Insulin sensitivity is an important determinant of renal health in adolescents with type 2 diabetes

Renal impairment is prevalent in pediatric NAFLD/MASLD and associated with disease severity

OBJECTIVES

Renal impairment is prevalent in adults with nonalcoholic fatty liver disease (NAFLD/metabolic dysfunction associated steatotic liver disease [MASLD]) and is associated with increased mortality. Pediatric data are limited. Our objective was to determine the prevalence of hyperfiltration or chronic kidney disease (CKD) in children with NAFLD/MASLD and determine links with liver disease severity.

METHODS

Data from children who had previously participated in prospective, multicenter, pediatric studies by the Nonalcoholic Steatohepatitis Clinical Research Network (NASH-CRN) were collected. Renal function was determined using the calculated glomerular filtration rate (cGFR). Hyperfiltration was defined as cGFR > 135 mL/min/1.73m2, while CKD stage 2 or higher as cGFR < 90 mL/min/1.73 m2. Renal dysfunction progression was defined as transition from normal to hyperfiltration or to CKD stage ≥ 2, or change in CKD by ≥1 stage. Multinomial logistic regression models were used to determine the prevalence of CKD and independent associations between CKD and liver disease severity.

RESULTS

The study included 1164 children (age 13 ± 3 years, 72% male, 71% Hispanic). The median cGFR was 121 mL/min/1.73 m2; 12% had CKD stage 2-5, while 27% had hyperfiltration. Hyperfiltration was independently associated with significant liver fibrosis (odds ratio: 1.45). Baseline renal function was not associated with progression in liver disease over a 2-year period (n = 145). Renal dysfunction worsened in 19% independently of other clinical risk factors. Progression of renal impairment was not associated with change in liver disease severity.

CONCLUSIONS

Renal impairment is prevalent in children with NAFLD/MASLD and hyperfiltration is independently associated with significant liver fibrosis. Almost 1/5 children have evidence of progression in renal dysfunction over 2 years, not associated with change in liver disease severity. Future assessments including additional renal impairment biomarkers are needed.

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

OBJECTIVE

β-Cell dysfunction and insulin resistance magnify the risk of kidney injury in type 2 diabetes. The relationship between these factors and intraglomerular hemodynamics and kidney oxygen availability in youth with type 2 diabetes remains incompletely explored.

RESEARCH DESIGN AND METHODS

Fifty youth with type 2 diabetes (mean age ± SD 16 ± 2 years; diabetes duration 2.3 ± 1.8 years; 60% female; median HbA1c 6.4% [25th, 75th percentiles 5.9, 7.6%]; BMI 36.4 ± 7.4 kg/m2; urine albumin-to-creatinine ratio [UACR] 10.3 [5.9, 58.0] mg/g) 21 control participants with obesity (OCs; age 16 ± 2 years; 29% female; BMI 37.6 ± 7.4 kg/m2), and 20 control participants in the normal weight category (NWCs; age 17 ± 3 years; 70% female; BMI 22.5 ± 3.6 kg/m2) underwent iohexol and p-aminohippurate clearance to assess glomerular filtration rate (GFR) and renal plasma flow, kidney MRI for oxygenation, hyperglycemic clamp for insulin secretion (acute C-peptide response to glucose [ACPRg]) and disposition index (DI; ×103 mg/kg lean/min), and DXA for body composition.

RESULTS

Youth with type 2 diabetes exhibited lower DI (0.6 [0.0, 1.6] vs. 3.8 [2.4, 4.5] × 103 mg/kg lean/min; P < 0.0001) and ACPRg (0.6 [0.3, 1.4] vs. 5.3 [4.3, 6.9] nmol/L; P < 0.001) and higher UACR (10.3 [5.9, 58.0] vs. 5.3 [3.4, 14.3] mg/g; P = 0.003) and intraglomerular pressure (77.8 ± 11.5 vs. 64.8 ± 5.0 mmHg; P < 0.001) compared with OCs. Youth with type 2 diabetes and OCs had higher GFR and kidney oxygen availability (relative hyperoxia) than NWCs. DI was associated inversely with intraglomerular pressure and kidney hyperoxia.

CONCLUSIONS

Youth with type 2 diabetes demonstrated severe β-cell dysfunction that was associated with intraglomerular hypertension and kidney hyperoxia. Similar but attenuated findings were found in OCs.

Triglyceride-glucose index is associated with the risk of chronic kidney disease progression in type 2 diabetes

OBJECTIVE

The study aimed to investigate the association of TyG index with chronic kidney disease (CKD) progression in type 2 diabetes mellitus (T2DM).

METHODS

A total of 179 T2DM patients with CKD were retrospectively included. CKD progression was defined as a doubling of baseline serum creatinine or onset of end-stage kidney disease (ESKD). Internal validation was performed by the Kidney Failure Risk Equation (KFRE) model and Net reclassification improvement (NRI).

RESULTS

The optimal cut-off value of the TyG index was 9.17. The cumulative incidence of kidney outcomes was significantly higher in the high-TyG group (v.s low-TyG group, P = 0.019). In addition, the high-TyG index was associated with a greater risk of CKD progression (HR 1.794, 95% CI 1.026-3.137, P = 0.040). And reclassification analyses confirmed the final adjusted model improved NRI (61.90% v.s model 2, 43.80% v.s model 1). The further RCS curves presented an inverted S-shaped relationship between the TyG index and the risk of CKD progression. Internal validation verified that a higher TyG index was associated with 2.10-fold increased odds of 2-year ESKD risk >10% (95% CI 1.82-8.21). Moreover, subgroup analysis suggested that the association was more pronounced in those at relatively early CKD stages (higher than stage 2) and with no medication history of oral hypoglycemic agents.

