Association of serum bilirubin levels with development and progression of albuminuria, and decline in estimated glomerular filtration rate in patients with type 2 diabetes mellitus

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 between bilirubin and chronic kidney disease in hypertensive patients: The China hypertension registry study

Limited data exists on the association between Direct bilirubin (DBIL) and Indirect bilirubin (IBIL) with the risk of chronic kidney disease (CKD) among patients with hypertension. This study aimed to assess the relationship between DBIL and IBIL with the risk of CKD in a cohort of Chinese adults diagnosed with hypertension. This study included 14 182 Chinese patients with hypertension between the ages of 27 and 96. CKD, the outcome variable, was defined by an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 . The study employed multivariate linear and multivariate logistic regression analysis to evaluate the correlation between DBIL and IBIL with the risk of CKD. The prevalence of CKD in the study population was 9.77%. Multivariate logistic regression analysis showed that the increase in DBIL (OR: 0.66; 95% CI: 0.61, 0.71) and IBIL (OR: 0.75; 95% CI: 0.71, 0.81) were independently and negatively correlated with CKD. Further analyses using a restricted cubic spline (smooth-fitting curve) confirmed the linearly negative association between DBIL and IBIL with the risk of CKD. The subgroup analysis showed that the correlation between IBIL and CKD was stronger among men and populations <65 years of age (p for interaction <.05). DBIL and IBIL were independently and negatively associated with CKD. Furthermore, the correlation between DBIL and IBIL with CKD in the hypertensive population is more significant in those under 65 years of age. These findings may inform future strategies for the management of CKD.

High-normal serum bilirubin decreased the risk of lower limb atherosclerosis in type 2 diabetes: a real-world study

BACKGROUND

Bilirubin has been found to protect against overt atherosclerotic diseases, but to date, few studies have investigated the effects of bilirubin especially within the normal range on lower limb atherosclerosis. Therefore, we aimed to assess the associations of bilirubin within normal limits including total bilirubin (TB), conjugated bilirubin (CB) and unconjugated bilirubin (UCB) with lower limb atherosclerosis in Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

7284 T2DM patients with normal levels of serum bilirubin were included in this cross-sectional, real-world study. Patients were divided into quintiles by TB levels (< 8.7, 8.7-10.19, 10.20-11.99, 12-13.99, > 13.99 µmol/L). Lower limb ultrasonography was conducted to detect lower limb plaque and stenosis. The association between serum bilirubin and lower limb atherosclerosis was explored by multiple logistic regression.

RESULTS

A remarkable decrease in the prevalence of lower limb plaque (77.5, 75.3, 70.7, 71.7 and 67.9%) and stenosis (21.1, 17.2, 13.3, 13.0 and 12.0%) was observed across the TB quintiles. Multivariable regression analysis showed that serum TB levels were negatively correlated with higher risks of lower limb plaque and stenosis, both as a continuous variable [OR (95%CI): 0.870 (0.784-0.964), p = 0.008 for plaque; and 0.835 (0.737-0.946), p = 0.005 for stenosis] and as categorized in quintiles (p = 0.015 and 0.016 for plaque and stenosis). Interestingly, serum CB levels were only negatively correlated with lower limb stenosis [OR (95%CI): 0.767 (0.685-0.858), p < 0.001], whereas serum UCB levels were only negatively associated with lower limb plaque [ OR (95%CI): 0.864 (0.784-0.952), p = 0.003] after a fully-adjusted analysis. Furthermore, serum CRP was significantly decreased across the TB quintiles and negatively associated with serum TB (r = -0.107, p < 0.001), CB (r = -0.054, p < 0.001), and UCB (r = -0.103, p < 0.001).

CONCLUSIONS

High-normal serum bilirubin levels were independently and significantly related to reduced risks of lower limb atherosclerosis in T2DM patients. Furthermore, serum bilirubin levels including TB, CB and UCB were inversely correlated with CRP. These results suggested that higher-normal serum bilirubin may exhibit an anti-inflammatory and protective effect against lower limb atherosclerotic progression in T2DM subjects.

