Abnormalities of glucose metabolism in patients with early renal failure

Cortisol secretion and abnormalities of glucose metabolism in nondiabetic patients with hypertension

OBJECTIVE

Glycometabolic changes are associated with hypercortisolism in Cushing's syndrome. Because impaired glucose tolerance (IGT) and insulin resistance are frequently detected in patients with essential hypertension, we hypothesized that in these patients, early glycometabolic abnormalities might be related to differences in regulation of cortisol secretion.

METHODS

In a cross-sectional study, we included 155 nondiabetic, essential hypertensive patients who were free of organ complications. The homeostasis model assessment (HOMA) index and the area under the curve of plasma glucose (AUC-glucose) and insulin (AUC-insulin) concentration following an oral glucose tolerance test were measured, together with daily plasma cortisol (8 a.m., 3 p.m. and 12 a.m.; AUC-cortisol) and 8 a.m. cortisol after 1 mg overnight dexamethasone suppression test (DST).

RESULTS

IGT was present in 27% of patients who were older and had higher BMI, plasma triglycerides and uric acid, AUC-cortisol and DST-cortisol, and lower HDL-cholesterol. Frequency of IGT increased progressively across tertiles of DST-cortisol, together with levels of glycated hemoglobin, fasting insulin and C-peptide, HOMA-index, AUC-glucose, and AUC-insulin. AUC-cortisol and DST-cortisol were directly correlated with insulin, C-peptide, HOMA-index, AUC-glucose, and AUC-insulin. Multivariate regression analysis showed that DST-cortisol was directly and independently correlated with HOMA index, AUC-glucose, and AUC-insulin. In a logistic regression model, both AUC-cortisol and DST-cortisol independently predicted IGT.

CONCLUSION

Daily cortisol and cortisol response to DST are independent determinants of IGT and insulin resistance in nondiabetic patients with hypertension, suggesting that even subtle differences in regulation of cortisol secretion might increase the risk of these patients to develop diabetes.

Vitamin D Deficiency Is Associated with Glycometabolic Changes in Nondiabetic Patients with Arterial Hypertension

Recent evidence indicates that mildly increased fasting and post-oral load blood glucose concentrations contribute to development of organ damage in nondiabetic patients with hypertension. In previous studies, vitamin D deficiency was associated with decreased glucose tolerance. The aim of this study was to examine the relationships between serum 25(OH)D levels and glucose tolerance and insulin sensitivity in hypertension. In 187 nondiabetic essential hypertensive patients free of cardiovascular or renal complications, we measured serum 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) and performed a standard oral glucose tolerance test (OGTT). Patients with 25(OH)D deficiency/insufficiency were older and had significantly higher blood pressure, fasting and post-OGTT (G-AUC) glucose levels, post-OGTT insulin (I-AUC), PTH levels, and prevalence of metabolic syndrome than patients with normal serum 25(OH)D. 25(OH)D levels were inversely correlated with age, blood pressure, fasting glucose, G-AUC, triglycerides, and serum calcium and PTH, while no significant relationships were found with body mass index (BMI), fasting insulin, I-AUC, HOMA index, and renal function. In a multivariate regression model, greater G-AUC was associated with lower 25(OH)D levels independently of BMI and seasonal vitamin D variations. Thus, in nondiabetic hypertensive patients, 25(OH)D deficiency/insufficiency could contribute to impaired glucose tolerance without directly affecting insulin sensitivity.

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.

Selective colorimetric urine glucose detection by paper sensor functionalized with polyaniline nanoparticles and cell membrane

For the diabetes diagnosis, noninvasive methods are preferred to invasive methods; urine glucose measurement is an example of a noninvasive method. However, conventional noninvasive methods for urine glucose measurement are not intuitive. Furthermore, such methods exhibit low selectivity because they can detect interfering molecules in addition to glucose. Herein, we fabricate a noninvasive, intuitive, and highly selective paper sensor consisting of polyaniline nanoparticles (PAni-NPs) and red blood cell membranes (RBCMs). The PAni-NPs (adsorbed on the paper) are highly sensitive to hydrogen ions and change color from emeraldine blue to emeraldine green within a few seconds. The RBCM (coated on the PAni-NP-adsorbed paper) having the glucose transporter-1 protein plays the role of a smart filter that transports glucose but rejects other interfering molecules. In particular, the selectivity of the RBCM-coated PAni-NP-based paper sensor was approximately improved ∼85%, compared to the uncoated paper sensors. The paper sensor could detect urine glucose over the range of 0-10 mg/mL (0-56 mM), with a limit of detection of 0.54 mM. The proposed paper sensor will facilitate the development of a highly selective and colorimetric urine glucose monitoring system.

Predictors of 30-day unplanned hospital readmission among adult patients with diabetes mellitus: a systematic review with meta-analysis

Adult patients with diabetes mellitus (DM) represent one-fifth of all 30-day unplanned hospital readmissions but some may be preventable through continuity of care with better DM self-management. We aim to synthesize evidence concerning the association between 30-day unplanned hospital readmission and patient-related factors, insurance status, treatment and comorbidities in adult patients with DM. We searched full-text English language articles in three electronic databases (MEDLINE, Embase and CINAHL) without confining to a particular publication period or geographical area. Prospective and retrospective cohort and case-control studies which identified significant risk factors of 30-day unplanned hospital readmission were included, while interventional studies were excluded. The study participants were aged ≥18 years with either type 1 or 2 DM. The random effects model was used to quantify the overall effect of each factor. Twenty-three studies published between 1998 and 2018 met the selection criteria and 18 provided information for the meta-analysis. The data were collected within a period ranging from 1 to 15 years. Although patient-related factors such as age, gender and race were identified, comorbidities such as heart failure (OR=1.81, 95% CI 1.67 to 1.96) and renal disease (OR=1.69, 95% CI 1.34 to 2.12), as well as insulin therapy (OR=1.45, 95% CI 1.24 to 1.71) and insurance status (OR=1.41, 95% CI 1.22 to 1.63) were stronger predictors of 30-day unplanned hospital readmission. The findings may be used to target DM self-management education at vulnerable groups based on comorbidities, insurance type, and insulin therapy.

Evidence-based treatment of hyperglycaemia with incretin therapies in patients with type 2 diabetes and advanced chronic kidney disease

Type 2 diabetes is the leading cause of chronic kidney disease (CKD). The prevalence of CKD is growing in parallel with the rising number of patients with type 2 diabetes globally. At present, the optimal approach to glycaemic control in patients with type 2 diabetes and advanced CKD (categories 4 and 5) remains uncertain, as these patients were largely excluded from clinical trials of glucose-lowering therapies. Nonetheless, clinical trial data are available for the use of incretin therapies, dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists, for patients with type 2 diabetes and advanced CKD. This review discusses the role of incretin therapies in the management of these patients. Because the presence of advanced CKD in patients with type 2 diabetes is associated with a markedly elevated risk of cardiovascular disease (CVD), treatment strategies must include the reduction of both CKD and CVD risks because death, particularly from cardiovascular causes, is more probable than progression to end-stage kidney disease. The management of hyperglycaemia is essential for good diabetes care even in advanced CKD. Current evidence supports an individualized approach to glycaemic management in patients with type 2 diabetes and advanced CKD, taking account of the needs of each patient, including the presence of co-morbidities and concomitant therapies. Although additional studies are needed to establish optimal strategies for glycaemic control in patients with type 2 diabetes and advanced CKD, treatment regimens with currently available pharmacotherapy can be individually tailored to meet the needs of this growing patient population.

