Progression of microalbuminuria to proteinuria in type 1 diabetes: nonlinear relationship with hyperglycemia

The fragmentomic property of plasma cell-free DNA enables the non-invasive detection of diabetic nephropathy in patients with diabetes mellitus

Background

Diabetic nephropathy (DN) is one of the most prevalent complications of diabetes mellitus (DM). However, there is still a lack of effective methods for non-invasive diagnosis of DN in clinical practice. We aimed to explore biomarkers from plasma cell-free DNA as a surrogate of renal biopsy for the differentiation of DN patients from patients with DM.

Materials and methods

The plasma cell-free DNA (cfDNA) was sequenced from 53 healthy individuals, 53 patients with DM but without DN, and 71 patients with both DM and DN. Multidimensional features of plasma DNA were analyzed to dissect the cfDNA profile in the DM and DN patients and identify DN-specific cfDNA features. Finally, a classification model was constructed by integrating all informative cfDNA features to demonstrate the clinical utility in DN detection.

Results

In comparison with the DM patients, the DN individuals exhibited significantly increased cfDNA concentration in plasma. The cfDNA from the DN patients showed a distinct fragmentation pattern with an altered size profile and preferred motifs that start with "CC" in the cfDNA ending sites, which were associated with deoxyribonuclease 1 like 3 (DNASE1L3) expression in the kidney. Moreover, patients with DM or DN were found to carry more alterations in whole-genome cfDNA coverage when compared with healthy individuals. We integrated DN-specific cfDNA features (cfDNA concentration, size, and motif) into a classification model, which achieved an area under the receiver operating characteristic curve (AUC) of 0.928 for the differentiation of DN patients from DM patients.

Conclusion

Our findings showed plasma cfDNA as a reliable non-invasive biomarker for differentiating DN patients from DM patients. The utility of cfDNA in clinical practice in large prospective cohorts is warranted.

Prevalence of Microalbuminuria Among Diabetes Patients in Africa: A Systematic Review and Meta-Analysis

Background

Microalbuminuria (MAU) is considered the earliest sign of diabetic nephropathy among diabetes patients. In order to effectively manage diabetic nephropathy and its consequences early, detection of microalbuminuria as soon as possible, especially for diabetes patients, is critical. Therefore, the present study aimed to determine the pooled prevalence of microalbuminuria among diabetes patients in Africa.

Methods

Electronic databases such as Google Scholar, PubMed, African Journals Online, Web of Science, Cochrane Library, EMBASE, and ResearchGate were searched for articles and grey literature. The STATA version 14 software was used to conduct the meta-analysis. I² and Cochran's Q test were employed to assess the presence of heterogeneity between studies. Due to the presence of heterogeneity, a random effect model was used. The publication bias was assessed using the symmetry of the funnel plot and Egger's test statistics. Moreover, subgroup analysis, trim and fill analysis, and sensitivity analysis were also done.

Results

The overall pooled prevalence of microalbuminuria among diabetes patients in Africa was 37.11% (95% CI 31.27-42.95). Substantial heterogeneity was observed between studies, with I² values of 94.7%. Moreover, this meta-analysis showed that the pooled estimate of microalbuminuria among type 1 and type 2 diabetes patients was 35.34% (95% CI: 23.89-46.80, I²=94.2), and 40.24% (95% CI: 32.0-48.47, I²=94.9) respectively. MAU, on the other hand, was more common in people with diabetes for more than 5 years 38.73% (95% CI: 29.34-48.13) than in people with diabetes for less than 5 years 31.48% (95% CI: 18.73-44.23).

Conclusion

This systematic review and meta-analysis found a high prevalence of microalbuminuria among diabetes patients. As a result, early detection of microalbuminuria is critical for preventing and treating microvascular complications such as diabetic nephropathy and the onset of end-stage renal disease.

Potential Plasma Metabolite Biomarkers of Diabetic Nephropathy: Untargeted Metabolomics Study

Diabetic nephropathy (DN) is one of the specific complications of diabetes mellitus and one of the leading kidney-related disorders, often requiring renal replacement therapy. Currently, the tests commonly used for the diagnosis of DN, albuminuria (AU) and glomerular filtration rate (GFR), have limited sensitivity and specificity and can usually be noted when typical morphological changes in the kidney have already been manifested. That is why the extreme urgency of the problem of early diagnosis of this disease exists. The untargeted metabolomics analysis of blood plasma samples from 80 patients with type 1 diabetes and early and late stages of DN according to GFR was performed using direct injection mass spectrometry and bioinformatics analysis for diagnosing signatures construction. Among the dysregulated metabolites, combinations of 15 compounds, including amino acids and derivatives, monosaccharides, organic acids, and uremic toxins were selected for signatures for DN diagnosis. The selected metabolite combinations have shown high performance for diagnosing of DN, especially for the late stage (up to 99%). Despite the metabolite signature determined for the early stage of DN being characterized by a diagnostic performance of 81%, these metabolites as potential biomarkers might be useful in the evaluation of treatment of the disease, especially at early stages that may reduce the risk of kidney failure development.