Nutritional, antioxidant, carbohydrate hydrolyzing enzyme inhibitory activities, and glyceamic index of wheat bread as influence by bambara groundnut substitution

The research was designed to ascertain the potential of bambara groundnut inclusion in wheat bread to improve antioxidant activity, modulate carbohydrate hydrolyzing enzyme activities, and lower glyceamic index/ load. Protein (g/100 g) (11.2—11.73) and energy value (kcal/100 g) (421.5—435.5) of the bread were significantly higher than commercial wheat flour bread (CWF—10.45; 388.7). However, developed experimental bread samples exhibited higher growth performance in rats, free radical scavenging potentials, inhibitory activities against carbohydrate hydrolyzing enzymes and low glycemic index than other bread samples. Nevertheless, experimental bread samples were rated lower compared with the controls samples as regards organoleptic properties. The study authenticates that WBO3—25% wheat, and 75% bamabara groundnut WBO3 exhibits higher potentials as regards nutritional composition, growth indices, free radical scavenging potentials, ability to modulate carbohydrate hydrolyzing enzyme and lower glycemic index/ load. Hence, WBO3 may be recommended as functional bread for hyperglycemia prevention/ management.

Serum bilirubin as a predictor of graft outcomes after renal transplant

Bilirubin is a signaling molecule that alters the immune response and metabolism. While bilirubin has been employed as a marker of renal and cardiovascular health, its role in renal transplant recipients is not known. In this study, we sought to determine the impact of bilirubin (total, direct and indirect) on the estimated glomerular filtration rate (eGFR) after renal transplantation. We conducted a retrospective review of pre- and postoperative bilirubin levels in 457 renal transplant recipients at a single center. Pre- and post-rejection bilirubin levels were also assessed in those patients who experienced a rejection episode. No statistically significant differences were found in bilirubin levels during the pre-transplant to post-rejection period among patients who experienced rejection with kidney allograft survival. No statistically significant associations were observed between baseline bilirubin and post-transplant eGFR in the full patient group or within the gender- or race-stratified groups. Baseline bilirubin was not correlated with time to rejection. Our results suggest that bilirubin may not offer renoprotection in renal transplant recipients.

Sex differences between serum total bilirubin levels and cognition in patients with schizophrenia

BACKGROUND

Cognitive deficits are common in patients with schizophrenia (SCZ). Abnormal serum total bilirubin (TBIL) levels have been involved in cognitive deficits associated with neuropsychiatric diseases such as mild cognitive impairment and subcortical ischemic vascular disease. However, this relationship has not yet been fully investigated in patients with SCZ. Therefore, the aim of this study was to investigate the association between the serum TBIL concentration and cognitive deficits in SCZ patients and to determine whether a sex difference exists in the association.

METHODS

A total of 455 participants were eligible and included in this cross-sectional study. Cognition was evaluated using the Montreal Cognitive Assessment. Serum TBIL concentration was measured with an automatic biochemistry analyzer according to the routine protocol in the hospital medical laboratory.

RESULTS

Serum TBIL levels were lower in the cognition impairment group than in the cognition normal group in male patients. In contrast, serum TBIL levels tended to be increased in the cognition impairment group in female patients, although the difference was not significant. Further stepwise multiple regression analysis stratified by sex showed that serum TBIL was independently and positively associated with cognitive function in male patients but not in female patients. Moreover, the association between serum TBIL level and cognitive function was also identified by the propensity score matching (PSM) method in male patients, but not in female patients.

CONCLUSION

These findings suggest that lower serum TBIL levels may be associated with cognitive impairment in male SCZ patients.

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.

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.

NRF2-Related Epigenetic Modifications in Cardiac and Vascular Complications of Diabetes Mellitus

Diabetes mellitus (DM) is a highly prevalent chronic disease that is accompanied with serious complications, especially cardiac and vascular complications. Thus, there is an urgent need to identify new strategies to treat diabetic cardiac and vascular complications. Nuclear factor erythroid 2-related factor 2 (NRF2) has been verified as a crucial target for the prevention and treatment of diabetic complications. The function of NRF2 in the treatment of diabetic complications has been widely reported, but the role of NRF2-related epigenetic modifications remains unclear. The purpose of this review is to summarize the recent advances in targeting NRF2-related epigenetic modifications in the treatment of cardiac and vascular complications associated with DM. We also discuss agonists that could potentially regulate NRF2-associated epigenetic mechanisms. This review provides a better understanding of strategies to target NRF2 to protect against DM-related cardiac and vascular complications.

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 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.