Cholesterol Disturbances and the Role of Proper Nutrition in CKD Patients

Chronic kidney disease (CKD) is a widespread disease with increasing prevalence in the modern society. Lipid disturbances are common in this group of patients. In most patients with CKD atherogenic dyslipidemia is observed. Dyslipidemia in patients with renal diseases increases the risk of cardiovascular diseases and it accelerates the progression of chronic kidney disease to its end stage. The amelioration of dyslipidemia and the lowering of oxidative stress, inflammatory processes, insulin sensitivity and remnant lipoproteins levels may lead to the reduction in cardiovascular burden. Nutritional interventions can strengthen the beneficial effect of treatment and they play an important role in the preservation of overall well-being of the patients with CKD since the aim of appropriate diet is to reduce the risk of cardiovascular events, prevent malnutrition, and hamper the progression of kidney disease. The management of dyslipidemia, regardless of the presence of chronic kidney disease, should be initiated by the introduction of therapeutic lifestyle changes. The introduction of diet change was shown to exert beneficial effect on the lipid level lowering that reaches beyond pharmacological therapy. Currently available evidence give the impression that data on dietary interventions in CKD patients is not sufficient to make any clinical practice guidelines and is of low quality.

The association of glycated hemoglobin with mortality and ESKD among persons with diabetes and chronic kidney disease

CONTEXT

Diabetic kidney disease (DKD) is the leading cause of end stage kidney disease (ESKD) and is associated with a considerably shortened lifespan. While glucose-lowering therapy targeting glycated hemoglobin (HbA1c) <7% is proven to reduce the risk of developing DKD, its effects on complications of DKD are unclear.

OBJECTIVE

We examined the associations of HbA1c with risks of progression to ESKD and death within a clinic-based study of CKD. We hypothesized that higher HbA1c concentrations would be associated with increased risks of ESKD and death.

DESIGN AND SETTING

We studied 618 participants from the Seattle Kidney Study (mean eGFR 42 ml/min), 308 of whom had diabetes, and tested associations of baseline HbA1c with time to a composite outcome of initiation of renal replacement therapy or death.

RESULTS

During a median follow-up of 4.2 years, there were 343 instances of the composite outcome (11.5 per 100 person-years). Among participants with diabetes, in both crude and adjusted analyses, higher HbA1c levels (examined continuously or categorically) were not associated with the risk of the composite outcome (HR (95% CI): 0.99 (0.88, 1.10) per 1% additional HbA1c, p = 0.79). HbA1c was not associated with ESKD or mortality when the outcomes were examined separately, nor when stratified between insulin users and non-users.

CONCLUSION

In a referred population of established DKD, higher HbA1c was not associated with higher risk of ESKD or death. These data support current recommendations to be conservative with glycemic control among patients with advanced diabetes complications, such as CKD.

Metabolic Abnormalities in Diabetes and Kidney Disease: Role of Uremic Toxins

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is characterized by the accumulation of uremic retention solutes (URS) and is associated with perturbations of glucose homeostasis even in absence of diabetes. The underlying mechanisms of insulin resistance, β cell failure, and increase risk of diabetes in CKD, however, remain unclear. Metabolomic studies reported that some metabolites are similar in CKD and diabetic kidney disease (DKD) and contribute to the progression to end-stage renal disease. We attempted to discuss the mechanisms involved in the disruption of carbohydrate metabolism in CKD by focusing on the specific role of URS.

RECENT FINDINGS

Recent clinical data have demonstrated a defect of insulin secretion in CKD. Several studies highlighted the direct role of some URS (urea, trimethylamine N-oxide (TMAO), p-cresyl sulfate, 3-carboxylic acid 4-methyl-5-propyl-2-furan propionic (CMPF)) in glucose homeostasis abnormalities and diabetes incidence. Gut dysbiosis has been identified as a potential contributor to diabetes and to the production of URS. The complex interplay between the gut microbiota, kidney, pancreas β cell, and peripheral insulin target tissues has brought out new hypotheses for the pathogenesis of CKD and DKD. The characterization of intestinal microbiota and its associated metabolites are likely to fill fundamental knowledge gaps leading to innovative research, clinical trials, and new treatments for CKD and DKD.

Relationship between Plasma Proprotein Convertase Subtilisin/Kexin Type 9 and Estimated Glomerular Filtration Rate in the General Chinese Population

BACKGROUND

Elevated levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) have been reported to be related to dyslipidemia, including patients with kidney dysfunction. However, its association with estimated glomerular filtration rate (eGFR) in individuals with normal serum creatinine (SCr) has not been determined.

METHODS

A total of 2,089 subjects with normal SCr and without lipid-lowering treatment were consecutively enrolled in this study. Plasma PCSK9 levels were measured by ELISA kit and eGFR was evaluated by the Chronic Kidney Disease Epidemiology Collaboration equation. Subjects were divided into a normal eGFR group (n = 1,205, ≥90 mL/min/1.73 m2) and a decreased eGFR group (n = 884, < 90 mL/min/1.73 m2). Baseline characteristics and laboratory findings were compared between the two groups. Spearman's correlation and linear regression were performed to determine the association between PCSK9 and eGFR.

RESULTS

No significant difference in PCSK9 levels was found between the normal eGFR group and the decreased eGFR group (236.84 ± 67.87 vs. 239.98 ± 68.72 ng/mL, p = 0.303). In Spearman's correlation and multivariable linear regression analysis, no association of PCSK9 levels with eGFR was detected in the total cohort (r = -0.039, p = 0.079; adjusted β = -0.013, p = 0.630). This result remained the same in the subgroups of normal eGFR (r = -0.038, p = 0.190; adjusted β = -0.031, p = 0.367) and decreased eGFR (r = -0.054, p = 0.109; adjusted β = -0.034, p = 0.319).

CONCLUSION

In this single-center study with moderate sample size, the data showed no relationship of PCSK9 levels with normal or decreased eGFR in untreated patients with normal SCr, suggesting that further studies may be needed to understand the relationship between PCSK9 and lipid disorder in different stage of kidney dysfunction.

Renal function markers and insulin sensitivity after 3 years in a healthy cohort, the EGIR-RISC study

BACKGROUND

People with chronic renal disease are insulin resistant. We hypothesized that in a healthy population, baseline renal function is associated with insulin sensitivity three years later.