The Association Between Serum Magnesium Level and Microalbuminuria in Type 2 Diabetes Mellitus Patients

Background: Diabetic nephropathy occurs in 20 - 30% of diabetic cases globally, and microalbuminuria (MA) is the first symptom of this disorder. Some studies have suggested that there is an association between the serum magnesium (Mg) level and MA. Objectives: Therefore, we investigated the association between the serum Mg level and MA in type 2 diabetes mellitus (T2DM) patients. Methods: We conducted a cross-sectional study on 122 subjects with T2DM. We categorized them into two groups of microalbuminuria (MA) and non-microalbuminuria (NMA) according to their urine albumin-creatinine ratio (UACR). MA was considered as a UACR of 30 to 300 mg/g. Participants were excluded if they had the following conditions: The age of under 16 years, cardiac, renal, or hepatic disorders, using corticosteroids, diuretics, Mg /calcium (Ca) supplements, and antiepileptic drugs, heavy physical activity within 24 hours before the test, pregnant and breastfeeding women, febrile patients, and patients who were unwilling to participate in the study. The analysis was performed using SPSS version 15. A P-value < 0.05 was considered significant. Results: Among the patients, 50.81% were male. Also, the mean body mass index (BMI) of the NMA group was greater than the MA group (29.84 ± 5.64 vs. 27.31 ± 3.14, P-value = 0.003). Mg levels of the MA and NMA groups showed no significant differences (2.13 ± 0.42 and 2.10 ± 0.43, respectively; P-value = 0.67). Overall, data analysis provided no significant difference between Mg level and the urine albumin concentration between the MA and NMA groups (P-value = 0.21 and 0.81, respectively.). Conclusions: Serum Mg level and MA have no significant relationship. Further prospective studies are needed to assay this issue.

Prevalence and Factors Associated with Microalbuminuria in Pediatric Patients with Type 1 Diabetes Mellitus at a Large Tertiary-Level Hospital in Botswana

INTRODUCTION

Microalbuminuria is considered the earliest sign of diabetic nephropathy among patients with type 1 diabetes mellitus (T1DM). The prevalence of microalbuminuria among African children with T1DM is reported to be high, yet its prevalence and population-specific risk factors in Botswana are not known.

AIM

This study aimed to determine the prevalence of microalbuminuria among children and young adults with T1DM in Botswana and identify factors associated with microalbuminuria in this population.

METHODS

A retrospective cross-sectional study was conducted on 127 T1DM patients aged <24 years followed at a pediatric endocrinology clinic in Botswana from 2010 to 2017. Clinical, laboratory, and demographic data were collected using chart review and patient surveys. Descriptive statistics were reported as mean and standard deviation for continuous variables, and frequency and percentage for categorical variables. Prevalence of microalbuminuria was calculated as a simple proportion. Group comparison was done using two-sample independent t-test, X ²-test, or Fisher's exact test and logistic regression to assess for associations. Level of significance was set at p<0.05.

RESULTS

There were a total of 71 (55.9%) females. The mean age was 18.7 (±5) years and mean duration of T1DM was 6.6 (±4.6) years. Most study participants were of African descent. The prevalence of microalbuminuria was 28.3%. Group comparison revealed gender (p= 0.040), duration of diabetes (p= 0.002), systolic blood pressure (p=0.003), baseline glycated hemoglobin (HbA1c) (p=0.009) and Tanner's stage (p=008) to be significantly associated with microalbuminuria. On binary logistic regression, only gender (p=0.039) and baseline HbA1c (p=0.039) were independently associated with the presences of microalbuminuria.

CONCLUSION

This study identified a high prevalence of microalbuminuria among children and young adults with T1DM in Botswana and reaffirms the importance of early detection, glycemic control, and regular screening to prevent diabetic nephropathy.

