Evaluation of early biomarkers of renal dysfunction in diabetic patients

Changes in Urinary NGAL, FN, and LN Excretion in Type 2 Diabetic Patients Following Anti-Diabetic Therapy with Metformin

Background: Excessive accumulation of glomerular extracellular matrix (ECM) is a key factor in the development and progression of diabetic nephropathy (DN). As kidney dysfunction has been reported in normoalbuminuric patients, identifying novel diagnostic and prognostic markers is essential for the prevention and treatment of DN. Methods: Urinary excretion of neutrophil gelatinase-associated lipocalin (NGAL) and ECM-related glycoproteins, i.e., fibronectin (FN) and laminin (LN), was measured in obese patients with newly diagnosed type 2 diabetes mellitus (T2DM) before and after 6 months of metformin therapy. Results: Baseline NGAL (1.27 (0.80-2.36) ng/mg Cr), FN (11.19 (5.31-21.56) ng/mg Cr) and LN (123.17 (54.56-419.28) pg/mg Cr) levels did not significantly differ between T2DM patients and controls (1.95 (1.09-2.97) ng/mg Cr, 11.94 (7.78-18.01) ng/mg Cr and 157.85 (83.75-326.40) pg/mg Cr, respectively). In multivariate regression analysis, the body mass index was identified as the only significant predictor influencing urinary NGAL and FN levels at baseline, with β = 0.249, p = 0.005 and β = 1.068, p = 0.010, respectively. Metformin treatment significantly increased urinary levels of both ECM proteins, i.e., FN (18.48 (11.64-32.46) ng/mg Cr) and LN (179.51 (106.22-414.68) pg/mg Cr), without any effect on NGAL levels (1.44 (0.81-2.72) ng/mg Cr). FN and LN were positively associated with NGAL both before (r = 0.709 and r = 0.646, both p < 0.001, respectively) and after (r = 0.594 and r = 0.479, both p < 0.001, respectively) therapy. No correlations were found between NGAL, FN, LN, and albuminuria. However, NGAL was positively correlated with the albumin/creatinine ratio (ACR) both before (r = 0.323, p < 0.05) and after (r = 0.287, p < 0.05) therapy, and negatively with estimated glomerular filtration rate (eGFR) in pre-treatment diabetics (r = -0.290, p < 0.05). FN and LN were also correlated with ACR (r = 0.384, p < 0.01 and r = 0.470, p < 0.001), although the association for LN was limited to untreated patients (r = 0.422, p < 0.01). Conclusions: Our results suggest that metformin has a beneficial effect on ECM turnover with a significant increase in urinary excretion of non-collagenous markers of glomerular injury, i.e., FN and LN. Additionally, ECM-related markers may serve as useful tools for monitoring early renal injury in obese diabetic patients.

Early Detection of Diabetic Nephropathy Based on Urinary and Serum Biomarkers: An Updated Systematic Review

Diabetic nephropathy (DN) is a leading cause of chronic kidney disease (CKD) and end-stage renal disease worldwide, particularly among individuals with type 2 diabetes mellitus (T2DM). Early detection and intervention are crucial in slowing the progression of DN and improving patient outcomes. Traditional diagnostic methods, such as the measurement of albuminuria and serum creatinine, often fail to detect early renal damage because structural kidney damage may occur before albumin excretion. This systematic review aims to evaluate the diagnostic value of various urinary and serum biomarkers in the early detection of DN in patients with T2DM. A comprehensive literature search was conducted using databases such as PubMed, Scopus, and Web of Science. We only considered studies involving human populations for inclusion in our analysis. Animal and in vitro studies were excluded from our review. Our analysis of 17 observational studies identified several key serum biomarkers, such as netrin-1, osteopontin, adiponectin, and specific cytokines (e.g., IL-6, IL-8), which show significant promise for early detection of DN. Urinary biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), transferrin, N-acetyl-β-D-glucosaminidase (NAG), and various cytokines, have also proven to be reliable indicators. The combination of both serum and urinary biomarkers may enhance diagnostic accuracy and enable earlier intervention. Additionally, incorporating genetic and mRNA markers could provide a more comprehensive approach to early DN detection. Implementing these biomarkers in clinical practice could significantly improve outcomes for patients with DN by facilitating early diagnosis and timely management.

Evaluation of N-acetyl-β-D-glucosaminidase as a prognostic marker for diabetic nephropathy in type 2 diabetics: systematic review and meta-analysis

OBJECTIVE

This review aimed to assess the utility of urinary N-acetyl-β-D-glucosaminidase (uNAG) as a prognostic biomarker for nephropathy in patients with type 2 diabetes mellitus.

