Chronic kidney disease and intensive glycemic control increase cardiovascular risk in patients with type 2 diabetes

Diabetes Control and the Risks of ESRD and Mortality in Patients With CKD

BACKGROUND

Diabetes is the leading cause of end-stage renal disease (ESRD) and a significant contributor to mortality in the general population. We examined the associations of hemoglobin A1c (HbA1c) levels with ESRD and death in a population with diabetes and chronic kidney disease (CKD).

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

6,165 patients with diabetes (treated with oral hypoglycemic agents and/or insulin) and CKD stages 1 to 5 at a large health care system.

PREDICTOR

HbA1c level (examined as a categorical and continuous measure).

OUTCOMES

All-cause and cause-specific mortality ascertained from the Ohio Department of Health mortality files and ESRD ascertained from the US Renal Data System.

RESULTS

During a median 2.3 years of follow-up, 957 patients died (887 pre-ESRD deaths) and 205 patients reached ESRD. In a Cox proportional hazards model, after multivariable adjustment including for kidney function, HbA1c level < 6% was associated with higher risk for death when compared with HbA1c levels of 6% to 6.9% (HR, 1.23; 95% CI, 1.01-1.50). Similarly, HbA1c level ≥ 9% was associated with higher risk for all-cause death (HR, 1.34; 95% CI, 1.06-1.69). In competing-risk models, baseline HbA1c level was not associated with ESRD. For cause-specific mortality, diabetes accounted for >12% of deaths overall and >19% of deaths among those with HbA1c levels > 9%.

LIMITATIONS

Small proportion of participants with advanced kidney disease; single-center population.

CONCLUSIONS

In this cohort of patients with CKD with diabetes, HbA1c levels < 6% and ≥9% were associated with higher risk for death. HbA1c levels were not associated with ESRD in this specific CKD population. Diabetes-related deaths increased with higher HbA1c levels.

The chronic kidney disease - Mineral bone disorder (CKD-MBD): Advances in pathophysiology

The causes of excess cardiovascular mortality associated with chronic kidney disease (CKD) have been attributed in part to the CKD-mineral bone disorder syndrome (CKD-MBD), wherein, novel cardiovascular risk factors have been identified. New advances in the causes of the CKD-MBD are discussed in this review. They demonstrate that repair and disease processes in the kidneys release factors to the circulation that cause the systemic complications of CKD. The discovery of WNT inhibitors, especially Dickkopf 1 (Dkk1), produced during renal repair as participating in the pathogenesis of the vascular and skeletal components of the CKD-MBD implied that additional pathogenic factors are critical. This lead to the discovery that activin A is a second renal repair factor circulating in increased levels during CKD. Activin A derives from peritubular myofibroblasts of diseased kidneys, wherein it stimulates fibrosis, and decreases tubular klotho expression. Activin A binds to the type 2 activin A receptor, ActRIIA, which is variably affected by CKD in the vasculature. In diabetic/atherosclerotic aortas, specifically in vascular smooth muscle cells (VSMC), ActRIIA signaling is inhibited and contributes to CKD induced VSMC dedifferentiation, osteogenic transition and neointimal atherosclerotic calcification. In nondiabetic/nonatherosclerotic aortas, CKD increases VSMC ActRIIA signaling, and vascular fibroblast signaling causing the latter to undergo osteogenic transition and stimulate vascular calcification. In both vascular situations, a ligand trap for ActRIIA prevented vascular calcification. In the skeleton, activin A is responsible for CKD stimulation of osteoclastogenesis and bone remodeling increasing bone turnover. These studies demonstrate that circulating renal repair and injury factors are causal of the CKD-MBD and CKD associated cardiovascular disease.

Glucose targets for preventing diabetic kidney disease and its progression

BACKGROUND

Diabetes is the leading cause of end-stage kidney disease (ESKD) around the world. Blood pressure lowering and glucose control are used to reduce diabetes-associated disability including kidney failure. However there is a lack of an overall evidence summary of the optimal target range for blood glucose control to prevent kidney failure.

OBJECTIVES

To evaluate the benefits and harms of intensive (HbA1c < 7% or fasting glucose levels < 120 mg/dL versus standard glycaemic control (HbA1c ≥ 7% or fasting glucose levels ≥ 120 mg/dL for preventing the onset and progression of kidney disease among adults with diabetes.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register up to 31 March 2017 through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials evaluating glucose-lowering interventions in which people (aged 14 year or older) with type 1 or 2 diabetes with and without kidney disease were randomly allocated to tight glucose control or less stringent blood glucose targets.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for eligibility and risks of bias, extracted data and checked the processes for accuracy. Outcomes were mortality, cardiovascular complications, doubling of serum creatinine (SCr), ESKD and proteinuria. Confidence in the evidence was assessing using GRADE. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes.