Protective Effects of Kaempferol on D-Ribose-Induced Mesangial Cell Injury

Recently, it has been found that the level of urinary D-ribose in type 2 diabetes is notably higher than that in age-matched normal control, and D-ribose is more reactive in the glycation than D-glucose and induces oxidative stress. Kaempferol is one of the main bioactive components in Astragalus membranaceus, with numerous physiological actives, such as antioxidant. The present study investigated the protective effects of kaempferol on D-ribose-treated mesangial cells. CCK-8 and LDH assay were used to test cell viability and cell toxicity. Immunofluorescence and flow cytometry were used to detect the AGE formation and ROS accumulation. GSH level was measured to reflect oxidation resistance. Cell apoptosis was evaluated by Hoechst 33258 staining, AO/EB staining, and western blot. Mitochondrial membrane integrity was detected by JC-1 staining, western blot, and RT-PCR. The change of autophagy level was tested by western blot. The results indicated that D-ribose induced not only cell damage and increased AGE formation and ROS accumulation but also GSH depletion. Further studies demonstrated that D-ribose induced mitochondrial depolarization and the activation of caspase-9/3. But kaempferol could partly block these damages. Subsequently, it was confirmed that kaempferol repaired the autophagy disturbance induced by D-ribose, and 3-MA could reverse the protective effect of kaempferol under D-ribose condition. Our study demonstrated that D-ribose induced AGE accumulation and ROS production in mesangial cell and caused mitochondrial apoptosis, but kaempferol could attenuate these changes and its protective effect might be related to the repair of autophagy.

Interactive effect of serum uric acid and total bilirubin for micro-vascular disease of type 2 diabetes in China

AIMS

Serum uric acid (SUA) and bilirubin at high levels had both pro-oxidant and anti-oxidant properties. The present study aimed to examine additive interactions between SUA and total bilirubin (TBIL) for the risk of micro-vascular disease (MVD) in type 2 diabetes mellitus (T2DM).

METHODS

A cross-sectional survey of 6713 inpatients with T2DM was conducted in 81 tertiary care hospitals in China. MVD was defined as having either prior diabetic retinopathy (DR) or diabetic nephropathy (DN). Binary logistic regression was used to estimate odds ratios of SUA and TBIL for MVD. Additive interaction was measured by three indices, i.e., relative excess risk due to interaction, attributable proportion due to interaction and synergy index.

RESULTS

Among 6713 inpatients, 408 (6.08%) suffered from MVD. SUA ≥ 283 μmol/l (i.e., its media) was defined as high SUA, and TBIL <11.5 μmol/l (n = 2290 or 34.11%) was defined as low TBIL. Overall, 621 patients were exposed to co-presence of high SUA and low TBIL. The co-presence of both factors greatly increased the effect sizes from 1.03(95%CI: 0.72-1.46) (high SUA alone) or 0.70(95%CI: 0.48-1.05) (low TBIL alone) to 1.90 (95%CI: 1.26-2.87) for MVD in multivariable analysis. The additive interaction of both factors was significant for MVD in both univariable analysis and multivariable analysis.

CONCLUSIONS

Co-presence of both high SUA and low TBIL indentified a group of patients at a markedly increased risk of MVD in high-risk Chinese patients with T2DM.

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.

Relationship between serum bilirubin levels s and the progression of renal function in patients with chronic kidney disease and hyperuricemia

It is known that inflammation and oxidative stress have strong influences on chronic kidney disease (CKD). As an antioxidant, bilirubin is currently under extensive scrutiny. However, there are disagreements with regard to the oxidative and antioxidative roles of serum uric acid (SUA). This study aimed to investigate the relationship between serum bilirubin and the progression of renal function in CKD patients with hyperuricemia (HUA). This retrospective longitudinal study included 427 CKD patients. The endpoint was renal replacement therapy or death. Patients were divided into the following two groups according to the SUA level: HUA group (SUA ≥ 420 μmol/L for men; SUA ≥ 360 μmol/L for women) and normal uric acid level (NUA) group. A Cox proportional hazards model was used to evaluate the risk factors for renal outcomes in the two patient groups. The median follow-up time was 36 months. In the Cox regression analysis, the risk of renal outcomes in patients with serum indirect bilirubin (IBIL) levels >4.55 μmol/L was 0.15 times the risk in patients with serum IBIL levels ≤4.55 μmol/L (hazard ratio = 0.15, p = .013). Our findings suggest that a high serum IBIL level might be a protective factor for the progression of renal function in CKD patients with HUA.

