Albuminuric and non-albuminuric patterns of chronic kidney disease in type 2 diabetes

Metabolic Differences in Diabetic Kidney Disease Patients with Normoalbuminuria versus Moderately Increased Albuminuria

Key Points

The pathophysiological mechanisms of diabetic kidney disease (DKD) with normal (nonalbuminuric DKD) versus moderately increased albuminuria (A-DKD) are not well-understood. Fatty acid biosynthesis and oxydation, gluconeogenesis, TCA cycle, and glucose-alanine cycle were more disturbed in patients with A-DKD compared with those with nonalbuminuric DKD with identical eGFR. DKD patients with and without microalbuminuria could represent different clinical phenotypes.

Background

The pathophysiological mechanisms of diabetic kidney disease (DKD) with normal versus moderately increased albuminuria (nonalbuminuric DKD [NA-DKD] and A-DKD) are currently not well-understood and could have implications for diagnosis and treatment.

Methods

Fourteen patients with NA-DKD with urine albumin–creatinine ratio <3 mg/mmol, 26 patients with A-DKD with albumin–creatinine ratio 3–29 mg/mmol, and 60 age- and sex-matched healthy controls were randomly chosen from a population-based cohort study (Nord-Trøndelag Health Study-3, Norway). Seventy-four organic acids, 21 amino acids, 21 biogenic acids, 40 acylcarnitines, 14 sphingomyelins, and 88 phosphatidylcholines were quantified in urine. One hundred forty-six patients with diabetes from the US-based Chronic Renal Insufficiency Cohort study were used to verify main findings.

Results

Patients with NA-DKD and A-DKD had similar age, kidney function, diabetes treatment, and other traditional risk factors. Still, partial least-squares discriminant analysis showed strong metabolite-based separation (R2, 0.82; Q2, 0.52), with patients with NA-DKD having a metabolic profile positioned between the profiles of healthy controls and patients with A-DKD. Seventy-five metabolites contributed significantly to separation between NA-DKD and A-DKD (variable importance in projection scores ≥1.0) with propionylcarnitine (C3), phosphatidylcholine C38:4, medium-chained (C8) fatty acid octenedioic acid, and lactic acid as the top metabolites (variable importance in projection scores, 2.7–2.2). Compared with patients with NA-DKD, those with A-DKD had higher levels of short-chained acylcarnitines, higher long-chained fatty acid levels with more double bounds, higher branched-chain amino acid levels, and lower TCA cycle intermediates. The main findings were similar by random forest analysis and in the Chronic Renal Insufficiency Cohort study. Formal enrichment analysis indicated that fatty acid biosynthesis and oxydation, gluconeogenesis, TCA cycle, and glucose-alanine cycle were more disturbed in patients with A-DKD compared with those with NA-DKD with identical eGFR. We also found indications of a Warburg-like effect in patients with A-DKD (i.e. , metabolism of glucose to lactate despite adequate oxygen).

Conclusion

DKD patients with normoalbuminuria differ substantially in their metabolic disturbances compared with patients with moderately increase albuminuria and could represent different clinical phenotypes.

Zinc Alpha 2 Glycoprotein as an Early Biomarker of Diabetic Nephropathy in Type 2 Diabetes Mellitus Patients

Background and objectives Microalbuminuria is an early sign of diabetic nephropathy (DN). However, pathological abnormalities occur before the onset of microalbuminuria. Renal impairment progresses in about 50% of cases in type 2 diabetes mellitus (T2DM) without significant albuminuria. Diabetes mellitus (DM) is linked with obesity, metabolic syndrome, and lifestyle changes, where adipokines play an important role. Zinc alpha 2 glycoprotein (ZAGP) is an adipokine, and in this study, it was assessed as a potential biomarker for early DN as well as its progression. Materials and methods This study was a cross-sectional case-control study conducted at a tertiary hospital in northern India. T2DM patients aged 18-65 years old were included in the study and were divided into four groups based on their albuminuria level. This study included 160 participants, with 40 participants in each group. Group I included healthy volunteers, while Groups II, III, and IV were normoalbuminuric, microalbuminuric, and macroalbuminuric diabetic patients, respectively. The groups were evaluated for demographic variables, biochemical parameters, urine albumin-creatinine ratio (UACR), and serum ZAGP. Data between the groups were compared statistically. Results This study included 160 participants, with 40 participants in each group. There was a significant difference between the groups based on the serum ZAGP (p<0.001). Serum ZAGP was significantly negatively correlated with serum creatinine, glycosylated hemoglobin (HbA1c), serum cholesterol, serum triglyceride, low-density lipoprotein (LDL) cholesterol, and UACR. ZAGP was positively correlated with the estimated glomerular filtration rate (eGFR). Conclusion The present study showed that ZAGP was an early biomarker of diabetic nephropathy, and its value decreased as DN progressed. It also suggested that ZAGP, an adipokine, has an anti-inflammatory mechanism of action and its depletion worsens the disease.

