Multicentre, retrospective cohort study protocol to identify racial and ethnic differences in acute kidney injuries in children and adolescents with diabetic ketoacidosis.

INTRODUCTION: Approximately 40% of children with diabetic ketoacidosis (DKA) develop acute kidney injury (AKI), which increases the risk of chronic kidney damage. At present, there is limited knowledge of racial or ethnic differences in diabetes-related kidney injury in children with diabetes. Understanding whether such differences exist will provide a foundation for addressing disparities in diabetes care that may continue into adulthood. Further, it is currently unclear which children are at risk to develop worsening or sustained DKA-related AKI. The primary aim is to determine whether race and ethnicity are associated with DKA-related AKI. The secondary aim is to determine factors associated with sustained AKI in children with DKA. METHODS AND ANALYSIS: This retrospective, multicentre, cross-sectional study of children with type 1 or type 2 diabetes with DKA will be conducted through the Paediatric Emergency Medicine Collaborative Research Committee. Children aged 2-18 years who were treated in a participating emergency department between 1 January 2020 and 31 December 2023 will be included. Children with non-ketotic hyperglycaemic-hyperosmolar state or who were transferred from an outside facility will be excluded. The relevant predictor is race and ethnicity. The primary outcome is the presence of AKI, defined by Kidney Disease: Improving Global Outcomes criteria. The secondary outcome is 'sustained' AKI, defined as having AKI ≥48 hours, unresolved AKI at last creatinine measurement or need for renal replacement therapy. Statistical inference of the associations between predictors (ie, race and ethnicity) and outcomes (ie, AKI and sustained AKI) will use random effects regression models, accounting for hospital variation and clustering. ETHICS AND DISSEMINATION: The Institutional Review Board of Children's Minnesota approved this study. 12 additional sites have obtained institutional review board approval, and all sites will obtain local approval prior to participation. Results will be presented at local or national conferences and for publication in peer-reviewed journals.

Biomarkers of Neurodegeneration and Alzheimer's Disease Neuropathology in Adolescents and Young Adults with Youth-Onset Type 1 or Type 2 Diabetes: A Proof-of-Concept Study.

Adult-onset diabetes increases one's risk of neurodegenerative disease including Alzheimer's disease (AD); however, the risk associated with youth-onset diabetes (Y-DM) remains underexplored. We quantified plasma biomarkers of neurodegeneration and AD in participants with Y-DM from the SEARCH cohort at adolescence and young adulthood (Type 1, n = 25; Type 2, n = 25; 59% female; adolescence, age = 15 y/o [2.6]; adulthood, age = 27.4 y/o [2.2]), comparing them with controls (adolescence, n = 25, age = 14.8 y/o [2.7]; adulthood, n = 21, age = 24.9 y/o [2.8]). Plasma biomarkers, including glial fibrillary acidic protein (GFAP), neurofilament light chain protein (NfL), phosphorylated tau-181 (pTau181), and amyloid beta (Aß40, Aß42), were measured via Simoa. A subset of participants (n = 7; age = 27.5 y/o [5.7]) and six controls (age = 25.1 y/o [4.5]) underwent PET scans to quantify brain amyloid and tau densities in AD sensitive brain regions. Y-DM adolescents exhibited lower plasma levels of Aß40, Aß42, and GFAP, and higher pTau181 compared to controls (p < 0.05), a pattern persisting into adulthood (p < 0.001). All biomarkers showed significant increases from adolescence to adulthood in Y-DM (p < 0.01), though no significant differences in brain amyloid or tau were noted between Y-DM and controls in adulthood. Preliminary evidence suggests that preclinical AD neuropathology is present in young people with Y-DM, indicating a potential increased risk of neurodegenerative diseases.

Assessing Cognition in Chronic Kidney Disease Using the NIH Toolbox®.