CONCLUSION

An elevated TyG index was associated with a higher risk of CKD progression in T2DM patients. Our findings suggested that timely targeting insulin sensitivity at the early stages of T2DM might be associated with declined future risk of CKD development.

Glomerular hyperfiltration: part 2-clinical significance in children

Glomerular hyperfiltration (GHF) is a phenomenon that can occur in various clinical conditions affecting the kidneys such as sickle cell disease, diabetes mellitus, autosomal dominant polycystic kidney disease, and solitary functioning kidney. Yet, the pathophysiological mechanisms vary from one disease to another and are not well understood. More so, it has been demonstrated that GHF may occur at the single-nephron in some clinical conditions while in others at the whole-kidney level. In this review, we explore the pathophysiological mechanisms of GHF in relation to various clinical conditions in the pediatric population. In addition, we discuss the role and mechanism of action of important factors such as gender, low birth weight, and race in the pathogenesis of GHF. Finally, in this current review, we further highlight the consequences of GHF in the progression of kidney disease.

Youth versus adult-onset type 2 diabetic kidney disease: Insights into currently known structural differences and the potential underlying mechanisms

Type 2 diabetes (T2D) is a global health pandemic with significant humanitarian, economic, and societal implications, particularly for youth and young adults who are experiencing an exponential rise in incident disease. Youth-onset T2D has a more aggressive phenotype than adult-onset T2D, and this translates to important differences in rates of progression of diabetic kidney disease (DKD). We hypothesize that youth-onset DKD due to T2D may exhibit morphometric, metabolic, and molecular characteristics that are distinct from adult-onset T2D and develop secondary to inherent differences in renal energy expenditure and substrate metabolism, resulting in a central metabolic imbalance. Kidney structural changes that are evident at the onset of puberty also serve to exacerbate the organ’s baseline high rates of energy expenditure. Additionally, the physiologic state of insulin resistance seen during puberty increases the risk for kidney disease and is exacerbated by both concurrent diabetes and obesity. A metabolic mismatch in renal energetics may represent a novel target for pharmacologic intervention, both for prevention and treatment of DKD. Further investigation into the underlying molecular mechanisms resulting in DKD in youth-onset T2D using metabolomics and RNA sequencing of kidney tissue obtained at biopsy is necessary to expand our understanding of early DKD and potential targets for therapeutic intervention. Furthermore, large-scale clinical trials evaluating the duration of kidney protective effects of pharmacologic interventions that target a metabolic mismatch in kidney energy expenditure are needed to help mitigate the risk of DKD in youth-onset T2D.

Renal insulin resistance in type 2 diabetes mellitus and progression of chronic kidney disease: potential pathogenic mechanisms

INTRODUCTION

A bidirectional association exists between insulin resistance (IR) and chronic kidney disease (CKD) in Type 2 Diabetes Mellitus (T2DM). Baseline measures of IR are predictive of CKD progression, and uremia in progressive CKD is itself, in turn, associated with a worsening of IR. Pre-clinical research reveals that intrinsic IR in glomerular podocytes and the renal tubule may serve as a pathogenic driver of CKD in T2DM.

AREAS COVERED

The present manuscript takes as its point of departure, the recently identified prognostic utility of severe insulin resistance as a predictor of CKD in T2DM. Findings from a series of studies describing the association of IR with pathological alterations in both established, and less commonly assessed dynamic measures of renal impairment are discussed. Drawing upon the pre-clinical mechanistic evidence base, the cellular and molecular basis of intrinsic renal IR as a promoter of CKD is considered.

EXPERT OPINION

Measurement of insulin sensitivity may add value to profiling of renal risk in T2DM. Rational selection of therapeutic strategies targeting the enhancement of insulin sensitivity merits special attention regarding the personalized management of CKD in insulin resistance predominant T2DM.

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.

Understanding main pregnancy complications through animal models

Since human pregnancy is an inefficient process, achieving desired and pleasant outcome of pregnancy - the birth of a healthy and fit baby - is the main goal in any pregnancy. Spontaneous pregnancy failure is actually the most common complication of pregnancy and Most of these pregnancy losses are not known. Animal models have been utilized widely to investigate the system of natural biological adaptation to pregnancy along with increasing our comprehension of the most important hereditary and non-hereditary factors that contribute to pregnancy disorders. We use model organisms because their complexity better reproduces the human condition. A useful animal model for the disease should be pathologically similar to the disease conditions in humans. Animal models deserve a place in research because of the ethical limitations that apply to pregnant women's experiments. The present review provides insights into the overall risk factors involved in recurrent miscarriage, recurrent implant failure and preeclampsia and animal models developed to help researchers identify the source of miscarriage and the best research and treatment strategy for women with Repeated miscarriage and implant failure.