Urinary Markers of Tubular Injury and Renal Fibrosis in Patients with Type 2 Diabetes and Different Phenotypes of Chronic Kidney Disease

This study assessed the urinary excretion of markers and mediators of tubular injury and renal fibrosis in patients with type 2 diabetes (T2D) and non-albuminuric and albuminuric patterns of chronic kidney disease (CKD). One hundred and forty patients with long-term T2D and different patterns of CKD and twenty non-diabetic individuals were included. Urinary retinol-binding protein 4 (RBP-4), glutathione-S-transferase α₁ and π (GST-α₁ and GST-π), transforming growth factor β (TGF-β), type I and type IV collagen (Col1 and Col4), bone morphogenic protein 7 (BMP-7), and hepatocyte growth factor (HGF) were assessed by ELISA. Patients with T2D demonstrated increased urinary excretion of RBP-4, GST-π, Col4, BMP-7, and HGF (all p < 0.05 vs. control). The excretion of RBP-4, GST-π, Col1, and Col4 was increased in patients with elevated albumin-to-creatinine ratio (UACR; all p < 0.05 vs. control), while BMP-7 and HGF were increased innormoalbuminuric patients also (p < 0.05). Urinary RBP-4, GST-α₁, Col1, Col4, and HGF correlated positively with UACR; meanwhile, no correlations with glomerular filtration rate were found. The results demonstrate that elevated urinary excretions of the markers of tubular injury (RBP-4, GST-π) and renal fibrosis (Col1, Col4), as well as HGF, an antifibrotic regulator, are associated with the albuminuric pattern of CKD in subjects with T2D.

Albuminuria as a predictor of mortality in type II diabetic patients after living-donor liver transplantation

PURPOSE

Diabetes mellitus (DM) increases the risk of morbidity and mortality after liver resection. Albuminuria is associated with a higher risk for all-cause and cardiovascular mortality. This study evaluated albuminuria as a predictor of the outcome of living donor liver transplantation (LDLT) in patients with pre-existing DM.

METHODS

This retrospective study involved 103 type II diabetic patients with end-stage liver disease who received LDLT. Preoperative spot urine albumin: creatinine ratio was used to determine the degree of albuminuria. The primary outcome measure was the impact of urinary albumin excretion on the 3-year mortality rate after LDLT in this diabetic cohort.

RESULTS

Hepatitis C virus infection was the main cause of cirrhosis. Albuminuria was detected in 41 patients (39.8%); 15 had macroalbuminuria, while 26 had microalbuminuria. Patients with microalbuminuria were significantly older than those with macroalbuminuria and normal albumin in urine. After 3 years, twenty-four patients (23.3%) died within 3 years after LT. Myocardial infarction was the leading cause of death (25%). Albuminuria was an independent factor affecting 3-year mortality with an odds ratio of 5.17 (95% CI: 1.86-14.35).

CONCLUSION

Preoperative albuminuria is an independent factor affecting mortality within 3 years after LDLT in type II diabetic patients. Myocardial infarction was the leading cause of death in 25% of cases, followed by hepatocellular carcinoma recurrence, sepsis, and graft failure.KEY MESSAGESDiabetes mellitus (DM) increases the risk of morbidity and mortality after liver resection.Albuminuria is associated with a higher risk for all-cause and cardiovascular mortality.Preoperative albuminuria is a significant predictor of mortality within 3 years after LDLT in diabetic patients.

Association of renal function screening frequency with renal function decline in patients with type 2 diabetes: a real-world study in primary health care

Aims

To examine the association of the screening frequency of estimated glomerular filtration rate (eGFR) with the substantial reduction in eGFR (≥ 25%) among type 2 diabetes (T2D) patients with normal (eGFR≥60 ml/min/1.73 m2) and impaired kidney function (eGFR< 60 ml/min/1.73 m2).

Methods

A longitudinal study involving 5104 T2D patients with follow-up period of 6.8 years (1.9 SD) were treated at the Rovaniemi Health Center, Rovaniemi, Finland during 2011–2019. The association between the screening frequency of eGFR (yearly vs. non-yearly) and the substantial reduction in eGFR was studied with logistical models and adjusted with biochemical variables and preventive medications.

Results

Among the T2D patients with normal kidney function, non-yearly eGFR screening was significantly associated with substantial eGFR reduction in both unadjusted (odds ratio [OR] 3.29, 95% confidence interval [CI] 2.54–4.33) and adjusted models (OR 2.06, 95% CI 1.21–3.73) compared with yearly screening frequency. In the group of patients with impaired kidney function in the unadjusted model, non-yearly eGFR screening was significantly associated with substantial eGFR reduction (OR 2.38, 95% CI 1.30–4.73), but became non-significant after adjustments (OR 1.89, 95% CI 0.61–7.21).

Conclusions

This study underscores the role of regular eGFR screening in the prevention of kidney function decline.