MAIN RESULTS

Fourteen studies involving 29,319 people with diabetes were included and 11 studies involving 29,141 people were included in our meta-analyses. Treatment duration was 56.7 months on average (range 6 months to 10 years). Studies included people with a range of kidney function. Incomplete reporting of key methodological details resulted in uncertain risks of bias in many studies. Using GRADE assessment, we had moderate confidence in the effects of glucose lowering strategies on ESKD, all-cause mortality, myocardial infarction, and progressive protein leakage by kidney disease and low or very low confidence in effects of treatment on death related to cardiovascular complications and doubling of serum creatinine (SCr).For the primary outcomes, tight glycaemic control may make little or no difference to doubling of SCr compared with standard control (4 studies, 26,874 participants: RR 0.84, 95% CI 0.64 to 1.11; I2= 73%, low certainty evidence), development of ESKD (4 studies, 23,332 participants: RR 0.62, 95% CI 0.34 to 1.12; I2= 52%; low certainty evidence), all-cause mortality (9 studies, 29,094 participants: RR 0.99, 95% CI 0.86 to 1.13; I2= 50%; moderate certainty evidence), cardiovascular mortality (6 studies, 23,673 participants: RR 1.19, 95% CI 0.73 to 1.92; I2= 85%; low certainty evidence), or sudden death (4 studies, 5913 participants: RR 0.82, 95% CI 0.26 to 2.57; I2= 85%; very low certainty evidence). People who received treatment to achieve tighter glycaemic control probably experienced lower risks of non-fatal myocardial infarction (5 studies, 25,596 participants: RR 0.82, 95% CI 0.67 to 0.99; I2= 46%, moderate certainty evidence), onset of microalbuminuria (4 studies, 19,846 participants: RR 0.82, 95% CI 0.71 to 0.93; I2= 61%, moderate certainty evidence), and progression of microalbuminuria (5 studies, 13,266 participants: RR 0.59, 95% CI 0.38 to 0.93; I2= 75%, moderate certainty evidence). In absolute terms, tight versus standard glucose control treatment in 1,000 adults would lead to between zero and two people avoiding non-fatal myocardial infarction, while seven adults would avoid experiencing new-onset albuminuria and two would avoid worsening albuminuria.

AUTHORS' CONCLUSIONS

This review suggests that people who receive intensive glycaemic control for treatment of diabetes had comparable risks of kidney failure, death and major cardiovascular events as people who received less stringent blood glucose control, while experiencing small clinical benefits on the onset and progression of microalbuminuria and myocardial infarction. The adverse effects of glycaemic management are uncertain. Based on absolute treatment effects, the clinical impact of targeting an HbA1c < 7% or blood glucose < 6.6 mmol/L is unclear and the potential harms of this treatment approach are largely unmeasured.

Effects of glycaemic management on diabetic kidney disease

Hyperglycaemia contributes to the onset and progression of diabetic kidney disease (DKD). Observational studies have not consistently demonstrated a glucose threshold, in terms of HbA1c levels, for the onset of DKD. Tight glucose control has clearly been shown to reduce the incidence of micro- or macroalbuminuria. However, evidence is now also emerging to suggest that intensive glucose control can slow glomerular filtration rate loss and possibly progression to end stage kidney disease. Achieving tight glucose control needs to be balanced against the increasing appreciation that glucose targets for the prevention of diabetes related complications need be individualised for each patient. Recently, empagliflozin which is an oral glucose lowering agent of the sodium glucose cotransporter-2 inhibitor class has been shown to have renal protective effects. However, the magnitude of empagliflozin’s reno-protective properties are over and above that expected from its glucose lowering effects and most likely largely result from mechanisms involving alterations in intra-renal haemodynamics. Liraglutide and semaglutide, both injectable glucose lowering agents which are analogues of human glucagon like peptide-1 have also been shown to reduce progression to macroalbuminuria through mechanisms that remain to be fully elucidated. Here we review the evidence from observational and interventional studies that link good glucose control with improved renal outcomes. We also briefly review the potential reno-protective effects of newer glucose lowering agents.

Parathyroid hormone stimulates adipose tissue browning: a pathway to muscle wasting

PURPOSE OF REVIEW

Studying organ-to-organ communications (i.e. crosstalk) uncovers mechanisms regulating metabolism in several tissues. What is missing is identification of mediators of different catabolic conditions contributing to losses of adipose and muscle tissues. Identifying mediators involved in organ-to-organ crosstalk could lead to innovative therapeutic strategies because several disorders such as chronic kidney disease (CKD), cancer cachexia, and other catabolic conditions share signals of worsening metabolism and increased risk of mortality.

RECENT FINDINGS

A recent breakthrough published in Cell Metabolism leads to the conclusion that parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) cause 'browning' of white adipose tissue plus energy production via activation of uncoupling protein-1. Browning was associated with muscle wasting in mouse models of cancer and CKD. The pathway to browning includes PTH/PTHrP activation of protein kinase A (PKA) and lost muscle mass via the ubiquitin proteasome proteolytic system (UPS).

SUMMARY

The results suggest that crosstalk between muscle and fat contributes in a major way to tissue catabolism. The pathway initiated by PTH or PTHrP is novel and it suggests potential interrelationships that control metabolism in other catabolic conditions. Identifying how the parathyroid hormone-PKA-UPS axis relates to obesity, type 2 diabetes, and other insulin-resistant conditions remains unclear.

Hemoglobin A1c and Mortality in Older Adults With and Without Diabetes: Results From the National Health and Nutrition Examination Surveys (1988-2011)

OBJECTIVE

Hemoglobin A1c (HbA1c) level has been associated with increased mortality in middle-aged populations. The optimal intensity of glucose control in older adults with diabetes remains uncertain. We sought to estimate the risk of mortality by HbA1c levels among older adults with and without diabetes.

RESEARCH DESIGN AND METHODS

We analyzed data from adults aged ≥65 years (n = 7,333) from the Third National Health and Nutrition Examination Survey (NHANES III) (1998-1994) and Continuous NHANES (1999-2004) and their linked mortality data (through December 2011). Cox proportional hazards models were used to examine the relationship of HbA1c with the risk of all-cause and cause-specific (cardiovascular disease [CVD], cancer, and non-CVD/noncancer) mortality, separately for adults with diabetes and without diabetes.