Sex and Gender Related Differences in Diabetic Kidney Disease

Diversity in sex and gender are important considerations in the pathogenesis, prognostication, research, and management of diabetic kidney disease (DKD). Sex and gender differences in the disease risk, disease-specific mechanisms, and outcomes in DKD may be attributed to biological differences between males and females at the cellular and tissue level, inconsistencies in the diagnostic and assessment tools used in chronic kidney disease and DKD, as well societal differences in the way men, women, and gender-diverse individuals self-manage and interact with health care systems. This review outlines key considerations related to the impact of sex on DKD, specifically elaborating on how they contribute to observed differences in disease epidemiology, pathogenesis, and treatment strategies. We also highlight the effect of gender on DKD progression and care.

Structural Lesions on Kidney Biopsy in Youth-Onset and Adult-Onset Type 2 Diabetes

OBJECTIVE

Type 2 diabetes (T2D) is a leading cause of end-stage kidney disease worldwide. Recent studies suggest a more aggressive clinical course of diabetic kidney disease in youth-onset compared with adult-onset T2D. We compared kidney structural lesions in youth- and adult-onset T2D to determine if youth onset was associated with greater early tissue injury.

RESEARCH DESIGN AND METHODS

Quantitative microscopy was performed on kidney tissue obtained from research kidney biopsies in 161 Pima Indians (117 women, 44 men) with T2D. Onset of T2D was established by serial oral glucose tolerance testing, and participants were stratified as youth onset (age <25 years) or adult onset (age ≥25 years). Associations between clinical and morphometric parameters and age at onset were tested using linear models.

RESULTS

At biopsy, the 52 participants with youth-onset T2D were younger than the 109 with adult-onset T2D (39.1 ± 9.9 vs. 51.4 ± 10.2 years; P < 0.0001), but their diabetes duration was similar (19.3 ± 8.1 vs. 17.0 ± 7.8 years; P = 0.09). Median urine albumin-to-creatinine ratio was higher in the youth-onset group (58 [25th-75th percentile 17-470] vs. 27 [13-73] mg/g; P = 0.02). Youth-onset participants had greater glomerular basement membrane (GBM) width (552 ± 128 vs. 490 ± 114 nm; P = 0.002) and mesangial fractional volume (0.31 ± 0.10 vs. 0.27 ± 0.08; P = 0.001) than adult-onset participants. Glomerular sclerosis percentage, glomerular volume, mesangial fractional volume, and GBM width were also inversely associated with age at diabetes onset as a continuous variable.

CONCLUSIONS

Younger age at T2D onset strongly associates with more severe kidney structural lesions. Studies are underway to elucidate the pathways underlying these associations.

Insulin Resistance is Associated with Clinical Manifestations of Diabetic Kidney Disease (Glomerular Hyperfiltration, Albuminuria, and Kidney Function Decline)

Clinical features of diabetic kidney disease include glomerular hyperfiltration, albuminuria, and kidney function decline towards End-Stage Kidney Disease (ESKD). There are presently neither specific markers of kidney involvement in patients with diabetes nor strong predictors of rapid progression to ESKD. Serum-creatinine-based equations used to estimate glomerular filtration rate are notoriously unreliable in patients with diabetes. Early kidney function decline, reduced glomerular filtration rate, and proteinuria contribute to identifying diabetic patients at higher risk for rapid kidney function decline. Unlike proteinuria, the elevation of urinary albumin excretion in the range of microalbuminuria is frequently transient in patients with diabetes and does not always predict progression towards ESKD. Although the rate of progression of kidney function decline is usually accelerated in the presence of proteinuria, histological lesions of diabetes and ESKD may occur with normal urinary albumin excretion. No substantial reduction in the rate of ESKD associated with diabetes has been observed during the last decades despite intensified glycemic control and reno-protective strategies, indicating that existing therapies do not target underlying pathogenic mechanisms of kidney function decline. Very long-term effects of sodium-glucose transporters- 2 inhibitors and glucagon-like peptide-1 analogs remain to be defined. In patients with diabetes, glucagon secretion is typically elevated and induces insulin resistance. Insulin resistance is consistently and strongly associated with clinical manifestations of diabetic kidney disease, suggesting that reduced insulin sensitivity participates in the pathogenesis of the disease and may represent a therapeutic objective. Amelioration of insulin sensitivity in patients with diabetes is associated with cardioprotective and kidney-protective effects.

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.

Mechanisms of Cardiorenal Protection of Glucagon-Like Peptide-1 Receptor Agonists

The worldwide prevalence of type 2 diabetes (T2D) is steadily increasing, and it remains a challenging public health problem for populations in both developing and developed countries around the world. Despite the recent advances in novel antidiabetic agents, diabetic kidney disease and cardiovascular disease remain the leading causes of morbidity and mortality in T2D. Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs), incretin hormones that stimulate postprandial insulin secretion, serve as a promising avenue for treatment of T2D as they result in a variety of antihyperglycemic effects including increased endogenous insulin secretion, decreased gluconeogenesis, inhibition of pancreatic α-cell glucagon production, decreased pancreatic β-cell apoptosis, and increased β-cell proliferation. GLP-1RAs have also been found to delay gastric emptying, promote weight loss, increase satiety, decrease hypertension, improve dyslipidemia, reduce inflammation, improve albuminuria, induce natriuresis, improve cardiovascular function, and prevent thrombogenesis. In this review, we will present risk factors for the development of cardiac and kidney disease in individuals with T2D and discuss possible mechanisms for the cardiorenal protective effects seen with GLP-1RAs. We will also present the possibility of dual- and tri-receptor agonist therapies with GLP-1, gastric inhibitory peptide, and glucagon RAs as an area of possible mechanistic synergy in the treatment of T2D and the prevention of cardiorenal complications.

