Association between nonalbumin proteinuria and renal tubular damage of N-acetyl-β-d-glucosaminidase and its clinical relevance in patients with type 2 diabetes without albuminuria

Association between continuous glucose monitoring-derived glycemic control indices and urinary biomarkers of diabetic kidney disease: Hyogo Diabetes Hypoglycemia Cognition Complications study

AIMS

Glomerular damage and proximal tubular damage play an important role in the pathogenesis of diabetic kidney disease. This study aimed to investigate the relationship between the urinary markers of proximal tubular injury, including urinary liver-type fatty acid-binding protein-to-creatinine ratio (uL-FABP/Cr) and urinary N-acetyl-β-D-glucosaminidase-to-creatinine ratio (uNAG/Cr), and glycemic control status.

METHODS

This cross-sectional study included 245 and 39 patients with type 2 diabetes mellitus (T2DM) and non-T2DM (NDM), respectively. The participants of this study were fitted with retrospective CGM, and glycemic control indices, such as time in range (TIR) and glycemia risk index (GRI), were calculated.

RESULTS

The results were presented as medians (interquartile ranges). The uL-FABP/Cr was significantly higher in the microalbuminuria than in the normo-albuminuria group [4.2 (2.7-7.1) and 2.2 (1.4-3.4) μg/gCr, respectively, P < 0.001], while the uNAG/Cr in the normo-albuminuria group [6.3 (4.5-10.1) U/gCr] was significantly higher than that in the NDM group [5.3 (3.8-6.3) U/gCr, P = 0.048] but significantly lower than that in the microalbuminuria group [9.2 (6.4-11.1) U/gCr, P = 0.004]. The multivariate logistic regression analysis indicated that CGM-derived TIR was significantly associated with the urinary albumin-to-creatinine ratio [uAlb/Cr, odds ratio (OR) 0.985, 95% confidence interval (CI) 0.971-0.998, P = 0.029] and uNAG/Cr (OR 0.973, 95% CI 0.957-0.989, P = 0.001) independent of renal function. GRI was similarly associated with uAlb/Cr and uNAG/Cr.

CONCLUSION

The findings of this study indicated that uNAG/Cr was elevated before albuminuria development and was associated with CGM-derived TIR and GRI.

A nomogram for predicting the risk of new-onset albuminuria based on baseline urinary ACR, orosomucoid, and HbA1c in patients with type 2 diabetes

OBJECTIVES

Numerous biomarkers have been shown to be associated with albuminuria. However, few of them are valuable separate predictors of albuminuria development. This study aimed to develop a model for predicting the short-term risk of new-onset albuminuria in normoalbuminuric patients with type 2 diabetes (T2D).

METHODS

213 patients with T2D who were normoalbuminuric at the baseline were enrolled in this study. Basal levels of clinical characteristics and renal biomarkers including urinary orosomucoid (alpha-1-acid-glycoprotein, UORM), neutrophil gelatinase-associated lipocalin, retinol-binding protein, alpha-1-microglobulin, transferrin, and albumin-to-creatinine ratio (ACR) were utilized to analyze the association with the short-term risk of new-onset albuminuria.

RESULTS

19.72% of normoalbuminuric subjects at baseline progressed to albuminuria over the 2-year follow-up period. Except for NGAL, the basal levels of the other five renal biomarkers were significantly associated with new-onset albuminuria risk in the univariate analysis. In the multivariate logistic regression analysis using Forward: LR method, a model incorporating UORM/Cr, ACR, and HbA1c was established. Comparatively, this model had a higher potential to predict new-onset albuminuria risk compared with the single use of renal markers. In the validation of this model performed by 5-fold cross-validation method, the accuracy of this model was 0.818 ± 0.008 in the training sets, 0.827 ± 0.062 in the test sets, indicating a good capability for assessing albuminuria risk. Finally, a nomogram based on this model was constructed to facilitate its use in clinical practice.

CONCLUSION

The combined analysis of UORM/Cr, ACR and HbA1c may be of potential value for predicting the short-term risk of new-onset albuminuria in such patients.