RESULTS

Over a median follow-up of 8.9 years, 4,729 participants died (1,262 from CVD, 850 from cancer, and 2,617 from non-CVD/noncancer causes). Compared with those with diagnosed diabetes and an HbA1c <6.5%, the hazard ratio (HR) for all-cause mortality was significantly greater for adults with diabetes with an HbA1c >8.0%. HRs were 1.6 (95% CI 1.02, 2.6) and 1.8 (95% CI 1.3, 2.6) for HbA1c 8.0-8.9% and ≥9.0%, respectively (P for trend <0.001). Participants with undiagnosed diabetes and HbA1c >6.5% had a 1.3 (95% CI 1.03, 1.8) times greater risk of all-cause mortality compared with participants without diabetes and HbA1c 5.0-5.6%.

CONCLUSIONS

An HbA1c >8.0% was associated with increased risk of all-cause and cause-specific mortality in older adults with diabetes. Our results support the idea that better glycemic control is important for reducing mortality; however, in light of the conflicting evidence base, there is also a need for individualized glycemic targets for older adults with diabetes depending on their demographics, duration of diabetes, and existing comorbidities.

The role of renal proximal tubule transport in the regulation of blood pressure

The electrogenic sodium/bicarbonate cotransporter 1 (NBCe1) on the basolateral side of the renal proximal tubule plays a pivotal role in systemic acid-base homeostasis. Mutations in the gene encoding NBCe1 cause severe proximal renal tubular acidosis accompanied by other extrarenal symptoms. The proximal tubule reabsorbs most of the sodium filtered in the glomerulus, contributing to the regulation of plasma volume and blood pressure. NBCe1 and other sodium transporters in the proximal tubule are regulated by hormones, such as angiotensin II and insulin. Angiotensin II is probably the most important stimulator of sodium reabsorption. Proximal tubule AT_1A receptor is crucial for the systemic pressor effect of angiotensin II. In rodents and rabbits, the effect on proximal tubule NBCe1 is biphasic; at low concentration, angiotensin II stimulates NBCe1 via PKC/cAMP/ERK, whereas at high concentration, it inhibits NBCe1 via NO/cGMP/cGKII. In contrast, in human proximal tubule, angiotensin II has a dose-dependent monophasic stimulatory effect via NO/cGMP/ERK. Insulin stimulates the proximal tubule sodium transport, which is IRS2-dependent. We found that in insulin resistance and overt diabetic nephropathy, stimulatory effect of insulin on proximal tubule transport was preserved. Our results suggest that the preserved stimulation of the proximal tubule enhances sodium reabsorption, contributing to the pathogenesis of hypertension with metabolic syndrome. We describe recent findings regarding the role of proximal tubule transport in the regulation of blood pressure, focusing on the effects of angiotensin II and insulin.

Epidemiology and outcomes of hypoglycemia in patients with advanced diabetic kidney disease on dialysis: A national cohort study

Background

Patients with advanced diabetic kidney disease (DKD) behave differently to diabetic patients without kidney disease. We aimed to investigate the associations of hypoglycemia and outcomes after initiation of dialysis in patients with advanced DKD on dialysis.

Methods

Using National Health Insurance Research Database, 20,845 advanced DKD patients beginning long-term dialysis between 2002 and 2006 were enrolled. We investigated the incidence of severe hypoglycemia episodes before initiation of dialysis. Patients were followed from date of first dialysis to death, end of dialysis, or 2008. Main outcomes measured were all-cause mortality, myocardial infarction (MI), and subsequent severe hypoglycemic episodes after dialysis.

Results

19.18% patients had at least one hypoglycemia episode during 1-year period before initiation of dialysis. Advanced DKD patients with higher adapted Diabetes Complications Severity Index (aDCSI) scores were associated with more frequent hypoglycemia (P for trend < 0.001). Mortality and subsequent severe hypoglycemia after dialysis both increased with number of hypoglycemic episodes. Compared to those who had no hypoglycemic episodes, those who had one had a 15% higher risk of death and a 2.3-fold higher risk of subsequent severe hypoglycemia. Those with two or more episodes had a 19% higher risk of death and a 3.9-fold higher risk of subsequent severe hypoglycemia. However, previous severe hypoglycemia was not correlated with risk of MI after dialysis.

Conclusions

The rate of severe hypoglycemia was high in advanced DKD patients. Patients with higher aDCSI scores tended to have more hypoglycemic episodes. Hypoglycemic episodes were associated with subsequent hypoglycemia and mortality after initiation of dialysis. We studied the associations and further study is needed to establish cause. In addition, more attention is needed for hypoglycemia prevention in advanced DKD patients, especially for those at risk patients.

Effect of spironolactone on the risks of mortality and hospitalization for heart failure in pre-dialysis advanced chronic kidney disease: A nationwide population-based study

BACKGROUND

Spironolactone has been shown to reduce cardiovascular death in patients with mild-to-moderate chronic kidney disease (CKD), but its risks and benefits in advanced CKD remain unsettled. We aimed to assess whether spironolactone reduces cardiovascular mortality and morbidity in pre-dialysis stage 5 CKD patients.

METHODS

Using Taiwan's National Health Insurance Research Database from January 2000 to June 2009, we enrolled 27,213 pre-dialysis stage 5 CKD adult patients, in whom 1363 patients were treated with spironolactone (user) and 25,850 were not (nonuser). Outcomes were all-cause mortality, hospitalization for heart failure (HHF) and major adverse cardiac event (MACE, the composite of acute myocardial infarction and ischemic stroke). Patients were followed up till December 31, 2009.