Identification of biomarkers for early diagnosis of diabetic nephropathy disease using direct flow through mass spectrometry

BACKGROUND AND AIMS

Albuminuria is not an effective marker for early diagnosis of diabetic renal complication with several subjects progressing to chronic kidney disease without any albuminuria. A biomarker that can predict early changes of the diabetic kidney will be useful in effective management of type 2 diabetes. Mass spectrometry based metabolomics approach offers tremendous promise for the identification of novel metabolite biomarkers.

METHODS

A case-control approach was carried out to identify renal biomarkers among Asian Indian subjects in a hospital setting. A total of 29 subjects were included in the study that included groups of diabetic controls, diabetic subjects with eGFR >90 ml/min/1.72 m² and diabetic subjects with eGFR between 60 and 89 ml/min/1.72 m² and eGFR between 15 and 30 ml/min/1.72 m². We employed an un-targeted mass spectrometry method for the identification of plasma metabolites.

RESULTS

A total of 1414 and 975 metabolites were identified in the positive and negative ion mode respectively. 19 metabolites were up regulated and 18 metabolites were down regulated in CKD2 and CKD4 groups when compared to control. Correlation analysis of the differential metabolites revealed Pregnenolone sulfate, creatinine and ganglioside GA1 to be negatively correlated and hexyl glucoside, all-trans-carophyll yellow and PG to be positively correlated with eGFR.

CONCLUSION

We have identified Pregnenolone sulfate, GA1, PG and all-trans-Carophyll yellow as biomarkers for early identification of diabetic nephropathy. These markers could aid in better management of diabetic nephropathy that may result delaying the progression of the disease.

High fractional excretion of glycation adducts is associated with subsequent early decline in renal function in type 1 diabetes

Increased protein glycation, oxidation and nitration is linked to the development of diabetic nephropathy. We reported levels of serum protein glycation, oxidation and nitration and related hydrolysis products, glycation, oxidation and nitration free adducts in patients with type 1 diabetes (T1DM) during onset of microalbuminuria (MA) from the First Joslin Kidney Study, a prospective case-control study of patients with T1DM with and without early decline in GFR. Herein we report urinary excretion of the latter analytes and related fractional excretion values, exploring the link to MA and early decline in GFR. We recruited patients with T1DM and normoalbuminuria (NA) (n = 30) or new onset MA with and without early GFR decline (n = 22 and 33, respectively) for this study. We determined urinary protein glycation, oxidation and nitration free adducts by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry (LC-MS/MS) and deduced fractional excretion using reported plasma levels and urinary and plasma creatinine estimates. We found urinary excretion of pentosidine was increased ca. twofold in patients with MA, compared to normoalbuminuria (0.0442 vs 0.0103 nmol/mg creatinine, P < 0.0001), and increased ca. threefold in patients with early decline in GFR, compared to patients with stable GFR (0.0561 vs 0.0176 nmol/mg creatinine, P < 0.01). Urinary excretion of all other analytes was unchanged between the study groups. Remarkably, fractional excretions of 6 lysine and arginine-derived glycation free adducts were higher in patients with early decline in GFR, compared to those with stable GFR. Impaired tubular reuptake of glycation free adducts by lysine and arginine transporter proteins in patients with early GFR decline is likely involved. We conclude that higher fractional excretions of glycation adducts are potential biomarkers for early GFR decline in T1DM and MA. Measurement of these analytes could provide the basis for identifying patients at risk of early decline in renal function to target and intensify renoprotective treatment.

Urinary Biomarkers in the Assessment of Early Diabetic Nephropathy

Diabetic nephropathy (DN) is a frequent and severe complication of diabetes mellitus (DM). Its diagnosis in incipient stages may allow prompt interventions and an improved prognosis. Towards this aim, biomarkers for detecting early DN can be used. Microalbuminuria has been proven a remarkably useful biomarker, being used for diagnosis of DN, for assessing its associated condition-mainly cardiovascular ones-and for monitoring its progression. New researches are pointing that some of these biomarkers (i.e., glomerular, tubular, inflammation markers, and biomarkers of oxidative stress) precede albuminuria in some patients. However, their usefulness is widely debated in the literature and has not yet led to the validation of a new "gold standard" biomarker for the early diagnosis of DN. Currently, microalbuminuria is an important biomarker for both glomerular and tubular injury. Other glomerular biomarkers (transferrin and ceruloplasmin) are under evaluation. Tubular biomarkers in DN seem to be of a paramount importance in the early diagnosis of DN since tubular lesions occur early. Additionally, biomarkers of inflammation, oxidative stress, podocyte biomarkers, and vascular biomarkers have been employed for assessing early DN. The purpose of this review is to provide an overview of the current biomarkers used for the diagnosis of early DN.

