Impaired fasting glucose is associated with renal hyperfiltration in the general population

Renal Hyperfiltration as a New Mechanism of Smoking-Related Mortality

INTRODUCTION

Renal hyperfiltration (RHF), an established risk factor for mortality, is prevalent among tobacco smokers. The aim of this study was to assess the mediating role of RHF in the association between smoking and mortality.

AIMS AND METHODS

Data of this study were retrieved from the cohort of the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD), including 2064 males from Finland. Study participants were followed over a 35-year period. Using classic and counterfactual mediation analysis approaches, we estimated the mediative effect of RHF in the association between smoking and each of the following outcomes: All-cause mortality, cardiovascular disease (CVD) mortality, and non-CVD mortality.

RESULTS

The risk of all-cause mortality in smokers was twice that in nonsmokers (hazard ratio [HR], 2.06; 95% confidence interval [CI]: 1.84 to 2.31). Under the counterfactual framework the direct effect of smoking on all-cause mortality, controlled for RHF, corresponded to an HR of 2.00 (95% CI: 1.78 to 2.30). Of the effect of smoking on mortality, 5% (p-value = .016) was mediated by RHF. This finding concerned particularly non-CVD mortality.

CONCLUSIONS

RHF mediated the effect of smoking on non-CVD and all-cause mortality, but not on CVD mortality. The generalizability of our study results is however limited by its focus on a Finnish male cohort, underscoring the need for further investigation into RHF's broader implications across diverse populations.

IMPLICATIONS

This study elucidates the complex interplay between smoking, renal hyperfiltration (RHF), and mortality, offering novel insights into the mediating role of RHF. Our findings demonstrate that RHF significantly mediates the relationship between smoking and non-cardiovascular disease (non-CVD), but not CVD mortality. This distinction underscores the multifaceted role of RHF beyond its established association with cardiovascular events. By highlighting the specific pathways through which RHF mediates some of the smoking-attributed mortality, this research contributes to our understanding of the mechanisms linking smoking to mortality.

Dapagliflozin in diabetic kidney disease patients with different filtration status

BACKGROUND

Few studies have discussed the effects and mechanism of dapagliflozin on diabetic kidney disease (DKD) with different glomerular filtration rate (GFR) and systolic blood pressure (SBP). This study aimed to investigate the variation in the eGFR and proteinuria after dapagliflozin treatment in DKD patients with different filtration status and SBP levels.

METHODS

First, we conducted a cross-sectional study to determined hyperfiltration threshold for the DKD trial. Then, we enrolled 259 DKD patients with an eGFR greater than 70 mL/min/1.73m2 and an albumin-to-creatinine ratio (ACR) between 30 and 200 mg/g to receive treatment with dapagliflozin. Hyperfiltration was defined as the 95th percentile of eGFR above the age- and gender- specific in healthy subjects, DKD patients were divided into hyperfiltration and non-hyperfiltration groups, and SBP > 120 mmHg and ≤ 120 mmHg groups. The eGFR, ACR, and blood and urine electrolytes were measured before and after treatment.

RESULTS

The mean eGFR change at 2 weeks in the hyperfiltration with SBP > 120 mmHg group was greater than in the non-hyperfiltration with SBP ≤ 120 mmHg group (P = 0.048). The mean ACR reduction values were greater in the non-hyperfiltration with SBP ≤ 120 mmHg group than in the hyperfiltration with SBP > 120 mmHg group at 12 weeks (P = 0.042). There was no difference in other blood or urine electrolytes before and after treatment, except for the fractional excretion of sodium (FENa), which significantly increased after 2 weeks (P < 0.001) and recovered after 8 weeks (P = 0.305).

CONCLUSION

DKD with non-hyperfiltration with SBP ≤ 120 mmHg had a lower mean eGFR decline and greater decrease in the ACR after treatment. The initial increase in FENa and subsequent decrease after dapagliflozin treatment may be the main mechanism behind the eGFR variation.

Serum Osmolality as a Predictor of Renal Function Decline: A Retrospective Cohort Study

Background and Aims: Dehydration is a prevalent and costly healthcare concern, linked to heightened risks of acute kidney injury and in-hospital mortality. Despite its significance, limited evidence exists regarding its prevalence and correlation with renal function decline in apparently healthy individuals. This retrospective cohort study aimed to investigate the prevalence and association of dehydration with renal function decline and the development or progression of chronic kidney disease (CKD) in the general population. Methods: The medical records of subjects undergoing annual health check-ups from 2016 to 2019 at a single center in Taiwan were analyzed, and those with CKD stage V, insufficient data, or an increased estimated glomerular filtration rate (eGFR) were excluded. Serum osmolality, eGFR, and relevant parameters were measured. Logistic regression and Kaplan-Meier analyses were used to assess associations between osmolality and CKD-related outcomes. Results: Among the 4449 eligible subjects, those in the higher osmolality quartiles had an elevated risk of CKD or CKD progression. Multivariate analyses identified age, systolic blood pressure, serum osmolality, uric acid, proteinuria, and a history of diabetes as independent risk factors, with high-density lipoprotein being protective. Cumulative incidence curves demonstrated a significant increase in the risk of CKD with increasing osmolality levels. Restricted cubic spline analyses confirmed a nonlinear relationship between osmolality and CKD risk. Conclusions: Elevated serum osmolality independently predicted renal function decline and CKD development in apparently healthy individuals, and this effect persisted after adjusting for established risk factors. Our findings underscore the importance of addressing dehydration as a modifiable risk factor for CKD.

Vitamin D inhibits ferroptosis and mitigates the kidney injury of prediabetic mice by activating the Klotho/p53 signaling pathway

Diabetic nephropathy (DN) is a serious public health problem worldwide, and ferroptosis is deeply involved in the pathogenesis of DN. Prediabetes is a critical period in the prevention and control of diabetes and its complications, in which kidney injury occurs. This study aimed to explore whether ferroptosis would induce kidney injury in prediabetic mice, and whether vitamin D (VD) supplementation is capable of preventing kidney injury by inhibiting ferroptosis, while discussing the potential mechanisms. High-fat diet (HFD) fed KKAy mice and high glucose (HG) treated HK-2 cells were used as experimental subjects in the current study. Our results revealed that serious injury and ferroptosis take place in the kidney tissue of prediabetic mice; furthermore, VD intervention significantly improved the kidney structure and function in prediabetic mice and inhibited ferroptosis, showing ameliorated iron deposition, enhanced antioxidant capability, reduced reactive oxygen species (ROS) and lipid peroxidation accumulation. Meanwhile, VD up-regulated Klotho, solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) expression, and down-regulated p53, transferrin receptor 1 (TFR1) and Acyl-Coenzyme A synthetase long-chain family member 4 (ACSL4) expression. Moreover, we demonstrated that HG-induced ferroptosis is antagonized by treatment of VD and knockdown of Klotho attenuates the protective effect of VD on ferroptosis in vitro. In conclusion, ferroptosis occurs in the kidney of prediabetic mice and VD owns a protective effect on prediabetic kidney injury, possibly by via the Klotho/p53 pathway, thus inhibiting hyperglycemia-induced ferroptosis.

Iohexol plasma clearance measurement protocol standardization for adults: a consensus paper of the European Kidney Function Consortium

International consensus supports the development of standardized protocols for measured glomerular filtration rate (mGFR) to facilitate the integration of mGFR testing in both clinical and research settings. To this end, the European Kidney Function Consortium convened an international group of experts with relevant experience in mGFR. The working group performed an extensive literature search to inform the development of recommendations for mGFR determination using 1-compartment plasma clearance models and iohexol as the exogenous filtration marker. Iohexol was selected as it is non-radio labeled, inexpensive, and safe, can be assayed at a central laboratory, and the other commonly used non-radio-labeled tracers have been (inulin) or are soon to be (iothalamate) discontinued. A plasma clearance model was selected over urine clearance as it requires no urine collection. A 1 compartment was preferred to 2 compartments as it requires fewer samples. The recommendations are based on published evidence complemented by expert opinion. The consensus paper covers practical advice for patients and health professionals, preparation, administration, and safety aspects of iohexol, laboratory analysis, blood sample collection and sampling times using both multiple and single-sample protocols, description of the mGFR mathematical calculations, as well as implementation strategies. Supplementary materials include patient and provider information sheets, standard operating procedures, a study protocol template, and support for mGFR calculation.

Association of Renal Hyperfiltration with Incidence of New-Onset Diabetes Mellitus: A Nationwide Cohort Study

Background and Objectives: While the connection between decreased kidney function and diabetes mellitus (DM) is commonly acknowledged, there is insufficient research examining the relationship between higher-than-normal estimated glomerular filtration rate (eGFR) and the incidence risk of new-onset DM. Our research aimed to explore the relationship between an eGFR and the incidence risk of new-onset DM in the Korean general population through a nationwide longitudinal study. Methods: This research employed the cohort records of the National Health Insurance Service in Korea, analyzing records from 2,294,358 individuals between the ages of 20 and 79 who underwent health check-ups between 2010 and 2011. The eGFR levels from the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation were used to assess the renal function. New-onset DM was defined as two or more claims with the International Classification of Diseases-10 classification codes E10 to E14, being prescribed any medication for lowering blood glucose, or having a record of fasting plasma glucose levels of ≥126 mg/dL from a health examination after the index date. Results: The mean age of subjects was 47.34 ± 13.76 years. The 150,813 (6.57%) new-onset DM cases were identified over a median follow-up of 9.63 years. In the multivariable Cox regression analysis, in comparison with the 5th decile, the 10th (≥114.12 mL/min/1.73 m2) (hazard ratio (HR): 0.52, 95% confidence interval (CI) (0.50-0.54), p < 0.001) eGFR decile was significantly associated with a decreased incidence of new-onset DM. Moreover, eGFR >120 mL/min/1.73 m2 was associated with a reduced risk of new-onset DM (HR: 0.40, 95% CI (0.39-0.42), p < 0.001). These results were consistent regardless of the presence of impaired glucose tolerance, age, or obesity. Conclusion: Our study showed higher-than-normal eGFR levels were associated with a lower risk of incidence for new-onset DM regardless of the presence of impaired glucose tolerance, age, or obesity. In general population, higher-than-normal eGFR may be associated with a lower risk of incidence of new-onset DM.

Prediabetes: A Benign Intermediate Stage or a Risk Factor in Itself?