RESULTS

Over 85,758 person-years of follow-up, spironolactone users had higher incidence for all-cause mortality (24.7/100 person-years vs. 10.6/100 person-years), infection-related death (4.4/100 person-years vs. 1.7/100 person-years) and HHF (4.0/100 person-years vs. 1.4/100 person-years). Multivariable Cox hazards model showed that spironolactone users were associated with higher risks of all-cause mortality (adjusted hazard ratio [aHR] 1.35, 95% confidence interval [CI] 1.24-1.46), infection-related death (aHR 1.42, CI 1.16-1.73) and HHF (aHR 1.35, CI 1.08-1.67) as compared to nonusers. The risks for cardiovascular mortality, MACE and hyperkalemia-associated hospitalization were similar between two groups. After matching users and nonusers (1:3 ratio) by propensity scores, the results were consistent in matched cohort and across subgroups.

CONCLUSIONS

Spironolactone may be associated with higher risks for all-cause and infection-related mortality and HHF in pre-dialysis stage 5 CKD patients. Spironolactone should be used with caution in advanced CKD patients.

Current therapeutic approaches in the management of hyperglycemia in chronic renal disease

Diabetes mellitus (DM) and chronic kidney disease (CKD) are intricately intertwined. DM is the most common cause of CKD. Adequate control of DM is necessary for prevention of progression of CKD, while careful management of the metabolic abnormalities in CKD will assist in achieving better control of DM. Two of the key organs involved in glucose production are the kidney and the liver. Furthermore, the kidney also plays a role in glucose filtration and reabsorption. In CKD, monitoring of glycemic control using traditional methods such as Hemoglobin A1c (Hba1c) must be done with caution secondary to associated hematological abnormalities in CKD. With regard to medication management in the care of patients with DM, CKD has significant effects. For example, the dosages of oral and non-insulin anti-hyperglycemic agents often need to be modified according to renal function. Insulin metabolism is altered in CKD, and a reduction in insulin dose is almost always needed. Dialysis also affects various aspects of glucose homeostasis, necessitating appropriate changes in therapy. Due to the aforementioned factors glycemic management in patients with DM and CKD can be quiet challenging.

Effects of High Density Lipoprotein Raising Therapies on Cardiovascular Outcomes in Patients with Type 2 Diabetes Mellitus, with or without Renal Impairment: The Action to Control Cardiovascular Risk in Diabetes Study

BACKGROUND

The role of high density lipoprotein-raising interventions in addition to statin therapy in patients with diabetes remains controversial. Chronic kidney disease (CKD) is a strong modifier of cardiovascular (CV) outcomes. We therefore investigated the impact of CKD status at baseline on outcomes in patients with diabetes randomized to standard statin or statin plus fenofibrate treatment in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) lipid trial.

METHODS

Among 5,464 participants in the ACCORD lipid trial, 3,554 (65%) were free of CKD at baseline, while 1,910 (35%) had mild to moderate CKD. Differences in CV outcomes during follow-up between CKD and non-CKD subgroups were examined. In addition, the effect of fenofibrate as compared to placebo on CV outcomes was examined for both subgroups.

RESULTS

All CV outcomes were 1.4-3 times higher among patients with CKD as compared to non-CKD patients. In patients with CKD, the addition of fenofibrate had no effect on any of the primary or secondary outcomes. In patients without CKD, however, the addition of fenofibrate was associated with a significant 36% reduction of CV mortality (hazards ratio [HR] 0.64; 95% CI 0.42-0.97; p value for treatment interaction <0.05) and 44% lower rate of fatal or non-fatal congestive heart failure (CHF; HR 0.56; 95% CI 0.37-0.84; p value treatment interaction <0.03).

CONCLUSIONS

For patients with type 2 diabetes at high CV risk but no CKD, fenofibrate therapy added to statin reduced the CV mortality and the rate of fatal and non-fatal CHF.

Glucose Control and Vascular Outcomes in Type 2 Diabetes: Is the Picture Clear?

The overall impact of glucose lowering on vascular complications and major clinical outcomes, including mortality, in type 2 diabetes is still an open issue. While intensive glucose control has undoubted benefit for microvascular end points, the relationship between glucose-lowering approaches and reduced incidence and/or progression of macrovascular complications is less clear. This review article will discuss the effect of glucose lowering per se as well as the effects of specific glucose-lowering therapies on vascular outcomes in type 2 diabetes. The role of lifestyle changes on cardiovascular outcomes will be also addressed. Recent analyses from large cardiovascular outcome studies (ACCORD, ADVANCE, and VADT) provide new information on factors that modulate the impact of intensive glucose lowering on outcomes, helping to identify the specific clinical characteristics of the patients receiving the intervention that would show a better response. While several studies on cardiovascular outcomes with diabetes drugs are available, they do not clearly highlight a benefit from using a specific medication or will require additional evidence, as for the sodium-glucose cotransporter 2 blockers.

An updated systematic review and meta-analysis on the efficacy and tolerability of dipeptidyl peptidase-4 inhibitors in patients with type 2 diabetes with moderate to severe chronic kidney disease

OBJECTIVE

This updated meta-analysis determines the effect of dipeptidyl peptidase-4 inhibitors on glycemic and tolerability outcomes in patients with type 2 diabetes mellitus and chronic kidney disease with glomerular filtration rate of ⩽60 mL/min or on dialysis.