Non-albuminuric Diabetic Kidney Disease Phenotype: Beyond Albuminuria

Diabetic kidney disease (DKD) is the leading cause of chronic and end-stage kidney disease worldwide. Its pathogenic mechanism is complex, and it can affect the entire structures of the kidneys such as the glomerulus, tubules and interstitium. Currently, the urinary albumin excretion rate and the estimated glomerular filtration rate are widely accepted as diagnostic criteria. However, some studies have reported a different or non-classical clinical course of DKD, with some patients showing declined kidney function with normal levels of albuminuria, known as the 'non-albuminuric DKD' phenotype. The pathogenesis of this phenotype remains unclear, but some clinical and pathological features have been postulated. This review explores the evidence regarding this topic.

Heart and kidney outcomes with ertugliflozin in people with non-albuminuric diabetic kidney disease

Introduction

Using data from the VERTIS CV trial (NCT01986881), the impact of ertugliflozin in patients with nonalbuminuric diabetic kidney disease (DKD-non-Alb) was assessed.

Methods

Patients with type 2 diabetes mellitus (T2DM) and atherosclerotic cardiovascular disease (ASCVD) were randomized to ertugliflozin or placebo. Subgroups were defined by estimated glomerular filtration rate (eGFR) (ml/min per 1.73 m²) and urinary albumin-to-creatinine ratios (UACRs) (mg/g): DKD-Non-Alb (eGFR < 60 + UACR < 30, n = 867); Alb DKD stage 3 (DKD stage 3 Alb, eGFR < 60 + UACR ≥ 30, n = 891); Alb DKD stages 1 + 2 (DKD stages 1–2 Alb, eGFR ≥ 60 + UACR ≥ 30, n = 2356); and no DKD (non-DKD, eGFR ≥ 60 + UACR < 30, n = 3916). eGFR slopes, eGFR and UACR over time, time to first event of a prespecified exploratory kidney composite outcome, albuminuria progression, and hospitalization for heart failure (HHF) were assessed.

Results

Total eGFR slopes (ml/min per 1.73 m² per year; weeks 0–260) with placebo were −0.23, −1.27, −2.29, and −1.19 for the DKD-Non-Alb, DKD stage 3 Alb, DKD stages 1 to 2 Alb, and non-DKD subgroups, respectively (P < 0.0001). Similar trends were found with ertugliflozin but with reduced rates of decline. Ertugliflozin treatment resulted in a significant reduction in the risk for albuminuria progression across subgroups, with Alb subgroups having the largest relative risk reduction (P_interaction = 0.04). The hazard ratios (HRs) for ertugliflozin revealing reduction in the risk of the exploratory kidney composite outcome versus placebo was consistent across subgroups (P_interaction = 0.34). Alb and the DKD-non-Alb subgroups had a larger relative risk reduction in the HHF outcome compared with other subgroups (P_interaction = 0.046).

Conclusion

Among the subgroups, participants with DKD-non-Alb had the slowest rate of eGFR decline. Ertugliflozin treatment resulted in reductions in albuminuria and slower decline in eGFR across subgroups. The effect of ertugliflozin on the HHF outcome was larger in those with more advanced kidney disease.

Plasma or Urine Neutrophil Gelatinase-Associated Lipocalin (NGAL): Which Is Better at Detecting Chronic Kidney Damage in Type 2 Diabetes?

Background and study aims—Albuminuria, defined as an enhanced urine albumin/creatinine ratio (ACR) on a spot sample, is a validated biomarker of glomerular damage. However, it cannot always detect early renal failures in patients with type 2 diabetes (T2D), thus prompting the search for more sensitive and specific parameters. Herein, we investigated the differential role of plasma and urine neutrophil-gelatinase-associated lipocalin (NGALp,—NGALu) for the detection of diabetic kidney disease (DKD). Methods—Traditional glomerular (serum creatinine, cystatin C, ACR) damage biomarkers were evaluated in 84 patients with T2D and in 21 metabolically healthy controls. Diabetic patients were stratified into four groups based on T2D duration (less or more than 5 years) and presence and severity of DKD (early- or advanced-stage), as defined by the ACR and estimated glomerular filtration rate (eGFR). NGALp and NGALu were determined by ELISA methodology and compared among groups. Results—There was no difference in NGALp and NGALu levels between the metabolically healthy individuals and the age-matched, newly diagnosed diabetic patients in the absence of DKD. However, in contrast to NGALu, NGALp was found to be substantially increased in patients with long-standing diabetes without biochemical evidence of DKD, closely mirroring the modest, but still accelerated, decline in the eGFR typical of this chronic dysmetabolic condition, and remained overexpressed throughout the stages of DKD progression. Increased NGALu levels were, instead, rather specific in patients with biochemical evidence of DKD (i.e., marked by increased albuminuria), regardless of T2D duration. Spearman’s correlation and regression analyses showed that patient age and T2D duration could exert a strong positive impact exclusively on NGALp concentrations (ρ = 0.419, p < 0.001 for age; ρ = 0.581, p < 0.001 for T2D), and none on NGALu. Furthermore, receiver operating characteristic (ROC) analysis showed the best performance of NGALp compared to NGALu for the detection of DKD (AUC = 0.817 for NGALp, AUC = 0.711 for NGALu). Conclusions—Our data suggest a different pathophysiological and predictive role for urine and plasma NGAL in the context of T2D and DKD.