METHODS

We studied 405 men and 528 women from the European Group for the study of Insulin Resistance - Relationship between Insulin Sensitivity and Cardiovascular disease cohort. Renal function was characterized by the estimated glomerular filtration rate (eGFR) and by the urinary albumin-creatinine ratio (UACR). At baseline only, insulin sensitivity was quantified using a hyperinsulinaemic-euglycaemic clamp; at baseline and three years, we used surrogate measures: the Matsuda insulin sensitivity index (ISI), the HOmeostasis Model Assessment of Insulin Sensitivity (HOMA-IS). Associations between renal function and insulin sensitivity were studied cross-sectionally and longitudinally.

RESULTS

In men at baseline, no associations were seen with eGFR, but there was some evidence of a positive association with UACR. In women, all insulin sensitivity indices showed the same negative trend across eGFR classes, albeit not always statistically significant; for UACR, women with values above the limit of detection, had higher clamp measured insulin sensitivity than other women. After three years, in men only, ISI and HOMA-IS showed a U-shaped relation with baseline eGFR; women with eGFR> 105 ml/min/1.73m² had a significantly higher insulin sensitivity than the reference group (eGFR: 90-105 ml/min/1.73m²). For both men and women, year-3 insulin sensitivity was higher in those with higher baseline UACR. All associations were attenuated after adjusting on significant covariates.

CONCLUSIONS

There was no evidence to support our hypothesis that markers of poorer renal function are associated with declining insulin sensitivity in our healthy population.

Postgastric bypass hypoglycaemia in a patient with end-stage renal disease: a diagnostic and management pitfall

Roux-en-Y gastric bypass (RYGB) surgery is currently one of the most popular procedures to aid weight loss. Hypoglycaemia associated with gastric bypass surgery is an underdiagnosed but life-threatening potential consequence of the surgical procedure. We present a case of a 44-year-old woman with end-stage renal disease presenting with refractory hypoglycaemia after 10 years of RYGB. Extensive history and work-up excluded medications, renal disease, insulinoma and dumping syndrome as the cause of hypoglycaemia. Dietary modifications or pharmacological trial of drugs did not ameliorate her symptoms with progressive worsening of hypoglycaemia leading to continuous dextrose infusion. Distal pancreatectomy was performed with subsequent resolution of hypoglycaemia. Surgical pathology results showed diffuse hyperplastic islet cells, confirming the diagnosis of postgastric bypass hypoglycaemia.

Glycaemic changes in patients with chronic kidney disease

In Argentina, there have been no studies aimed at establishing the prevalence of dysglycaemia (impaired fasting glucose [IFG], impaired glucose tolerance [IGT] and diabetes mellitus [DM]) in patients with chronic kidney disease (CKD). Our group decided to conduct an observational study to evaluate the frequency with oral glucose tolerance test (OGTT) in CKD patients with no previous data for dysglycaemia in their medical records. OGTT was performed in 254 patients (60.62% male) with stage 3, 4 and 5 CKD under conservative treatment, haemodialysis or transplantation. Results for DM were found in 10 patients according to fasting glucose alone (3.94%; 95% CI: 1.35-6.53%), 11 patients with exclusively the second hour criterion (4.33%; 95% CI: 1.63-7.03%), 15 with both criteria (5.91%; 95% CI: 2.81-9.00%) and 36 patients with at least one criteria (14.17%; 95% CI: 9.69-18.66%). In a multivariate analysis, DM was associated with waist circumference (OR=1.033 per cm; 95% CI, 1.005 to 1.062; P=.019) and with conservative treatment vs. replacement therapy (OR=0.41; 95% CI: 0.19-0.92; P=.028). IGT was evident in 24.6% and 20.3 on conservative vs. replacement therapy, with no statistically significant difference. IFG (ADA criteria) was 19.75 vs. 9.24% in conservative vs. replacement therapy, with a statistically significant difference. OGTT is suggested for all CKD patients since it is able to detect the full range of unknown dysglycaemias, which avoids underdiagnoses and favours performing treatments to prevent progression in DM risk groups (IFG and/or IGT). It also aids in the selection of the most appropriate medication for transplantation or treatment initiation in new cases of undiagnosed DM to decrease morbidity and mortality.

Urinary Extracellular Vesicles: Potential Biomarkers of Renal Function in Diabetic Patients

The aim of this study was to check the relationship between the density of urinary EVs, their size distribution, and the progress of early renal damage in type 2 diabetic patients (DMt2). Patients were enrolled to this study, and glycated hemoglobin (HbA1c) below 7% was a threshold for properly controlled diabetic patients (CD) and poorly controlled diabetic patients (UD). Patients were further divided into two groups: diabetic patients without renal failure (NRF) and with renal failure (RF) according to the Glomerular Filtration Rate. Density and diameter of EVs were determined by Tunable Resistive Pulse Sensing. Additionally, EVs were visualized by means of Transmission and Environmental Scanning Electron Microscopy. Nano-liquid chromatography coupled offline with mass spectrometry (MALDI-TOF-MS/MS) was applied for proteomic analysis. RF had reduced density of EVs compared to NRF. The size distribution study showed that CD had larger EVs (mode) than UD (115 versus 109 nm; p < 0.05); nevertheless the mean EVs diameter was smaller in controls than in the CD group (123 versus 134 nm; p < 0.05). It was demonstrated that EVs are abundant in urine. Albumin, uromodulin, and number of unique proteins related to cell stress and secretion were detected in the EVs fraction. Density and size of urinary EVs reflect deteriorated renal function and can be considered as potential renal damage biomarkers.

Cardiovascular risk factors following renal transplant

Kidney transplantation is the gold-standard treatment for many patients with end-stage renal disease. Renal transplant recipients (RTRs) remain at an increased risk of fatal and non-fatal cardiovascular (CV) events compared to the general population, although rates are lower than those patients on maintenance haemodialysis. Death with a functioning graft is most commonly due to cardiovascular disease (CVD) and therefore this remains an important therapeutic target to prevent graft failure. Conventional CV risk factors such as diabetes, hypertension and renal dysfunction remain a major influence on CVD in RTRs. However it is now recognised that the morbidity and mortality from CVD are not entirely accounted for by these traditional risk-factors. Immunosuppression medications exert a deleterious effect on many of these well-recognised contributors to CVD and are known to exacerbate the probability of developing diabetes, graft dysfunction and hypertension which can all lead on to CVD. Non-traditional CV risk factors such as inflammation and anaemia have been strongly linked to increased CV events in RTRs and should be considered alongside those which are classified as conventional. This review summarises what is known about risk-factors for CVD in RTRs and how, through identification of those which are modifiable, outcomes can be improved. The overall CV risk in RTRs is likely to be multifactorial and a complex interaction between the multiple traditional and non-traditional factors; further studies are required to determine how these may be modified to enhance survival and quality of life in this unique population.

Diabetes mellitus and renal failure: Prevention and management

Nowadays, diabetes mellitus (DM) and hypertension are considered as the most common causes of end-stage renal disease (ESRD). In this paper, other than presenting the role of DM in ESRD, glucose metabolism and the management of hyperglycemia in these patients are reviewed. Although in several large studies there was no significant relationship found between tight glycemic control and the survival of ESRD patients, it is recommended that glycemic control be considered as the main therapeutic goal in the treatment of these patients to prevent damage to other organs. Glycemic control is perfect when fasting blood sugar is less than 140 mg/dL, 1-h postprandial blood glucose is less than 200 mg/dL, and glycosylated hemoglobin (HbA1c) is 6-7 in patients with type 1 diabetes and 7-8 in patients with type 2 diabetes. Administration of metformin should be avoided in chronic renal failure (CRF) because of lactic acidosis, the potentially fatal complication of metformin, but glipizide and repaglinide seem to be good choices.