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.

The Association between Serum Bilirubin Level and Electrochemical Skin Conductance in Chinese Patients with Type 2 Diabetes

Bilirubin is an antioxidant and plays a protective role against cardiovascular and microvascular disease. The aim of this study is to explore the possible protective effect of bilirubin on small nerve function. A total of 265 Chinese patients with type 2 diabetes mellitus (T2DM) were enrolled in the study. Both SUDOSCAN and other traditional diabetic neuropathy examinations including neuropathy symptom score (NSS), the neuropathy disability score (NDS) and Michigan Neuropathy Screening Instrument (MNSI) scores were performed in all patients with T2DM. Blood bilirubin levels were tested in the study. Spearman correlation analysis and multivariate regression analysis were performed to determine the relation between bilirubin level and hands and feet ESC values. Spearman correlation analysis demonstrated a correlation between total bilirubin and ESC levels including hands (r = 0.165, P < 0.05) and feet (r = 0.122, P < 0.05) as well as between UCBil and ESC levels including both hands (r = 0.172, P < 0.05) and feet (r = 0.175, P < 0.05). Multivariate regression linear analyses showed both total bilirubin and UCBil level were independently associated with hands and feet ESC levels. All these results suggested a positive association between bilirubin level and ESC level, indicating a possible protective role of bilirubin in peripheral small nerve dysfunction of type 2 diabetes mellitus.

The Saudi Diabetic Kidney Disease study (Saudi-DKD): clinical characteristics and biochemical parameters

BACKGROUND

Saudi Arabia is facing an epidemic of type 2 diabetes that is complicated by a high rate of chronic complications such as kidney disease, which have a major impact on the healthcare system and economy. The Saudi diabetic kidney disease (SAUDI-DKD) study was launched to understand the implications of chronic diabetic kidney disease .

OBJECTIVES

Examine the hematological, biochemical and metabolic parameters of the selected cohorts to look for biomarkers of diabetic nephropathy.

DESIGN

Cross-sectional, hospital-based.

SETTING

Four general hospitals and two dialysis centers in Riyadh.

PATIENTS AND METHODS

We recruited adult type 2 diabetic patients aged between 35 and 70 years, with a duration of diabetes > 10 years, including subjects with microalbuminuria, macroalbuminuria and end stage renal disease (ESRD). They were compared with subjects with normal albumin excretion classified according to American Diabetes Association (ADA) criteria.

MAIN OUTCOME MEASURES

The effect of different stages of diabetic nephropathy on hematological and biochemical parameters.

RESULTS

Of 427 subjects with nephropathy, 184 (43%) had microalbuminuria, 83 (19%) had macroalbu.minuria and 160 (37%) had end stage renal disease (ESRD). The remaining 213 (50%) subjects did not have nephropathy. Patients with nephropathy were older with a mean age (SD) of 55.62 (6.00) years and had a longer duration of diabetes (mean [SD], 19.04 [6.33]) years), and had a lower monthly income and body mass index (BMI) than patients without nephropathy. Insulin resistance, elevated uric acid level, low red blood cells (RBCs) count and low hemoglobin level were associated with significantly increased risk of macroalbuminuria and ESRD. Elevated uric acid and LDH were associated with significantly increased risk of microalbuminuria and ESRD, while elevated red blood cell distribution width was significantly associated with an increased risk of ESRD.

CONCLUSION

Diabetic nephropathy is associated with insulin resistance, changes in liver enzymes and uric acid in addition to abnormalities in the red blood cell count and red blood cell shape that warrant frequent monitoring among patients with diabetic kidney disease.

LIMITATIONS

Cross-sectional study design and exclusion of patients with some risk factors.