Prediabetes is a condition when the blood glucose levels are above the normal range but below the threshold for defining diabetes. Previously considered benign, it is now recognized to be associated with various macrovascular and microvascular complications, with increases in the risk of cardiovascular events, nephropathy neuropathy, and retinopathy. Early identification of prediabetics may help detect the risk for these future complications at an earlier stage. Moreover, therapeutic options for prediabetes are available, which can retard its progression to diabetes and the subsequent development of complications. Hence, we make a case for the early identification of prediabetes through screening methods and appropriate institution of management strategies.

Determinants of early chronic kidney disease in patients with recently diagnosed type 2 diabetes mellitus: a retrospective study from the Taiwan Diabetes Registry

BACKGROUND

We tried to identify the risk factor associate with early chronic kidney disease (CKD) in recently diagnosed type 2 diabetes mellitus patients by utilizing real-world data from Taiwan Diabetes Registry.

MATERIALS AND METHODS

Patients with type 2 diabetes mellitus recently diagnosed within 1 year. We divided the study participants into control group and early CKD group. Early CKD was defined as either CKD stage G1 with albuminuria, CKD stage G2 with albuminuria, or CKD stage G3a regardless of albuminuria (Urine-albumin to creatinine ratio (UACR) ≥ 3 mg/mmol). Control group was defined as CKD G1 or CKD G2 without albuminuria. Logistic regression analyses were used to compare differences in clinical characteristics between the subgroups. Linear regression models were employed to examine the factors predicting estimated glomerular filtration rate (eGFR) and UACR.

RESULTS

Total 2217 patients with recently diagnosed type 2 diabetes mellitus were included. 1545 patients were assigned to control group and 618 patients were assigned to the early CKD group. Age (odds ratio (OR) 1.215, 95% confidence interval [CI] 1.122-1.316), systolic blood pressure (OR 1.203, 95% CI 1.117-1.296), glycated hemoglobin (OR 1.074, 95% CI 1.023-1.129) and triglyceride (OR 2.18, 95% CI 1.485-3.199) were found to be significant risk factors. Further, presence of bidirectional association between UACR and eGFR was found.

CONCLUSIONS

We reported factors associated with early CKD in recently diagnosed type 2 diabetes mellitus patients. Variables that associated with eGFR and UACR were identified respectively, included a mutual influence between UACR and eGFR.

Pros and cons of live kidney donation in prediabetics: A critical review and way forward

There is shortage of organs, including kidneys, worldwide. Along with deceased kidney transplantation, there is a significant rise in live kidney donation. The prevalence of prediabetes (PD), including impaired fasting glucose and impaired glucose tolerance, is on the rise across the globe. Transplant teams frequently come across prediabetic kidney donors for evaluation. Prediabetics are at risk of diabetes, chronic kidney disease, cardiovascular events, stroke, neuropathy, retinopathy, dementia, depression and nonalcoholic liver disease along with increased risk of all-cause mortality. Unfortunately, most of the studies done in prediabetic kidney donors are retrospective in nature and have a short follow up period. There is lack of prospective long-term studies to know about the real risk of complications after donation. Furthermore, there are variations in recommendations from various guidelines across the globe for donations in prediabetics, leading to more confusion among clinicians. This increases the responsibility of transplant teams to take appropriate decisions in the best interest of both donors and recipients. This review focuses on pathophysiological changes of PD in kidneys, potential complications of PD, other risk factors for development of type 2 diabetes, a review of guidelines for kidney donation, the potential role of diabetes risk score and calculator in kidney donors and the way forward for the evaluation and selection of prediabetic kidney donors.

The Association Between Metabolic Syndrome, Hyperfiltration, and Long-Term GFR Decline in the General Population

Introduction

One-quarter of adults worldwide meet the criteria of metabolic syndrome (MetS). MetS increases the risk of diabetes, chronic kidney disease (CKD), and cardiovascular disease. However, the association between MetS, hyperfiltration, and long-term glomerular filtration rate (GFR) decline in the general population is unknown.

Methods

In the Renal Iohexol Clearance Survey (RENIS), we investigated 1551 people aged 50 to 63 years; representative of the general population without diabetes, cardiovascular disease, or kidney disease. The GFR was measured using iohexol clearance at baseline and twice during 11 years of follow-up. Hyperfiltration at baseline was defined as an absolute GFR (ml/min) above the 90th percentile adjusted for sex, age, and height, because these variables correlate with nephron number. MetS was defined as increased waist circumference and 2 risk factors among hypertension, hyperglycemia, elevated triglycerides, and low high density lipoprotein (HDL)-cholesterol levels. The GFR decline rate was calculated using linear mixed models.

Results

MetS was associated with hyperfiltration at baseline (odds ratio [OR] 2.4; 95% CI: 1.7-3.5, P < 0.001) and a steeper GFR decline rate during follow-up (-0.30 [-0.43 to -0.16] ml/min per 1.73 m2/yr). Compared to those without MetS, GFR decline was -0.83 (95% CI: -1.13 to -0.53) ml/min per 1.73 m2/yr in those with MetS and baseline hyperfiltration and -0.15 (-0.30 to 0.00) in those MetS without hyperfiltration, P = 0.2 for interaction.

Conclusions

In the nondiabetic general population, those with MetS had an increased OR of hyperfiltration and steeper long-term GFR decline. Randomized controlled trials are needed to explore whether treatment of hyperfiltration can prevent loss of GFR in persons with MetS.

NMR-based metabolomic profiling identifies inflammation and muscle-related metabolites as predictors of incident type 2 diabetes mellitus beyond glucose: the Di@bet.es study

AIMS

The aim of this study was to combine nuclear magnetic resonance-based metabolomics and machine learning to find a glucose-independent molecular signature associated with future type 2 diabetes mellitus development in a subgroup of individuals from the Di@bet.es study.

METHODS

The study group included 145 individuals developing type 2 diabetes mellitus during the 8-year follow-up, 145 individuals matched by age, sex and BMI who did not develop diabetes during the follow-up but had equal glucose concentrations to those who did and 145 controls matched by age and sex. A metabolomic analysis of serum was performed to obtain the lipoprotein and glycoprotein profiles and 15 low molecular weight metabolites. Several machine learning-based models were trained.

RESULTS

Logistic regression performed the best classification between individuals developing type 2 diabetes during the follow-up and glucose-matched individuals. The area under the curve was 0.628, and its 95% confidence interval was 0.510-0.746. Glycoprotein-related variables, creatinine, creatine, small HDL particles and the Johnson-Neyman intervals of the interaction of Glyc A and Glyc B were statistically significant.

CONCLUSIONS

The model highlighted a relevant contribution of inflammation (glycosylation pattern and HDL) and muscle (creatinine and creatine) in the development of type 2 diabetes as independent factors of hyperglycemia.

Association Between Obesity and Chronic Kidney Disease: Multivariable Mendelian Randomization Analysis and Observational Data From a Bariatric Surgery Cohort

Obesity is postulated to independently increase chronic kidney disease (CKD), even after adjusting for type 2 diabetes (T2D) and hypertension. Dysglycemia below T2D thresholds, frequently seen with obesity, also increases CKD risk. Whether obesity increases CKD independent of dysglycemia and hypertension is unknown and likely influences the optimal weight loss (WL) needed to reduce CKD. T2D remission rates plateau with 20-25% WL after bariatric surgery (BS), but further WL increases normoglycemia and normotension. We undertook bidirectional inverse variance weighted Mendelian randomization (IVWMR) to investigate potential independent causal associations between increased BMI and estimated glomerular filtration rate (eGFR) in CKD (CKDeGFR) (<60 mL/min/1.73 m2) and microalbuminuria (MA). In 5,337 BS patients, we assessed whether WL influences >50% decline in eGFR (primary outcome) or CKD hospitalization (secondary outcome), using <20% WL as a comparator. IVWMR results suggest that increased BMI increases CKDeGFR (b = 0.13, P = 1.64 × 10-4; odds ratio [OR] 1.14 [95% CI 1.07, 1.23]) and MA (b = 0.25; P = 2.14 × 10-4; OR 1.29 [1.13, 1.48]). After adjusting for hypertension and fasting glucose, increased BMI did not significantly increase CKDeGFR (b = -0.02; P = 0.72; OR 0.98 [0.87, 1.1]) or MA (b = 0.19; P = 0.08; OR 1.21 [0.98, 1.51]). Post-BS WL significantly reduced the primary outcome with 30 to <40% WL (hazard ratio [HR] 0.53 [95% CI 0.32, 0.87]) but not 20 to <30% WL (HR 0.72 [0.44, 1.2]) and ≥40% WL (HR 0.73 [0.41, 1.30]). For CKD hospitalization, progressive reduction was seen with increased WL, which was significant for 30 to <40% WL (HR 0.37 [0.17, 0.82]) and ≥40% WL (HR 0.24 [0.07, 0.89]) but not 20 to <30% WL (HR 0.60 [0.29, 1.23]). The data suggest that obesity is likely not an independent cause of CKD. WL thresholds previously associated with normotension and normoglycemia, likely causal mediators, may reduce CKD after BS.

Association of glomerular hyperfiltration with carotid artery plaque in the general population

BACKGROUND AND AIMS

Glomerular hyperfiltration (GHF) is a hemodynamic change of the kidney as an adaptive response to nephron loss. Although GHF is associated with metabolic risk factors and cardiovascular disease (CVD), the mechanisms that explain these relationships remain largely unknown. This is partially caused by a non-unified definition of GHF based on pathophysiologic vascular changes. Thus, the objective of this study was to evaluate the association between various definitions of GHF and carotid plaque in a health checkup cohort.

METHODS

A total of 4493 individuals without history of CVD who had carotid ultrasonography (USG) results available between January 2016 and June 2018 were enrolled. GHF was defined as >90th percentile of eGFR residuals after adjusting for confounding factors. Carotid plaque score was calculated based on carotid USG results.

RESULTS

Of 4493 individuals (mean age, 52.3 ± 10.1 years; 3224 [71.8%] males), 449 subjects were included in the GHF group (mean eGFR, 107.0 ± 7.1 ml/min/1.73 m²) and 4044 subjects were included in the non-GHF group (mean eGFR, 92.5 ± 12.3 ml/min/1.73 m²). When the GHF group was compared to the non-GHF group, GHF was associated with the presence of significant carotid plaque (carotid plaque score ≥2) (adjusted OR: 1.46; 95% CI: 1.16 to 1.83; p = 0.001). GHF defined in this study showed higher sensitivity to the presence of carotid plaque than other definitions of GHF.

CONCLUSIONS

GHF status was associated with risk of carotid plaque in individuals without history of CVD. Presence of subclinical carotid plaque was associated with risk of future CVD. Therefore, GHF based on creatinine could be a useful surrogate marker for surveillance of CVD in asymptomatic individuals.