Insulin Resistance in Nondiabetic Peritoneal Dialysis Patients: Associations with Body Composition, Peritoneal Transport, and Peritoneal Glucose Absorption

BACKGROUND AND OBJECTIVES

Insulin resistance has been associated with cardiovascular disease in peritoneal dialysis patients. Few studies have addressed the impact of fast transport status or dialysis prescription on insulin resistance. The aim of this study was to test whether insulin resistance is associated with obesity parameters, peritoneal transport rate, and glucose absorption.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Insulin resistance was evaluated with homeostasis model assessment method (HOMA-IR), additionally corrected by adiponectin (HOMA-AD). Enrolled patients were prevalent nondiabetics attending at Santo António Hospital Peritoneal Dialysis Unit, who were free of hospitalization or infectious events in the previous 3 months (51 patients aged 50.4 ± 15.9 years, 59% women). Leptin, adiponectin, insulin-like growth factor-binding protein 1 (IGFBP-1), and daily glucose absorption were also measured. Lean tissue index, fat tissue index (FTI), and relative fat mass (rel.FM) were assessed using multifrequency bioimpedance. Patients were categorized according to dialysate to plasma creatinine ratio at 4 hours, 3.86% peritoneal equilibration test, and obesity parameters.

RESULTS

Obesity was present in 49% of patients according to rel.FM. HOMA-IR correlated better with FTI than with body mass index. Significant correlations were found in obese, but not in nonobese patients, between HOMA-IR and leptin, leptin/adiponectin ratio (LAR), and IGFBP-1. HOMA-IR correlated with HOMA-AD, but did not correlate with glucose absorption or transport rate. There were no significant differences in insulin resistance indices, glucose absorption, and body composition parameters between fast and nonfast transporters. A total of 18 patients (35.3%) who had insulin resistance presented with higher LAR and rel.FM (7.3 [12.3, interquartile range] versus 0.7 [1.4, interquartile range], P<0.001, and 39.4 ± 10.1% versus 27.2 ± 11.5%, P=0.002, respectively), lower IGFBP-1 (8.2 ± 7.2 versus 21.0 ± 16.3 ng/ml, P=0.002), but similar glucose absorption and small-solute transport compared with patients without insulin resistance. FTI and LAR were independent correlates of HOMA-IR in multivariate analysis adjusted for glucose absorption and small-solute transport (r=0.82, P<0.001).

CONCLUSIONS

Insulin resistance in nondiabetic peritoneal dialysis patients is associated with obesity and LAR independent of glucose absorption and small-solute transport status. Fast transport status was not associated with higher likelihood of obesity or insulin resistance.

Early renal failure as a cardiovascular disease: Focus on lipoprotein(a) and prothrombotic state

Patients with renal failure are at increased risk of cardiovascular events even at the earliest stages of disease. In addition to many classic cardiovascular risk factors, many conditions that are commonly identified as emerging risk factors might contribute to occurrence of cardiovascular disease. Changes in circulating levels of many of these emerging risk factors have been demonstrated in patients with early stages of renal failure caused by different types of renal disease and have been associated with detection of cardiovascular complications. However, for most of these factors evidence of benefits of correction on cardiovascular outcome is missing. In this article, we comment on the role of lipoprotein(a) and prothrombotic factors as potential contributors to cardiovascular events in patients with early renal failure.

Acute porcine renal metabolic effect of endogastric soft drink administration assessed with hyperpolarized [1-(13)C]pyruvate

PURPOSE

Our aim was to determine the quantitative reproducibility of metabolic breakdown products in the kidney following intravenous injection of hyperpolarized [1-(13)C]pyruvate and secondly to investigate the metabolic effect on the pyruvate metabolism of oral sucrose load using dissolution dynamic nuclear polarization. By this technique, metabolic alterations in several different metabolic related diseases and their metabolic treatment responses can be accessed.

METHODS

In four healthy pigs the lactate-to-pyruvate, alanine-to-pyruvate and bicarbonate-to-pyruvate ratio was measured following administration of regular cola and consecutive injections of hyperpolarized [1-(13)C]pyruvate four times within an hour.

RESULTS

The overall lactate-to-pyruvate metabolic profile changed significantly over one hour following an acute sucrose load leading to a significant rise in blood glucose.

CONCLUSION

The reproducibility of hyperpolarized magnetic resonance spectroscopy in the healthy pig kidney demonstrated a repeatability of more than 94% for all metabolites and, furthermore, that the pyruvate to lactate conversion and the blood glucose level is elevated following endogastric sucrose administration.

A systematic review investigating the cumulative incidence of chronic kidney disease in young adults with impaired glucose tolerance

BACKGROUND

It is known that risk of chronic kidney disease (CKD) is elevated in patients with diabetes mellitus but it is not clear whether the risk is also elevated with impaired glucose tolerance (IGT). If the risk is increased, it is not known if this is confined to people with IGT who progress to type 2 diabetes (T2DM). The purpose of this systematic review is to determine the relative risk of CKD in young adults (aged 18 to 40 years) with IGT (exposed group) compared to those without glycaemic abnormality (comparator group).

METHODS/DESIGN

The following electronic databases will be systematically searched from inception to January 2015 for relevant studies: CINAHL, EMBASE, MEDLINE, PubMed, Cochrane libraries and grey literature. Two independent reviewers will screen search results, extract data, select studies for inclusion and assess their quality. Studies including young adults (aged 18 to 40 years) with IGT containing any of the following CKD markers will be included: estimated glomerular filtration rate (eGFR), albumin creatinine ratio (ACR), protein creatinine ratio (PCR), serum creatinine (SCr) and creatinine clearance (CrCl) levels. Studies at any time period after diagnosis of IGT and with any length of follow-up will be included. The proportion of IGT participants reporting each outcome will be documented. Relative risks (RR) and odds ratios (OR) will be extracted or calculated from raw data. If possible, study results will be combined in a meta-analysis.

DISCUSSION

The results of this comprehensive review will establish the evidence for the association between IGT and the risk of developing CKD in young adults (aged 18 to 40 years).

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42014007081.

Relationships of plasma lipoprotein(a) levels with insulin resistance in hypertensive patients

BACKGROUND

Lipoprotein(a) [Lp(a)] is an emergent cardiovascular risk factor that is related to the presence and severity of cardiovascular damage in hypertensive patients. In these patients, insulin resistance is frequently detected but its relationship with plasma Lp(a) is not clear. The aim of this study was to examine the relationships between Lp(a) and variables of glucose metabolism in hypertension.

METHODS

In 527 consecutive, non-diabetic, middle-aged hypertensive patients we measured anthropometric indexes, 24-hour creatinine clearance, lipid profile including Lp(a) levels, fasting glucose, insulin and C-peptide, and calculated the Homeostatic Model Assessment (HOMA) index.