Inverse Relationship Between Serum Bilirubin Levels and Diabetic Foot in Chinese Patients with Type 2 Diabetes Mellitus

BACKGROUND Several studies demonstrated that bilirubin, a potent endogenous antioxidant, is a strong protective factor for many diabetic complications such as nephropathy, retinopathy, neuropathy, and vasculopathy. The purpose of this study was to assess the association between serum bilirubin levels and diabetic foot (DF) in Chinese patients with type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS The present cross-sectional study of bilirubin levels in relation to DF was conducted in 1,269 T2DM patients with (n=578) and without (n=691) DF. Blood test results were obtained on hospital admission, including total bilirubin (T-BIL), direct bilirubin (D-BIL), and indirect bilirubin (I-BIL). Data on Wagner classification and amputation procedure in patients with DF were collected by reviewing electronic medical records. Univariate or multivariate analysis were performed to explore the association between bilirubin and DF. RESULTS Serum I-BIL levels were shown to play a protective role regarding the presence and severity of DF (OR=0.75, p=0.029 and OR=0.90, p=0.021, respectively). In addition, in a comparison of the lowest and highest tertiles of serum bilirubin concentration, the highest tertile of serum T-BIL (OR=0.51, p=0.011) and I-BIL (OR=0.28, p<0.001) was significantly related with a lower Wagner grade of DF. Patients with DF in the highest tertiles of T-BIL carried a significantly lower risk of amputation events than those in the lowest tertiles (OR=0.47, p=0.025). CONCLUSIONS The present study provided evidence that decreased serum bilirubin levels were independently associated with the presence and severity of DF and amputation events in patients with DF.

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.

Relationship between serum bilirubin concentrations and diabetic nephropathy in Shanghai Han's patients with type 1 diabetes mellitus

Background

Recent studies highlight a negative association between total bilirubin concentrations and albuminuria in patients with type 2 diabetes mellitus. Our study evaluated the relationship between bilirubin concentrations and the prevalence of diabetic nephropathy (DN) in Chinese patients with type 1 diabetes mellitus (T1DM).

Methods

A total of 258 patients with T1DM were recruited and bilirubin concentrations were compared between patients with or without diabetic nephropathy. Multiple stepwise regression analysis was used to examine the relationship between bilirubin concentrations and 24 h urinary microalbumin. Binary logistic regression analysis was performed to assess independent risk factors for diabetic nephropathy. Participants were divided into four groups according to the quartile of total bilirubin concentrations (Q1, 0.20–0.60; Q2, 0.60–0.80; Q3, 0.80–1.00; Q4, 1.00–1.90 mg/dL) and the chi-square test was used to compare the prevalence of DN in patients with T1DM.

Results

The median bilirubin level was 0.56 (interquartile: 0.43–0.68 mg/dL) in the DN group, significantly lower than in the non-DN group (0.70 [interquartile: 0.58–0.89 mg/dL], P < 0.001). Spearman’s correlational analysis showed bilirubin concentrations were inversely correlated with 24 h urinary microalbumin (r = -0.13, P < 0.05) and multiple stepwise regression analysis showed bilirubin concentrations were independently associated with 24 h urinary microalbumin. In logistic regression analysis, bilirubin concentrations were significantly inversely associated with nephropathy. In addition, in stratified analysis, from the first to the fourth quartile group, increased bilirubin concentrations were associated with decreased prevalence of DN from 21.90% to 2.00%.

Conclusion

High bilirubin concentrations are independently and negatively associated with albuminuria and the prevalence of DN in patients with T1DM.

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.

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.

Elevated serum total bilirubin levels are negatively associated with major diabetic complications among Chinese senile diabetic patients

AIMS

This study aimed to evaluate the association between total bilirubin (TBiL) and major diabetic complications among Chinese senile diabetic patients.

METHODS

A cross-sectional study was conducted in all the cadre sanitariums in Beijing, between May 2012 and December 2014. All the diagnoses of diabetic complications were extracted from the medical records including chronic kidney disease, retinopathy, peripheral vascular disease, coronary heart disease, and ischemic stroke.

RESULTS

The mean age of the 1839 senile diabetic patients were 87.4±4.0 (80-102years) and mean TBiL level was 13.2±6.0μmol/L. The prevalence of chronic kidney disease, retinopathy, peripheral vascular disease, coronary heart disease and ischemic stroke was 13.8%, 17.8%, 5.8%, 62.5%, and 44.5%, respectively. TBiL level was negatively correlated with age, weight, SBP, TC, FBG, 2hPG, diabetic duration and positively correlated with HDL-C. Prevalence of all five diseases gradually decreased with the increase of TBiL level (p<0.05). Also, number of diabetic complications showed a decreasing trend along with TBiL tertiaries. After adjusted age, education, marital status, current smoking, current drinking, physical activity ≥0.5h/day, BMI, hypertension, dyslipidemia, treatment and control status of diabetes, patients with higher TBiL level were at significantly decreased ORs for prevalence of major diabetic complications. The ORs were 0.97 (95%CI: 0.96-0.99), 0.90 (95%CI: 0.87-0.93), 0.98 (95%CI: 0.97-0.99), 0.97 (95%CI: 0.95-.99) and 0.98 (95%CI: 0.97-0.99) for chronic kidney disease, retinopathy, peripheral vascular disease, coronary heart disease and ischemic stroke (p<0.005). Similar results were obtained when TBiL was used as tertiary variable.