METHODS

In all, 14 citations were identified from multiple databases. Qualitative assessments and quantitative analyses were performed.

RESULTS

There were 2261 participants, 49-79 years of age, 49% men and 44% Caucasians. In seven placebo-comparator studies, reduction in hemoglobin A1c at weeks 12-24 was 0.55% (95% confidence interval: -0.68 to -0.43), P < 0.00001). In three sulfonylurea-comparator studies, dipeptidyl peptidase-4 inhibitors did not significantly reduce hemoglobin A1c at weeks 52-54 (-0.15% (95% confidence interval: -0.32 to 0.02)). In one sitagliptin versus albiglutide study, albiglutide significantly reduced hemoglobin A1c in patients with moderate renal impairment (-0.51%). A similar reduction in hemoglobin A1c was seen with sitagliptin versus vildagliptin (-0.56% vs -0.54%). Compared with placebo or sulfonylurea, dipeptidyl peptidase-4 inhibitors did not significantly reduce hemoglobin A1c after 12 and 54 weeks in patients on dialysis. Hypoglycemia was reported by ~30% of patients in both dipeptidyl peptidase-4 inhibitors and placebo groups over 24-52 weeks. While hypoglycemia was more common with a sulfonylurea at 52-54 weeks (risk ratio: 0.46 (95% confidence interval: 0.18 to 1.18)), there was significant heterogeneity (I (2) = 87%). Limitations included high drop-out rate from most studies and small number of active-comparator studies.

CONCLUSIONS

Dipeptidyl peptidase-4 inhibitors in patients with chronic kidney disease caused a modest reduction in hemoglobin A1c versus placebo, but not when compared with sulfonylureas or albiglutide, or when used in patients on dialysis. Additional active-comparator studies are needed to further elucidate the role of dipeptidyl peptidase-4 inhibitors in patients with chronic kidney disease stages 3-5 or on dialysis.

Urinary NGAL-Positive Acute Kidney Injury and Poor Long-term Outcomes in Hospitalized Patients

Introduction

Neutrophil gelatinase−associated lipocalin (NGAL) is a widely studied biomarker of renal tubular injury. Urinary NGAL (uNGAL) during acute kidney injury (AKI) predicts short-term adverse outcomes. However, the long-term predictive value is unknown.

Methods

We performed a prospective observational study of 145 patients with hospital-acquired AKI according to Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) criteria and analyzed the long-term predictive value of uNGAL at the time of AKI. We defined a composite outcome of all-cause mortality and the development of end-stage renal disease (ESRD).

Results

In all, 61 AKI patients died and 22 developed ESRD within 6 months. The uNGAL levels were significantly higher in patients with poor long-term outcomes. uNGAL levels ≥362 μg/l (highest quartile) and uNGAL levels between 95 and 362 μg/l (third quartile) were associated with hazard ratios of 3.7 (95% confidence interval, 2.1–6.5) and 1.9 (1.1–3.5), respectively, compared with uNGAL levels <95 μg/l (lower quartiles). After 6 months, 67% and 43% of patients within the highest and third uNGAL quartile, respectively, had either progressed to ESRD or died, compared to only 21% of patients with uNGAL in the lower 2 quartiles (P < 0.001). In multivariable Cox regression analyses accounting for conventional predictors, uNGAL was the strongest independent predictor of adverse long-term outcomes. The association of uNGAL levels and poor long-term outcomes remained significant in the subgroup of 107 AKI survivors discharged without requiring dialysis (P = 0.002).

Discussion

These data indicate that elevated uNGAL levels at AKI diagnosis predict poor long-term outcomes.

Intensive glycemic control and the risk of end-stage renal disease: an ADVANCE in the management of diabetes?

Posttrial follow-up of participants randomized to intensive versus standard glycemic control in the ADVANCE trial has demonstrated a significant benefit of intensive glycemic control on the risk of end-stage renal disease. In a more detailed analysis, intensive glycemic control appears to be of benefit only before the development of clinically evident kidney disease or in patients with documented early-stage chronic kidney disease.

Silymarin in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Type 2 diabetes mellitus (T2DM) is associated with increased risk of cardiovascular disease and nephropathy-now the leading cause of end-stage renal disease and dialysis in Europe and the United States. Inflammation and oxidative stress play a pivotal role in the development of diabetic complications. Silymarin, an herbal drug with antioxidant and anti-inflammatory properties, may improve glycemic control and prevent the progression of the complications. In a systematic review and meta-analysis including five randomized controlled trials and 270 patients, routine silymarin administration determines a significant reduction in fasting blood glucose levels (-26.86 mg/dL; 95% CI -35.42-18.30) and HbA1c levels (-1.07; 95% CI -1.73-0.40) and has no effect on lipid profile. Benefits for silymarin on proteinuria and CKD progressions are reported in only one small study and are uncertain. However, being aware of the low quality of the available evidence and elevated heterogeneity of these studies, no recommendation can be made and further studies are needed.

