Diabetic Kidney Disease: The "Silent" Majority?

The expert consensus on care and education for patients with diabetic kidney disease in Taiwan

Increasing prevalence of type 2 DM (T2DM) and diabetic kidney disease (DKD) has posed a great impact in Taiwan. However, guidelines focusing on multidisciplinary patient care and patient education remain scarce. By literature review and expert discussion, we propose a consensus on care and education for patients with DKD, including general principles, specifics for different stages of chronic kidney disease (CKD), and special populations. (i.e. young ages, patients with atherosclerotic cardiovascular disease or heart failure, patients after acute kidney injury, and kidney transplant recipients). Generally, we suggest performing multidisciplinary patient care and education in alignment with the government-led Diabetes Shared Care Network to improve the patients' outcomes for all patients with DKD. Also, close monitoring of renal function with early intervention, control of comorbidities in early stages of CKD, and nutrition adjustment in advanced CKD should be emphasized.

Prevalence of diabetic kidney disease and the associated factors among patients with type 2 diabetes in a multi-ethnic Asian country

The actual prevalence of diabetic kidney disease (DKD) in patients with type 2 diabetes (T2D) in Malaysia is unknown. We aimed to determine the prevalence of DKD and its associated risk factors among T2D patients in Malaysia. An analytical cross-sectional study was conducted using the year 2022 clinical audit dataset from the National Diabetes Registry. DKD was defined as albuminuria, a decreased glomerular filtration rate, or both. Among 80,360 patients, 62.2% were female, 68.4% were Malay, and the mean age was 61.4 years. A total of 56.7% (95% CI 56.4-57.1%) of patients were found to have DKD. Increasing age, male sex, Malay ethnicity, longer duration of diabetes, overweight, obesity, hypertension, diabetic retinopathy, diabetic foot ulcer, nontraumatic lower-extremity amputation, ischaemic heart disease, stroke, insulin, higher numbers of antihypertensive agents, antiplatelet agents, poorer HbA1c control, higher systolic blood pressure, non-achievement of triglyceride target, and non-attainment of HDL-cholesterol goal were independent risk factors associated with DKD. Clinicians, program managers, and health policymakers should target modifiable factors to manage DKD and prevent its progression to end-stage kidney disease in Malaysia.

Urinary N-acetyl-β-d-glucosaminidase-creatine ratio is a valuable predictor for advanced diabetic kidney disease

BACKGROUND

Many biomarkers show high diagnostic values for diabetic kidney disease (DKD), but fewer studies focus on the predictive assessment of DKD progression by blood and urinary biomarkers.

AIM

This study aims to find powerful risk predictors and identifying biomarkers in blood and urine for DKD progression.

METHODS

A total of 117 patients with type 2 DKD including early and advanced stages and their laboratory parameters were statistically assessed. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the significance of discriminating between early and advanced DKD, and the predictive power for advanced DKD was analyzed by regression analysis and trisector grouping.

RESULTS

N-acetyl-β-d-glucosaminidase-creatine (NAG/CR) level in advanced DKD was statistically higher than that in early DKD (p < 0.05), and there was a higher incidence of advanced DKD (72% vs. 56%) and high odds ratio (OR: 3.917, 95% CI: 1.579-10.011) of NAG/CR with ≥2.79 U/mmol compared with <2.79 U/mmol (p < 0.05). NAG/CR ratio also showed a higher area under the ROC curve of 0.727 (95% CI: 0.616-0.828, p = 0.010) with a high sensitivity (0.75) and a moderate specificity (0.66) when 1.93 U/mmol was set as the optimal cutoff value. The adjusted-multivariable analysis revealed that NAG/CR had an OR of 1.021 (95% CI: 1.024-1.038) and 2.223 (95% CI: 1.231-4.463) based on a continuous and categorical variable, respectively, for risk of advanced DKD. Moreover, the prevalence of advanced DKD exhibited an increasing tendency by an increment of the trisector of NAG/CR.

CONCLUSIONS

This study suggests that NAG/CR ratio is an independent predictor for advanced DKD, and it also can be used as a powerful identifying marker between early and advanced DKD.

Diabetic Proteinuria Revisited: Updated Physiologic Perspectives

Albuminuria, a hallmark of diabetic nephropathy, reflects not only injury and dysfunction of the filtration apparatus, but is also affected by altered glomerular hemodynamics and hyperfiltration, as well as by the inability of renal tubular cells to fully retrieve filtered albumin. Albuminuria further plays a role in the progression of diabetic nephropathy, and the suppression of glomerular albumin leak is a key factor in its prevention. Although microalbuminuria is a classic manifestation of diabetic nephropathy, often progressing to macroalbuminuria or overt proteinuria over time, it does not always precede renal function loss in diabetes. The various components leading to diabetic albuminuria and their associations are herein reviewed, and the physiologic rationale and efficacy of therapeutic interventions that reduce glomerular hyperfiltration and proteinuria are discussed. With these perspectives, we propose that these measures should be initiated early, before microalbuminuria develops, as substantial renal injury may already be present in the absence of proteinuria. We further advocate that the inhibition of the renin–angiotensin axis or of sodium–glucose co-transport likely permits the administration of a normal recommended or even high-protein diet, highly desirable for sarcopenic diabetic patients.