BACKGROUND: Chronic kidney disease (CKD) is largely an age-related clinical disorder with accelerated cognitive and cardiovascular aging. Cognitive impairment is a well-documented occurrence in midlife and older adults with CKD and affects multiple domains. We examined cognition function and potential sex differences in cognition in adults with CKD. METHODS: We included 105 individuals (49.5% women) with CKD stage 3b-4 (eGFR 15-44 mL/min) from the Bicarbonate Administration in CKD Trial (NCT02915601). We measured cognitive function using the National Institutes of Health (NIH) Toolbox® Cognition Battery, which assesses cognitive and motor measures such as executive function, attention, memory, and dexterity. All study measures were collected and analyzed at the study baseline. RESULTS: The mean (SD) age and eGFR were 61 ± 12 years and 34.9 ± 9.8 mL/min/1.73m2. Overall, when compared to the NIH Toolbox reference population, participants scored, on average, below the 50th percentile across all cognitive domain tests and the dexterity test. Total cognition scores were also below the 50th percentile. Participants with stage 4 CKD had significantly lower fluid cognition scores compared to those with CKD stage 3b (ß-Estimate -5.4 (95% CI-9.8 to -0.9); p=0.03). Female participants with CKD performed significantly better on the episodic memory tests and dexterity tests (dominant and non-dominant pegboard tests), and had higher crystallized cognition scores, on average, compared to males. CONCLUSIONS: Participants with CKD had detectable cognitive deficits in fluid cognition, dexterity, and total cognition. Additionally, sex differences in cognitive measures were found among people with CKD.

Kidney Energetics and Cyst Burden in Autosomal Dominant Polycystic Kidney Disease: A Pilot Study.

RATIONALE & OBJECTIVE: In this pilot study, we hypothesized that autosomal dominant polycystic kidney disease (ADPKD) is characterized by impaired kidney oxidative metabolism that associates with kidney size and cyst burden. STUDY DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: Twenty adults with ADPKD (age, 31±6 years; 65% women; body mass index [BMI], 26.8 [22.7-30.4] kg/m2; estimated glomerular filtration rate [eGFR, 2021 CKD-EPI creatinine], 103±18mL/min/1.73m2; height-adjusted total kidney volume [HTKV], 731±370mL/m; Mayo classifications 1B [5%], 1C [42%], 1D [21%], and 1E [32%]) and 11 controls in normal weight category (NWC) (age, 25±3 years; 45% women; BMI, 22.5 [21.7-24.2] kg/m2; eGFR, 113±15mL/min/1.73m2; HTKV, 159±31mL/m) at the University of Colorado Anschutz Medical Campus. PREDICTORS: ADPKD status (yes/no) and severity (Mayo classifications). OUTCOME: HTKV and cyst burden by magnetic resonance imaging, kidney oxidative metabolism, and perfusion by 11C-acetate positron emission tomography/computed tomography, insulin sensitivity by hyperinsulinemic-euglycemic clamps (presented as ratio of M-value of steady state insulin concentration [M/I]). ANALYTICAL APPROACH: For categorical variables, χ2/Fisher's exact tests, and for continuous variables t tests/Mann-Whitney U tests. Pearson correlation was used to estimate the relationships between variables. RESULTS: Compared with NWC individuals, the participants with ADPKD exhibited lower mean±SD M/I ratio (0.586±0.205 vs 0.424±0.171 [mg/kg lean/min]/(µIU/mL), P=0.04), lower median cortical perfusion (1.93 [IQR, 1.80-2.09] vs 0.68 [IQR, 0.47-1.04] mL/min/g, P<0.001) and lower median total kidney oxidative metabolism (0.17 [IQR, 0.16-0.19] vs. 0.14 [IQR, 0.12-0.15] min-1, P=0.001) in voxel-wise models excluding cysts. HTKV correlated inversely with cortical perfusion (r: -0.83, P < 0.001), total kidney oxidative metabolism (r: -0.61, P<0.001) and M/I (r: -0.41, P = 0.03). LIMITATIONS: Small sample size and cross-sectional design. CONCLUSIONS: Adults with ADPKD and preserved kidney function exhibited impaired renal perfusion and kidney oxidative metabolism across a wide range of cysts and kidney enlargements. FUNDING: Grants from government (National Institutes of Health, Centers for Disease Control and Prevention) and not-for-profit (JDRF) entities. TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study numbers NCT04407481 and NCT04074668. PLAIN-LANGUAGE SUMMARY: In our study, we explored how a common genetic kidney condition, autosomal dominant polycystic kidney disease (ADPKD), relates to kidney metabolism. ADPKD leads to the growth of numerous cysts in the kidneys, which can impact their ability to work properly. We wanted to understand the kidneys' ability to process oxygen and blood flow in ADPKD. Our approach involved using advanced imaging techniques to observe kidney metabolism and blood flow in people with ADPKD compared with healthy individuals. We discovered that those with ADPKD had significant changes in kidney oxygen metabolism even when their kidney function was still normal. These findings are crucial as they provide deeper insights into ADPKD, potentially guiding future treatments to target these changes.