CONCLUSION

Higher TBiL was significantly associated with lower prevalence of major diabetic complication among senile diabetic patients, and this association was graded with TBiL level and independent of age and control status of diabetes.

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.

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.

Differences in risk factors for the onset of albuminuria and decrease in glomerular filtration rate in people with Type 2 diabetes mellitus: implications for the pathogenesis of diabetic kidney disease

AIMS

To determine differences in predictors of albuminuria and decreased estimated GFR in Japanese people with Type 2 diabetes mellitus without chronic kidney disease.

METHODS

This single-centre observational cohort study involved 1802 Japanese people with Type 2 diabetes with normoalbuminuria and estimated GFR ≥ 60 ml/min/1.73 m(2) (740 women; mean ± sd age 58 ± 12 years). Two separate outcomes were evaluated: onset of albuminuria ( ≥ 30 mg/g creatinine, albuminuria cohort; n = 1655) and decrease in estimated GFR ( < 60 ml/min/1.73 m(2) ; estimated GFR cohort; n = 1777). A Cox proportional hazards model was used to identify significant predictors for each outcome.

RESULTS

During a median follow-up period of 6.9 years for the albuminuria cohort and 8.0 years for the estimated GFR cohort, 181 and 316 individuals reached the respective outcome. The 5-year cumulative incidence of albuminuria was 8.3%, and that of decreased estimated GFR was 10.4%. In the multivariate Cox model, greater urinary albumin-to-creatinine ratio, presence of diabetic retinopathy and higher HbA1c levels were associated with both outcomes. Unique risk factors for onset of albuminuria were male gender and higher uric acid levels; those for decreased estimated GFR were older age, greater systolic blood pressure, and lower baseline estimated GFR and HDL cholesterol levels.

CONCLUSIONS

Identification of both common and distinct predictive factors for onset of albuminuria and decreased estimated GFR support the hypothesis that both common and distinct pathophysiological mechanisms are involved in the development of these two manifestations of chronic kidney disease in diabetes.

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.

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.

Association of serum bilirubin levels with development and progression of albuminuria, and decline in estimated glomerular filtration rate in patients with type 2 diabetes mellitus

AIMS/INTRODUCTION

Recent observational studies suggest elevated levels of bilirubin, an endogenous anti-oxidant, might protect against kidney disease. We carried out an observational cohort study to assess whether higher baseline levels of bilirubin, within normal range, could predict the rate of development and progression of diabetic nephropathy in patients with type 2 diabetes.

MATERIALS AND METHODS

Japanese type 2 diabetic patients with normo- or microalbuminuria and normal serum bilirubin (<1.2 mg/dL) were recruited from a single center, and categorized according to baseline serum bilirubin levels. Two independent end-points were specified: development or progression of diabetic nephropathy, based on transition to a more advanced stage of albuminuria (albuminuria cohort), and the rate of change in estimated glomerular filtration rate (eGFR cohort).

RESULTS

Albuminuria and eGFR cohorts were constructed consisting of 1,915 patients and 1,898 patients, respectively, with 1,738 patients overlapping. Mean follow up was 4.4 and 5.4 years for the two cohorts, respectively. Within the albuminuria cohort, 132 (9%) of 1,418 patients with normoalbuminuria developed microalbuminuria, and 56 (11%) of 497 patients with microalbuminuria developed macroalbuminuria. Higher baseline bilirubin levels were associated with significantly lower risk of progression from microalbuminuria to macroalbuminuria in both the univariate and multivariate analyses. In normoalbuminuric patients, an inverse association was found when restricted to a subgroup with elevated hemoglobin A1c levels. There was no relationship between bilirubin levels and the rate of change in eGFR.

CONCLUSIONS

Higher serum bilirubin levels, within normal range, might be predictive of a lower risk of progression of nephropathy in type 2 diabetic patients.