RESULTS

Lp(a) levels were significantly and progressively lower with increasing HOMA-index values. Lp(a) was inversely related to fasting glucose, insulin, and C-peptide, HOMA-index, and creatinine clearance and directly related to LDL-cholesterol. Multiple regression analysis adjusted for age, sex, body mass index, blood pressure, smoking habit, alcohol intake, renal function, lipid profile, history of cardiovascular events, and drug use showed that HOMA-index and creatinine clearance were inversely and independently associated to Lp(a) levels.

CONCLUSIONS

Insulin resistance and higher fasting insulin levels are associated with lower plasma Lp(a) in hypertensive patients. This association might be relevant in the assessment of cardiovascular risk in these patients.

Plasma glucose levels and left ventricular diastolic function in nondiabetic hypertensive patients

BACKGROUND

Changes in left ventricular (LV) diastolic filling anticipate diastolic heart failure and are frequently detected in patients with hypertension or diabetes. We tested the hypothesis that increased fasting and postload glucose levels are associated with diastolic dysfunction as assessed by tissue Doppler imaging (TDI) in hypertensive patients.

METHODS

In 104 untreated, nondiabetic, hypertensive patients free of cardiovascular complications, we measured glucose and insulin at fast and after an oral glucose load, calculated the Homeostatic Model Assessment (HOMA) index, and performed electrocardiogram (ECG), conventional echocardiography, and TDI.

RESULTS

Thirty-one patients who had impaired fasting glucose/impaired glucose tolerance had more frequent LV strain at ECG and worse TDI markers of diastolic function than patients with normal plasma glucose but no differences in variables LV mass, LV geometry, systolic function, and early-/late-wave transmitral diastolic velocity. TDI detected diastolic dysfunction in 46 patients who were older and had greater body mass index, blood pressure, fasting and postload glucose, insulin, HOMA index, LV mass, and left atrial diameter than patients with preserved diastolic function. Variables of diastolic function measured at TDI were significantly related with age, body mass index, LV mass, and fasting and postload plasma glucose. Stepwise regression analysis showed that the relationship of markers of diastolic dysfunction with both fasting and postload glucose levels was independent of possible confounders.

CONCLUSIONS

Initially abnormal fasting and postload glucose levels are associated with more prominent diastolic impairment in uncomplicated hypertensive patients, suggesting that hyperglycemia might increase the risk of diastolic heart failure even in the absence of diabetes.

Inverse association between body mass index and chronic kidney disease in older diabetic adults

PURPOSE

To identify associations among body mass index (BMI), diabetes, and chronic kidney disease (CKD) in older adults in Taiwan.

METHODS

This study enrolled 3334 participants aged 65 years and above who underwent an annual health screening at a medical center from January 2006 to December 2010. CKD was defined as an estimated glomerular filtration rate less than 60 mL/min/1.73 m(2). A multiple logistic regression analysis was used to determine associations among BMI, diabetes, and CKD.

RESULTS

The prevalence rate of CKD was 19.7% and 10.5% in diabetic and nondiabetic subjects, respectively. A multivariate model indicated that age, diabetes, hypertriglyceridemia, low levels of high-density lipoprotein cholesterol, and hyperuricemia were associated with an increased risk of CKD. Furthermore, there was an inverse association between BMI and CKD in older diabetic patients, with odds ratios of 3.71, 2.32, 2.12, and 1.31 in underweight, normal, overweight, and obese subjects, respectively, compared with nondiabetic subjects of normal weight.

CONCLUSIONS

There was an inverse association between BMI and CKD in older diabetic patients but no such association was found in nondiabetic older adults. More attention should be given to older underweight diabetic patients because they have a higher risk of CKD.

Combined pancreatic islet and kidney transplantation in a child with unstable type 1 diabetes and end-stage renal disease

Islet transplantation after successful kidney transplantation is a recognized treatment for adults with diabetes and end-stage renal disease (ESRD), but has not been considered an option in the pediatric population. To our knowledge, we report the first combined islet and kidney transplant in a child. The patient was born with bilateral renal hypoplasia and was diagnosed with type 1 diabetes mellitus at age 13 months. He had erratic glycemic control and hypoglycemia unawareness. At 6 years of age, the child safely underwent simultaneous islet and live donor kidney transplantation. Although function of the islet graft was transient, the combined transplant provided significant benefits in terms of glucose control and overall growth and development. Such an approach represents a viable treatment option for pediatric patients with ESRD and unstable diabetes.

Deletion of the insulin receptor in the proximal tubule promotes hyperglycemia

Nearly all renal tubular epithelial cells express insulin receptor. The insulin receptor in the distal tubule appears to modulate BP, but the role of the insulin receptor in the proximal tubule is unknown. Here, we selectively knocked out the insulin receptor from the proximal tubules of mice. Western blotting confirmed a two- to three-fold reduction in renal cortical homogenate insulin receptor-β among knockout mice compared with wild-type littermates. Young knockout mice exhibited a mildly diabetic phenotype, evidenced by higher fasting plasma glucose levels than wild-type mice. Assessments by hyperinsulinemic-euglycemic clamp and a glucose tolerance test revealed no differences in insulin sensitivity or overt pancreatic function, respectively. Renal cortical mRNA expression and enzyme activity of glucose-6-phosphatase, which catalyzes the final step of glucose production, were significantly higher in knockout mice. Taken together, these results support a role for insulin receptor in the proximal tubule in the modulation of systemic glucose levels. Downregulation of the insulin receptor in the proximal tubule, which occurs in insulin-resistant states, may promote hyperglycemia through enhanced gluconeogenesis.

Paricalcitol does not improve glucose metabolism in patients with stage 3-4 chronic kidney disease

Patients with chronic kidney disease are often insulin resistant and glucose intolerant--abnormalities that promote cardiovascular disease. Administration of 1,25-dihydroxyvitamin D (calcitriol) has improved glucose metabolism in patients with end-stage renal disease. We conducted a randomized, placebo-controlled clinical trial to test whether paricalcitol, a 1,25-dihydroxyvitamin D analog, changes glucose tolerance in earlier stages of chronic kidney disease. In a crossover design, 22 nondiabetic patients with estimated glomerular filtration rates of stage 3-4 chronic kidney disease and fasting plasma glucose of 100-125 mg/dl were given daily oral paricalcitol for 8 weeks and matching placebo for 8 weeks, separated by an 8-week washout period. The order of interventions was random and blinded to both participants and investigators. Paricalcitol significantly reduced serum concentrations of parathyroid hormone, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D while significantly increasing serum concentrations of fibroblast growth factor-23 and 24,25-dihydroxyvitamin D. Paricalcitol, however, had no significant effect on glucose tolerance (the primary outcome measure), insulin sensitivity, beta-cell insulin response, plasma free fatty acid suppression, or urinary F2-isoprostane excretion. Thus, despite substantial effects on vitamin D metabolism, paricalcitol did not improve glucose metabolism in nondiabetic patients with stage 3-4 chronic kidney disease.