Combination therapy for kidney disease in people with diabetes mellitus.

Diabetic kidney disease (DKD), defined as co-existing diabetes and chronic kidney disease in the absence of other clear causes of kidney injury, occurs in approximately 20-40% of patients with diabetes mellitus. As the global prevalence of diabetes has increased, DKD has become highly prevalent and a leading cause of kidney failure, accelerated cardiovascular disease, premature mortality and global health care expenditure. Multiple pathophysiological mechanisms contribute to DKD, and single lifestyle or pharmacological interventions have shown limited efficacy at preserving kidney function. For nearly two decades, renin-angiotensin system inhibitors were the only available kidney-protective drugs. However, several new drug classes, including sodium glucose cotransporter-2 inhibitors, a non-steroidal mineralocorticoid antagonist and a selective endothelin receptor antagonist, have now been demonstrated to improve kidney outcomes in people with type 2 diabetes mellitus. In addition, emerging preclinical and clinical evidence of the kidney-protective effects of glucagon-like-peptide-1 receptor agonists has led to the prospective testing of these agents for DKD. Research and clinical efforts are geared towards using therapies with potentially complementary efficacy in combination to safely halt kidney disease progression. As more kidney-protective drugs become available, the outlook for people living with DKD should improve in the next few decades.

Glycoprotein Acetyls Associate With Intraglomerular Hemodynamic Dysfunction, Albuminuria, Central Adiposity, and Insulin Resistance in Youth With Type 1 Diabetes.

OBJECTIVES: Glycoprotein acetyls (GlycA's) are biomarkers of systemic inflammation and cardiovascular disease, yet little is known about their role in type 1 diabetes (T1D). In this study we examined the associations among GlycA's, central adiposity, insulin resistance, and early kidney injury in youth with T1D. METHODS: Glomerular filtration rate and renal plasma flow by iohexol and p-aminohippurate clearance, urine albumin-to-creatinine ratio (UACR), central adiposity by dual-energy x-ray absorptiometry, and estimated insulin sensitivity were assessed in 50 youth with T1D (16±3.0 years of age, 50% female, glycated hemoglobin 8.7%±1.3%, T1D duration 5.7±2.6 years). Concentrations of GlycA were quantified by targeted nuclear magnetic resonance spectroscopy. Correlation and multivariable linear regression analyses were performed. RESULTS: GlycA's were higher in girls vs boys (1.05±0.26 vs 0.84±0.15 mmol/L, p=0.001) and in participants living with overweight/obesity vs normal weight (1.12±0.23 vs 0.87±0.20 mmol/L, p=0.0004). GlycA's correlated positively with estimated intraglomerular pressure (r=0.52, p=0.001), UACR (r=0.53, p<0.0001), and trunk mass (r=0.45, p=0.001), and inversely with estimated insulin sensitivity (r=-0.36, p=0.01). All relationships remained significant after adjustment for age, sex, and glycated hemoglobin. CONCLUSIONS: As biomarkers of inflammation, GlycA's were higher in girls and those with overweight or obese body habitus in T1D. GlycA's associated with parameters of early kidney dysfunction, central adiposity, and insulin resistance.