Glycemia is associated with subclinical atherosclerosis through renal function in nondiabetic apparently healthy adults: a mediation analysis

The causative associations between glycemia and early alterations in renal and vascular function remain unclear. To examine the interplay among glycemia, renal function, and markers of subclinical atherosclerosis in apparently healthy subjects. Nondiabetic (30-60 years old) individuals (n = 205) without chronic kidney disease or cardiovascular disease were consecutively recruited from a cardiovascular prevention clinic. All subjects underwent arterial stiffness assessment by measuring the carotid-femoral pulse wave velocity (cfPWV). Glomerular filtration rate (GFR) was estimated by CKD-EPI equation. Study procedures were identical in the two visits (median follow-up 66 months). We employed structural equation modeling (SEM) analysis to investigate the directionality of associations. Baseline fasting plasma glucose (FPG) was independently and inversely associated with GFR (p = 0.008). GFR was significantly associated with cfPWV (p < 0.001) at baseline. By SEM analysis decreasing baseline GFR directly correlated with increasing cfPWV (p = 0.003) whereas FPG correlated with cfPWV indirectly through GFR (mediation) (P = 0.032). FPG did not mediate the effect of GFR on cfPWV (P = 0.768). SEM analysis of longitudinal data revealed bidirectional correlations between changes in FPG and GFR (P < 0.001). Alterations in GFR were directly related to changes in cfPWV (p < 0.001) whereas FPG only indirectly correlated with cfPWV through GFR changes (P = 0.002). In apparently healthy nondiabetic subjects, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status. These findings provide the first clinical evidence supporting the directionality between kidney function and glycemia in nondiabetic subjects leading to vascular dysfunction. In apparently healthy nondiabetic subjects, without cardiovascular disease or chronic kidney disease, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status.

High Triglyceride-Glucose Index with Renal Hyperfiltration and Albuminuria in Young Adults: The Korea National Health and Nutrition Examination Survey (KNHANES V, VI, and VIII)

Background: High triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, is associated with an increased risk of albuminuria in adults. However, the relationship between high TyG index associated with renal hyperfiltration (RHF) and albuminuria among young adults is unclear. Methods: A total of 5420 participants aged 19−39 years were enrolled from the Korean National Health and Nutrition Examination Survey (2011−2014 and 2019) and their TyG index levels were analyzed. RHF was defined as eGFR with residuals > 90th percentile after adjusting for age, sex, weight, and height. Albuminuria was defined as urinary albumin-to-creatinine ratio ≥ 30 mg/g Cr. Logistic regression analyses were used to evaluate the association between TyG index, RHF, and albuminuria. Results: The mean age was 30.7 ± 6.0 years and 46.4% were male. The prevalence of albuminuria and RHF was higher in the higher tertiles of TyG index. In our multivariable model, high TyG index showed higher risk of albuminuria (odds ratio (OR) per 1.0 increase in TyG index, 1.56; 95% confidence interval (CI), 1.24−1.95 and OR in the highest tertile, 1.65; 95% CI, 1.08−2.52). High TyG index was associated with higher risk of RHF (OR per 1.0 increase in TyG index, 1.56; 95% CI, 1.32−1.84 and OR in the highest tertile, 1.73; 95% CI, 1.31−2.30). When participants were divided into with or without RHF, high-TyG index-associated high risk of albuminuria was only observed in those with RHF. Participants with concurrent high TyG index and RHF showed the highest risk of albuminuria. Mediation analysis showed that 54.2% of the relation between TyG index and albuminuria was mediated by RHF (95% CI of indirect effect, 0.27−0.76). Finally, incorporating TyG index into our basic model improved the predictive value for albuminuria only in participants with RHF. Conclusion: High TyG index associated with RHF was the strongest risk factor for albuminuria in this study. Early identification of high TyG index with RHF may prevent future development of CKD in relatively healthy and young adults.

Sex Differences in Age-Related Loss of Kidney Function

BACKGROUND

CKD is more prevalent in women, but more men receive kidney replacement therapy for kidney failure. This apparent contradiction is not well understood.

METHODS

We investigated sex differences in the loss of kidney function and whether any sex disparities could be explained by comorbidity or CKD risk factors. In the Renal Iohexol Clearance Survey (RENIS) in northern Europe, we recruited 1837 persons (53% women, aged 50-62 years) representative of the general population and without self-reported diabetes, CKD, or cardiovascular disease. Participants' GFR was measured by plasma iohexol clearance in 2007-2009 (n=1627), 2013-2015 (n=1324), and 2018-2020 (n=1384). At each study visit, healthy persons were defined as having no major chronic diseases or risk factors for CKD. We used generalized additive mixed models to assess age- and sex-specific GFR decline rates.

RESULTS

Women had a lower GFR than men at baseline (mean [SD], 90.0 [14.0] versus 98.0 [13.7] ml/min per 1.73 m2; P<0.001). The mean GFR change rate was -0.96 (95% confidence interval [CI], -0.88 to -1.04) ml/min per 1.73 m2 per year in women and -1.20 (95% confidence interval [CI], -1.12 to -1.28) in men. Although the relationship between age and GFR was very close to linear in women, it was curvilinear in men, with steeper GFR slopes at older ages (nonlinear effect; P<0.001). Healthy persons had a slower GFR decline, but health status did not explain the sex difference in the GFR decline.

CONCLUSION

Among middle-aged and elderly individuals in the general population, decline in the mean GFR in women was slower than in men, independent of health status.

Pulse pressure and the risk of renal hyperfiltration in young adults: Results from Korea National Health and Nutrition Examination Survey (2010–2019)

Background

High pulse pressure (PP) is associated with increased risk of decline of kidney function. However, little is known about the association between PP and RHF in young adults. This study aimed to evaluate the association between PP and RHF in healthy young adults.

Methods

Data were retrieved from the Korea National Health and Nutrition Examination Survey from 2010 to 2019. A total of 10,365 participants aged 19–39 years with no hypertension and normal kidney function were analyzed. RHF was defined as logarithm transformed estimated glomerular filtration rate (eGFR) with residuals >90th percentile after adjustment for sex, logarithm transformed age, weight, and height. Participants were divided into tertile based on PP levels.

Results

The prevalence of RHF was higher in higher PP tertile group (6.6, 10.5, and 12.7% in T1, T2, and T3; P for trend < 0.001). In multivariable logistic regression analyses, the risk for RHF was increased in higher PP tertiles compared to the lowest tertile [odds ratio (OR), 1.42; 95% confidence interval (CI), 1.19–1.69 in T2; OR, 1.44; 95% CI, 1.20–1.73 in T3]. When PP levels were treated as continuous variable, the risk of RHF was increased 2.36 per 1.0 increase of PP (P < 0.001). In subgroup analyses stratified sex, histories of diabetes or dyslipidemia, and isolated systolic hypertension or isolated diastolic hypertension, there were no significant interactions with PP for the risk for RHF, suggesting that high PP was associated with increased risk of RHF regardless of subgroups. However, the subgroup with BMI showed significant interaction with PP for the risk of RHF, indicating that participants with BMI ≥ 25 kg/m² were at higher risk of RHF with increasing PP levels than those with BMI < 25 kg/m² (OR, 1.89; 95% CI, 1.25–2.87 in BMI < 25 kg/m²; OR, 3.16; 95% CI, 1.74–5.73 in BMI ≥ 25 kg/m²; P for interaction = 0.01).

Conclusion

High PP is associated with an increased risk of RHF in healthy young adults and this association is prominent in obese young adults. The assessment of PP and associated RHF may give benefit to early detect the potential risk of CKD development in young adults.

Progressive, Qualitative, and Quantitative Alterations in HDL Lipidome from Healthy Subjects to Patients with Prediabetes and Type 2 Diabetes

Prediabetes is a clinically silent, insulin-resistant state with increased risk for the development of type 2 diabetes (T2D) and cardiovascular disease (CVD). Since glucose homeostasis and lipid metabolism are highly intersected and interrelated, an in-depth characterization of qualitative and quantitative abnormalities in lipoproteins could unravel the metabolic pathways underlying the progression of prediabetes to T2D and also the proneness of these patients to developing premature atherosclerosis. We investigated the HDL lipidome in 40 patients with prediabetes and compared it to that of 40 normoglycemic individuals and 40 patients with established T2D using Nuclear Magnetic Resonance (NMR) spectroscopy. Patients with prediabetes presented significant qualitative and quantitative alterations, potentially atherogenic, in HDL lipidome compared to normoglycemic characterized by higher percentages of free cholesterol and triglycerides, whereas phospholipids were lower. Glycerophospholipids and ether glycerolipids were significantly lower in prediabetic compared to normoglycemic individuals, whereas sphingolipids were significantly higher. In prediabetes, lipids were esterified with saturated rather than unsaturated fatty acids. These changes are qualitatively similar, but quantitatively milder, than those found in patients with T2D. We conclude that the detailed characterization of the HDL lipid profile bears a potential to identify patients with subtle (but still proatherogenic) abnormalities who are at high risk for development of T2D and CVD.

Increased Risk of NAFLD in Adults with Glomerular Hyperfiltration: An 8-Year Cohort Study Based on 147,162 Koreans

This study evaluated whether glomerular hyperfiltration (GHF) could predict nonalcoholic fatty liver disease (NAFLD) and fibrosis. A longitudinal cohort study including 147,479 participants aged 20–65 years without NAFLD and kidney disease at baseline was performed. GHF cutoff values were defined as age- and sex-specific estimated glomerular filtration rate (eGFRs) above the 95th percentile, and eGFR values between the 50th and 65th percentiles were used as reference groups. NAFLD was diagnosed via abdominal ultrasonography, and the fibrosis status was evaluated using the NAFLD fibrosis score and Fibrosis-4. During 598,745 person years of follow-up (median, 4.6 years), subjects with GHF at baseline had the highest hazard ratio (HR) for the development of NAFLD (HR 1.21; 95% CI 1.14–1.29) and fibrosis progression (HR 1.42; 95% CI 1.11–1.82) after adjusting for confounding factors. A higher baseline eGFR percentile maintained a higher risk of NAFLD and fibrosis probability. The persistent GHF group during follow-up had the highest HR for NAFLD compared to the persistent non-GHF group (HR 1.31; 95% CI 1.14–1.51). These results were consistent in all subgroups and statistically more prominent in participants without diabetes. GHF was positively associated with increased risk of NAFLD and probability of liver fibrosis in healthy adults.