Plasma aldosterone levels and development of insulin resistance: prospective study in a general population

Aldosterone plays a role in hypertension, and hypertension is prevalent in patients with insulin resistance. Cross-sectional studies have reported that plasma aldosterone levels are higher in patients with insulin resistance. However, it is not known whether plasma aldosterone levels predict the development of insulin resistance. Subjects of the present study were 1235 local residents (490 men and 745 women) who participated in health screenings in Japan in 1999. Plasma aldosterone levels were measured by radioimmunoassay. We investigated the cross-sectional relationship between plasma aldosterone levels and insulin resistance (homeostasis model assessment index ≥1.73 according to the diagnostic criteria used in Japan) in 1088 nondiabetic participants. At the 10-year follow-up, 141 subjects had died, and 260 subjects refused re-examination. We performed a prospective analysis of 564 subjects to predict incident insulin resistance. We found a significant (P<0.001) cross-sectional relationship between plasma aldosterone and homeostasis model assessment index at baseline. In the prospective analysis, a significantly higher (P<0.05) relative risk (1.71 [95% CI: 1.03-2.84]) was observed in the highest tertile versus lowest tertile of plasma aldosterone for the development of insulin resistance, after adjustment for confounding factors. This 10-year prospective study demonstrated that plasma aldosterone levels predicted the development of insulin resistance in a general population.

Dyslipidemia associated with chronic kidney disease

Cardiovascular disease is a major cause of morbidity and mortality in patients with impaired renal function. Dyslipidemia has been established as a well-known traditional risk factor for cardiovascular disease (CVD) in the general population and it is well known that patients with chronic kidney disease (CKD) exhibit significant alterations in lipoprotein metabolism. In this review, the pathogenesis and treatment of CKD-induced dyslipidemia are discussed. Studies on lipid abnormalities in predialysis, hemodialysis and peritoneal dialysis patients are analyzed. In addition, the results of the studies that tested the effects of the hypolipidemic drugs on cardiovascular morbidity and mortality in patients with CKD are reported.

To eat or not to eat: dietary fat in uremia is the question

Although a diet low in protein is well known to reduce the risk of progression in patients with chronic kidney disease (CKD), the impact of dietary fat content and fat quality has largely been ignored. As a reduced protein intake results in an obligatory reduction in energy intake, and as CKD patients often suffer from energy malnutrition, this issue deserves greater attention. The present review aims to summarize what is currently known about dietary fat intake in CKD and suggests areas for further study. We conclude that although overweight per se is an important risk factor for the development of CKD, the role of obesity as a risk factor for complications in manifest CKD remains unclear. Current data support a balanced increase in dietary fat intake in patients with CKD to compensate for reduced energy intake in protein-restricted diets and anorexic patients. However, patients who are obese should be encouraged to lose weight while maintaining or, preferably, increasing muscle mass.

End-Stage Renal Disease and Sudden Cardiac Death

Patients with end-stage renal disease (ESRD) are at a high risk for sudden cardiac death (SCD). SCD is the most common cause of death in this population and, as in the general population, ventricular arrhythmias seem to be the most common cause of SCD. The increased risk of SCD in ESRD is likely due to factors that are unique to the metabolic derangements associated with this state, as well as the increased prevalence of traditional risk factors. Despite this, the evidence base for the assessment and management of SCD in these patients is limited. This article reviews the current data on underlying risk factors for SCD in patients with ESRD, the role of common medical and device-based therapies for the prevention and treatment of SCD, and the applicability of common methods of risk stratification to patients with ESRD.

Insulin therapy in renal disease

Diabetes mellitus (DM) is the main cause of end-stage renal disease (ESRD). Conversely, chronic renal failure (CRF) is also associated with diverse alterations in carbohydrate and insulin metabolism. CRF-induced metabolic disorders should be borne in mind when treating diabetic patients, to ensure the introduction of adequate therapy adjustments that are in line with the onset of renal function decline. Moreover, several specific therapies employed in CRF may also influence pharmacological therapy of DM in uraemic patients. Adequate glycaemic control has also been associated with a reduction in the onset and progression of diabetic nephropathy as well as in the morbidity and mortality in uraemic diabetic patients during dialysis. Intensive insulin therapy can notably improve glycemic control and it should be considered part of the management of insulin-treated CRF diabetic patients. Insulin analogues have been recently evaluated in CRF diabetic patients, with encouraging results. In this study, we review the more relevant aspects related to insulin therapy in diabetic patients with different degrees of renal failure and in patients with ESRD, both in conservative therapy and dialysis.

Is serum cystatin-C a reliable marker for metabolic syndrome?

PURPOSE

Chronic kidney disease and metabolic syndrome are recognized as major cardiovascular risk factors. It has been shown that cystatin C has a stronger association with mortality risk than creatinine-based estimations of glomerular filtration rate. We measured cystatin values in dyslipidemic patients and looked for correlations between renal function, cystatin, and metabolic syndrome.

METHODS

There were 925 dyslipidemic patients prospectively included in this cross-sectional study and evaluated over 10 months. Each visit included clinical and biological assessment.

RESULTS

Most patients exhibited cardiovascular risk factors other than dyslipidemia: hypertension in 34%, diabetes in 11%, and smoking in 18%. Mean triglycerides were 149 +/- 136 mg/dL, mean high-density lipoprotein cholesterol 54 +/- 14 mg/dL, and low-density lipoprotein 167 +/- 48 mg/dL. Metabolic syndrome was present in 238 (26%) patients. Plasma creatinine did not differ between control group and metabolic syndrome patients (80 +/- 26 vs 82 +/- 20 micromol/L, respectively, P = .2), but creatinine clearance evaluated by abbreviated Modification of Diet in Renal Disease Study formula was lower in the metabolic syndrome group than in the non-metabolic-syndrome group (83.3 +/- 18.8 mL/min/1.73 m(2) vs 86.8+/-16.9 mL/min/1.73 m(2), respectively, P < .007). Cystatin value was significantly higher in metabolic syndrome patients than in others (0.86 +/- 0.23 vs 0.79 +/- 0.20 mg/L, respectively, P < .0001), independently of serum creatinine level and creatinine clearance. Furthermore, there was a progressive increase in cystatin, as a function of the number of metabolic syndrome components.

CONCLUSIONS

Our study shows that cystatin is associated with metabolic syndrome in dyslipidemic patients. Cystatin may be an interesting marker of metabolic syndrome and of increased cardiovascular and renal risk.

Inflammation and insulin resistance in uremia

Low-grade systemic inflammation is an important potential factor in the pathogenesis of insulin resistance in end-stage renal disease (ESRD). Insulin resistance and diabetes, characterized by impaired skeletal muscle glucose uptake or excess hepatic glucose production, are in turn relevant contributors to morbidity and mortality in ESRD patients. Oxidative stress is increased in ESRD, in conservative therapy as well as hemodialysis treatment. Recent evidence suggests that oxidative stress contributes, at least in part, to both inflammation and insulin resistance by modulating the production of proinflammatory cytokines and adipokines in monocytes and in adipose tissue. This review focuses on the pathogenesis of inflammation and oxidative stress, and the effects of their interplay on insulin resistance in ESRD.