MicroRNAs and their delivery in diabetic fibrosis

The global prevalence of diabetes mellitus was estimated to be 463 million people in 2019 and is predicted to rise to 700 million by 2045. The associated financial and societal costs of this burgeoning epidemic demand an understanding of the pathology of this disease, and its complications, that will inform treatment to enable improved patient outcomes. Nearly two decades after the sequencing of the human genome, the significance of noncoding RNA expression is still being assessed. The family of functional noncoding RNAs known as microRNAs regulates the expression of most genes encoded by the human genome. Altered microRNA expression profiles have been observed both in diabetes and in diabetic complications. These transcripts therefore have significant potential and novelty as targets for therapy, therapeutic agents and biomarkers.

Progranulin and Its Receptor Predict Kidney Function Decline in Patients With Type 2 Diabetes

Progranulin (PGRN), a growth factor, is abundantly expressed in a broad range of tissues and cell types with pleiotropic functions including inflammation, neurodegeneration, and facilitating lysosome acidification. PGRN binds to TNF receptors (TNFR) and inhibits downstream inflammatory signaling pathways. TNFR is a well-known predictor of glomerular filtration rate (GFR) decline in a variety of diseases. Therefore, we measured circulating PGRN in addition to TNFR using an enzyme-linked immunosorbent assay and explored whether it predicted renal prognosis in 201 Japanese patients with type 2 diabetes. During a median follow-up of 7.6 years, 21 participants reached primary renal endpoint, which involves a decline of at least 57% in eGFR from baseline, or the onset of end-stage renal disease. Univariate Cox regression analysis revealed that classical renal measures (GFR and albuminuria), two TNF-related biomarkers (PGRN and TNFR), and BMI were associated with this outcome. Multivariate analysis demonstrated that high levels of PGRN [HR 2.50 (95%CI 2.47-2.52)] or TNFR1 [HR 5.38 (95%CI 5.26-5.50)] were associated with this outcome after adjusting for relevant covariates. The high levels of PGRN as well as TNFR1 were associated with a risk of primary renal outcome in patients with type 2 diabetes after adjusting for established risk factors.

A study on the status of normoalbuminuric renal insufficiency among type 2 diabetes mellitus patients: A multicenter study based on a Chinese population

BACKGROUND

Patients with normoalbuminuria and a reduced estimated glomerular filtration rate (eGFR) account for a considerable proportion of type 2 diabetes patients. The aim of this research was to investigate the epidemiological and clinical characteristics of normoalbuminuric kidney disease in a Chinese population.

METHODS

We included 8131 diabetic patients from a multicenter prospective study in China. Based on eGFR and urinary albumin-to-creatinine ratio (UACR), participants were stratified into four groups-normal albuminuria, albuminuria, normoalbuminuria with eGFR < 60 mL/min/1.73 m² , and albuminuria with eGFR < 60 mL/min/1.73 m² . Clinical parameters and characteristics of patients with normoalbuminuria and eGFR < 60 mL/min/1.73 m² were retrospectively analyzed.

RESULTS

A total of 1060 out of 8131 individuals with diabetes had decreased eGFR (<60 mL/min/1.73 m² ). Normoalbuminuria accounted for 63.3% of participants with eGFR < 60 mL/min/1.73 m² , and microalbuminuria and macroalbuminuria accounted for 30.1% and 6.3%, respectively. Patients with normoalbuminuria and reduced eGFR were more frequently male, older, and had higher levels of triglycerides than patients with normal albuminuria and eGFR. We also detected a correlation between lower extremity arterial disease, newly diagnosed diabetes, and normoalbuminuria-reduced eGFR. Compared with participants with both albuminuria and eGFR decline, those with normoalbuminuria had better metabolic indicators, including systolic blood pressure and glycosylated hemoglobin, and shorter diabetes duration. Even in the normal range, UACR has a significant correlation with the risk of eGFR insufficiency.

CONCLUSIONS

Normoalbuminuric renal insufficiency, characterized by male sex, older age, a higher level of triglyceride levels, and a higher risk of lower extremity arterial disease, accounted for a dominant proportion of diabetic patients with eGFR decline.