Association between changes in lipid indexes and early progression of kidney dysfunction in participants with normal estimated glomerular filtration rate: a prospective cohort study

PURPOSE

To investigate whether non-high-density lipoprotein cholesterol (Non-HDL-C), remnant cholesterol (RC), and the ratios of lipid indexes are more closely associated with early progression of kidney dysfunction than traditional lipid indexes; and to explore the association between changes in serum lipids during follow-up and annual decline rate in estimated glomerular filtration rate (eGFR).

METHODS

In this prospective cohort study, 3909 participants with normal eGFR and age≥40 years at baseline were followed for 3.3 years. Progression of kidney dysfunction was assessed as annual decline rate in eGFR. Spearman correlation analysis, linear correlation models, and multiple logistic regression were used to assess the associations between lipid indexes at baseline/both baseline and follow-up and the annual decline rate in eGFR.

RESULTS

Compared with ΔLDL-C (β = 0.412), other lipid indexes such as ΔLDL-C/HDL-C (β = 0.565), ΔTC/HDL-C (β = 0.448), and ΔNon-HDL-C/HDL-C (β = 0.448) were more closely associated with annual decline rate in eGFR. High TG/HDL-C (OR = 1.699(1.177-2.454)) and TC/HDL-C (OR = 1.567(1.095-2.243)) at baseline, as well as high TC/HDL-C (OR = 1.478 (1.003-2.177)) and TG/HDL-C (OR = 1.53(1.044-2.244)) at both baseline and follow-up were associated with the annual decline rate in eGFR <0.5. High Non-HDL-C (OR = 1.633(1.025-2.602)) and LCI (OR = 1.631(1.010-2.416)) at both baseline and follow-up resulted in a 63% increase in risk of annual decline rate in eGFR >1.

CONCLUSION

High Non-HDL-C, RC and the ratios of lipid indexes were more closely associated with early progression of kidney injury than the increase of traditional lipid indexes. These lipid indexes should be monitored, even in participants with normal traditional serum lipid levels.

Repeatedly Measured Serum Creatinine and Cognitive Performance in Midlife: The Cardiovascular Risk in Young Finns Study

BACKGROUND AND OBJECTIVES

Serum creatinine is typically used to assess kidney function. Impaired kidney function and thereby high serum creatinine increases risk of poor cognitive performance. However, serum creatinine might have a non-linear association as low serum creatinine has been linked with cardiovascular risk and impaired cognitive performance. We studied the longitudinal association between serum creatinine and cognitive performance in midlife.

METHODS

Since 2001, participants from the Cardiovascular Risk in Young Finns Study were followed up for 10 years. Serum creatinine was measured repeatedly in 2001, 2007, and 2011. Sex-specific longitudinal trajectories for serum creatinine among participants without kidney disease were identified using latent class growth mixture modeling. Overall cognitive function and four specific domains such as 1) working memory, 2) episodic memory and associative learning, 3) reaction time, and 4) information processing were assessed using a computerized cognitive test.

RESULTS

Four serum creatinine trajectory groups all with clinically normal serum creatinine were identified for both men (N=973) and women (N=1,204). After 10 years of follow-up, cognitive testing was performed for 2,026 participants aged 34 to 49 years (mean age 41.8 years). In men and women, consistently low serum creatinine was associated with poor childhood school performance, low adulthood education, low adulthood annual income, low physical activity, and smoking. Compared to the men in the low serum creatinine trajectory group, those in the high serum creatinine group had better overall cognitive performance (β=0.353 SD, 95%CI 0.022-0.684) and working memory (β=0.351 SD, 95%CI 0.034-0.668), while those in the moderate (β=0.247 SD, 95%CI 0.026-0.468) or the normal (β=0.244 SD, 95%CI 0.008-0.481) serum creatinine groups had better episodic memory and associative learning. No associations were found for women.

DISCUSSION

Our results indicate that, in men, compared to low serum creatinine levels consistently high levels may associate with better memory and learning function in midlife.

Effect of Anagliptin versus Sitagliptin on Renal Function: Subanalyzes from the REASON Trial

PURPOSE

The effects of two types of dipeptidyl peptidase-4 (DPP-4) inhibitors on renal function remain unclear. Thus, we investigated the effect of anagliptin (ANA) and sitagliptin (SITA) on renal function in patients with type 2 diabetes who participated in the randomized evaluation of ANA versus SITA on low-density lipoprotein-cholesterol (LDL-C) in diabetes (REASON) trial.

PATIENTS AND METHODS

We measured the estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) before and after the REASON trial. ANA 200 mg/day was administered to 177 patients for 52 weeks, while SITA 50 mg/day was given to 176 patients. We investigated the relationship between differences in renal function and differences in hemoglobin A1c (HbA1c) levels, LDL-C levels, and blood pressure (BP).

RESULTS

No significant differences were found in baseline eGFR and UACR between the two groups. The eGFR levels were significantly decreased in both groups; however, the UACR level was unchanged in the ANA group but elevated in the SITA group, although the difference did not reach significance between the two groups. The difference in eGFR was affected by the differences in HbA1c level and BP, and the difference in the UACR was affected by the differences in LDL-C level and BP, which were reduced only in the ANA group.

CONCLUSION

These findings imply that the effects of DPP-4 inhibitors on renal function, especially on UACR, may be different between the types of DPP-4 inhibitors.

Impaired fasting blood glucose is associated with incident albuminuria: Data from a Chinese community-based cohort

OBJECTIVE

Growing evidence links hyperglycemia in the diabetic range to albuminuria, while the association between impaired fasting glucose (IFG) and albuminuria is not well established. The study intends to explore whether IFG is longitudinally associated with incident albuminuria in a non-diabetic Chinese community-based cohort.

METHODS

Participants with urine albumin creatinine ratio (UACR) both in 2014 and 2018 from the atherosclerotic cohort were included. A total of 1649 non-diabetic subjects were ultimately included in the analysis after ruling out participants with UACR≥30 mg/g and self-reported history of renal diseases at baseline. Fasting blood glucose (FBG) was assessed by Roche C8000 Automatic Analyzer and UACR was measured with Unicel DxC 800 Synchron biochemistry analyzer using spot morning urine sample. Incident albuminuria was defined as an advance from normal to microalbuminuria or macroalbuminuria. Multivariable logistic regression model was used to investigate the relationship between FBG and incident albuminuria.

RESULTS

During a mean follow-up of 4.38 years, 82 (4.97%) participants developed incident albuminuria. Logistic regression analysis showed that after adjustment, the risk of incident albuminuria increased by 71% (OR = 1.71, 95%CI: 1.11-2.62, P = 0.014) for every 18 mg/dl (1 mmol/l) increase of FBG level. Besides, FBG level was independently and gradably associated with incident albuminuria. Compared with the FBG < 100 mg/dl (5.6 mmol/l) group, the risk increased 1.63-fold for incident albuminuria (OR = 2.63, 95%CI:1.42-4.87, P = 0.002) in the FBG 110-126 mg/dl (6.1-7.0 mmol/l) group while the association between FBG 100-110 mg/dl (5.6-6.1 mmol/l) group and the outcome was not significant. Subgroup and interaction analyses were performed and no significant modification effect was found.

CONCLUSION

IFG was independently associated with incident albuminuria in Chinese community-based population. The higher the FBG level, the higher the risk of incident albuminuria, which may suggest that screening for albuminuria should be emphasized in population with IFG so as to prevent and treat it in an early stage.

Diabetic kidney disease in children and adolescents: an update

Diabetic kidney disease (DKD), previously encountered predominantly in adult patients, is rapidly gaining center stage as a childhood morbidity and one that pediatric nephrologists are likely to encounter with increasing frequency. This is in large part due to the obesity epidemic and the consequent rise in type 2 diabetes in children and adolescents, as well as the more aggressive diabetes phenotype in today's youth with more rapid β-cell decline and faster development and progression of diabetes-related complications along with lower responsiveness to the treatments used in adults. DKD, an end-organ complication of diabetes, is at the very least a marker of, and more likely a predisposing factor for, the development of adverse cardiovascular outcomes and premature mortality in children with diabetes. On an optimistic note, several new therapeutic approaches are now available for the management of diabetes in adults, such as GLP1 receptor agonists, SGLT2 inhibitors, and DPP4 inhibitors, that have also been shown to have a favorable impact on cardiorenal outcomes. Also promising is the success of very low-energy diets in inducing remission of diabetes in adults. However, the addition of these pharmacological and dietary approaches to the management toolbox of diabetes and DKD in children and adolescents awaits thorough assessment of their safety and efficacy in this population. This review outlines the scope of diabetes and DKD, and new developments that may favorably impact the management of children and young adults with diabetes and DKD.

Lipidomic and Metabolomic Signature of Progression of Chronic Kidney Disease in Patients with Severe Obesity

Severe obesity is a major risk for chronic kidney disease (CKD). Early detection and careful monitoring of renal function are critical for the prevention of CKD during obesity, since biopsies are not performed in patients with CKD and diagnosis is dependent on the assessment of clinical parameters. To explore whether distinct lipid and metabolic signatures in obesity may signify early stages of pathogenesis toward CKD, liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-high resolution accurate mass-mass spectrometry (GC-HRAM-MS) analyses were performed in the serum and the urine of severely obese patients with and without CKD. Moreover, the impact of bariatric surgery (BS) in lipid and metabolic signature was also studied, through LC-MS and GC-HRAM-MS analyses in the serum and urine of patients with severe obesity and CKD before and after undergoing BS. Regarding patients with severe obesity and CKD compared to severely obese patients without CKD, serum lipidome analysis revealed significant differences in lipid signature. Furthermore, serum metabolomics profile revealed significant changes in specific amino acids, with isoleucine and tyrosine, increased in CKD patients compared with patients without CKD. LC-MS and GC-HRAM-MS analysis in serum of patients with severe obesity and CKD after BS showed downregulation of levels of triglycerides (TGs) and diglycerides (DGs) as well as a decrease in branched-chain amino acid (BCAA), lysine, threonine, proline, and serine. In addition, BS removed most of the correlations in CKD patients against biochemical parameters related to kidney dysfunction. Concerning urine analysis, hippuric acid, valine and glutamine were significantly decreased in urine from CKD patients after surgery. Interestingly, bariatric surgery did not restore all the lipid species, some of them decreased, hence drawing attention to them as potential targets for early diagnosis or therapeutic intervention. Results obtained in this study would justify the use of comprehensive mass spectrometry-based lipidomics to measure other lipids aside from conventional lipid profiles and to validate possible early markers of risk of CKD in patients with severe obesity.