Minireview: Understanding and targeting inflammatory, hemodynamic and injury markers for cardiorenal protection in type 1 diabetes.

The coexistence of cardiovascular disease (CVD) and diabetic kidney disease (DKD) is common in people with type 1 diabetes (T1D) and is strongly associated with an increased risk of morbidity and mortality. Hence, it is imperative to explore robust tools that can accurately reflect the development and progression of cardiorenal complications. Several cardiovascular and kidney biomarkers have been identified to detect at-risk individuals with T1D. The primary aim of this review is to highlight biomarkers of injury, inflammation, or renal hemodynamic changes that may influence T1D susceptibility to CVD and DKD. We will also examine the impact of approved pharmacotherapies for type 2 diabetes, including renin-angiotensin-aldosterone system (RAAS) inhibitors, sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1RAs) on candidate biomarkers for cardiorenal complications in people with T1D and discuss how these changes may potentially mediate kidney and cardiovascular protection. Identifying predictive and prognostic biomarkers for DKD and CVD may highlight potential drug targets to attenuate cardiorenal disease progression, implement novel risk stratification measures in clinical trials, and improve the assessment, diagnosis, and treatment of at-risk individuals with T1D.

Interactive Effects of Empagliflozin and Hyperglycemia on Urinary Amino Acids in Individuals With Type 1 Diabetes.

Optimizing energy use in the kidney is critical for normal kidney function. Here, we investigate the effect of hyperglycemia and sodium-glucose cotransporter 2 (SGLT2) inhibition on urinary amino acid excretion in individuals with type 1 diabetes (T1D). The open-label ATIRMA trial assessed the impact of 8 weeks of 25 mg empagliflozin orally once per day in 40 normotensive normoalbuminuric young adults with T1D. A consecutive 2-day assessment of clamped euglycemia and hyperglycemia was evaluated at baseline and posttreatment visits. Principal component analysis was performed on urinary amino acids grouped into representative metabolic pathways using MetaboAnalyst. At baseline, acute hyperglycemia was associated with changes in 25 of the 33 urinary amino acids or their metabolites. The most significant amino acid metabolites affected by acute hyperglycemia were 3-hydroxykynurenine, serotonin, glycyl-histidine, and nicotinic acid. The changes in amino acid metabolites were reflected by the induction of four biosynthetic pathways: aminoacyl-tRNA; valine, leucine, and isoleucine; arginine; and phenylalanine, tyrosine, and tryptophan. In acute hyperglycemia, empagliflozin significantly attenuated the increases in aminoacyl-tRNA biosynthesis and valine, leucine, and isoleucine biosynthesis. Our findings using amino acid metabolomics indicate that hyperglycemia stimulates biosynthetic pathways in T1D. SGLT2 inhibition may attenuate the increase in biosynthetic pathways to optimize kidney energy metabolism.

ß1-Integrin blockade prevents podocyte injury in experimental models of minimal change disease.