Body mass index and fat mass are the primary correlates of insulin resistance in nondiabetic stage 3-4 chronic kidney disease patients

BACKGROUND

Insulin resistance has been noted in patients with chronic kidney disease (CKD). The determinants of insulin resistance have not been well-studied in CKD patients.

OBJECTIVE

The objective of this study was to examine the degree and determinants of insulin resistance in persons without diabetes but with stage 3-4 CKD.

DESIGN

Demographic characteristics, metabolic hormones, and inflammatory markers were measured in 95 nonobese stage 3-4 CKD patients without prior diagnosis of diabetes mellitus and 36 control subjects without CKD. The estimated glomerular filtration rate (eGFR) was measured by using the Modification of Diet in Renal Disease study equation. Insulin resistance was measured with the use of the homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

After age and sex adjustments, HOMA-IR scores were significantly and positively correlated with body mass index (BMI) and percentage body fat. After control for age, race, adiponectin concentrations, sex, and eGFR in a multivariate regression model, BMI remained as the only significant predictor of insulin resistance (standardized regression coefficient = 0.55; P < 0.001). When substituted for BMI, percentage body fat also was an independent predictor of insulin resistance. The prevalence of abnormal HOMA did not differ significantly between CKD patients (98%) and BMI-matched control subjects (94%).

CONCLUSION

Whereas insulin resistance is highly prevalent in stage 3-4 CKD, the primary determinant of insulin resistance in this population is BMI, specifically, fat mass.

Hyperinsulinemia in pediatric patients with chronic kidney disease: the role of tumor necrosis factor-alpha

We sought to determine the prevalence of hyperinsulinemia and insulin resistance in pediatric patients with chronic kidney disease (CKD) stages 2-4. Data were collected on 43 subjects, aged 6-21 years with mean glomerular filtration rate (GFR) = 47 ml/min per 1.73 m(2) body surface area. Patients were grouped by body mass index (BMI) as either non-lean (>85th percentile) or lean (<or=85th percentile). Fourteen (33%) subjects had hyperinsulinemia, and seven (16%) had elevated homeostasis model assessment of insulin resistance (HOMA-IR). Non-lean subjects had a higher serum insulin level (21.0 microU/ml vs 13.4 microU/ml, P < 0.0001) and HOMA-IR (4.9 vs 3.2, P < 0.001) than lean subjects had. The prevalence of hyperinsulinemia was higher in non-lean patients (40%) than in lean patients (29%) but was not statistically significant. High HOMA-IR was present in six (40%) non-lean subjects and in one lean subject (P < 0.001). Correlation analysis demonstrated that serum insulin level was significantly associated with BMI, leptin and tumor necrosis factor (TNF)-alpha. Stepwise regression determined that increased BMI (P = 0.003) and TNF-alpha (P = 0.01) independently predicted higher insulin level in the whole cohort. Separate analysis for lean subjects showed no significant associations between serum insulin level and BMI; TNF-alpha was the only independent predictor of serum insulin (beta = 1.11, P = 0.01). We conclude that hyperinsulinemia and insulin resistance are frequent in pediatric CKD. In lean patients inflammation appears to be an important determinant of serum insulin level.

Insulin resistance and hyperinsulinemia are related to plasma aldosterone levels in hypertensive patients

OBJECTIVE

An association between aldosterone and insulin resistance has been demonstrated in obesity and primary aldosteronism and in blacks with the metabolic syndrome. The aim of this study was to evaluate the relationship of plasma aldosterone with insulin sensitivity in white subjects.

RESEARCH DESIGN AND METHODS

In 356 patients with essential hypertension and 102 normotensive control subjects of comparable age and BMI, we measured, after discontinuation of treatment, plasma active renin, aldosterone, cortisol, glucose, insulin, and C-peptide levels and calculated markers of insulin sensitivity. Direct assessment of insulin sensitivity was obtained in a subset of 64 hypertensive patients by a hyperinsulinemic clamp.

RESULTS

Hypertensive patients had significantly greater fasting plasma insulin and C-peptide concentrations and homeostasis model assessment (HOMA) indexes than normotensive control subjects. A positive association with increasing plasma aldosterone concentrations was demonstrated for plasma glucose, insulin, C-peptides, and HOMA. Assessment of insulin sensitivity by clamp showed a significant decrease of the metabolic clearance rate of glucose with increasing aldosterone levels. Significant correlations were found between plasma aldosterone, plasma insulin, and C-peptide levels, HOMA, and glucose metabolic clearance rate. Blood pressure and plasma potassium, plasma cortisol, and renin levels, but not BMI, were also directly correlated with plasma aldosterone. Multiple regression analysis showed that HOMA, together with plasma potassium, cortisol, and renin levels, was independently correlated with plasma aldosterone.

CONCLUSIONS

This study demonstrates a direct relationship between aldosterone, insulin resistance, and hyperinsulinemia in white subjects. In patients with hypertension, this relationship might contribute to maintenance of high blood pressure and increased cardiovascular risk.

Metabolic risk factors associated with serum creatinine in a non-diabetic population

Insulin resistance, low HDL-cholesterol and microalbuminuria are important components of the metabolic syndrome as defined by WHO. Insulin resistance and low HDL-cholesterol are also common in chronic kidney disease (CKD), but it is not clear whether they are early or late phenomenons in the development of renal failure. This study examined whether low-grade albuminuria (microalbuminuria), lipoprotein fractions, and the insulin/glucose ratio (IGR)-a surrogate marker of insulin resistance-were related to renal function (expressed as serum creatinine) in persons without diabetes and with apparently normal renal function. The study included 4,131 men and women aged 55-75 years from the cross-sectional Tromsø IV survey (1994-1995). Lifestyle factors, waist circumference and blood pressure were included in the analyses. Gender stratified multivariate analysis was used to assess the relationship between serum creatinine and microalbuminuria, lipoprotein fractions and IGR. Serum creatinine was positively associated with microalbuminuria in men (beta = 2.50, 95% confidence interval (CI) 0.66-4.34), but not in women. HDL-cholesterol and IGR were strongly associated with creatinine in both genders (HDL-cholesterol: Men: beta = -4.82, 95% CI -6.27 to -3.37; women: beta = -2.12, 95% CI -3.28 to -0.96. IGR: Second, third and fourth quartile compared with first quartile, men: beta = 0.94, 95% CI -0.63 to 2.51; 2.10, 95% CI 0.52-3.69 and 2.40, 95% CI 0.75-4.04; women: beta = 1.91, 95% CI 0.59-3.22; 2.61, 95% CI 1.28-3.95 and 3.20, 95% CI 1.80-4.60). These findings suggest that even early impairment of renal function may be associated with insulin resistance and dyslipidemia, regardless of renal albumin leakage.