Relative Hypoxia and Early Diabetic Kidney Disease in Type 1 Diabetes

The objective of this study was to compare the ratio of renal oxygen availability (RO₂) to glomerular filtration rate (GFR), a measure of relative renal hypoxia, in adolescents with and without type 1 diabetes (T1D) and relate the ratio to albuminuria, renal plasma flow (RPF), fat mass, and insulin sensitivity (M/I). RO₂ was estimated by blood oxygen level-dependent MRI; fat mass was estimated by DXA; GFR and RPF were estimated by iohexol and p-aminohippurate clearance; albuminuria was estimated by urine albumin-to-creatinine ratio (UACR); and M/I was estimated from steady-state glucose infusion rate/insulin (mg/kg/min) by hyperglycemic clamp in 50 adolescents with T1D (age 16.1 ± 3.0 years, HbA_1c 8.6 ± 1.2%) and 20 control patients of similar BMI (age 16.1 ± 2.9 years, HbA_1c 5.2 ± 0.2%). The RO₂:GFR (ms/mL/min) was calculated as RO₂ (T2*, ms) divided by GFR (mL/min). Whole-kidney RO₂:GFR was 25% lower in adolescents with T1D versus control patients (P < 0.0001). In adolescents with T1D, lower whole-kidney RO₂:GFR was associated with higher UACR (r = -0.31, P = 0.03), RPF (r = -0.52, P = 0.0009), and fat mass (r = -0.33, P = 0.02). Lower medullary RO₂:GFR was associated with lower M/I (r = 0.31, P = 0.03). In conclusion, adolescents with T1D exhibited relative renal hypoxia that was associated with albuminuria and with increased RPF, fat mass, and insulin resistance. These data suggest a potential role of renal hypoxia in the development of diabetic kidney disease.

Association between the triglyceride-glucose index and diabetic nephropathy in patients with type 2 diabetes: A cross-sectional study

Aims/Introduction

The triglyceride–glucose (TyG) index has been proposed as a reliable and simple marker of insulin resistance. We investigated the association between TyG index and diabetic nephropathy (DN) in patients with type 2 diabetes.

Materials and Methods

A consecutive case series of 682 adult patients with type 2 diabetes hospitalized in the Department of Endocrinology at the Tongji Hospital (Wuhan, Hubei, China) from January 2007 to December 2009 was included in this cross‐sectional analysis. Receiver operating characteristics curve analysis, correlation analysis and multiple logistic regression analysis were carried out.

Results

A total of 232 (34.0%) participants were identified with DN. Compared with the non‐DN group, the DN group had longer disease duration, and higher bodyweight, systolic blood pressure, diastolic blood pressure, glycated hemoglobin, triglycerides, total cholesterol, serum uric acid, 24 h‐urinary albumin, TyG index and homeostasis model assessment 2 estimates for insulin resistance (HOMA2‐IR; P < 0.05 for each). The TyG index with an optimal cut‐off point >9.66 showed a higher area under the receiver operating characteristic curve of 0.67 (P = 0.002) than HOMA2‐IR (area under the curve 0.61, P = 0.029) on receiver operating characteristic curve analysis for DN identification. Additionally, the TyG index positively correlated with the levels of metabolic indicators (bodyweight, glycated hemoglobin, triglycerides, total cholesterol, serum uric acid, fasting glucose and HOMA2‐IR) and natural logarithmic 24 h‐urinary albumin (P < 0.05 for each), but not natural logarithm of estimated glomerular filtration rate. On multiple regression analysis, an increased TyG index was shown to be an independent risk factor (odds ratio 1.91, P = 0.001) for DN.

Conclusions

The TyG index was independently associated with DN in patients with type 2 diabetes, and was a better marker than HOMA2‐IR for identification of DN in type 2 diabetes patients.

Five-year kidney outcomes of bariatric surgery differ in severely obese adolescents and adults with and without type 2 diabetes

Bariatric surgery improves markers of kidney health in severe obesity, yet it is unclear if kidney disease outcomes differ according to age at surgery. Therefore, we examined health effects of Roux-en-Y gastric bypass between 161 adolescents and 396 adults participating in two related but distinct studies. Primary outcomes were elevated urine albumin-to-creatinine ratio (UACR) of 30 mg/g or more and hyperfiltration (an estimated glomerular filtration rate of 135 ml/min/1.73m² or more). Analyses were stratified by the presence of pre-operative type 2 diabetes. Adolescents with pre-operative type 2 diabetes had a significantly increased prevalence of elevated UACR prior to surgery compared to adults (22.5 vs. 9.0%). Resolution of elevated UACR following surgery differed between adolescents and adults with type 2 diabetes, with adolescents experiencing a significantly earlier improvement following surgery. Adolescents without pre-operative type 2 diabetes demonstrated a significantly increased prevalence of UACR prior to surgery compared to adults (9.4 vs. 4.5%), with no improvement occurring in either group post-operatively. Adolescents with pre-operative type 2 diabetes had a significantly increased prevalence of hyperfiltration that remained throughout the study period, whereas hyperfiltration prevalence was similar among those without type 2 diabetes. Thus, adolescents with pre-operative type 2 diabetes experienced earlier attenuation of elevated UACR compared to adults with pre-operative type 2 diabetes in response to gastric bypass.