Update on pathogenesis and diagnosis flow of normoalbuminuric diabetes with renal insufficiency

In recent decades, the prevalence of diabetic kidney disease has remained stable and appears to be a wide heterogeneity. Normoalbuminuric diabetes with renal insufficiency, which is characterized by a decline in the glomerular filtration rate in the absence of albuminuria, has been identified as an albuminuria-independent phenotype of diabetic kidney disease. Epidemiological data demonstrate that normoalbuminuric phenotype is prevalent. Compared to albuminuric phenotype, normoalbuminuric phenotype has distinct clinical characteristics and a wide heterogeneity of pathological features. Currently, the pathogenesis of normoalbuminuric phenotype remains unclear. Additionally, the flow of diagnosing normoalbuminuric phenotype is not perfect. In this article, we review the latest studies addressing the epidemiology, clinical characteristics, and pathology of normoalbuminuric phenotype. Based on the studies of clinical features and renal histopathologic changes, we attempt to propose an underlying pathogenesis model and a flow chart for diagnosing normoalbuminuric phenotype.

Hypertension and cardiovascular risk factor management in a multi-ethnic cohort of adults with CKD: a cross sectional study in general practice

Background

Hypertension, especially if poorly controlled, is a key determinant of chronic kidney disease (CKD) development and progression to end stage renal disease (ESRD).

Aim

To assess hypertension and risk factor management, and determinants of systolic blood pressure control in individuals with CKD and hypertension.

Design and setting

Cross-sectional survey using primary care electronic health records from 47/49 general practice clinics in South London.

Methods

Known effective interventions, management of hypertension and cardiovascular disease (CVD) risk in patients with CKD Stages 3–5 were investigated. Multivariable logistic regression analysis examined the association of demographic factors, comorbidities, deprivation, and CKD coding, with systolic blood pressure control status as outcome. Individuals with diabetes were excluded.

Results

Adults with CKD Stages 3–5 and hypertension represented 4131/286,162 (1.4%) of the total population; 1984 (48%) of these individuals had undiagnosed CKD without a recorded CKD clinical code. Hypertension was undiagnosed in 25% of the total Lambeth population, and in patients with CKD without diagnosed hypertension, 23.0% had systolic blood pressure > 140 mmHg compared with 39.8% hypertensives, p < 0.001. Multivariable logistic regression revealed that factors associated with improved systolic blood pressure control in CKD included diastolic blood pressure control, serious mental illness, history of cardiovascular co-morbidities, CKD diagnostic coding, and age < 60 years. African ethnicity and obesity were associated with poorer systolic blood pressure control.

Conclusion

We found both underdiagnosed CKD and underdiagnosed hypertension in patients with CKD. The poor systolic blood pressure control in older age groups ≥ 60 years and in Black African or obese individuals is clinically important as these groups are at increased risk of mortality for cardiovascular diseases.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-021-01149-0.

Effect of a sodium restriction diet on albuminuria and blood pressure in diabetic kidney disease patients: a meta-analysis

BACKGROUND

A sodium restriction diet is a key component of chronic kidney disease (CKD) management. However, the efficacy of its use in patients with diabetic kidney disease (DKD) is uncertain. The present meta-analysis explored the effects of restricting sodium intake on albuminuria and blood pressure in DKD patients with albuminuria.

METHODS

We searched the Cochrane Central Register of Controlled Trials, Web of Science, MEDLINE, and EMBASE for randomized controlled trials, and we reviewed the references of all searched articles to avoid omitting other relevant articles. Our primary endpoints were blood pressure, albumin excretion rate, and plasma renin activity. We assessed pooled data using a random-effects model.

RESULTS

Of the 661 articles identified, a total of 12 articles were included in the meta-analysis. The random-effects model indicated that salt-restriction diet interventions led to a poled - 4.72 mmHg (95% CI - 6.71, - 2.73) difference in systolic blood pressure and that the intervention resulted in a 2.33 mmHg lower diastolic blood pressure (95% CI - 3.61, - 1.05). In patients with microalbuminuria, restricted sodium intake decreased the albumin excretion rate (AER) by 12.62 mg/min (95% CI - 19.64, - 5.60). Furthermore, the AER was 127.69 mg/min lower in patients with macroalbuminuria (95% CI - 189.07, - 66.32).

CONCLUSION

Moderate sodium restriction diets reduce urinary albumin excretion and decrease the level of blood pressure, especially for patients with macro-albuminuria. Thus, it is necessary to strengthen the intervention and health education as well as to provide individualized dietary advice.

Sodium-Glucose Cotransporter 2 Inhibitors and the Kidney

Diabetic kidney disease (DKD) accounts for about half of individuals entering end-stage renal disease programs. Patients with DKD frequently have associated microvascular complications and are at very high risk for developing macrovascular complications. Comprehensive treatment involves slowing or preventing the decline in glomerular filtration rate (GFR) and preventing macrovascular and further microvascular complications. Maintaining an A1C <6.5% represents primary prevention; in established DKD, tight blood pressure control is essential. ACE inhibitors/angiotensin receptor blockers (ARBs) and sodium-glucose cotransporter 2 (SGLT2) inhibitors can be used in combination to slow the rate of decline in GFR. This article reviews the general approach to DKD treatment and summarizes renal outcomes in four cardiovascular outcomes trials of SGLT2 inhibitors. Together, these trials provide conclusive evidence that SGLT2 inhibitors, added to an ACE inhibitor or ARB, slow the progression of DKD.