Predictive significance of joint plasma fibrinogen and urinary alpha-1 microglobulin-creatinine ratio in patients with diabetic kidney disease

Background

Although many biomarkers have high diagnostic and predictive power for diabetic kidney disease (DKD), less studies were performed for the predictive assessment in DKD and its progression with combined blood and urinary biomarkers. This study aims to explore the predictive significance of joint plasma fibrinogen (FIB) concentration and urinary alpha-1 microglobulin-creatinine (α1-MG/CR) ratio in DKD.

Methods

A total of 234 patients with type 2 diabetes were enrolled, and their clinical and laboratory data were retrospectively assessed. A ROC curve analysis was performed to evaluate the power of plasma FIB and urinary α1-MG/CR ratio for identifying DKD and advanced DKD, respectively. The predictive power for DKD and advanced DKD was analyzed by regression analysis.

Results

Plasma FIB and urinary α1-MG/CR levels were higher in patients with DKD than with pure T2D (p<0.001). The multivariate-adjusted odds ratios (ORs) were 5.047 (95%CI: 2.276–10.720) and 2.192 (95%CI: 1.539–3.122) (p<0.001) for FIB and α1-MG/CR as continuous variables for DKD prediction, respectively. The optimal cut-off values were 3.21 g/L and 2.11mg/mmol for identifying DKD, and 5.58 g/L and 11.07 mg/mmol for advanced DKD from ROC curves. At these cut-off values, the sensitivity and specificity of joint FIB and α1-MG/CR were 0.95 and 0.92 for identifying DKD, and 0.62 and 0.67 for identifying advanced DKD, respectively. The area under curve was 0.972 (95%CI: 0.948–0.995) (p<0.001) and 0.611, 95%CI: 0.488–0.734) (p>0.05). The multivariate-adjusted ORs for joint FIB and α1-MG/CR at the cut-off values were 214.500 (95%CI: 58.054–792.536) and 3.252 (95%CI: 1.040–10.175) (p<0.05), respectively.

Conclusion

The present study suggests that joint plasma FIB concentration and urinary α1-MG/CR ratio can be used as a powerful predictor for general DKD, but it is less predictive for advanced DKD.

Stratification of diabetic kidney diseases via data-independent acquisition proteomics-based analysis of human kidney tissue specimens

AIM

The aims of this study were to analyze the proteomic differences in renal tissues from patients with diabetes mellitus (DM) and diabetic kidney disease (DKD) and to select sensitive biomarkers for early identification of DKD progression.

METHODS

Pressure cycling technology-pulse data-independent acquisition mass spectrometry was employed to investigate protein alterations in 36 formalin-fixed paraffin-embedded specimens. Then, bioinformatics analysis was performed to identify important signaling pathways and key molecules. Finally, the target proteins were validated in 60 blood and 30 urine samples.

RESULTS

A total of 52 up- and 311 down-regulated differential proteins were identified as differing among the advanced DKD samples, early DKD samples, and DM controls (adjusted p<0.05). These differentially expressed proteins were mainly involved in ion transport, apoptosis regulation, and the inflammatory response. UniProt database analysis showed that these proteins were mostly enriched in signaling pathways related to metabolism, apoptosis, and inflammation. NBR1 was significantly up-regulated in both early and advanced DKD, with fold changes (FCs) of 175 and 184, respectively (both p<0.01). In addition, VPS37A and ATG4B were significantly down-regulated with DKD progression, with FCs of 0.140 and 0.088, respectively, in advanced DKD and 0.533 and 0.192, respectively, in early DKD compared with the DM control group (both p<0.01). Bioinformatics analysis showed that NBR1, VPS37A, and ATG4B are closely related to autophagy. We also found that serum levels of the three proteins and urine levels of NBR1 decreased with disease progression. Moreover, there was a significant difference in serum VPS37A and ATG4B levels between patients with early and advanced DKD (both p<0.05). The immunohistochemistry assaay exhibited that the three proteins were expressed in renal tubular cells, and NBR1 was also expressed in the cystic wall of renal glomeruli.

CONCLUSION

The increase in NBR1 expression and the decrease in ATG4B and VPS37 expression in renal tissue are closely related to inhibition of the autophagy pathway, which may contribute to DKD development or progression. These three proteins may serve as sensitive serum biomarkers for early identification of DKD progression.