Bariatric surgery and kidney disease outcomes in severely obese youth

Bariatric surgery, an emerging treatment for severely obese youth with and without T2D, provides marked improvement in insulin resistance, beta-cell function, and central adiposity. Further, preliminary data suggest that bariatric surgery also results in significant improvement in markers of obesity-related nephropathy and DKD, beyond that which can be achieved with current medical interventions. Yet, the mechanisms whereby bariatric surgery attenuates kidney disease remain unclear. This review summarizes the data on the effects of bariatric surgery on obesity-related nephropathy and DKD in youth with and without T2D, in addition to potential mechanisms underlying the nephroprotective effects of weight loss surgery and how these may differ in Roux-en-Y gastric bypass vs. vertical sleeve gastrectomy. Finally, we discuss potential future non-surgical therapies to mitigate kidney disease.

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.

Lipid mediators of insulin signaling in diabetic kidney disease

Diabetic kidney disease (DKD) affects ∼40% of patients with diabetes and is associated with high mortality rates. Among different cellular targets in DKD, podocytes, highly specialized epithelial cells of the glomerular filtration barrier, are injured in the early stages of DKD. Both clinical and experimental data support the role of preserved insulin signaling as a major contributor to podocyte function and survival. However, little is known about the key modulators of podocyte insulin signaling. This review summarizes the novel knowledge that intracellular lipids such as cholesterol and sphingolipids are major determinants of podocyte insulin signaling. In particular, the implications of these lipids on DKD development, progression, and treatment will be addressed.

Progress in understanding youth-onset type 2 diabetes in the United States: recent lessons from clinical trials

BACKGROUND

Due to the dramatic increase in the rates of childhood obesity and youth-onset type 2 diabetes (T2D) in the late 1990s in the United States, the US government, through the National Institute of Diabetes, Digestive Disease, and Kidney (NIDDK) and the Centers for Disease Control, funded a series of large studies and trials which, together, have formed the basis for much of what we currently understand about youth-onset T2D.

DATA SOURCES

The review focus on the recent results and implications of the treatment options for Type 2 Diabetes in Adolescents and Youth (TODAY) study and the Restoring Insulin Secretion (RISE) study.

RESULTS AND CONCLUSIONS

Both TODAY and RISE studies have provided critical insight into the unique aspects of the pathophysiology of youth-onset type 2 diabetes and also provided the evidence base for our current approach to the management of this disorder.

A new strategy for vascular complications in young people with type 1 diabetes mellitus

Diabetes vascular complications, including cardiovascular disease, diabetic nephropathy and retinopathy, have a negative effect on the long-term prognosis of young people with type 1 diabetes mellitus (T1DM). Poor glycaemic control and consequent increased HbA_1c levels are major risk factors for the development of vascular complications. HbA_1c levels are the main focus of current management strategies; however, the recommended target is rarely achieved in adolescents. Thus, a clear need exists for improved biomarkers to identify high-risk young people early and to develop new intervention strategies. Evidence is accumulating that early increases in urinary albumin excretion could be predictive of adolescents with T1DM who are at an increased risk of developing vascular complications, independent of HbA_1c levels. These findings present an opportunity to move towards the personalized care of adolescents with T1DM, which takes into consideration changes in albumin excretion and other risk factors in addition to HbA_1c levels.

Probing insulin sensitivity in diabetic kidney disease: is there a stronger role for functional imaging?

Clinical and experimental evidence support a cause-effect relationship between altered insulin signaling and development of kidney disease of metabolic and non-metabolic origin. However, the current criteria to measure and/or estimate the insulin resistance (IR) are available as research tool but are very difficult to implement in the clinical practice. Therefore, a better understanding of the key players contributing to IR may lead to the development of new non-invasive tools to assess organ-specific insulin sensitivity (IS). We will therefore first introduce the concept that IR and kidney disease may be causally linked as suggested by clinical and experimental studies. We will then, expand on the potential mechanisms leading to altered renal insulin signaling. After reviewing the limitation of currently available strategies to determine IR, this review article will focus on imaging techniques that could be utilized to determine renal IR and that could be tested to predict kidney disease development and progression.

Renal Hyperfiltration in Adolescents with Type 2 Diabetes: Physiology, Sex Differences, and Implications for Diabetic Kidney Disease

PURPOSE OF REVIEW

Compared to adult-onset type 2 diabetes (T2D), youth with T2D have a more aggressive phenotype with greater insulin resistance (IR), more rapid β cell decline, and higher prevalence of diabetic kidney disease (DKD).

RECENT FINDINGS

Hyperfiltration is common in youth with T2D and predicts progressive DKD. Hyperfiltration is a consequence of early changes in intrarenal hemodynamic function, including increased renal plasma flow (RPF) and glomerular pressure. Girls with T2D are disproportionally affected by DKD, with a 3-fold greater risk of developing hyperfiltration over 5 years compared to boys. Despite the high prevalence and gravity of DKD in youth-onset T2D, widely effective therapeutic options are lacking. In this review, we focus on pathophysiology underlying early DKD in T2D and sex differences and summarize promising novel medical therapies and bariatric surgery.