Clinical features of and risk factors for normoalbuminuric diabetic kidney disease in hospitalized patients with type 2 diabetes mellitus: a retrospective cross-sectional study

BACKGROUND

Normoalbuminuric diabetic kidney disease (NADKD) is a newly defined DKD, the clinical features and pathogenesis for which are still being understood. This study aimed to investigate the features and risk factors for NADKD in patients with type 2 diabetes mellitus (T2DM).

METHODS

A retrospective cross-sectional study was conducted. The related clinical and laboratory data of patients with T2DM hospitalized between August 2012 and January 2020 were collected for statistical analysis. We classified the patients with T2DM into four groups on the basis of the presence or absence of albuminuria and reduced estimated glomerular filtration rate (eGFR). Analysis of variance, the Kruskal-Wallis test, and the chi-square test were used to compare the groups. Binary logistic regression analyses with a forward stepwise method were performed to explore the risk factors for renal dysfunction in hospitalized patients with normoalbuminuric T2DM.

RESULTS

Among the 1620 patients evaluated, 500 (30.9%) had DKD, of which 9% had NADKD. The prevalence of stroke, cardiovascular events, carotid plaque, and peripheral arterial disease in NADKD was significantly higher than in a non-DKD control group (normoalbuminuric T2DM patients with eGFR of ≥60 ml/min/1.73 m²). Regression analyses revealed that three significant independent factors were associated with NADKD: age (OR = 1.089, confidence interval [CI] 95% [1.055-1.123], p < 0.001), previous use of renin-angiotensin system inhibitors (RASIs; OR = 2.330, CI 95% [1.212-4.481], p = 0.011), and glycated hemoglobin (HbA1c; OR = 0.839, CI 95% [0.716-0.983], p = 0.03).

CONCLUSIONS

NADKD is mainly associated with macrovascular rather than microvascular complications. NADKD is more common in patients with normoalbuminuric T2DM with older age, previous use of RASIs, and good glycemic control.

Poor Glycemic Control Can Increase the Plasma Kidney Injury Molecule-1 Concentration in Normoalbuminuric Children and Adolescents with Diabetes Mellitus

Diabetic nephropathy (DN) is a serious microvascular complication in childhood diabetes and microalbuminuria has been a solid indicator in the assessment of DN. Nevertheless, renal injury may still occur in the presence of normoalbuminuria (NA) and various tubular injury biomarkers have been proposed to assess such damage. This case-controlled study aimed to evaluate plasma and urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 (KIM-1) levels in diabetic children particularly in those with normo- and high-NA stages and determine their role in predicting DN. Fifty-four children/adolescents with type 1 and 2 diabetes and forty-four controls aged 7–18 years were included. The baseline clinical and laboratory characteristics including plasma and urinary biomarkers were compared. The plasma KIM-1 levels were significantly higher in diabetic children than in the controls and in high-NA children than normo-NA children. Glycosylated hemoglobin (HbA1c) was identified as a significant risk factor for increased plasma KIM-1. The optimal cutoff for HbA1c when the plasma KIM-1 was > 23.10 pg/mL was 6.75% with an area under the curve of 0.77. For diabetic children with mildly increased albuminuria, the plasma KIM-1 complementary to MA may help increase the yield of detecting DN. Our findings also suggested an HbA1c cutoff of 6.75% correlated with increased plasma KIM-1.

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.

The cross-sectional association of renal dysfunction with tests of cognition in middle-aged adults with early type 2 diabetes: The GRADE Study

OBJECTIVE

The association of renal dysfunction with tests of cognition in type 2 diabetes has been examined in individuals with moderate and advanced renal disease. Here we examine the association of renal dysfunction with tests of cognition in a cohort of middle-aged adults with short duration diabetes (mean 4.0 ± 2.8 years).

METHODS

Baseline data were examined from the Glycemia Reduction Approaches in Diabetes (GRADE) study (n = 4998). Renal dysfunction was defined by the presence of albumin in the urine or by estimated glomerular filtration rate (eGFR). Cognition was assessed with the Spanish English Verbal Learning Test, Letter and Animal fluency tests, and the Digit Symbol Substitution Test.

RESULTS

Participants with albuminuria or eGFR <60 ml/min/1.73 m2 had significantly lower test scores of information processing speed and perception, executive function and ability to categorize information, and of verbal learning and memory compared to participants without renal disease. Adjustment for hypertension, dyslipidemia, and waist circumference attenuated many of these findings but markers of impaired learning and executive function continued to remain lower in association with higher urine albumin levels.

CONCLUSION

In type 2 diabetes of short duration, there are already subtle deficiencies in markers of cognition in association with renal disease in middle aged adults.