METHODS

The search for relevant studies was conducted across multiple databases, including PubMed (Medline), EMBASE, LILACS, CENTRAL, IBECS, and gray literature. We employed a random effects model to calculate the standardized mean difference and 95% confidence interval. Furthermore, we assessed heterogeneity using Cochrane's Q test and Higgins' I2 statistics.

RESULTS

This review included a total of 16 articles involving 1669 patients, with 13 being case-control studies and three being cohorts. The meta-analysis conducted across all studies revealed significant heterogeneity. However, subgroup analysis of four studies indicated that an increase in uNAG among normoalbuminuric patients was associated with the development of macroalbuminuria (DMP = - 1.47; 95% CI = - 1.98 to 0.95; p < 0.00001; I2 = 45%). Conversely, it did not demonstrate effectiveness in predicting the development of microalbuminuria (DMP = 0.26; 95% CI = - 0.08 to 0.60; p = 0.13; I2 = 17%).

CONCLUSIONS

Elevated uNAG levels in normoalbuminuric patients may indicate an increased risk for the development of macroalbuminuria, but not microalbuminuria. However, the high heterogeneity observed among the studies highlights the necessity for further research to validate these findings.

Re-understanding and focusing on normoalbuminuric diabetic kidney disease

Diabetes mellitus (DM) has grown up to be an important issue of global public health because of its high incidence rate. About 25% of DM patients can develop diabetic foot/ulcers (DF/DFU). Diabetic kidney disease (DKD) is the main cause of end-stage kidney disease (ESKD). DF/DFU and DKD are serious complications of DM. Therefore, early diagnosis and timely prevention and treatment of DF/DFU and DKD are essential for the progress of DM. The clinical diagnosis and staging of DKD are mostly based on the urinary albumin excretion rate (UAER) and EGFR. However, clinically, DKD patients show normoalbuminuric diabetic kidney disease (NADKD) instead of clinical proteinuria. The old NADKD concept is no longer suitable and should be updated accordingly with the redefinition of normal proteinuria by NKF/FDA. Based on the relevant guidelines of DM and CKD and combined with the current situation of clinical research, the review described NADKD from the aspects of epidemiology, pathological mechanism, clinical characteristics, biomarkers, disease diagnosis, and the relationship with DF/DFU to arouse the new understanding of NADKD in the medical profession and pay attention to it.

The potential use of urinary transferrin, urinary adiponectin, urinary Retinol Binding Protein, and serum zinc alpha 2 glycoprotein levels as novel biomarkers for early diagnosis of diabetic nephropathy: A case-control study

BACKGROUND AND AIMS

The level of albuminuria is used to evaluate diabetic nephropathy (DN). However, to detect or predict the early stages of DN, better biomarkers are needed.

METHODS

This study is a case-control observational study. 80 Egyptians participated in the study: 60 patients with type 2 diabetes mellitus (T2DM) were divided into three groups (20 patients each), and 20 healthy subjects with matched age and gender were used as controls. Demographic and laboratory data were analyzed. An enzyme-linked immunosorbent assay was used to determine the levels of four biomarkers of DN; urinary adiponectin (ADP), urinary transferrin, serum Zinc Alpha 2 Glycoprotein (ZAG), and urinary Retinol Binding Protein (RBP).

RESULTS

The levels of DN biomarkers urinary ADP, transferrin, RBP, and serum, ZAG were significantly higher in patients with T2DM than in controls. The ROC curve of the validity of the simultaneous use of all four biomarkers in predicting albuminuria indicates a sensitivity of 90% and a specificity of 90%. The Area Under the Curve (AUC) was 0.948, the 95% confidence interval was 0.998-0.897, and the p-value was 0.001.

CONCLUSIONS

In patients with T2DM, urine adiponectin, transferrin, RBP, and serum ZAG concentration may be useful biomarkers in the early diagnosis of DN. A further longitudinal prospective study is required to explore the potential utility of these biomarkers.

Increased serum cystatin C levels and responses of pancreatic α- and β-cells in type 2 diabetes

BACKGROUND

Increased serum cystatin C (CysC) can predict the onset of type 2 diabetes (T2D). Meanwhile, impaired pancreatic α- and β-cell functions get involved in the pathophysiological processes of T2D. So this study was to explore the relationships between serum CysC levels and pancreatic α- and β-cell functions in T2D.

METHODS

In this cross-sectional observational study, a total of 2634 patients with T2D were consecutively recruited. Each recruited patient received a serum CysC test and oral glucose tolerance test for synchronous detection of serum C-peptide and plasma glucagon. As components of pancreatic β-cell function, insulin secretion and sensitivity indices were evaluated by C-peptide area under the curve (AUC-CP) and C-peptide-substituted Matsuda's index (Matsuda-CP), respectively. Fasting glucagon (F-GLA) and post-challenge glucagon calculated by glucagon area under the curve (AUC-GLA) were used to assess pancreatic α-cell function. These skewed indices and were further natural log-transformed (ln).