INTRODUCTION: Activation of the focal adhesion kinase (FAK) in podocytes is involved in the pathogenesis of minimal change disease (MCD), but the pathway leading to its activation in this disease is unknown. Here, we tested whether podocyte ß1 integrin is the upstream modulator of FAK activation and podocyte injury in experimental models of MCD-like injury. METHODS: We used lipopolysaccharide (LPS) and MCD sera to induce MCD-like changes in vivo and in cultured human podocytes, respectively. We performed functional studies using specific ß1 integrin inhibitors in vivo and in vitro, and integrated histological analysis, western blotting, and immunofluorescence to assess for morphological and molecular changes in podocytes. By ELISA, we measured serum LPS levels in 35 children with MCD or presumed MCD (idiopathic nephrotic syndrome [INS]) and in 18 healthy controls. RESULTS: LPS-injected mice showed morphological (foot process effacement, and normal appearing glomeruli on light microscopy) and molecular features (synaptopodin loss, nephrin mislocalization, FAK phosphorylation) characteristic of human MCD. Administration of a ß1 integrin inhibitor to mice abrogated FAK phosphorylation, and ameliorated proteinuria and podocyte injury following LPS. Children with MCD/INS in relapse had higher serum LPS levels than controls. In cultured human podocytes, ß1 integrin blockade prevented cytoskeletal rearrangements following exposure to MCD sera in relapse. CONCLUSIONS: Podocyte ß1 integrin activation is an upstream mediator of FAK phosphorylation and podocyte injury in models of MCD-like injury.

Insulin Secretion, Sensitivity, and Kidney Function in Young Individuals With Type 2 Diabetes.

OBJECTIVE: ß-Cell dysfunction and insulin resistance magnify the risk of kidney injury in type 2 diabetes. The relationship between these factors and intraglomerular hemodynamics and kidney oxygen availability in youth with type 2 diabetes remains incompletely explored. RESEARCH DESIGN AND METHODS: Fifty youth with type 2 diabetes (mean age ± SD 16 ± 2 years; diabetes duration 2.3 ± 1.8 years; 60% female; median HbA1c 6.4% [25th, 75th percentiles 5.9, 7.6%]; BMI 36.4 ± 7.4 kg/m2; urine albumin-to-creatinine ratio [UACR] 10.3 [5.9, 58.0] mg/g) 21 control participants with obesity (OCs; age 16 ± 2 years; 29% female; BMI 37.6 ± 7.4 kg/m2), and 20 control participants in the normal weight category (NWCs; age 17 ± 3 years; 70% female; BMI 22.5 ± 3.6 kg/m2) underwent iohexol and p-aminohippurate clearance to assess glomerular filtration rate (GFR) and renal plasma flow, kidney MRI for oxygenation, hyperglycemic clamp for insulin secretion (acute C-peptide response to glucose [ACPRg]) and disposition index (DI; ×103 mg/kg lean/min), and DXA for body composition. RESULTS: Youth with type 2 diabetes exhibited lower DI (0.6 [0.0, 1.6] vs. 3.8 [2.4, 4.5] × 103 mg/kg lean/min; P < 0.0001) and ACPRg (0.6 [0.3, 1.4] vs. 5.3 [4.3, 6.9] nmol/L; P < 0.001) and higher UACR (10.3 [5.9, 58.0] vs. 5.3 [3.4, 14.3] mg/g; P = 0.003) and intraglomerular pressure (77.8 ± 11.5 vs. 64.8 ± 5.0 mmHg; P < 0.001) compared with OCs. Youth with type 2 diabetes and OCs had higher GFR and kidney oxygen availability (relative hyperoxia) than NWCs. DI was associated inversely with intraglomerular pressure and kidney hyperoxia. CONCLUSIONS: Youth with type 2 diabetes demonstrated severe ß-cell dysfunction that was associated with intraglomerular hypertension and kidney hyperoxia. Similar but attenuated findings were found in OCs.

Renal hemodynamic changes in patients with type 2 diabetes and their clinical impact.