Role of Albuminuria in Detecting Cardio-Renal Risk and Outcome in Diabetic Subjects

The clinical significance of albuminuria in diabetic subjects and the impact of its reduction on the main cardiorenal outcomes by different drug classes are among the most interesting research focuses of recent years. Although nephrologists and cardiologists have been paying attention to the study of proteinuria for years, currently among diabetics, increased urine albumin excretion ascertains the highest cardio-renal risk. In fact, diabetes is a condition by itself associated with a high-risk of both micro/macrovascular complications. Moreover, proteinuria reduction in diabetic subjects by several treatments lowers both renal and cardiovascular disease progression. The 2019 joint ESC-EASD guidelines on diabetes, prediabetes and cardiovascular (CV) disease assign to proteinuria a crucial role in defining CV risk level in the diabetic patient. In fact, proteinuria by itself allows the diabetic patient to be staged at very high CV risk, thus affecting the choice of anti-hyperglycemic drug class. The purpose of this review is to present a clear update on the role of albuminuria as a cardio-renal risk marker, starting from pathophysiological mechanisms in support of this role. Besides this, we will show the prognostic value in observational studies, as well as randomized clinical trials (RCTs) demonstrating the potential improvement of cardio-renal outcomes in diabetic patients by reducing proteinuria.

Multiplex Bead Array Assay of a Panel of Circulating Cytokines and Growth Factors in Patients with Albuminuric and Non-AlbuminuricDiabetic Kidney Disease

A panel of cytokines and growth factors, mediating low-grade inflammation and fibrosis, was assessed in patients with type 2 diabetes (T2D) and different patterns of chronic kidney disease (CKD). Patients with long-term T2D (N = 130) were classified into four groups: no signs of CKD; estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² without albuminuria; albuminuria and eGFR ≥60 mL/min/1.73 m²; albuminuria and eGFR <60 mL/min/1.73 m². Thirty healthy subjects were acted as control. Twenty-seven cytokines and growth factors were assessed in serum by multiplex bead array assay. Serum hs-CRP, urinary nephrin, podocine, and WFDC2 were measured by ELISA. Patients with T2D showed elevated IL-1Ra, IL-6, IL-17A, G-CSF, IP-10, MIP-1α, and bFGF levels; concentrations of IL-4, IL-12, IL-15, INF-γ, and VEGF were decreased. IL-6, IL-17A, G-CSF, MIP-1α, and bFGF correlated negatively with eGFR; IL-10 and VEGF demonstrated negative associations with WFDC2; no relationships with podocyte markers were found. Adjusted IL-17A and MIP-1α were predictors of non-albuminuric CKD, IL-13 predicted albuminuria with preserved renal function, meanwhile, IL-6 and hsCRP were predictors of albuminuria with eGFR decline. Therefore, albuminuric and non-albuminuric CKD in T2D patients are associated with different pro-inflammatory shifts in the panel of circulating cytokines.

Kidney disease progression and all-cause mortality across estimated glomerular filtration rate and albuminuria categories among patients with vs. without type 2 diabetes

BACKGROUND

Studies of progression of kidney dysfunction typically focus on renal replacement therapy or percentage decline in estimated glomerular filtration rate (eGFR) as outcomes. Our aim was to compare real-world patients with and without T2D to estimate progression from and to clinically defined categories of kidney disease and all-cause mortality.

METHODS

This was an observational cohort study of 31,931 patients with and 33,201 age/sex matched patients without type 2 diabetes (T2D) who had a serum creatinine and urine albumin-to-creatinine ratio (UACR) or dipstick proteinuria (DP) values. We used the first available serum creatinine value between 2006 and 2012 to calculate baseline eGFR and categorized them and the corresponding UACR/DP values using the Kidney Disease Improving Global Outcomes (KDIGO) categories. To assess our primary outcomes, we extracted probabilities of eGFR progression or mortality from life-table analyses and conducted multivariable Cox regression analyses of relative risk adjusted for age, sex, race/ethnicity, smoking, ischemic heart disease, heart failure, and use of renal-angiotensin-aldosterone system inhibitors.

RESULTS

Patterns of eGFR decline were comparable among patients with vs. without T2D with larger percentage declines at higher albuminuria levels across all eGFR categories. eGFR decline was generally larger among T2D patients, particularly in those with severely increased albuminuria. Across all CKD categories, risk of progression to the next higher category of eGFR was substantially increased with increasing albuminuria. For example, the risk was 23.5, 36.2, and 65.1% among T2D patients with eGFR 30-59 ml/min/1.73m2 and UACR < 30, 30-299, and > 300 mg/dL, respectively (p < 0.001). Other comparisons were similarly significant. Among patients with low eGFR and normal to mildly increased albuminuria, the relative risk was up to 8-fold greater for all-cause mortality compared with the non-CKD subgroup (eGFR> 60 ml/min/1.73m2 with normal to mildly increased albuminuria).

CONCLUSIONS

Presence of albuminuria was associated with accelerated eGFR decline independent of T2D. Risk for adverse outcomes was remarkably high among patients with CKD and normal to mildly increased albuminuria levels. Independent of T2D or albuminuria, a substantial risk for adverse outcomes exists for CKD patients in a routine care setting.