RESULTS

With quartiles of serum CysC levels ascending, AUC-CP, F-GLA and AUC-GLA were increased, while Matsuda-CP was decreased (P for trend <0.001). Moreover, serum CysC levels were positively related to lnAUC-CP, lnF-GLA and lnAUC-GLA (r= 0.241, 0.131 and 0.208, respectively, P < 0.001), and inversely related to lnMatsuda-CP (r= -0.195, P < 0.001). Furthermore, after controlling for other relevant variables via multivariable linear regression analysis, serum CysC levels were identified to account for lnAUC-CP (β= 0.178, t= 10.518, P < 0.001), lnMatsuda-CP (β= -0.137, t= -7.118, P < 0.001), lnF-GLA (β= 0.049, t= 2.263, P = 0.024) and lnAUC-GLA (β= 0.121, t= 5.730, P < 0.001).

CONCLUSIONS

Increased serum CysC levels may be partly responsible for increased insulin secretion from β-cells, decreased systemic insulin sensitivity, and elevated fasting and postprandial glucagon secretion from α-cells in T2D.

Correlation of Cystatin-c with Albumin Creatinine Ratio for the Diagnosis of Diabetic Nephropathy in Patients with Type 2 Diabetes: A Cross-sectional Study in Medan Indonesia

BACKGROUND: Diabetic nephropathy (ND) is one of the main complications of chronic microvascular diabetes mellitus (DM) and the leading cause of the end-stage renal disease (ESRD), accounting for nearly half of all ND cases with ESRD incidence in developed countries. Recently, cystatin C serum has been considered as a new biomarker for the diagnosis of kidney damage. Cystatin-C is an appropriate marker for GFR measurement because it is not affected by age, weight, gender, and protein intake. Early detection of abnormal renal function is essential to slow progression to a further stage of nephropathy or the final stage of kidney disease. AIM: The aim of the study was to analyze the correlation between cystatin-C and ACR to early detection of nephropathy complications. MATERIALS AND METHODS: This study uses an observational analytical research design with a cross-sectional approach. The research was conducted on patients with type 2 diabetes mellitus (T2DM) who were visiting the primary health service in Medan that met the inclusion and exclusion criteria. The sample count was 89 respondents. The sampling method is done through consecutive sampling. The source of this research data is primary data, including the results of cystatin-c examination and albumin. Data analysis used Spearman correlation using SPSS for Windows software. RESULTS: There was a significant relationship between cystatin-C levels and albuminuria (p<0.05). CONCLUSION: Diabetic nephropathy is a clinical syndrome characterized by persistent albuminuria and progressive decline of renal function, cystatin-C and albuminuria levels can be used as early detection of nephropathy complications.

Urinary cystatin C as a biomarker of early renal dysfunction in type 2 diabetic patients

AIMS

We aimed to evaluate urinary CysC (cystanin c) as an early marker of diabetic nephropathy in patients with type 2 diabetes and investigate the correlation of urinary CysC with albuminuria and GFR.

METHODOLOGY

This case-controlled study was conducted on 66 type 2 diabetic patients who were classified according to albuminuria into 3 groups and consisting of 20 healthy subjects as the control group. We assessed urinary CysC, urinary albumin excretion rate (UACR).

RESULTS

Urinary CysC levels were significantly higher in normoalbuminuric diabetic compared with healthy control and there was a progressive linear increase in urinary CysC levels with increasing albuminuria in the diabetic patients. Despite insignificant deference in creatinine between participants groups, we observed significant differences between these groups as regard eGFR, urinary CysC, and UACR. Urinary CysC did not have significant correlations with any clinical or biochemical parameters. Moreover, urinary CysC had a statistically significant association with albuminuria and eGFR.

CONCLUSION

Urinary CysC levels correlated with UACR and GFR. It is linked to subclinical tubular injury and can be an earlier marker of kidney involvement, even before albuminuria and it is less influenced by non-renal factors. Therefore, Urinary CysC is useful biomarker for early diagnosis of diabetic nephropathy.

Non-Albumin Proteinuria (NAP) as a Complementary Marker for Diabetic Kidney Disease (DKD)

Diabetic kidney disease (DKD) is one of the most common forms of chronic kidney disease. Its pathogenic mechanism is complex, and it can affect entire structures of the kidney. However, conventional approaches to early stage DKD have focused on changes to the glomerulus. Current standard screening tools for DKD, albuminuria, and estimated glomerular filtration rate are insufficient to reflect early tubular injury. Therefore, many tubular biomarkers have been suggested. Non-albumin proteinuria (NAP) contains a wide range of tubular biomarkers and is convenient to measure. We reviewed the clinical meanings of NAP and its significance as a marker for early stage DKD.