Glomerular Hyperfiltration Interacts With Abnormal Metabolism to Enhance Arterial Stiffness in Middle-Aged and Elderly People

Introduction: Glomerular hyperfiltration (GHF) is an early kidney injury. We investigated whether GHF is associated with arterial stiffness expressed by increase of brachial-ankle pulse wave velocity (baPWV) and pulse pressure (PP), and whether the coexistence of GHF and abnormal metabolism increases the risk of arterial stiffness. Methods: In this prospective cohort study, 2,133 non-chronic kidney disease (CKD) participants aged ≥40 years were followed for a mean period of 3.3 years. The extent of arterial stiffness was expressed by measures of baPWV and PP. GHF was defined as eGFR exceeding the age- and sex-specific 90th percentile. Multivariate logistic regression models were used to assess the association between GHF/abnormal metabolism and increased baPWV/PP. The interaction indexes of GHF and abnormal metabolism on arterial stiffness were calculated based on the OR in a multivariate logistic regression model. Results: GHF alone was not associated with increased baPWV or PP in all participants in this study. However, when GHF coexisted with abnormal metabolism, the risk of increased PP increased 3.23-fold [OR = 3.23(1.47-7.13)] compared with participants with normal filtration and normal metabolism, in which the interaction accounted for 55.1% of the total effect and 79.8% of the effect from GHF and abnormal metabolism. After subtracting the independent effects of GHF and abnormal metabolism, their combined effect still resulted in a 1.78-fold increase in PP. Conclusion: GHF could interact with abnormal metabolism to significantly enhance arterial stiffness. Since abnormal metabolism commonly exists in the general population, even slight changes in renal function should be distinguished to prevent arterial stiffness risk.

The association of glucose metabolism and kidney function in middle-aged adults

BACKGROUND

Previous clinical studies have shown that various measures of glucose metabolism are associated with a risk of chronic kidney disease in different populations, but results were not consistent. In this study we assessed measures of glucose metabolism and their association with kidney function in a population-based study.

METHODS

The Netherlands Epidemiology of Obesity study is a population-based cohort study of middle-aged men and women. We categorized the study population according to glycaemic levels into normoglycaemia (reference group), pre-diabetes mellitus (pre-DM), known DM and newly diagnosed DM. Outcome variables were serum creatinine, estimated glomerular filtration rate (eGFR), glomerular hyperfiltration (defined as an eGFR >90th percentile; >102 mL/min/1.73 m2) and micro-albuminuria. We examined the association between measures of glucose metabolism [fasting glucose, haemoglobin A1c (HbA1c), fasting insulin, glucose area under the curve (AUC), insulin AUC, Homoeostatic Model Assessment of Insulin Resistance (HOMA-IR), HOMA of β-cell function (HOMA-B) and disposition index] and measures of kidney function.

RESULTS

Of the total population (N = 6338), 55% of participants were classified as normoglycaemic (reference), 35% as pre-DM, 7% as DM and 4% as newly diagnosed DM. Compared with the reference group, diagnosed and newly diagnosed DMs were associated with a slightly higher trend in eGFR {+2.1 mL/min/1.73 m2 [95% confidence interval (CI) -0.2-4.4] and +2.7 mL/min/1.73 m2 [95% CI -0.3-5.7], respectively}. A 1% higher HbA1c was associated with increased odds of hyperfiltration [odds ratio (OR) 1.41 (95% CI 1.06-1.88)]. Higher levels of fasting plasma glucose, AUC glucose and HOMA-B were associated with hyperfiltration. Fasting insulin, AUC insulin and HOMA-IR were not associated with hyperfiltration. The OR of microalbuminuria was 1.21 (95% CI 1.04-1.42) per mmol/L higher fasting glucose concentrations.

CONCLUSIONS

Both fasting and post-prandial glucose and HOMA-B, but not measures of insulin resistance, were associated with glomerular hyperfiltration, while fasting glucose was also associated with microalbuminuria.

Renal Dysfunction in Prediabetes: Confirmed by Glomerular Hyperfiltration and Albuminuria

Objectives Prediabetes is defined as an intermediate state of hyperglycemia with glucose levels above normal but below the diagnostic cutoff of diabetes mellitus. Prediabetes is considered as an important risk factor for the development of diabetes and complications associated with diabetes. Since glomerular hyperfiltration (elevated GFR) and albuminuria represent early and reversible stages of kidney damage seen in patients with type 2 diabetes, we aim to assess the impact of hyperglycemia in prediabetic range on renal functions measured by estimated GFR and urine albumin excretion (UAE).

Materials and Methods The study included 1,031 patients aged 30 to 70 years, attending regular health checkup. Patients were grouped as normal, prediabetes, and diabetes according to the American Diabetic Association (ADA) criteria based on fasting blood sugar and hemoglobin A1c (HbA1c). Further, the patients were grouped into multiple subgroups based on age and gender. UAE was measured by using immunoturbidimetric method, and GFR was estimated by chronic kidney disease epidemiology collaboration (CKD EPI) equation.

Statistical Analysis Prevalence of hyperfiltration (estimated glomerular filtration rate above the age and gender specific 95th percentile), and albuminuria in prediabetes and diabetes was compared with normal controls. Odds ratio and 95% confidence interval were calculated by using logistic regression analysis to predict the occurrence of hyperfiltration in prediabetes and diabetes. Analysis of variance followed by post hoc comparison was done to assess the significance of difference, and p -value < 0.05 was considered statistically significant.

Results Prevalence of hyperfiltration was more in prediabetes and diabetes compared with normal controls, and it increased with surging HbA1c level that was shown as higher odds ratio for hyperfiltration in both the groups. UAE was more in the prediabetes and diabetes group when compared with normal controls, but the difference was significant only in diabetes.

Conclusion Since glomerular hyperfiltration represents an early and reversible stage of renal damage manifesting before the appearance of albuminuria, elevated GFR can be used to identify asymptomatic patients with intermediate hyperglycemia having high risk of developing nephropathy in the future. Prediabetes represents a window of opportunity to initiate preventive strategies at an early stage before the occurrence of significant renal damage.

Life course pathways from parental education to age-related decrements in kidney function among Black and white American adults

OBJECTIVE

Using cross-sectional data on Black and white adults, this analysis examined whether age-related decrements in kidney function across adulthood were associated with parental education, and whether the association was differentially influenced by race. Further, this study assessed racial differences in life course pathways from parental education to age-related decrements in kidney function, through current SES and health-related risk factors.

METHOD

Data from the main survey and the Biomarker Project of the Midlife in the United States (MIDUS) Wave 2 and Refresher samples were combined, resulting in 1861 adults (54.5% female; age 25-84, Mage = 53.37) who self-identified as non-Hispanic Black (n = 326) and non-Hispanic white (n = 1535). Estimated glomerular filtration rate (eGFR) was based on serum creatinine, calculated using the CKD-EPI formula. Adults SES was based on education, income, and financial strains. Health-related risk factors included obesity, elevated blood pressure (BP), and insulin resistance. Hypotheses were tested by utilizing multiple linear regression and regression-based moderated mediation analysis.

RESULTS

Lower parental education was associated with steeper age-related decrements in eGFR (B = 0.38, SE = 0.15, p = .013, 95%CI = 0.08, 0.68), due to higher eGFR among younger participants and lower eGFR among older participants. In addition, age-related decrements in kidney function were steeper among Black relative to white adults (B = 0.41, SE = 0.13, p < .01, 95%CI = 0.16, 0.66), driven by higher proportion of younger Black adults that met criterion for renal hyperfiltration. Furthermore, parental education and race were associated with age-related decrements in kidney function in an additive rather than interactive way. There were some racial differences in the life course pathways from parental education to age-related differences in eGFR, glucoregulation, and hypertension. Among Black adults, lower parental education was associated with elevated eGFR among younger participants through insulin resistance. Among white adults, lower parental education was linked to higher eGFR among younger adults and lower eGFR among older adults, and the association was mediated by current SES, elevated BP, and insulin resistance.

DISCUSSION

Early life SES can have a long-lasting influence on the preclinical renal senescence that is associated with the normal biology of aging for both Black and white adults.

Validation of Indian Diabetes Risk Score for Screening Prediabetes in West Tripura District of India

Background:

Viswanathan Mohan and his team have developed “Indian Diabetes Risk Score” (IDRS) for identifying the Indians at risk for developing diabetes and prediabetes. Due to heterogeneity of Indian population, this risk score needs further validation in different parts across the country.

Objectives:

The objective is to estimate the sensitivity, specificity, positive, and negative predictive values of IDRS for screening prediabetes in West Tripura District.

Methodology:

It was a community-based cross-sectional study conducted in West Tripura district during January 1, 2018–December 31, 2019 among 325 self-declared nondiabetic individuals, selected by multistage sampling. Fasting blood sugar value was used as the gold standard to validate IDRS. Data were collected using a validated and pretested interview schedule. Data entry and analysis were performed in computer using SPSS-24. Receiver operating characteristic (ROC) curve was constructed to validate IDRS.

Results:

Among the study individuals, 19% and 6.5% were identified as prediabetic and diabetics, respectively. Optimum sensitivity of 83.13% and specificity of 82.64%, with positive and negative predictive values 62.16% and 93.45%, respectively, were observed at an IDRS score of ≥60 for identifying prediabetes and diabetes in this study population. IDRS showed good accuracy with an area under ROC curve of 0.832 (95% confidence interval: 0.77–0.88).

Conclusion:

IDRS is found to be a valid tool for screening prediabetes at community level in West Tripura district of India.

Association of High-Density Lipoprotein Cholesterol With GFR Decline in a General Nondiabetic Population

Introduction

Although lower high-density lipoprotein cholesterol (HDL-C) levels are considered a risk factor for cardiovascular disease (CVD), experimental evidence suggest that aging, inflammation, and oxidative stress may remodel HDL-C, leading to dysfunctional HDL-C. Population studies on HDL-C and loss of the glomerular filtration rate (GFR) reported inconsistent results, but they used inaccurate estimates of the GFR and may have been confounded by comorbidity.

Methods

We investigated the association of HDL-C levels with risk of GFR loss in a general population cohort; the participants were aged 50-62 years and did not have diabetes, CVD, or chronic kidney disease (CKD) at baseline. The GFR was measured using iohexol-clearance at baseline (n=1627) and at the follow-up (n=1324) after a median of 5.6 years. We also investigated any possible effect modification by low-grade inflammation, physical activity, and sex.