The dysfunction of the internal mechanics within the kidney's filtering units, known as glomeruli, has been linked to the emergence and progression of diabetic kidney disease (DKD). To better understand this crucial aspect of kidney function and the pathology of DKD, a variety of methods are employed in research, from the introduction of external compounds, such as inulin, iohexol, iothalamate and p-aminohippurate, to cutting-edge imaging techniques and computational analysis. Given the significance of intraglomerular hemodynamic dysfunction in the pathogenesis and treatment of DKD, it is essential to thoroughly examine the available data on this topic. Accordingly, the aim of this review is to provide a comprehensive appraisal of the role of intraglomerular hemodynamic dysfunction in the development of DKD and the effects of current therapies used to mitigate DKD. Through this analysis, we can gain a deeper understanding of the complex pathogenesis of DKD and potentially discover new avenues for tailored therapeutic management of patients with DKD.

Cystatin C-Based eGFR Changes during Gender-Affirming Hormone Therapy in Transgender Individuals.

BACKGROUND: Men with CKD tend to experience a faster eGFR decline than women, potentially because of sex hormones. Limited research exists regarding the effect of gender-affirming hormone therapy (GAHT) on kidney function. Furthermore, monitoring kidney function during GAHT is challenging because serum creatinine is confounded by body composition. To investigate the relationship between sex hormones and kidney function, we studied the changes of serum creatinine and serum cystatin C, a filtration marker less affected by sex, during 1 year of GAHT. METHODS: As part of the European Network for the Investigation of Gender Incongruence study, we measured serum creatinine and serum cystatin C in 260 transgender women and 285 transgender men before and 12 months after initiating GAHT. Transgender women received estradiol plus cyproterone acetate, while transgender men received testosterone. Cystatin C-based eGFR was calculated using the full-age-spectrum equation. RESULTS: In transgender women, cystatin C decreased by 0.069 mg/L (95% confidence interval [CI], 0.049 to 0.089), corresponding with a 7 ml/min per 1.73 m 2 increase in eGFR. In transgender men, cystatin C increased by 0.052 mg/L (95% CI, 0.031 to 0.072), corresponding with a 6 ml/min per 1.73 m 2 decrease in eGFR. Creatinine concentrations decreased (-0.065 mg/dl; 95% CI, -0.076 to -0.054) in transgender women and increased (+0.131 mg/dl; 95% CI, 0.119 to 0.142) in transgender men. Changes in creatinine-based eGFR varied substantially depending on the sex used in the equation. CONCLUSIONS: In this cohort of transgender individuals, cystatin C-based eGFR increased with estradiol and antiandrogen therapy and decreased with testosterone therapy.

Endogenous adenine mediates kidney injury in diabetic models and predicts diabetic kidney disease in patients.

Diabetic kidney disease (DKD) can lead to end-stage kidney disease (ESKD) and mortality; however, few mechanistic biomarkers are available for high-risk patients, especially those without macroalbuminuria. Urine from participants with diabetes from the Chronic Renal Insufficiency Cohort (CRIC) study, the Singapore Study of Macro-angiopathy and Micro-vascular Reactivity in Type 2 Diabetes (SMART2D), and the American Indian Study determined whether urine adenine/creatinine ratio (UAdCR) could be a mechanistic biomarker for ESKD. ESKD and mortality were associated with the highest UAdCR tertile in the CRIC study and SMART2D. ESKD was associated with the highest UAdCR tertile in patients without macroalbuminuria in the CRIC study, SMART2D, and the American Indian study. Empagliflozin lowered UAdCR in nonmacroalbuminuric participants. Spatial metabolomics localized adenine to kidney pathology, and single-cell transcriptomics identified ribonucleoprotein biogenesis as a top pathway in proximal tubules of patients without macroalbuminuria, implicating mTOR. Adenine stimulated matrix in tubular cells via mTOR and stimulated mTOR in mouse kidneys. A specific inhibitor of adenine production was found to reduce kidney hypertrophy and kidney injury in diabetic mice. We propose that endogenous adenine may be a causative factor in DKD.

Sodium glucose co-transporter 2 inhibition increases epidermal growth factor expression and improves outcomes in patients with type 2 diabetes.