Selective Insulin Resistance in the Kidney

Insulin resistance has been characterized as attenuation of insulin sensitivity at target organs and tissues, such as muscle and fat tissues and the liver. The insulin signaling cascade is divided into major pathways such as the PI3K/Akt pathway and the MAPK/MEK pathway. In insulin resistance, however, these pathways are not equally impaired. For example, in the liver, inhibition of gluconeogenesis by the insulin receptor substrate (IRS) 2 pathway is impaired, while lipogenesis by the IRS1 pathway is preserved, thus causing hyperglycemia and hyperlipidemia. It has been recently suggested that selective impairment of insulin signaling cascades in insulin resistance also occurs in the kidney. In the renal proximal tubule, insulin signaling via IRS1 is inhibited, while insulin signaling via IRS2 is preserved. Insulin signaling via IRS2 continues to stimulate sodium reabsorption in the proximal tubule and causes sodium retention, edema, and hypertension. IRS1 signaling deficiency in the proximal tubule may impair IRS1-mediated inhibition of gluconeogenesis, which could induce hyperglycemia by preserving glucose production. In the glomerulus, the impairment of IRS1 signaling deteriorates the structure and function of podocyte and endothelial cells, possibly causing diabetic nephropathy. This paper mainly describes selective insulin resistance in the kidney, focusing on the proximal tubule.

Long-term Benefits of Intensive Glucose Control for Preventing End-Stage Kidney Disease: ADVANCE-ON

OBJECTIVE

The Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation (ADVANCE) trial reported that intensive glucose control prevents end-stage kidney disease (ESKD) in patients with type 2 diabetes, but uncertainty about the balance between risks and benefits exists. Here, we examine the long-term effects of intensive glucose control on risk of ESKD and other outcomes.

RESEARCH DESIGN AND METHODS

Survivors, previously randomized to intensive or standard glucose control, were invited to participate in post-trial follow-up. ESKD, defined as the need for dialysis or kidney transplantation, or death due to kidney disease, was documented overall and by baseline CKD stage, along with hypoglycemic episodes, major cardiovascular events, and death from other causes.

RESULTS

A total of 8,494 ADVANCE participants were followed for a median of 5.4 additional years. In-trial HbA1c differences disappeared by the first post-trial visit. The in-trial reductions in the risk of ESKD (7 vs. 20 events, hazard ratio [HR] 0.35, P = 0.02) persisted after 9.9 years of overall follow-up (29 vs. 53 events, HR 0.54, P < 0.01). These effects were greater in earlier-stage CKD (P = 0.04) and at lower baseline systolic blood pressure levels (P = 0.01). The effects of glucose lowering on the risks of death, cardiovascular death, or major cardiovascular events did not differ by levels of kidney function (P > 0.26).

CONCLUSIONS

Intensive glucose control was associated with a long-term reduction in ESKD, without evidence of any increased risk of cardiovascular events or death. These benefits were greater with preserved kidney function and with well-controlled blood pressure.

Cardiovascular Outcomes in Action to Control Cardiovascular Risk in Diabetes: Impact of Blood Pressure Level and Presence of Kidney Disease

BACKGROUND

Persons with chronic kidney disease (CKD) represent a population prone to cardiovascular disease (CVD) but vulnerable to adverse medication effects. We assessed the impact of intensive antihypertensive therapy on the cerebrovascular and other CVD outcomes in high-risk patients with type 2 diabetes and baseline CKD.

METHODS

Using current guideline criteria, 1,726 (36.9%) of 4,678 participants in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) blood pressure (BP) arm had mild to moderate CKD (CKD1-3B) at baseline. Participants of this study were randomized to intensive (systolic <120 mm Hg) or standard (systolic <140 mm Hg) BP goals. Fatal and non-fatal stroke were pre-specified secondary outcomes of the ACCORD study.

RESULTS

Total cerebrovascular events were significantly higher in participants with baseline CKD (0.66%/year) compared with participants free of CKD (0.28%/year). A significantly higher rate of events was observed in CKD participants. Intensive antihypertensive therapy in participants without CKD at baseline resulted in a 55% significant reduction of any stroke (hazard ratio 0.447; 95% CI 0.227-0.880) and a 50% reduction of non-fatal stroke (hazard ratio 0.498; 95% CI 0.250-0.993). In participants with CKD at baseline, the occurrence of any stroke was reduced by 38% (hazard ratio 0.623; 95% CI 0.361-1.074) and non-fatal stroke by 36% (hazard ratio 0.642; 95% CI 0.361-1.142). Test for interaction was NS between the 2 groups. Changes in other CVD outcomes did not reach statistical significance.

CONCLUSIONS

These findings suggest that intensive antihypertensive therapy offers significant cerebrovascular protection in diabetic participants without CKD at baseline, but significant benefit to patients with CKD cannot be excluded.

Diagnosis and treatment of early renal disease in patients with type 2 diabetes mellitus: what are the clinical needs?

Renal disease is prevalent in patients with diabetes mellitus type 2. Aggressive metabolic control and lowering of systemic and/or intraglomerular blood pressure are effective interventions but not without side effects. Thus a better, early identification of patients at risk for incidence or progression to end-stage renal failure by the use of new, validated biomarkers is highly desirable. In the majority of patients, hypertension and hyperglycaemia are pathogenetically important pathways for the progression of renal disease. Nonetheless even aggressive therapy targeting these factors does not eliminate the risk of end-stage renal failure and experimental evidence suggests that many other pathways (e.g. tubulointerstitial hypoxia or inflammation etc.) also contribute. As their individual importance might vary from patient to patient, interventions which interfere are likely not to be therapeutically effective in all subjects. In this situation, an option to preserve the statistical power of clinical trials is to rely on biomarkers that reflect individual pathophysiology. In current clinical practice, albuminuria is the biomarker that has been best evaluated to guide stratified/personalized therapy but there is a clear need to expand our diagnostic abilities.