Results

Higher HDL-C levels were associated with steeper GFR decline rates and increased risk of rapid GFR decline (>3 ml/min per 1.73 m² per year) in multivariable adjusted linear mixed models and logistic regression (-0.64 ml/min per 1.73 m² per year [95% CI -0.99, -0.29; P < 0.001] and odds ratio 2.7 [95% CI 1.4, 5.2; P < 0.001] per doubling in HDL-C). Effect modifications indicated a stronger association between high HDL-C and GFR loss in physically inactive persons, those with low-grade inflammation, and men.

Conclusion

Higher HDL-C levels were independently associated with accelerated GFR loss in a general middle-aged nondiabetic population.

The impact of baseline glomerular filtration rate on subsequent changes of glomerular filtration rate in patients with chronic kidney disease

Higher baseline glomerular filtration rate (GFR) may yield subsequent steeper GFR decline, especially in patients with diabetes mellitus (DM). However, this correlation in patients with chronic kidney disease (CKD) and the presence or absence of DM remains controversial. We conducted a longitudinal cohort study in a single medical center between 2011 and 2018. Participants with CKD stage 1 to 3A were enrolled and divided into DM groups and non-DM groups, and then followed up at least every 6 months. We used a linear mixed regression model with centering time variable to overcome the problem of mathematical coupling in the analysis of the relation between baseline GFR and the changes, and compared the results from correct and incorrect specifications of the mixed models. A total number of 1002 patients with 285 diabetic and 717 non-diabetic persons was identified. The linear mixed regression model revealed a significantly negative correlation between baseline GFR and subsequent GFR change rate in both diabetic group and non-diabetic group (r =  - 0.44 [95% confidence interval [CI], - 0.69 to - 0.09]), but no statistical significance in non-diabetic group after within-subject mean centering of time variable (r =  - 0.09 [95% CI, - 0.41 to 0.25]). Our study showed that higher baseline GFR was associated with a subsequent steeper GFR decline in the DM group but not in the non-DM group among patients with early-stage CKD. Exact model specifications should be described in detail to prevent from a spurious conclusion.

Independent and interactive effects of kidney stone formation and conventional risk factors for chronic kidney disease: a follow-up study of Japanese men

PURPOSE

To assess the impact of interactions between kidney stone formation and conventional risk factors on incident chronic kidney disease (CKD).

METHODS

A total of 11,402 subjects (men 30-69 years of age, Japanese) without CKD at baseline were observed over an average period of 4 years. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) to determine the association between incident CKD, kidney stone formation, and conventional risk factors (diabetes mellitus, hypertension, overweight/obesity, dyslipidemia, and hyperuricemia/gout). We also examined the interactions of renal stones and the conventional risk factors for CKD.

RESULTS

In total, 2301 men (20.2%) developed incident CKD during the follow-up period. After multivariable adjustment, kidney stones were found to increase the risk of incident CKD (HR 1.16; 95% CI 1.03-1.32). Kidney stone formers with hypertension, dyslipidemia, or hyperuricemia/gout presented a greater risk for incident CKD than those who had either kidney stones or other risk factors. However, no significant interactions between kidney stones and other risk factors were found to increase CKD risk. On the other hand, a negative interactive effect between kidney stones and overweight/obesity was observed, leading to reversed risk of incident CKD in coexistence of both factors.

CONCLUSION

Kidney stones were linked to a higher risk for the development of CKD. However, no positive interactive effects were identified between renal stones and conventional risk factors on the risk of incident CKD.

Renal functional impairment in the elderly, the importance of fasting plasma glucose: the Northern Shanghai Study

BACKGROUND

Chronic kidney disease is a global health problem that is closely related to the aging population. Although plasma glucose levels have been shown to be related to renal dysfunction, risk factors for renal functional impairment in the geriatric population are unknown. The authors therefore aimed to investigate the determinants of renal functional impairment in an elderly population.

METHODS

From June 2014 to August 2015, 912 participants (aged > 65 years) were recruited. Renal function was assessed at baseline; follow-up was conducted in 2016. Within the framework of comprehensive cardiovascular examinations, all conventional cardiovascular risk factors, fasting plasma glucose (FPG), and renal function were assessed. Renal function was evaluated by the estimated glomerular filtration rate (e-GFR) using a modified Modification of Diet in Renal Disease formula. Rapid decline in e-GFR was defined as an e-GFR slope > 5 mL/min per 1.73 m² per year.

RESULTS

We observed that FPG levels were significantly higher in participants with (6.15 ± 2.76 mmol/L) than in those without (5.56 ± 1.61 mmol/L) a rapid decline in e-GFR (p = 0.02). The average decline in e-GFR was 0.149 mL/min/1.73m² per year in this elderly population, and the increasing risk of having rapid decline in e-GFR was 0.44-fold each year. In the full adjustment model, decline in e-GFR (p = 0.02) and rapid decline in e-GFR (OR1.33, 95% CI 1.03-1.72) were significantly associated with FPG, independent of other conventional cardiovascular risk factors. Using the same models, decline in e-GFR (p = 0.04) and rapid decline in e-GFR (OR 1.57, 95% CI 1.05-2.35) were also significantly associated with FPG in diabetic population, but they were not in non-diabetic population.

CONCLUSIONS

In community-dwelling elderly Chinese, the average decline in e-GFR was 0.149 mL/min/1.73m² per year. FPG control is important for delaying renal functional impairment in elderly population. Trial registration NSS, NCT02368938.

Lipid Accumulation Product is Associated with Urinary Albumin-creatinine Ratio in Chinese Prediabitic Population: A Report from the REACTION Study

BACKGROUND

Lipid accumulation product (LAP) as a powerful marker of visceral obesity is an independent risk factor of chronic kidney disease. The present study attempted to explore the association between LAP and albuminuria in prediabetic individuals.

METHODS

We conducted a cross-sectional study and enrolled 26,529 participants with prediabetes over 40 years old with prediabetes from seven provinces in China. LAP was calculated from waist circumference and fasting triglycerides. Elevated albuminuria was defined by urinary albumin-creatinine ratio (uACR) ≥30 mg/g. Propensity score matching was applied to reduce bias, comparison between LAP and other traditional visceral obesity indices was performed and multiple logistic regression models were conducted to assess the association between LAP and albuminuria in the prediabetic population.

RESULTS

Individuals with uACR ≥30 mg/g were older and had higher BP, BMI, WC, TG, fasting insulin, glycohemoglobin and LAP, as well as lower eGFR and HDL level. Multiple logistic regression analysis showed elevated LAP was associated with increased odds of albuminuria (OR [95%CI]_{Q2 vs Q1} 1.09 [0.94, 1.27], OR [95%CI]_{Q3 vs Q1} 1.13 [0.97, 1.31], OR [95%CI]_{Q4 vs Q1} 1.42 [1.21, 1.67], P for trend=0.018), and superior over waist-to-hip ratio or waist-to-height ratio. Stratification indicated that the prediabetic population with higher LAP level and characterized by female gender, middle age, being overweight, and rise in blood pressure were more likely to have increased uACR.

CONCLUSION

Elevated level of LAP was associated with increased albuminuria in the prediabetic population in China.

Conventional and Genetic Evidence on the Association between Adiposity and CKD

BACKGROUND

The size of any causal contribution of central and general adiposity to CKD risk and the underlying mechanism of mediation are unknown.

METHODS

Data from 281,228 UK Biobank participants were used to estimate the relevance of waist-to-hip ratio and body mass index (BMI) to CKD prevalence. Conventional approaches used logistic regression. Genetic analyses used Mendelian randomization (MR) and data from 394 waist-to-hip ratio and 773 BMI-associated loci. Models assessed the role of known mediators (diabetes mellitus and BP) by adjusting for measured values (conventional analyses) or genetic associations of the selected loci (multivariable MR).

RESULTS

Evidence of CKD was found in 18,034 (6.4%) participants. Each 0.06 higher measured waist-to-hip ratio and each 5-kg/m² increase in BMI were associated with 69% (odds ratio, 1.69; 95% CI, 1.64 to 1.74) and 58% (1.58; 1.55 to 1.62) higher odds of CKD, respectively. In analogous MR analyses, each 0.06-genetically-predicted higher waist-to-hip ratio was associated with a 29% (1.29; 1.20 to 1.38) increased odds of CKD, and each 5-kg/m² genetically-predicted higher BMI was associated with a 49% (1.49; 1.39 to 1.59) increased odds. After adjusting for diabetes and measured BP, chi-squared values for associations for waist-to-hip ratio and BMI fell by 56%. In contrast, mediator adjustment using multivariable MR found 83% and 69% reductions in chi-squared values for genetically-predicted waist-to-hip ratio and BMI models, respectively.

CONCLUSIONS

Genetic analyses suggest that conventional associations between central and general adiposity with CKD are largely causal. However, conventional approaches underestimate mediating roles of diabetes, BP, and their correlates. Genetic approaches suggest these mediators explain most of adiposity-CKD-associated risk.

Comparison of high glomerular filtration rate thresholds for identifying hyperfiltration

BACKGROUND

High glomerular filtration rate (GFR) is often used as a surrogate for single-nephron hyperfiltration. Our objective was to determine the definition for high GFR that best reflects clinical and structural characteristics of hyperfiltration.

METHODS

We studied living kidney donors at the Mayo Clinic and Cleveland Clinic. Potential donors underwent evaluations that included measured GFR (mGFR) by iothalamate clearance and estimated GFR (eGFR) by the serum creatinine-based Chronic Kidney Disease-Epidemiology collaboration (CKD-EPI) equation. High GFR was defined by the 95th percentile for each method (mGFR or eGFR) using either overall or age-specific thresholds. High mGFR was defined as both corrected and uncorrected for body surface area. The association of high GFR by each definition with clinical characteristics and radiologic findings (kidney volume) was assessed. In the subset that donated, the association of high GFR with kidney biopsy findings (nephron number and glomerular volume) and single-nephron GFR was assessed.

RESULTS

We studied 3317 potential donors, including 2125 actual donors. The overall 95th percentile for corrected mGFR was 134 mL/min/1.73 m2 and for eGFR was 118 mL/min/1.73 m2. The age-based threshold for uncorrected mGFR was 198 mL/min - 0.943×Age, for corrected mGFR it was 164 mL/min/1.73 m2 - 0.730×Age and for eGFR it was 146 mL/min/1.73 m2 - 0.813×Age. High age-based uncorrected mGFR had the strongest associations with higher single-nephron GFR, larger glomerular volume, larger kidney volume, male gender, higher body mass index and higher 24-h urine albumin, but also had the strongest association with high nephron number. A high age-height-gender-based uncorrected mGFR definition performed almost as well but had a weaker association with nephron number and did not associate with male gender.