The Saudi Diabetic Kidney Disease study (Saudi-DKD): clinical characteristics and biochemical parameters

BACKGROUND

Saudi Arabia is facing an epidemic of type 2 diabetes that is complicated by a high rate of chronic complications such as kidney disease, which have a major impact on the healthcare system and economy. The Saudi diabetic kidney disease (SAUDI-DKD) study was launched to understand the implications of chronic diabetic kidney disease .

OBJECTIVES

Examine the hematological, biochemical and metabolic parameters of the selected cohorts to look for biomarkers of diabetic nephropathy.

DESIGN

Cross-sectional, hospital-based.

SETTING

Four general hospitals and two dialysis centers in Riyadh.

PATIENTS AND METHODS

We recruited adult type 2 diabetic patients aged between 35 and 70 years, with a duration of diabetes > 10 years, including subjects with microalbuminuria, macroalbuminuria and end stage renal disease (ESRD). They were compared with subjects with normal albumin excretion classified according to American Diabetes Association (ADA) criteria.

MAIN OUTCOME MEASURES

The effect of different stages of diabetic nephropathy on hematological and biochemical parameters.

RESULTS

Of 427 subjects with nephropathy, 184 (43%) had microalbuminuria, 83 (19%) had macroalbu.minuria and 160 (37%) had end stage renal disease (ESRD). The remaining 213 (50%) subjects did not have nephropathy. Patients with nephropathy were older with a mean age (SD) of 55.62 (6.00) years and had a longer duration of diabetes (mean [SD], 19.04 [6.33]) years), and had a lower monthly income and body mass index (BMI) than patients without nephropathy. Insulin resistance, elevated uric acid level, low red blood cells (RBCs) count and low hemoglobin level were associated with significantly increased risk of macroalbuminuria and ESRD. Elevated uric acid and LDH were associated with significantly increased risk of microalbuminuria and ESRD, while elevated red blood cell distribution width was significantly associated with an increased risk of ESRD.

CONCLUSION

Diabetic nephropathy is associated with insulin resistance, changes in liver enzymes and uric acid in addition to abnormalities in the red blood cell count and red blood cell shape that warrant frequent monitoring among patients with diabetic kidney disease.

LIMITATIONS

Cross-sectional study design and exclusion of patients with some risk factors.

Insulin Sensitivity and Diabetic Kidney Disease in Children and Adolescents With Type 2 Diabetes: An Observational Analysis of Data From the TODAY Clinical Trial

BACKGROUND

Diabetic kidney disease is a major cause of premature mortality in type 2 diabetes mellitus (T2DM). Worsening insulin sensitivity independent of glycemic control may contribute to the development of diabetic kidney disease. We investigated the longitudinal association of insulin sensitivity with hyperfiltration and increased albumin excretion in adolescents with T2DM.

STUDY DESIGN

Observational prospective cohort study.

SETTING & PARTICIPANTS

532 TODAY (Treatment Options for Type 2 Diabetes in Adolescents and Youth) participants aged 12 to 17 years with T2DM duration less than 2 years at baseline. The TODAY Study was a multicenter randomized clinical trial that examined the efficacy of 3 treatment regimens (metformin monotherapy, metformin plus rosiglitazone, or metformin plus an intensive lifestyle intervention program) to achieve durable glycemic control.

PREDICTORS

Natural log-transformed estimated insulin sensitivity (reciprocal of fasting insulin), hemoglobin A_1c concentration, age, race-ethnicity, treatment group, body mass index, loss of glycemic control, and hypertension.

OUTCOMES

Hyperfiltration was defined as 99th percentile or higher of estimated glomerular filtration rate (≥140mL/min/1.73m²) when referenced to healthy adolescents (NHANES 1999-2002) and albumin-creatinine ratio ≥ 30μg/mg at 3 consecutive annual visits.

RESULTS

Hyperfiltration was observed in 7.0% of participants at baseline and in 13.3% by 5 years, with a cumulative incidence of 5.0% over 5 years. The prevalence of increased albumin excretion was 6% at baseline and 18% by 5 years, with a cumulative incidence of 13.4%. There was an 8% increase in risk for hyperfiltration per 10% lower estimated insulin sensitivity in unadjusted and adjusted models (P=0.01). Increased albumin excretion was associated with hemoglobin A_1c concentration, but not estimated insulin sensitivity.

LIMITATIONS

Longer follow-up is needed to capture the transition from hyperfiltration to rapid glomerular filtration rate decline in youth-onset T2DM.

CONCLUSIONS

Lower estimated insulin sensitivity was associated with risk for hyperfiltration over time, whereas increased albumin excretion was associated with hyperglycemia in youth-onset T2DM.

Insulin resistance in type 2 diabetes youth relates to serum free fatty acids and muscle mitochondrial dysfunction

AIMS

Insulin resistance (IR) correlates with mitochondrial dysfunction, free fatty acids (FFAs), and intramyocellular lipid (IMCL) in adults with type 2 diabetes (T2D). We hypothesized that muscle IR would relate to similar factors in T2D youth.

METHODS

Participants included 17 youth with T2D, 23 normal weight controls (LCs), and 26 obese controls (OBs) of similar pubertal stage and activity level.