Ligand trap for the activin type IIA receptor protects against vascular disease and renal fibrosis in mice with chronic kidney disease

The causes of cardiovascular mortality associated with chronic kidney disease (CKD) are partly attributed to the CKD-mineral bone disorder (CKD-MBD). The causes of the early CKD-MBD are not well known. Our discovery of Wnt (portmanteau of wingless and int) inhibitors, especially Dickkopf 1, produced during renal repair as participating in the pathogenesis of the vascular and skeletal components of the CKD-MBD implied that additional pathogenic factors are critical. In the search for such factors, we studied the effects of activin receptor type IIA (ActRIIA) signaling by using a ligand trap for the receptor, RAP-011 (a soluble extracellular domain of ActRIIA fused to a murine IgG-Fc fragment). In a mouse model of CKD that stimulated atherosclerotic calcification, RAP-011 significantly increased aortic ActRIIA signaling assessed by the levels of phosphorylated Smad2/3. Furthermore, RAP-011 treatment significantly reversed CKD-induced vascular smooth muscle dedifferentiation as assessed by smooth muscle 22α levels, osteoblastic transition, and neointimal plaque calcification. In the diseased kidneys, RAP-011 significantly stimulated αklotho levels and it inhibited ActRIIA signaling and decreased renal fibrosis and proteinuria. RAP-011 treatment significantly decreased both renal and circulating Dickkopf 1 levels, showing that Wnt activation was downstream of ActRIIA. Thus, ActRIIA signaling in CKD contributes to the CKD-MBD and renal fibrosis. ActRIIA signaling may be a potential therapeutic target in CKD.

Plasma FGF23 and Calcified Atherosclerotic Plaque in African Americans with Type 2 Diabetes Mellitus

BACKGROUND

Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone implicated in disorders of serum phosphorus concentration and vitamin D. The role of FGF23 in vascular calcification remains controversial.

METHODS

Relationships between FGF23 and coronary artery calcified atherosclerotic plaque (CAC), aortoiliac calcified plaque (CP), carotid artery CP, volumetric bone mineral density (vBMD), albuminuria, and estimated glomerular filtration rate (eGFR) were determined in 545 African Americans with type 2 diabetes (T2D) and preserved kidney function in African American-Diabetes Heart Study participants. Generalized linear models were fitted to test associations between FGF23 and cardiovascular, bone, and renal phenotypes, and change in measurements over time, adjusting for age, gender, African ancestry proportion, body mass index, diabetes duration, hemoglobin A1c, blood pressure, renin-angiotensin-system inhibitors, statins, calcium supplements, serum calcium, and serum phosphate.

RESULTS

The sample was 56.7% female with a mean (SD) age of 55.6 (9.6) years, diabetes duration of 10.3 (8.2) years, eGFR 90.9 (22.1) ml/min/1.73 m2, urine albumin:creatinine ratio (UACR) 151 (588) (median 13) mg/g, plasma FGF23 161 (157) RU/ml, and CAC 637 (1,179) mg. In fully adjusted models, FGF23 was negatively associated with eGFR (p < 0.0001) and positively associated with UACR (p < 0.0001) and CAC (p = 0.0006), but not with carotid CP or aortic CP. Baseline FGF23 concentration did not associate with changes in vBMD or CAC after a mean of 5.1 years follow-up.

CONCLUSIONS

Plasma FGF23 concentrations were independently associated with subclinical coronary artery disease, albuminuria, and kidney function in the understudied African American population with T2D. Findings support relationships between FGF23 and vascular calcification, but not between FGF23 and bone mineral density, in African Americans lacking advanced nephropathy.

Enhanced fitness and renal function in Type 2 diabetes

AIMS

To investigate the renal effects of fitness in people with diabetes with mild renal dysfunction.

METHODS

The effect of a 12-week exercise programme on estimated GFR in 128 people with diabetes was evaluated.

RESULTS

All cardiometabolic variables improved after 12 weeks of supervised exercise. Although there was a modest 3.9% increase in estimated GFR from baseline in the 128 people who completed the study, those with baseline chronic kidney disease stages 2 and 3 were found to have significant (6 and 12%, respectively; p < 0.01) improvements in post-exercise estimated GFR. Moreover, 42% of the people with chronic kidney disease stage 3 improved to chronic kidney disease stage 2 after the intervention.

CONCLUSION

Short-term exercise improves renal function in those with more moderate baseline chronic kidney disease. Thus, renal function appears to be responsive to enhanced physical fitness. Being a strong and modifiable risk factor, enhanced fitness should be considered a non-pharmacological adjunct in the management of diabetic kidney disease.

Update on glycemic control for the treatment of diabetic kidney disease

Diabetic kidney disease (DKD) is a common, complex condition that has become a significant public health problem. The beneficial effects of intensive glycemic control in type 1 diabetes mellitus on development of DKD are proven; however, the evidence for nephroprotection in patients with type 2 diabetes is conflicting. Moreover, a strategy of intensive glycemic control increases the risk for adverse effects (hypoglycemic episodes) with no obvious impact on macrovascular events or mortality in recent large randomized controlled trials. The risk for hypoglycemia with intensive therapy is heightened in patients with significant renal dysfunction, due to decreased renal clearance of insulin. Establishing an ideal level of glycemic control in patients requires an individualized approach taking into account duration of diabetes and presence of coexisting comorbidities and pre-existing DKD. In this article, we review the available evidence from both observational studies and randomized controlled trials and provide suggestions about evaluating the potential benefits and harm from intensive glycemic control in patients. We also discuss how in the future, a personalized approach using biomarkers might help identify patients most likely to respond as well as those most susceptible to harm. We believe that using the optimal level of glycemic control in diabetic patients using a multi-pronged strategy will improve individual patient outcomes and decrease the overall burden of morbidity and mortality.