Diabetic nephropathy: What does the future hold?

The consensus management of diabetic nephropathy (DN) in 2015 involves good control of glycaemia, dyslipidaemia and blood pressure (BP). Blockade of the renin-angiotensin-aldosterone system using angiotensin-converting enzyme inhibitors, angiotensin-2 receptor blockers or mineralocorticoid inhibitors are key therapeutic approaches, shown to be beneficial once overt nephropathy is manifest, as either, or both, of albuminuria and loss of glomerular filtration rate. Some significant additional clinical benefits in slowing the progression of DN was reported from the Remission clinic experience, where simultaneous intensive control of BP, tight glycaemic control, weight loss, exercise and smoking cessation were prioritised in the management of DN. This has not proved possible to translate to more conventional clinical settings. This review briefly looks over the history and limitations of current therapy from landmark papers and expert reviews, and following an extensive PubMed search identifies the most promising clinical biomarkers (both established and proposed). Many challenges need to be addressed urgently as in order to obtain novel therapies in the clinic; we also need to examine what we mean by remission, stability and progression of DN in the modern era.

Aminaphtone therapy in patients with type 1 diabetes and albuminuria: a case report

Introduction

Microalbuminuria in type 1 diabetes is the earliest manifestation of diabetic microangiopathy (nephropathy). To date, the pharmacological approach to microangiopathy has not been shown to be useful. By using aminaphtone to control nephrologic complications of insulin-dependent diabetes mellitus we first obtained a significant improvement in microalbuminuria confirming this new pharmacological approach for insulin-dependent diabetes mellitus organospecific complications control.

Case presentation

After being treated with standard therapy for insulin-dependent diabetes mellitus (insulin) for more than 20 years, a 49-year-old white man affected by insulin-dependent diabetes mellitus adopted the standard therapy aminaphtone for a period of 2 months.

This therapy allowed a significant reduction of proteinuria from baseline evaluation that immediately increased after he stopped aminaphtone therapy.

Conclusions

Aminaphtone therapy, used globally in the treatment and prevention of endothelial dysfunctions, could be an interesting option for patients with insulin-dependent diabetes mellitus with the express purpose of preventing diabetic nephropathy.

Glycemic exposure and blood pressure influencing progression and remission of diabetic retinopathy: a longitudinal cohort study in GoDARTS

OBJECTIVE

This study sought to investigate the progression and regression of diabetic retinopathy (DR) and the effects of population risk factors on the rates of transition across retinopathy stages.

RESEARCH DESIGN AND METHODS

The study cohort consisted of 44,871 observed DR events between the calendar years 1990 and 2011 for 4,758 diabetic patients who were diagnosed at 35 years of age or older. The first retinal observation was recorded within a year from diagnosis, and the result was recorded as free of retinopathy. A multistate Markov model was applied for analyzing the development of DR and its relation to the patterns of changes in risk factors.

RESULTS

We observed a consistent risk effect of HbA1c on the progression (no retinopathy to mild background DR [BDR] hazard ratio per SD of HbA1c [HR] 1.42 [95% CI 1.32-1.52], mild BDR to observable BDR HR 1.32 [95% CI 1.08-1.60], and observable BDR to severe nonproliferative/proliferative DR HR 2.23 [95% CI 1.16-4.29]). Similarly, systolic blood pressure (SBP) and diastolic blood pressure increased the risk for the transition from the asymptomatic phase to mild BDR (HR 1.20 [95% CI 1.11-1.30]) and the mild BDR to observable BDR (HR 1.87 [95% CI 1.46-2.40]), respectively. Regression from mild BDR to no DR was associated with lower SBP (HR 0.79 [95% CI 0.64-0.97]) and lower HbA1c (HR 0.76 [95% CI 0.64-0.89]).

CONCLUSIONS

Progression and regression of DR were strongly associated with blood pressure and glycemic exposure.

Predictors of progression in albuminuria in the general population: results from the PREVEND cohort

Background

Urinary albumin excretion is known to be independently associated with progression of renal and cardiovascular disease. The aim of this study was to identify predictors for progression in albuminuria in the general population.