RESULTS

T2D and OB groups were of similar BMI. T2D youth were significantly more IR and had higher calf IMCL and serum FFA concentrations during hyperinsulinemia. ADP time constant (ADPTC), a blood-flow dependent mitochondrial function measure, was slowed and oxidative phosphorylation rates lower in T2D. In multiple linear regression of the entire cohort, lack of FFA suppression and longer ADPTC, but not IMCL or HbA1c, were independently associated with IR.

CONCLUSION

We found that elevated FFAs and mitochondrial dysfunction are early abnormalities in relatively well-controlled youth with T2D. Further, post-exercise oxidative metabolism appears affected by reduced blood flow, and is not solely an inherent mitochondrial defect. Thus, lowering FFAs and improving mitochondrial function and blood flow may be potential treatment targets in youth with T2D.

Youth-Onset Type 2 Diabetes Consensus Report: Current Status, Challenges, and Priorities

Type 2 diabetes is a significant and increasing burden in adolescents and young adults. Clear strategies for research, prevention, and treatment of the disease in these vulnerable patients are needed. Evidence suggests that type 2 diabetes in children is different not only from type 1 but also from type 2 diabetes in adults. Understanding the unique pathophysiology of type 2 diabetes in youth, as well as the risk of complications and the psychosocial impact, will enable industry, academia, funding agencies, advocacy groups, and regulators to collectively evaluate both current and future research, treatment, and prevention approaches. This Consensus Report characterizes type 2 diabetes in children, evaluates the fundamental differences between childhood and adult disease, describes the current therapeutic options, and discusses challenges to and approaches for developing new treatments.

Effect of Selenium Supplementation on Glycemic Control and Lipid Profiles in Patients with Diabetic Nephropathy

To our knowledge, data on the effects of selenium supplementation on glycemic control and lipid concentrations in patients with diabetic nephropathy (DN) are scarce. The current study was done to determine the effects of selenium supplementation on glycemic control and lipid concentrations in patients with DN. This was a randomized double-blind placebo-controlled clinical trial in which 60 patients with DN were randomly allocated into two groups to receive either 200 μg of selenium supplements (n = 30) or placebo (n = 30) daily for 12 weeks. Blood sampling was performed for the quantification of glycemic indicators and lipid profiles at the onset of the study and after 12 weeks of intervention. Selenium supplementation for 12 weeks resulted in a significant decrease in serum insulin levels (P = 0.01), homeostasis model of assessment-estimated insulin resistance (HOMA-IR) (P = 0.02), homeostasis model of assessment-estimated B cell function (HOMA-B) (P = 0.009) and a significant rise in plasma glutathione peroxidase (GPx) (P = 0.001) compared with the placebo. Taking selenium supplements had no significant effects on fasting plasma glucose (FPG), quantitative insulin sensitivity check index (QUICKI) and lipid profiles compared with the placebo. Overall, our study demonstrated that selenium supplementation for 12 weeks among patients with DN had beneficial effects on plasma GPx, serum insulin levels, HOMA-IR, and HOMA-B, while it did not affect FPG, QUICKI, and lipid profiles.

The dose-response effect of insulin sensitivity on albuminuria in children according to diabetes type

BACKGROUND

Insulin resistance is associated with microalbuminuria among youth with diabetes mellitus. We sought to determine the dose-response effect of insulin sensitivity (IS) on the magnitude of albuminuria and whether there is a threshold below which urine albumin excretion increases.

METHODS

These analyses included participants from the SEARCH for Diabetes in Youth Study with incident diabetes who completed a baseline study visit (n = 2988). We estimated IS using a validated equation incorporating waist circumference, HbA1C, and fasting serum triglycerides. Multivariate regression analyses were performed to assess the effect of IS on urine albumin creatinine ratio (UACR), stratified by diabetes type. The IS threshold was then determined using segmented regressions within each diabetes type and incorporated into the multivariate model.

RESULTS

There was an association between IS and UACR in type 2 diabetes only (beta = -0.39; p < 0.001). There was strong statistical evidence for a threshold effect of IS score on UACR in the group of youth with type 2 (beta = 0.40; p < 0.001) but not type 1 diabetes (p = 0.3).

CONCLUSIONS

In cross-sectional analyses, there is a negative association between IS and UACR in youth with type 2 but not type 1 diabetes, and this association likely includes a threshold effect of IS on UACR.

Estimated insulin sensitivity predicts incident micro- and macrovascular complications in adults with type 1 diabetes over 6 years: the coronary artery calcification in type 1 diabetes study

OBJECTIVE

Reduced insulin sensitivity (IS) is well documented in type 1 diabetes (T1D) and may contribute to vascular complications. We examined the association of estimated IS (eIS) with incident macro- and microvascular complications in adults with T1D in the prospective CACTI study.

METHODS

Participants (N=652) were 19-56 years old at baseline and re-examined 6.2±0.6years later. Urinary albumin excretion was measured, and categorized as microalbuminuria or greater. Diabetic retinopathy (DR) was based on self-reported history, proliferative DR (PDR) as history of laser eye therapy and coronary artery calcium (CAC) was measured using electron-beam CT. Progression of CAC was defined as a change in the square root transformed CAC volume score of ≥2.5. IS was estimated (eIS) by an equation derived from clamp studies. Predictors of each complication were examined using stepwise logistic regression and subjects with complications at baseline excluded. Age, T1D duration, sex, HbA1c, SBP, LDL-C, and eIS were considered for inclusion.