Insulin resistance is associated with skeletal muscle protein breakdown in non-diabetic chronic hemodialysis patients

Deranged protein metabolism is known to complicate uremia. Insulin resistance is evident in chronic hemodialysis (CHD) patients. We hypothesized that the degree of insulin resistance would predict protein catabolism in non-diabetic CHD patients. We examined the relationship between Homeostasis Model Assessment (HOMA) and fasting whole-body and skeletal muscle protein turnover in 18 non-diabetic CHD patients using primed-constant infusions of L-(1-(13)C) leucine and L-(ring-(2)H(5)) phenylalanine. Mean+/-s.d. fasting glucose and body mass index were 80.6+/-9.8 mg/dl and 25.4+/-4.4 kg/m(2), respectively. Median (interquartile range) HOMA was 1.6 (1.4, 3.9). Mean+/-s.e.m. skeletal muscle protein synthesis, breakdown, and net balance were 89.57+/-11.67, 97.02+/-13.3, and -7.44+/-7.14 microg/100 ml/min, respectively. Using linear regression, a positive correlation was observed between HOMA and skeletal muscle protein synthesis (R(2)=0.28; P=0.024), and breakdown (R(2)=0.49; P=0.001). An inverse association between net skeletal muscle protein balance and HOMA was also noted (R(2)=0.20; P=0.066). After adjustment for C-reactive protein, only the relationship between HOMA and skeletal muscle protein breakdown persisted (R(2)=0.49; P=0.006). There were no significant associations between components of whole-body protein turnover and HOMA. This study demonstrates that insulin resistance is evident in non-diabetic dialysis patients, is associated with skeletal muscle protein breakdown, and represents a novel target for intervention in uremic wasting.

Insulin sensitivity in patients with primary aldosteronism: a follow-up study

CONTEXT

The relationship between aldosterone and glucose metabolism is poorly understood, and there is substantial disparity among findings of studies that have examined glucose tolerance and insulin sensitivity in patients with primary aldosteronism.

OBJECTIVE

The objective of the study was to determine the outcome of glucose tolerance and insulin sensitivity in patients with primary aldosteronism after treatment.

DESIGN

This was a prospective study of patients who received a diagnosis of primary aldosteronism and were followed up for an average period of 5.7 yr (range, 3-9 yr).

SETTING

The study was conducted at a university referral center.

PATIENTS

A consecutive sample of 47 patients with tumoral or idiopathic aldosteronism was followed up after either surgical or medical treatment. Patients with primary aldosteronism were compared with 247 patients with essential hypertension with the same severity and duration of disease and 102 normotensive subjects.

MAIN OUTCOME MEASURES

Short- and long-term changes in glucose tolerance and insulin sensitivity were measured.

RESULTS

After adjustment for age, gender, and body mass index, patients with primary aldosteronism had greater homeostasis model assessment index (P < 0.05) and plasma insulin response to an oral glucose load (P < 0.05) and lower quantitative insulin sensitivity check index (P < 0.01) than normotensive controls. Changes in insulin sensitivity were significantly greater in essential hypertension than primary aldosteronism, and this difference was confirmed by assessment with the hyperinsulinemic-euglycemic clamp (P < 0.01). Treatment of primary aldosteronism decreased blood pressure significantly, and during the initial 6 months of follow-up, parameters of insulin sensitivity were restored to normal. Analysis of subsequent follow-up showed nonsignificant changes in glucose metabolism parameters in both adrenalectomized and spironolactone-treated patients.

CONCLUSIONS

Insulin resistance is present in patients with tumoral and idiopathic aldosteronism, but the defect appears less severe than in patients with essential hypertension. Treatment with surgery or aldosterone antagonists restores rapidly and persistently normal sensitivity to insulin.

Glycemic status and development of kidney disease: the Framingham Heart Study

OBJECTIVE

Diabetes is a major risk factor for the development of kidney disease and is the leading cause of end-stage renal disease in the U.S. Whether pre-diabetes is associated with the development of kidney disease is unclear.

RESEARCH DESIGN AND METHODS

Subjects free of chronic kidney disease (CKD) were drawn from the Framingham Heart Study offspring cohort (1991-1995), given an oral glucose tolerance test, and followed for an average of 7 years for development of CKD (glomerular filtration rate [GFR] of <59 ml/min per 1.73 m2 in women and <64 ml/min per 1.73 m2 in men). Multivariable logistic regression models, adjusted for cardiovascular disease risk factors including age, sex, hypertension, smoking, BMI, total and HDL cholesterol levels, and prevalent myocardial infarction or congestive heart failure, were used to estimate the odds of patients developing kidney disease among glycemic categories.

RESULTS

Of 2,398 subjects (53% women; mean age 54 years), 63% were normoglycemic, 29% had impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), 3.4% were newly diabetic, and 4.6% had known diabetes. By glycemic category, mean GFR at follow-up was 87, 85, 82, and 78 ml/min per 1.73 m2, respectively. The fully adjusted odds of developing CKD were 0.98 (95% CI 0.67-1.45), 1.71 (95% CI 0.83-3.55), and 1.93 (95% CI 1.06-3.49) among those with IFG or IGT, newly diagnosed diabetes, or known diabetes, respectively, compared with those who were normoglycemic at baseline. Among participants without diabetes, metabolic syndrome was not associated with kidney disease at follow-up (odds ratio 1.46, P = 0.06).

CONCLUSIONS

Cardiovascular disease risk factors explain much of the relationship between prediabetes and the development of chronic kidney disease. Clinical trials are warranted to determine whether vascular risk factor modification can slow the decline of kidney function among those with pre-diabetes.

Glucose metabolism in renal transplant recipients: effect of calcineurin inhibitor withdrawal and conversion to sirolimus

Cyclosporine A (CsA) and tacrolimus have been associated with an increased risk for diabetes after transplantation, whereas sirolimus is deemed to be devoid of any effect on glucose metabolism. This study was performed to investigate the effect of the withdrawal of calcineurin inhibitors and the switch to sirolimus on peripheral insulin resistance and pancreatic beta cell response. Twenty-six patients who received a kidney transplant and discontinued CsA and were converted to sirolimus and 15 recipients of suboptimal kidneys who were treated with tacrolimus plus sirolimus for the first 3 mo after grafting and thereafter with sirolimus alone were enrolled. All patients underwent an oral glucose tolerance test and intravenous insulin tolerance test before and 6 mo after the conversion to sirolimus-alone therapy. The withdrawal of CsA or tacrolimus was associated with a significant fall of insulin sensitivity (both P = 0.01) and with a defect in the compensatory beta cell response, as measured by the disposition index (P = 0.004 and P = 0.02, respectively). The increase of insulin resistance and the decrease of disposition index significantly correlated with the change of serum triglyceride concentration after the conversion to sirolimus-based therapy (R(2) = 0.30, P = 0.0002; and R(2) = 0.19, P = 0.004, respectively). Clinically, the switch to sirolimus was associated with a 30% increase of incidence of impaired glucose tolerance and with four patients' developing new-onset diabetes. In conclusion, the discontinuation of calcineurin inhibitors and their replacement by sirolimus fail to ameliorate the glycometabolic profile of kidney transplant recipients. Rather, it is associated with a worsening of insulin resistance and an inappropriately low insulin response.