Methods

Data were used of the first 4 screening rounds of a community-based prospective cohort study (PREVEND). Included were 5,825 subjects that at baseline had no known renal disease or macroalbuminuria. Subjects were defined as having progressive albuminuria when they belonged to the quintile of subjects with highest absolute increase in urinary albumin excretion per year and a urinary albumin excretion during the last screening in which they participated of ≥150 mg/24 h. Change in urinary albumin excretion per year was calculated as last available urinary albumin excretion minus baseline UAE divided by follow-up time.

Results

During 9.3 years follow-up 132 subjects had progressive albuminuria. These subjects were significantly older, more often of male gender and had a worse cardiovascular risk profile. In a multivariable model, testing baseline values, significant predictors of progressive albuminuria were male gender (OR 2.23; p<0.001), age (OR 1.03; p<0.001), BMI (OR 1.06; p = 0.02) and baseline albuminuria (OR 5.71; p<0.001). Based on these findings a risk score was made to estimate a subject's risk for progressive albuminuria.

Conclusion

A high baseline albuminuria is by far the most important predictor of progressive albuminuria. Thus, screening for baseline albuminuria will be more important than screening for cardiovascular risk factors in order to identify subjects at risk for progressive albuminuria.

Sitagliptin compared with thiazolidinediones as a third-line oral antihyperglycemic agent in type 2 diabetes mellitus

OBJECTIVE

To compare sitagliptin and thiazolidinediones as third-line oral antihyperglycemic agents among ethnic minority patients with poorly controlled type 2 diabetes mellitus.

METHODS

In an open-label, single-arm design, we treated type 2 diabetic patients who had suboptimal diabetes control on maximum tolerated dosages of metformin plus sulfonylureas with the addition of sitagliptin, 100 mg daily, and compared their responses with findings from a historical control group of similar patients treated with rosiglitazone, 8 mg daily, or pioglitazone, 45 mg daily, as their third-line oral agent. Patients were assessed bimonthly, and those who achieved hemoglobin A1c levels less than 7.5% at 4 months continued through 1 year of follow-up.

RESULTS

One hundred eight patients were treated with sitagliptin, and 104 patients constituted the historical control group treated with rosiglitazone or pioglitazone. At baseline, sitagliptin- and thiazolidinedione-treated patients had identical hemoglobin A1c levels (mean ± SD) (9.4 ± 1.8% and 9.4 ± 1.9%, respectively) and similar known diabetes duration (6.7 ± 5.0 years and 7.6 ± 5.8 years, respectively). Hemoglobin A1c was reduced in both groups at 4 months (P<.001), but the reduction was greater with thiazolidinediones than with sitagliptin (-2.0 ± 1.7% vs -1.3 ± 1.8%; P = .006), as was the proportion of patients achieving a hemoglobin A1c level less than 7.5% (62% vs 46%; P = .026). Of all patients achieving a hemoglobin A1c level less than 7.5% at 4 months, the same proportions in each group sustained their hemoglobin A1c level less than 7.5% by 12 months (59% vs 58%). Sitagliptin was well tolerated.

CONCLUSIONS

Among ethnic minority patients with poorly controlled type 2 diabetes while taking maximum tolerated dosages of metformin and sulfonylureas, third-line add-on therapy with a thiazolidinedione controlled hyperglycemia more effectively than sitagliptin after 4 months.

Reduced progression of diabetic microvascular complications with islet cell transplantation compared with intensive medical therapy

BACKGROUND

The effect of islet cell transplantation (ICT) on the progression of diabetic microvascular complications is not well understood.

METHODS

We have conducted a prospective, crossover, cohort study comparing ICT with intensive medical therapy on the progression of diabetic nephropathy, retinopathy, and neuropathy.

RESULTS

The rate of decline in glomerular filtration rate is slower after ICT than on medical therapy. There was significantly more progression of retinopathy in medically treated patients than post-ICT. There was a nonsignificant trend for improved nerve conduction velocity post-ICT.

CONCLUSIONS

ICT is associated with less progression of microvascular complications than intensive medical therapy. Multicenter, randomized trials are needed to further study the role of ICT in slowing the progression of diabetic complications.