Pathophysiology of the chronic kidney disease-mineral bone disorder

PURPOSE OF REVIEW

The causes of excess cardiovascular mortality associated with chronic kidney disease (CKD) have been attributed in part to the CKD-mineral bone disorder syndrome (CKD-MBD), wherein, novel cardiovascular risk factors have been identified. The causes of the CKD-MBD are not well known and they will be discussed in this review

RECENT FINDINGS

The discovery of WNT (portmanteau of wingless and int) inhibitors, especially Dickkopf 1, produced during renal repair and participating in the pathogenesis of the vascular and skeletal components of the CKD-MBD implied that additional pathogenic factors are critical, leading to the finding that activin A is a second renal repair factor circulating in increased levels during CKD. Activin A derives from peritubular myofibroblasts of diseased kidneys, where it stimulates fibrosis, and decreases tubular klotho expression. The type 2 activin A receptor, ActRIIA, is decreased by CKD in atherosclerotic aortas, specifically in vascular smooth muscle cells (VSMC). Inhibition of activin signaling by a ligand trap inhibited CKD induced VSMC dedifferentiation, osteogenic transition and atherosclerotic calcification. Inhibition of activin signaling in the kidney decreased renal fibrosis and proteinuria.

SUMMARY

These studies demonstrate that circulating renal repair factors are causal for the CKD-MBD and CKD associated cardiovascular disease, and identify ActRIIA signaling as a therapeutic target in CKD that links progression of renal disease and vascular disease.

Pleiotropic effects of type 2 diabetes management strategies on renal risk factors

In parallel with the type 2 diabetes pandemic, diabetic kidney disease has become the leading cause of end-stage renal disease worldwide, and is associated with high cardiovascular morbidity and mortality. As established in landmark randomised trials and recommended in clinical guidelines, prevention and treatment of diabetic kidney disease focuses on control of the two main renal risk factors, hyperglycaemia and systemic hypertension. Treatment of systemic hypertension with angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers is advocated because these drugs seem to exert specific renoprotective effects beyond blood pressure lowering. Emerging evidence shows that obesity, glomerular hyperfiltration, albuminuria, and dyslipidaemia might also adversely affect the kidney in diabetes. Control of these risk factors could have additional benefits on renal outcome in patients with type 2 diabetes. However, despite multifactorial treatment approaches, residual risk for the development and progression of diabetic kidney disease in patients with type 2 diabetes remains, and novel strategies or therapies to treat the disease are urgently needed. Several drugs used in the treatment of type 2 diabetes are associated with pleiotropic effects that could favourably or unfavourably change patients' renal risk profile. We review the risk factors and treatment of diabetic kidney disease, and describe the pleiotropic effects of widely used drugs in type 2 diabetes management on renal outcomes, with special emphasis on antihyperglycaemic drugs.

Physiologic Concepts That May Revise the Interpretation and Implications of HbA1C in Clinical Medicine: An American Perspective

HbA1c, a routinely used integrated measure of glycemic control, is traditionally thought to be equivalent to mean blood glucose in hematologically normal individuals. Therefore, particularly as the methodology of measuring HbA1c has been standardized, clinical decisions dependent on mean blood glucose are often predominantly decided based on the interpretation of measured HbA1c. In this commentary, however, now that a more routine method of measuring red cell life span has been developed, we present evidence that the relationship between HbA1c and mean blood glucose is influenced by variation in red blood cell survival even in the hematologically normal. This variation has consequences for the appropriate interpretation of HbA1c in diverse clinical conditions such as the diagnosis of diabetes and management of diabetes in chronic kidney disease.

Recent advances in glucose-lowering treatment to reduce diabetic kidney disease

INTRODUCTION

The epidemic of diabetes has now taken on epic proportions and therefore reducing the impact of diabetic complications represents one of the major global challenges in improving health and well-being worldwide. Preventing the development of diabetic kidney disease (DKD) is particularly important, as diabetes is one of the main risk factors for the development of chronic kidney disease, which in turn is strongly linked to development of cardiovascular disease, end-stage renal failure, hospitalization and premature death. Intensive glucose-lowering treatment has been shown to prevent and slow progression of DKD, yet to date, only certain populations have benefited from this intervention.

AREAS COVERED

We review the evidence for existing glucose-lowering treatments in the prevention of DKD, and research into techniques to better target individuals who will benefit from these therapies.

EXPERT OPINION

Diabetic patients with established kidney disease may benefit from glucose-lowering treatment, particularly if a safer side-effect profile of these treatments is achieved. Better understanding of glucose homeostasis and evaluation of compounds inhibiting its downstream effects are required in order to improve the outlook for individuals with DKD. An additional approach to improve the success rate of glucose-lowering treatment is to improve the selection of individuals who may benefit from treatment. A potential means to identify such subjects could involve the use of biomarkers.

[The metabolic memory phenomenon in predicting a risk for vascular complications in diabetes mellitus]

The paper presents data on positive and negative metabolic memory phenomena in patients with type 1 and type 2 diabetes mellitus (DM) as exemplified by the long-term randomized trials DCCT, UKPDS, ACCORD, VADT, and ADVANCE. It discusses the role of metabolic memory in predicting a risk for vascular complications in DM. Ideas on the mechanisms of this phenomenon, which are based on the activation of oxidative stress, the production of irreversible glycation products, and epigenetic disorders, are given.