CONCLUSIONS

High age-based uncorrected mGFR showed the most consistent associations reflective of hyperfiltration. However, high age-based uncorrected mGFR has limited clinical utility because it does not distinguish between hyperfiltration and high nephron number.

Cross-sectional associations between central and general adiposity with albuminuria: observations from 400,000 people in UK Biobank

BACKGROUND

Whether measures of central adiposity are more or less strongly associated with risk of albuminuria than body mass index (BMI), and by how much diabetes/levels of glycosylated haemoglobin (HbA1c) explain or modify these associations, is uncertain.

METHODS

Ordinal logistic regression was used to estimate associations between values of central adiposity (waist-to-hip ratio) and, separately, general adiposity (BMI) with categories of urinary albumin-to-creatinine ratio (uACR) in 408,527 UK Biobank participants. Separate central and general adiposity-based models were initially adjusted for potential confounders and measurement error, then sequentially, models were mutually adjusted (e.g. waist-to-hip ratio adjusted for BMI, and vice versa), and finally they were adjusted for potential mediators.

RESULTS

Levels of albuminuria were generally low: 20,425 (5%) had a uACR ≥3 mg/mmol. After adjustment for confounders and measurement error, each 0.06 higher waist-to-hip ratio was associated with a 55% (95%CI 53-57%) increase in the odds of being in a higher uACR category. After adjustment for baseline BMI, this association was reduced to 32% (30-34%). Each 5 kg/m2 higher BMI was associated with a 47% (46-49%) increase in the odds of being in a higher uACR category. Adjustment for baseline waist-to-hip ratio reduced this association to 35% (33-37%). Those with higher HbA1c were at progressively higher odds of albuminuria, but positive associations between both waist-to-hip ratio and BMI were apparent irrespective of HbA1c. Altogether, about 40% of central adiposity associations appeared to be mediated by diabetes, vascular disease and blood pressure.

CONCLUSIONS

Conventional epidemiological approaches suggest that higher waist-to-hip ratio and BMI are independently positively associated with albuminuria. Adiposity-albuminuria associations appear strong among people with normal HbA1c, as well as people with pre-diabetes or diabetes.

Prediabetes among HIV-infected individuals receiving antiretroviral therapy: prevalence, diagnostic tests, and associated factors

Background

Metabolic complications in human immunodeficiency virus (HIV)-infected individuals are common. Prediabetes represents a high risk for future diabetes development. This study aimed to determine the prevalence, diagnostic methods, and associated factors of prediabetes among HIV-infected individuals receiving antiretroviral therapy (ART).

Methods

A cross-sectional study was conducted among HIV-infected adults without a history of diabetes who were receiving ART. Fasting plasma glucose (FPG), 2-hour plasma glucose (2-h PG) after a 75-g oral glucose tolerance test, and hemoglobin A1c (HbA1c) were assessed.

Results

A total of 397 patients with a mean age of 47.0 ± 9.8 years and 55.7% male, were studied. All received ART with undetectable plasma viral load. The mean duration of ART was 9.6 ± 5.2 years, and the mean CD4 cell count was 554 ± 235 cells/mm³. Among the patients, 28 (7.1%) had first-diagnosed diabetes, and 133 (33.5%) patients had prediabetes. Glycemia estimation by FPG, 2-h PG, and HbA1c showed a prediabetes prevalence of 17.4%, 14.7%, and 12.5%, respectively. The kappa statistics for the agreement of FPG and 2-h PG, HbA1c and 2-h PG, and HbA1c and FPG were 0.317, 0.429, and 0.396, respectively. In multivariate analysis, hypertension [odds ratio (OR) 3.38; 95% confidence interval (CI), 1.16-9.91; p = 0.026), and triglycerides > 150 mg/dL (OR 2.11; 95% CI, 1.01-4.44; p = 0.047) were factors significantly associated with prediabetes.

Conclusions

Prediabetes among HIV-infected individuals receiving ART is common. The agreements of glycemia estimation methods are minimal to weak. HbA1c may underestimate prediabetes prevalence. Using FPG together with HbA1c increases the detection rate to approximately three-quarters of prediabetes patients. HIV-infected individuals who had hypertension and hypertriglyceridemia should be regularly assessed for prediabetes.

Trial registration ClinicalTrial.gov, NCT03545217. Registered 1 June 2018—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03545217

[The heart and kidney in diabetes: Heart and kidney in diabetes]

The diabetic kidney presents excess expression and activity of the SGLT2 transporter of the proximal tubule. This situation increases the renal reabsorption of Na and glucose and reduces their distal supply. In addition to the metabolic effects on the internal environment of this excess reabsorbed glucose, the renal tubule is subjected to glycosylated stress capable of locally activating both apoptosis and inflammasome. The result is a progressive loss of nephron units, activation of transition of mesangial epithelium and collagen deposition. Activation of insulin signalling by the MAP kinase pathway and resistance to the metabolic effects of insulin take place. This is simultaneously combined with afferent vasodilation due to hyperglycaemia, tubuloglomerular feedback inhibition due to reduced distal fluid supply, podocyte dedifferentiation and reduction in their number, the latter effects being due to insulin resistance. The result is self-feeding renal damage, with intraglomerular hyper-pressure, podocyte dedifferentiation, tubular apoptosis, and local and distant activation of inflammasome. All these effects are susceptible to be totally or partially corrected by inhibiting glucose transport via the SGLT transporters.

Insulin Sensitivity and Renal Hemodynamic Function in Metformin-Treated Adults With Type 2 Diabetes and Preserved Renal Function

OBJECTIVE

Impaired insulin sensitivity is associated with hyperfiltration (i.e., elevated glomerular filtration rate [GFR]) in adolescents with type 2 diabetes (T2D) and adults with prediabetes. Yet, these relationships are based on studies that relied on estimated GFR (eGFR), estimates of insulin sensitivity, or both. We aimed to verify the relationship between insulin sensitivity and renal hemodynamic function by gold standard methods in adults with T2D.

RESEARCH DESIGN AND METHODS

Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp (M value) (glucose infusion rate in mg/kg_lean/min) and renal hemodynamic function by urinary inulin (GFR) and para-aminohippuric acid (effective renal plasma flow [ERPF]) clearances in participants with T2D without overt kidney disease. Filtration fraction (FF) (GFR/ERPF) was calculated. Relationships between insulin sensitivity and renal hemodynamic parameters were examined by multivariable linear regression. Renal hemodynamic parameters were examined across tertiles of M values.

RESULTS

We tested 44 adults with T2D, of whom 77% were male, with mean ± SD age 63 ± 7 years, BMI 31.2 ± 4.0 kg/m², and HbA_1c 7.4 ± 0.6%. Average GFR was 110 ± 26 mL/min, with an FF of 22.1 ± 2.8% and median 24-h urinary albumin excretion of 11.3 mg (interquartile range 5.8-17.0). Average M value was 5.6 ± 2.9 mg/kg_lean/min. Insulin sensitivity inversely correlated with GFR (r = -0.44, P < 0.01) and FF (r = -0.40, P < 0.01), and these associations remained significant after multivariable adjustments for age, sex, renin-angiotensin system inhibitor use, and HbA_1c. In addition, GFR, FF, and urinary albumin excretion were highest in the participants in the lowest M value tertile.

CONCLUSIONS

For the first time, we demonstrate that impaired insulin sensitivity is associated with intrarenal hemodynamic dysfunction by gold standard techniques in adults with T2D treated with metformin monotherapy.

Renal hyperfiltration defined by high estimated glomerular filtration rate: A risk factor for cardiovascular disease and mortality

Renal hyperfiltration, defined as an increased glomerular filtration rate above normal values, is associated with early phases of kidney disease in the setting of various conditions such as obesity and diabetes. Although it is recognized that glomerular hyperfiltration, that is, increased filtration per nephron unit (usually studied at low glomerular filtration levels and often referred to as single nephron hyperfiltration), is a risk factor for the progression of chronic kidney disease, the implications of having renal hyperfiltration for cardiovascular disease and mortality risk are incompletely understood. Recent evidence from diverse populations, including healthy individuals and patients with diabetes or established cardiovascular disease, suggests that renal hyperfiltration is associated with a higher risk of cardiovascular disease and all-cause mortality. In this review, we critically summarize the existing studies, discuss possible mechanisms, and describe the remaining gaps in our knowledge regarding the association of renal hyperfiltration with cardiovascular disease and mortality risk.

Glomerular hyperfiltration may be a novel risk factor of restrictive spirometry pattern: Analysis of the Korea National Health and Nutrition Examination Survey (KNHANES) 2009-2015

BACKGROUND AND OBJECTIVES

There have been limited studies regarding the association between glomerular hyperfiltration (GHF) and restrictive spirometry pattern (RSP) in Korean adults.

METHODS

We used data of 23,189 adults from the Korea National Health and Nutritional Examination Survey 2009-2015 with a complete data set including spirometry, serum creatinine, and anthropometric measurements. Spirometry data included the forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). We defined GHF as the >90th percentile of age & sex adjusted estimated glomerular filtration rate (eGFR), and RSP was defined as an FVC <80%-predicted value and an FEV1/FVC ratio ≥0.7.

RESULTS

Participants with RSP showed higher blood pressure, fasting glucose, and triglyceride, reduced high density lipoprotein cholesterol, and central obesity, which resulted in a higher prevalence of metabolic syndrome (MetS) compared to those without RSP. Multivariate logistic regression revealed that the odds for RSP were significantly increased with an increased number of MetS components. In addition, increased eGFR was associated with decreased FVC, showing an inverted J-shaped relationship in a multivariate generalized additive model analysis. In the multivariate logistic regression analysis, the adjusted odds ratio and 95% confidence interval of GHF for RSP was 1.184 (1.026-1.368, P = 0.021), which was evident in groups without metabolic disorders.

CONCLUSIONS

We concluded that GHF was associated with increased odds for RSP, particularly in groups without metabolic disorders. Further prospective studies are needed to confirm our study results.

High levels of fasting glucose and glycosylated hemoglobin values are associated with hyperfiltration in a Spanish prediabetes cohort. The PREDAPS Study

AIM

This study aimed to investigate whether different levels of fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) in prediabetes are associated with hyperfiltration.