The New Biology of Diabetic Kidney Disease-Mechanisms and Therapeutic Implications

Diabetic kidney disease remains the most common cause of end-stage kidney disease in the world. Despite reductions in incidence rates of myocardial infarction and stroke in people with diabetes over the past 3 decades, the risk of diabetic kidney disease has remained unchanged, and may even be increasing in younger individuals afflicted with this disease. Accordingly, changes in public health policy have to be implemented to address the root causes of diabetic kidney disease, including the rise of obesity and diabetes, in addition to the use of safe and effective pharmacological agents to prevent cardiorenal complications in people with diabetes. The aim of this article is to review the mechanisms of pathogenesis and therapies that are either in clinical practice or that are emerging in clinical development programs for potential use to treat diabetic kidney disease.

Proteinuria is Associated with Carotid Artery Atherosclerosis in Non-Albuminuric Type 2 Diabetes: A Cross-Sectional Study

The association of specific urinary proteins other than albumin with cardiovascular (CV) outcomes in patients with type 2 diabetes (T2D) has been shown. In this respect, CV outcomes may differ in non-albuminuric T2D patients who were considered as a low risk group, according to the presence of proteinuria. We investigated the association between proteinuria and atherosclerosis assessed by carotid artery intima-media thickness (CIMT) in non-albuminuric T2D patients. 2047 T2D patients whose urine albumin-to-creatinine ratio was below 30 mg/g were recruited and classified into a non-proteinuria (NP, uPCR < 150 mg/g, n = 1865) group and a non-albuminuric proteinuria (NAP, uPCR ≥ 150 mg/g, n = 182) group. CIMT was compared between the two groups and logistic regression analysis was conducted to verify whether proteinuria could predict deteriorated CIMT status. In this cross-sectional study, mean CIMT of the NAP group were significantly thicker than those of the NP group (0.73 ± 0.16 vs. 0.70 ± 0.14, p = 0.016). The presence of proteinuria is associated with deteriorated CIMT after the adjustment for conventional risk factors (odds ratio, 2.342; 95% confidence interval, 1.082-5.070, p = 0.030) in regression analysis. We postulated that the measurement of urinary protein in conjunction with albumin might be helpful for predicting atherosclerosis, especially for non-albuminuric patients.

Risk factors and urinary biomarkers of non-albuminuric and albuminuric chronic kidney disease in patients with type 2 diabetes

BACKGROUND

A number of recent studies indicate a transformation in the natural course of chronic kidney disease (CKD) in type 2 diabetes (T2D) patients: an increasing prevalence of declined renal function without proceeding to the accompanying elevation of albuminuria. It has been suggested that albuminuric and non-albuminuric CKD patterns could be different in their phenotypes and pathogenic mechanisms.

AIM

To identify the risk factors and biomarkers of albuminuric and non-albuminuric patterns of CKD in patients with T2D.

METHODS

Three hundred sixty patients with T2D duration ≥ 10 years were included in this observational cross-sectional study. The associations of a panel of demographic and clinical characteristics, complications, comorbidities, and metabolic and hematology parameters with albuminuric and non-albuminuric CKD patterns were analyzed. The urinary excretion of nephrin and podocin, two podocyte-specific markers, and WAP-four-disulfide core domain protein 2 (WFDC-2), a marker of tubulointerstitial fibrosis, was determined by ELISA in comparison with healthy controls.

RESULTS

Non-albuminuric CKD was associated with age ≥ 65 years (P = 0.0001), female sex (P = 0.04), diabetes duration ≥ 15 years (P = 0.0009), and the use of diuretics (P = 0.0005). Male sex (P = 0.01), smoking (P = 0.01), waist-to-hip ratio >1.0 (P = 0.01) and hemoglobin A1c (HbA1c) > 8.0% (P = 0.005) were risk factors for elevated albuminuria not accompanied by a decrease in estimated glomerular filtration rate (eGFR). Duration of diabetes ≥ 15 years and the use of calcium channel blockers were risk factors for albuminuria with decreased eGFR (both P = 0.01). In multivariate logistic regression analysis, age, HbA1c, female sex and diuretics were significant predictors for reduced eGFR, while waist-to-hip ratio, HbA1c and male sex were associated with elevated urinary albumin-to-creatinine ratio (UACR). Excretion of nephrin and podocin was increased in patients with albuminuria, regardless of decline in renal function (P < 0.001), correlating positively with UACR. The urinary excretion of WFDC-2 was markedly higher in men than in women (P < 0.000001). Men with T2D demonstrated increased WFDC-2 levels independently of the CKD pattern (all P < 0.05). In T2D women, WFDC-2 excretion was increased in those with reduced renal function (P ≤ 0.01), correlating negatively with eGFR.

CONCLUSION

The data provide further evidence that albuminuric and non-albuminuric CKD phenotypes correspond to different pathways of diabetic kidney disease progression.