozotocin-induced diabetic nephropathy

We aimed to elucidate the effect of bilirubin on dyslipidemia and nephropathy in a diabetes mellitus (DM) type I animal model. Sprague-Dawley rats were separated into control, DM, and bilirubin-treated DM (Bil) groups. The Bil group was injected intraperitoneally with 60 mg/kg bilirubin 3 times per week and hepatoma cells were cultured with bilirubin at a concentration of 0.3 mg/dL. The Bil group showed lower serum creatinine levels 5 weeks after diabetes onset. Bilirubin treatment also decreased the amount of mesangial matrix, lowered the expression of renal collagen IV and transforming growth factor (TGF)-β1, and reduced the level of apoptosis in the kidney, compared to the DM group. These changes were accompanied by decreased tissue levels of hydrogen superoxide and NADPH oxidase subunit proteins. Bilirubin decreased serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), free fatty acids, and triglycerides (TGs), as well as the TG content in the liver tissues. Bilirubin suppressed protein expression of LXRα, SREBP-1, SCD-1, and FAS, factors involved in TG synthesis that were elevated in the livers of DM rats and hepatoma cells under high-glucose conditions. In conclusion, bilirubin attenuates renal dysfunction and dyslipidemia in diabetes by suppressing LXRα and SREBP-1 expression and oxidative stress.

Bilirubin and progression of nephropathy in type 2 diabetes: a post hoc analysis of RENAAL with independent replication in IDNT

Bilirubin, a potent endogenous antioxidant, was found to protect against the development of diabetic nephropathy (DN) in rodents. In humans, cross-sectional studies found an inverse relation between bilirubin and DN. We prospectively investigated whether bilirubin is associated with progression of DN toward end-stage renal disease (ESRD). To this end, we performed a post hoc analysis in the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) trial with independent replication in the Irbesartan Diabetic Nephropathy Trial (IDNT). Subjects with type 2 diabetes and nephropathy with alanine aminotransferase, aspartate aminotransferase (AST), and bilirubin levels <1.5 times the upper limit of normal were included. The renal end point was defined as the composite of confirmed doubling of serum creatinine or ESRD. Bilirubin was inversely associated with the renal end point in RENAAL independent of age, sex, race, BMI, smoking, total cholesterol, diastolic blood pressure, HbA1c, treatment, estimated glomerular filtration rate, albumin-to-creatinine ratio, and AST. These results were confirmed in IDNT. This study indicates an independent inverse association of bilirubin with progression of nephropathy in RENAAL and IDNT. These data suggest a protective effect of bilirubin against progression of nephropathy in type 2 diabetes. The well-established role of bilirubin as an antioxidant is a potential explanation for the findings.

Circulating bilirubin and defense against kidney disease and cardiovascular mortality: mechanisms contributing to protection in clinical investigations

Unconjugated bilirubin is an endogenous circulating antioxidant, bound to albumin, and therefore is retained in the vascular compartment. Bilirubin has well-documented neurotoxic effects in infants; however, current evidence indicates mildly elevated bilirubin is associated with protection from cardiovascular disease and all-cause mortality in adults. Recent clinical studies show mildly elevated bilirubin is associated with protection from kidney damage and dysfunction, in addition to cardiovascular events and all-cause mortality in patients undergoing hemodialysis. This is the first review to examine the clinical evidence and summarize the potential mechanisms of action that link bilirubin to protection from kidney damage, subsequent kidney failure, and dialysis-related mortality. With this understanding, it is hoped that new therapies will be developed to prevent renal dysfunction and mortality from cardiovascular disease in at-risk individuals.