METHODS

A prospective cohort of 2,022 individuals aged 30-74 years took part in the PREDAPS Study. One cohort of 1,184 participants with prediabetes and another cohort of 838 participants with normal FPG and normal HbA1c were followed for 5 years. Hyperfiltration was defined as an estimated glomerular filtration rate (eGFR) above the age- and gender-specific 95th percentile for healthy control participants, while hypofiltration was defined as an eGFR below the 5th percentile. The prevalence of hyperfiltration was compared for different levels of prediabetes: level 1 of prediabetes: FPG <100 mg/dL plus HbA1c 5.7-6.0% or FPG 100-109 mg/dL plus HbA1c < 5.7%; level 2 of prediabetes: FPG <100 mg/dL plus HbA1c 6.1-6.4% or FPG 100-109 mg/dL plus HbA1c 5.7-6.0% or FPG 110-125 mg/dL plus HbA1c <5.7% and level 3 of prediabetes: FPG 100-109 mg/dL plus HbA1c 6.1-6.4% or FPG 110-125 mg/dL plus HbA1c 5.7-6.4%.

RESULTS

The participants with hyperfiltration were significantly younger, had a higher percentage of active smokers, and lower levels of hemoglobin and less use of ACEIs or ARBs. Only level 3 prediabetes based on FPG 100-109 mg/dL plus HbA1c 6.1-6.4% or FPG 110-125 mg/dL plus HbA1c 5.7-6.4% had a significantly higher odds ratio (OR) of hyperfiltration (OR 1.69 (1.05-2.74); P < 0.001) compared with no prediabetes (FPG < 100 mg/dL and HbA1c < 5.7%) after adjustment for different factors. The odds ratios for different levels of HbA1c alone in prediabetes increased progressively, but not significantly.

CONCLUSIONS

Level 3 of prediabetes based on FPG 100-109 mg/dL plus HbA1c 6.1-6.4% or FPG 110-125 mg/dL plus HbA1c 5.7-6.4% had a significantly higher OR of hyperfiltration compared with participants without prediabetes.

High-protein diet with renal hyperfiltration is associated with rapid decline rate of renal function: a community-based prospective cohort study

Background

The effect of a high-protein diet with renal hyperfiltration (RHF) on decline of kidney function has rarely been explored. We investigated the association between a high-protein diet, RHF and declining kidney function.

Methods

A total of 9226 subjects from the Korean Genome and Epidemiology Study, a community-based prospective study (2001–14), were enrolled and classified into quartiles according to daily amount of protein intake based on food frequency questionnaires. RHF was defined as estimated glomerular filtration rate (eGFR) with residuals of >95th percentile after adjustment for age, sex, history of hypertension or diabetes, height and weight. Rapid decline of renal function was defined as decline rate of eGFR >3 mL/min/1.73 m2/year.

Results

The relative risk of RHF was 3.48-fold higher in the highest than in the lowest protein intake quartile after adjustment for confounding factors [95% confidence interval (CI) 1.39–8.71]. The mean eGFR decline rate was faster as quartiles of protein intake increased. Furthermore, the highest quartile was associated with 1.32-fold increased risk of rapid eGFR decline (95% CI 1.02–1.73). When subjects were divided into two groups with or without RHF, the highest quartile was associated with a rapid decline in renal function only in RHF subjects (odds ratio 3.35; 95% CI 1.07–10.51). The sensitivity analysis using the Korean National Health and Nutrition Examination Survey (2008–15) data with 40 113 subjects showed that higher quartile was associated with increased risk for RHF.

Conclusions

A high-protein diet increases the risk of RHF and a rapid renal function decline in the general population. These findings suggest that a high-protein diet has a deleterious effect on renal function in the general population.

Low-grade impairments in cognitive and kidney function in a healthy middle-aged general population: a cross-sectional study

Background

Although the relationship between manifest chronic kidney disease and reduced cognitive function is well established, limited data exists on GFR and cognitive function in the general population. Both the brain and kidneys have low-impedance vascular beds, rendering them susceptible to damage from pulsatile blood flow. An association between mildly reduced GFR and cognitive function in the healthy general population may reveal early disease mechanisms underlying low-grade impairment of both organs as well as the possibility for intervention. Our aim was to identify an early stage of low-grade impairments in both the brain and the kidneys in the general population.

Methods

This investigation was a population-based cross-sectional study that included 1627 participants aged 50–62 years who were representative of the general population in the municipality of Tromsø, Norway. The associations between GFR, measured as iohexol clearance, the urinary albumin-creatinine ratio and performance on five tests of cognitive function—the Digit Symbol Substitution Test, the finger tapping test, the Mini-Mental State Examination and the 12-word test parts 1 and 2 – were examined. The data were adjusted for factors known to be associated with both GFR and cognitive function, including cardiovascular risk factors, medications and education level.

Results

In multivariate adjusted linear regression analyses, we did not observe associations of the measured GFR or albumin-creatinine ratio with performance on any of the five cognitive tests. In an analysis without adjustment for the education level, an association of worse performance on the Digit Symbol Substitution Test with higher measured GFR (p = 0.03) was observed. An exploratory analysis revealed an inverse relationship between mGFR and a higher education level that remained significant after adjusting for factors known to influence mGFR.

Conclusions

We did not find evidence of an association between low-grade impairments in either the kidneys or the brain in the middle-aged general population. A possible association between a high GFR and reduced cognitive function should be investigated in future studies.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1356-4) contains supplementary material, which is available to authorized users.

Impaired Fasting Glucose and Chronic Kidney Disease, Albuminuria, or Worsening Kidney Function: a Secondary Analysis of the SPRINT

PURPOSE

Diabetes mellitus is a risk factor for the development and progression of chronic kidney disease (CKD). However, the association of prediabetes with adverse kidney outcomes is uncertain.

METHODS

We performed a secondary analysis of the Systolic Blood Pressure Intervention Trial (SPRINT), including 9,361 participants without diabetes at baseline. We categorized participants according to fasting glucose as having impaired fasting glucose (≥100 mg/dL [(≥5.6 mmol/L]) or normoglycemia (<100 mg/dL [(<5.6 mmol/L]). Unadjusted and adjusted proportional hazards models were fit to estimate the association of impaired fasting glucose (versus normoglycemia) with a composite outcome of worsening kidney function (≥30% decrease in eGFR to <60 ml/min/1.73 m2 in participants without baseline CKD; ≥50% decrease in eGFR or need of long-term dialysis/kidney transplantation in participants with CKD) or incident albuminuria (doubling of urinary albumin to creatinine ratio from <10 mg/g to >10 mg/g). These outcomes were also evaluated separately, and according to CKD status at baseline.

RESULTS

The mean age was 67.9 ± 9.4 years, 35.5% were female, and 31.4% were black. The median follow-up was 3.3 years and 41.8% had impaired fasting glucose. Impaired fasting glucose was not associated with higher rates of the composite outcome (HR 0.97; 95%CI 0.81-1.16), worsening kidney function (HR 1.02; 95%CI 0.75-1.37), or albuminuria (HR 0.98; 95%CI 0.78-1.23). Similarly, there was no association of impaired fasting glucose with outcomes according to baseline CKD status.

CONCLUSIONS

Impaired fasting glucose at baseline was not associated with the development of worsening kidney function or albuminuria in participants of SPRINT.

Association between prediabetes (defined by HbA1C, fasting plasma glucose, and impaired glucose tolerance) and the development of chronic kidney disease: a 9-year prospective cohort study

Background

The aim of the present study was to investigate the clinical impact of prediabetes on the development of incident chronic kidney disease (CKD) in a Korean adult population, using data from the Korea Genome and Epidemiology Study.

Methods

This prospective cohort study included 7728 Korean adults without baseline CKD and type 2 diabetes. Prediabetes was defined by impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and HbA1_C level. CKD was defined as estimated glomerular filtration rate < 60 mL/min/1.73 m². We assessed the predictive value of prediabetes for the incidence of CKD, and investigated the incidence of cardiovascular disease including coronary artery disease and stroke.

Results

Over a median follow-up period of 8.7 years, 871 of 7728 (11.3%) subjects developed incident CKD. Patients with prediabetes, as defined by IGT or HbA1_C, developed incident CKD more frequently than the non-prediabetic group did. The risk of CKD development at follow-up was analyzed according to different prediabetes definitions. Compared with the non-prediabetic group, the IGT- (Hazard ratio [HR] = 1.135, 95% confidence interval [CI] = 1.182–1.310, P = 0.043) and HbA1_C-defined prediabetic groups (HR = 1.391, 95% CI = 1.213–1.595, P < 0.001) were significantly associated with incident CKD after adjusting for traditional CKD risk factors; however, IFG was not associated with incident CKD.

Conclusion

IGT- or HbA1_C-defined prediabetes is an independent predictor of incident CKD. The measurement of these parameters might enable early detection of CKD risk, allowing physicians to initiate preventive measures and improve patient outcomes.

Correlation Between Baseline GFR and Subsequent Change in GFR in Norwegian Adults Without Diabetes and in Pima Indians

RATIONALE & OBJECTIVE

An elevated glomerular filtration rate (GFR), or renal hyperfiltration, may predispose individuals to subsequent rapid GFR decline in diabetes, obesity, and metabolic syndrome. Although this hypothesis is supported by results of experimental studies, the importance of hyperfiltration at the population level remains controversial. We investigated whether higher baseline GFR predicts a steeper decline in GFR.

STUDY DESIGN

Longitudinal cohort studies.

SETTING & PARTICIPANTS

1,594 middle-aged Norwegians without diabetes (the Renal Iohexol Clearance Survey [RENIS]) and 319 Pima Indians (83% with type 2 diabetes).

PREDICTOR

Baseline measured GFR using exogenous clearance methods.

OUTCOMES

Change in measured GFR over time.

ANALYTICAL APPROACH

Linear mixed regression models fit to assess the correlation between the random intercept (reflecting baseline GFR) and random slope (change in GFR over time).

RESULTS

Mean baseline GFRs were 104.0 ± 20.1 (SD) and 149.4 ± 43.3 mL/min, and median follow-up durations were 5.6 (IQR, 5.2-6.0) and 9.1 (IQR, 4.0-15.0) years in the RENIS and Pima cohorts, respectively. Correlation between baseline GFR (random intercept) and slope of GFR decline was -0.31 (95% CI, -0.40 to -0.23) in the RENIS cohort and -0.41 (95% CI, -0.55 to -0.26) in the Pima cohort, adjusted for age, sex, height, and weight, suggesting that higher baseline GFRs were associated with steeper GFR decline rates.

LIMITATIONS

Different methods for measuring GFR in the 2 cohorts. Renal hyperfiltration may not reflect higher single-nephron GFR. GFR decline is assumed to be linear, which may not match the actual pattern; observed correlations may arise from natural variation.

CONCLUSIONS

Higher baseline GFR is associated with faster decline in GFR over time. If this relationship were causal, elevated GFR would represent a potentially modifiable risk factor for medium- to long-term GFR decline.