Hepatic fibrosis is associated with total proteinuria in Korean patients with type 2 diabetes

The association between non-alcoholic fatty liver disease (NAFLD) and diabetic kidney disease assessed using either albuminuria or proteinuria remains controversial. This study aimed to investigate the association between hepatic steatosis or fibrosis and albuminuria or proteinuria in Korean patients with type 2 diabetes mellitus (T2D).We enrolled 1108 patients with T2D and categorized as 3 groups; non-proteinuria (NP), isolated non-albumin proteinuria (iNAP), and albuminuria. Urinary albumin and protein levels were assessed as urinary albumin-to-creatinine ratio (uACR) and urinary protein-to-creatinine ratio (uPCR), respectively. Hepatic steatosis and fibrotic burden were assessed using the NAFLD liver fat score, Fibrosis-4 calculator (FIB-4) index, and NAFLD fibrosis score (NFS).The prevalence of significant steatosis was similar among groups (NP: 74.6% vs iNAP: 70.3% vs albuminuria: 79.9%, P = .085). The prevalence of significant fibrosis was significantly higher in the iNAP (18.7%) and albuminuria (16.5%) groups than in the NP group (9.5%, P = .001). Both uPCR and uACR showed a correlation with NFS (uPCR: r = 0.123, P < .001; uACR: r = 0.064, P = .033). In multivariate logistic regression analysis, uPCR ≥150 mg/g was found to have a stronger association with hepatic fibrosis than uACR ≥30 mg/g (adjusted odds ratio 1.55 [95% CI 1.03-2.33] vs adjusted odds ratio 1.16 [95% CI, 0.72-1.87]).In conclusion, patients with iNAP and albuminuria had a higher prevalence of hepatic fibrosis than those without proteinuria. Total proteinuria was associated with advanced liver fibrosis, whereas albuminuria was related to hepatic steatosis.

High ACR level is a strong risk factor for renal tubular impairment in patients with type 2 diabetes: A longitudinal observational study

BACKGROUND

Several studies have indicated that high albuminuria is associated with renal function decline. However, the relationship between the urinary albumin-to-creatinine ratio (ACR) and risk of developing tubular injury remains unclear. Our aim was to investigate the association of ACR with the risk of developing tubular impairment in patients with type 2 diabetes.

METHODS

This longitudinal observational study compared baseline with follow-up data in 183 patients with type 2 diabetes. ACR, urinary alpha-1-microglobulin-to-creatinine ratio (A1MCR) and estimated glomerular filtration rate (eGFR) were used to evaluate albuminuira, tubular injury and glomerular filtration function, respectively.

RESULTS

Levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and A1MCR were significantly different at the two-year follow-up compared with baseline levels. Among patients both with baseline ACR above and below 30 mg/g, the percentage with A1MCR > 15 mg/g clearly increased after follow-up (P < 0.05). The risk of A1MCR rising from normal ranges to >15 mg/g over the follow-up increased with increasing baseline ACR values lower baseline eGFR. Among the patients with baseline ACR > 63.10 mg/g, all showed increased A1MCR values at follow-up compared with baseline. In the multivariate regression analysis, the patients with baseline ACR > 63.10 mg/g had a strong risk of A1MCR rising from normal to >15 mg/g (odds ratio (OR) = 11.12, P = 0.001) over the follow-up, while the males had a 2.89-fold risk of A1MCR increasing from normal to >15 mg/g compared with females.

CONCLUSION

Baseline ACR level is related to increased risk of developing renal tubular injury; in particular, this association is much stronger in patients with type 2 diabetes and baseline ACR > 63.10 mg/g.

Carbon dots as fluorescent nanoprobe for the determination of N-acetyl-β-d-glucosaminidase activity

Carbon dots (CDs) were synthesized from p-aminophenol and ethylenediamine via one-step under mild condition and used as a sensitive fluorescent nanoprobe for the activity determination of N-acetyl-β-d-glucosaminidase (NAG). In this assay, p-nitrophenol was in situ produced from p-nitrophenyl-β-D-N-acetyl-glucosaminide, which was exclusively hydrolyzed by NAG. The UV absorption peak of p-nitrophenol (maximum at 400 nm) overlapped the excitation peak of CDs with maximum wavelength at 415 nm, which caused the fluorescence decline of CDs based on inner filter effect. The activity of NAG was determined by the fluorescence changes. The assay is highly sensitive to NAG with a low detection limit of 0.75 U L^-1 (K = 3) and showed a good linear relationship in the range from 1 to 45 U L^-1. This CDs nanoprobe was successfully applied for the determination of NAG activity in human serum and urine samples.