Underlying molecular mechanisms of the kidney protective effects of sodium glucose co-transporter 2 (SGLT2) inhibitors are not fully elucidated. Therefore, we studied the association between urinary epidermal growth factor (uEGF), a mitogenic factor involved in kidney repair, and kidney outcomes in patients with type 2 diabetes (T2D). The underlying molecular mechanisms of the SGLT2 inhibitor canagliflozin on EGF using single-cell RNA sequencing from kidney tissue were examined. Urinary EGF-to-creatinine ratio (uEGF/Cr) was measured in 3521 CANagliflozin cardioVascular Assessment Study (CANVAS) participants at baseline and week 52. Associations of uEGF/Cr with kidney outcome were assessed using multivariable-adjusted Cox regression models. Single-cell RNA sequencing was performed using protocol kidney biopsy tissue from ten young patients with T2D on SGLT2i, six patients with T2D on standard care only, and six healthy controls (HCs). In CANVAS, each doubling in baseline uEGF/Cr was associated with a 12% (95% confidence interval 1-22) decreased risk of kidney outcome. uEGF/Cr decreased after 52 weeks with placebo and remained stable with canagliflozin (between-group difference +7.3% (2.0-12.8). In young persons with T2D, EGF mRNA was primarily expressed in the thick ascending loop of Henle. Expression in biopsies from T2D without SGLT2i was significantly lower compared to HCs, whereas treatment with SGLT2i increased EGF levels closer to the healthy state. In young persons with T2D without SGLT2i, endothelin-1 emerged as a key regulator of the EGF co-expression network. SGLT2i treatment was associated with a shift towards normal EGF expression. Thus, decreased uEGF represents increased risk of kidney disease progression in patients with T2D. Canagliflozin increased kidney tissue expression of EGF and was associated with a downstream signaling cascade linked to tubular repair and reversal of tubular injury.

Loss of Glomerular Permselectivity in Type 2 Diabetes Associates With Progression to Kidney Failure.

We examined whether defects in glomerular size selectivity in type 2 diabetes are associated with progressive kidney disease. Glomerular filtration rate (GFR) and fractional clearances of dextrans of graded sizes were measured in 185 American Indians. The permselectivity model that best fit the dextran sieving data represented the glomerular capillary as being perforated by small restrictive pores and a parallel population of larger nonrestrictive pores characterized by ω0, the fraction of total filtrate volume passing through this shunt. The hazard ratio (HR) for kidney failure was expressed per 1-SD increase of ω0 by Cox regression after adjusting for age, sex, mean arterial pressure, HbA1c, GFR, and the urine albumin-to-creatinine ratio (ACR). Baseline mean ± SD age was 43 ± 10 years, HbA1c 8.9 ± 2.5%, GFR 147 ± 46 mL/min, and median (interquartile range) ACR 41 (11-230) mg/g. During a median follow-up of 17.7 years, 67 participants developed kidney failure. After adjustment, each 1-SD increment in ω0 was associated with a higher risk of kidney failure (HR 1.55 [95% CI 1.17, 2.05]). Enhanced transglomerular passage of test macromolecules was associated with progression to kidney failure, independent of albuminuria and GFR, suggesting that mechanisms associated with impaired glomerular permselectivity are important determinants of progressive kidney disease.

Kidney Considerations in Pediatric Obesity.

PURPOSE OF REVIEW: Chronic kidney disease (CKD) is a common condition and a major cause of morbidity and mortality in adults, but children and adolescents are also at risk for early kidney injury and development of CKD. Obesity contributes both directly and indirectly to the development of CKD. The purpose of this review is to describe obesity-related kidney disease (ORKD) and diabetic kidney disease (DKD) and their impact in the pediatric population. RECENT FINDINGS: Although obesity-related CKD in childhood and adolescence is uncommon, nascent kidney damage may magnify the lifetime risk of CKD. Glomerular hyperfiltration is an early phenotype of both ORKD and DKD and typically manifests prior to albuminuria and progressive decline in GFR. Novel treatments for obesity and type 2 diabetes exerting protective effects on the kidneys are being investigated for use in the pediatric population. It is important to understand the impact of obesity on the kidneys more fully in the pediatric population to help detect injury earlier and intervene prior to the onset of irreversible progression of disease and to guide future research in this area.