RESULTS

Greater eIS at baseline predicted lower odds of developing albuminuria (OR: 0.67, 95% CI 0.51-0.88), DR (OR 0.79, 0.64-0.97), PDR (OR: 0.76, 0.57-0.99) and CACp (OR: 0.71, 0.60-0.85) in multivariable models.

CONCLUSIONS

Greater eIS conferred protection from the development of vascular complications over 6-years in T1D.

Diabetic Kidney Disease in Adolescents With Type 2 Diabetes: New Insights and Potential Therapies

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD) and dialysis in the Western world. Early DKD, including microalbuminuria and renal hyperfiltration, is common in adolescents with type 2 diabetes (T2D). Furthermore, youth-onset T2D carries a higher risk of progressive DKD than adult-onset T2D of similar diabetes duration. DKD is characterized by a long clinically silent period without signs of disease. Therefore, a major challenge in preventing DKD is the difficulty in identifying high-risk T2D patients at an early stage. The Type 2 Diabetes in Adolescents and Youth (TODAY) study demonstrated a high initial prevalence that increased over time, irrespective of treatment arm. This key observation underscores the importance of discovering new therapeutic targets to supplement conventional management, in order to reduce DKD risk. In this review, we focus on early DKD in T2D and summarize potential novel biomarkers and therapeutic targets.

Update on Estimation of Kidney Function in Diabetic Kidney Disease

The American Diabetes Association recommends annual assessment of glomerular filtration rate (GFR) to screen for diabetic nephropathy. GFR is measured indirectly using markers that, ideally, are eliminated only by glomerular filtration. Measured GFR, although the gold standard, remains cumbersome and expensive. GFR is therefore routinely estimated using creatinine and/or cystatin C and clinical variables. In pediatrics, the Schwartz creatinine-based equation is most frequently used even though combined creatinine and cystatin C-based equations demonstrate stronger agreement with measured GFR. In adults, the CKD Epidemiology Collaboration (CKD-EPI) equations with creatinine and/or cystatin C are the most accurate and precise estimating equations. Despite recent advances, current estimates of GFR lack precision and accuracy before chronic kidney disease stage 3 (GFR < 60 mL/min/1.73 m(2)). There is therefore an urgent need to improve the methods for estimating and measuring GFR. In this review, we examine the current literature and data addressing measurement and estimation of GFR in diabetes.

Insulin sensitivity and complications in type 1 diabetes: New insights

Despite improvements in glucose, lipids and blood pressure control, vascular complications remain the most important cause of morbidity and mortality in patients with type 1 diabetes. For that reason, there is a need to identify additional risk factors to utilize in clinical practice or translate to novel therapies to prevent vascular complications. Reduced insulin sensitivity is an increasingly recognized component of type 1 diabetes that has been linked with the development and progression of both micro- and macrovascular complications. Adolescents and adults with type 1 diabetes have reduced insulin sensitivity, even when compared to their non-diabetic counterparts of similar adiposity, serum triglycerides, high-density lipoprotein cholesterol, level of habitual physical activity, and in adolescents, pubertal stage. Reduced insulin sensitivity is thought to contribute both to the initiation and progression of macro- and microvascular complications in type 1 diabetes. There are currently clinical trials underway examining the benefits of improving insulin sensitivity with regards to vascular complications in type 1 diabetes. Reduced insulin sensitivity is an increasingly recognized component of type 1 diabetes, is implicated in the pathogenesis of vascular complications and is potentially an important therapeutic target to prevent vascular complications. In this review, we will focus on the pathophysiologic contribution of insulin sensitivity to vascular complications and summarize related ongoing clinical trials.

ABC goal achievement predicts microvascular but not macrovascular complications over 6-years in adults with type 1 diabetes: the Coronary Artery Calcification in Type 1 Diabetes Study

HYPOTHESIS

Vascular complications of type 1 diabetes are thought to cluster. We examined the prevalence and incidence of vascular complications and American Diabetes Association's ABC goal achievements in a prospective cohort of adults with type 1 diabetes. We hypothesized that ABC achievement at baseline would predict both micro- and macrovascular complications over 6-years.

METHODS

Participants (N=652) were 19-56 year old at baseline and re-examined 6-years later. Microvascular complications included diabetic nephropathy (DN), defined as incident albuminuria (AER≥20 μg/min) or rapid GFR decline (>3.3%/year) by CKD-EPI cystatin C and proliferative diabetic retinopathy (PDR), defined as laser eye-therapy. Macrovascular complications were defined as coronary artery calcium progression (CACp), measured by electron-beam computed-tomography. ABC goals were defined as HbA1c<7.0%, BP<130/80 mmHg and LDL-C<100mg/dL.

RESULTS

ABC control was suboptimal with only 6% meeting all goals. Meeting no ABC goals at baseline compared to meeting all goals was associated with increased odds of developing microvascular complications (OR: 8.5, 2.3-31.5, p=0.001), but did not reach significance for CACp (OR: 1.7, 0.8-3.9, p=0.19).

CONCLUSION

ABC achievement at baseline strongly predicted microvascular but not macrovascular complications over 6-years in adults with type 1 diabetes, suggesting a need for novel therapeutic targets to complement conventional risk factors in treating macrovascular complications.