Estimated glomerular filtration rate calculated by serum creatinine lacks precision and accuracy in adults with type 2 diabetes with preserved renal function.

AIMS: We evaluated the performance of creatinine-based equations that are currently used to estimate glomerular filtration rate (GFR) in people with type 2 diabetes compared to measured GFR using gold-standard methods. METHODS: In this post-hoc analysis, 32 participants underwent repeated measurement of GFR by inulin clearance (mGFR). GFR was estimated by serum creatinine using the MDRD (eGFRMDRD) and CKD-EPI (eGFRCKD-EPI) equations four times over the course of one month. Performance was evaluated using measurements of bias (mean difference), precision (SD), and inaccuracy (proportion of eGFR that differed by >20 % of mGFR). Treatment and time effects on bias were evaluated using linear mixed effects models. RESULTS: At baseline, participants (38 % female) were age 60 ± 8 years, had diabetes duration of 9 ± 7 years, HbA1c 56 ± 9 mmol/mol (7.2 ± 0.8 %), and BMI 31.0 ± 6.2 kg/m2. Mean mGFR was 113 ± 24, mean eGFRMDRD was 93 ± 12, and mean eGFRCKD-EPI was 94 ± 9 mL/min/1.73 m2. When 128 observations (32 participants measured 4 times) were evaluated, both equations substantially underestimated mGFR. For eGFRMDRD, mean bias was -21.5 mL/min/1.73 m2, precision was 22.7 mL/min/1.73 m2, and 46 % of observations differed by >20 %. Results were similar for eGFRCKD-EPI. No time or treatment effects on bias were observed. CONCLUSIONS: In adults with type 2 diabetes and preserved renal function, eGFR equations underestimated mGFR, lacked precision and accuracy, and performance was lower at higher ranges of mGFR. Current eGFR equations by serum creatinine are inaccurate in adults with type 2 diabetes with preserved renal function, highlighting the necessity to develop new methods to measure kidney function at earlier stages of diabetic kidney disease.

Role of endogenous adenine in kidney failure and mortality with diabetes.

Diabetic kidney disease (DKD) can lead to end-stage kidney disease (ESKD) and mortality, however, few mechanistic biomarkers are available for high risk patients, especially those without macroalbuminuria. Urine from participants with diabetes from Chronic Renal Insufficiency Cohort (CRIC), Singapore Study of Macro-Angiopathy and Reactivity in Type 2 Diabetes (SMART2D), and the Pima Indian Study determined if urine adenine/creatinine ratio (UAdCR) could be a mechanistic biomarker for ESKD. ESKD and mortality were associated with the highest UAdCR tertile in CRIC (HR 1.57, 1.18, 2.10) and SMART2D (HR 1.77, 1.00, 3.12). ESKD was associated with the highest UAdCR tertile in patients without macroalbuminuria in CRIC (HR 2.36, 1.26, 4.39), SMART2D (HR 2.39, 1.08, 5.29), and Pima Indian study (HR 4.57, CI 1.37-13.34). Empagliflozin lowered UAdCR in non-macroalbuminuric participants. Spatial metabolomics localized adenine to kidney pathology and transcriptomics identified ribonucleoprotein biogenesis as a top pathway in proximal tubules of patients without macroalbuminuria, implicating mammalian target of rapamycin (mTOR). Adenine stimulated matrix in tubular cells via mTOR and stimulated mTOR in mouse kidneys. A specific inhibitor of adenine production was found to reduce kidney hypertrophy and kidney injury in diabetic mice. We propose that endogenous adenine may be a causative factor in DKD.