In patients with type 1 diabetes and new-onset microalbuminuria the development of advanced chronic kidney disease may not require progression to proteinuria

We sought to study new-onset microalbuminuria, its progression, and the decline of renal function in patients with type 1 diabetes. Using a cohort of 109 patients who developed new-onset microalbuminuria in the first 4 years following enrollment in the 1st Joslin Kidney Study, we simultaneously tracked the change in their renal function and urinary albumin excretion. Of these, 79 patients were followed for an average of 12 years after microalbuminuria onset, wherein their glomerular filtration rate was estimated by the Modification of Diet in Renal Disease Study formula and compared with their microalbuminuria and proteinuria. The concordance between these outcomes was weak. Only 12 of the 23 patients who progressed to advanced (stage 3-5) chronic kidney disease developed proteinuria, which, in general, did not precede but accompanied the progression to advanced chronic kidney disease. The remaining 11 patients who developed advanced disease had persistent microalbuminuria or returned to normal albuminuria. Thus, we found that one-third of patients with type 1 diabetes developed advanced chronic kidney disease relatively soon after the onset of microalbuminuria and this was not conditional on the presence of proteinuria. Contrary to the existing concept of early nephropathy in type 1 diabetes, less emphasis should be placed on the mechanisms of progression to proteinuria and more placed on mechanisms initiating and promoting the early decline of renal function that eventually progresses to advanced chronic kidney disease.

Effect of age and race/ethnicity on HbA1c levels in people without known diabetes mellitus: implications for the diagnosis of diabetes

AIMS

To determine if age and race/ethnicity affect HbA1c levels independent of glycemia.

METHODS

We analyzed 2712 individuals from the NHANES III population 40-74 years old without diabetes history.

RESULTS

HbA1c levels increased by 0.10% per decade in people with NGT and 0.07% in those with IFG and/or IGT, independent of fasting and 2-h glucose on OGTT's. Compared to non-Hispanic whites, HbA1c levels increased by 0.12% (NGT) and 0.10% (IFG/IGT) in Mexican-Americans and 0.21% (NGT) and 0.35% (IFG/IGT) in non-Hispanic blacks, independent of glycemia. At HbA1c levels of >or=6.5%, >or=7.0% and 6.5-6.9%, diabetes diagnosed by current FPG/OGTT criteria occurred in 82%, 94% and 65%, respectively. In non-Hispanic blacks with HbA1c levels of 6.5-6.9%, 68% of those 40-74 years old and 87% of those over 64 years old would not have diabetes by FPG/OGTT criteria. Over 90% of all race/ethnicity groups would have diabetes with HbA1c levels >or=7.0%.

CONCLUSIONS

Because many people, especially older non-Hispanic blacks, with HbA1c levels of 6.5-6.9% would not have diabetes by current FPG/OGTT criteria and clinical retinopathy and nephropathy are very unusual in patients whose HbA1c levels are kept <7.0%; we recommend an HbA1c level of >or=7.0% to diagnose diabetes.

The endothelin receptor antagonist avosentan ameliorates nephropathy and atherosclerosis in diabetic apolipoprotein E knockout mice

AIMS/HYPOTHESIS

There is convincing evidence that the endothelin system contributes to diabetic nephropathy and cardiovascular disease. This study aimed to assess the effects of the non-peptidergic endothelin receptor A (ETA) antagonist avosentan in a mouse model of accelerated diabetic nephropathy and atherosclerosis in comparison with the ACE inhibitor, quinapril.

METHODS

Apolipoprotein E (Apoe) knockout (KO) mice (n = 20 per group, five groups) were randomised to the following groups: non-diabetic controls and streptozotocin-induced diabetic animals gavaged daily for 20 weeks with placebo, avosentan (high dose: 30 mg/kg, or low dose: 10 mg/kg) or quinapril (given in drinking water, 30 mg/kg).

RESULTS

BP was unchanged by avosentan treatment but decreased with quinapril treatment. Diabetes-associated albuminuria was significantly attenuated by high-dose avosentan after 10 and 20 weeks of treatment. Diabetic animals showed a decreased creatinine clearance, which was normalised by avosentan treatment. In diabetic mice, high-dose avosentan treatment significantly attenuated the glomerulosclerosis index, mesangial matrix accumulation, glomerular accumulation of the matrix proteins collagen IV, and renal expression of genes encoding connective tissue growth factor, vascular endothelial growth factor, transforming growth factor beta and nuclear factor kappaB (p65 subunit). Furthermore, high-dose avosentan treatment was also associated with reduced expression of the genes for ETA, ETB and angiotensin receptor 1. The renoprotective effects of avosentan were comparable or superior to those observed with quinapril. High-dose avosentan also significantly attenuated diabetes-associated aortic atherosclerosis in Apoe KO mice and reduced macrophage infiltration and aortic nitrotyrosine expression.

CONCLUSIONS/INTERPRETATION

This study demonstrates that ETA blockade with avosentan may provide an alternate therapeutic strategy for the treatment of diabetic micro- and macrovascular complications.

Relationship between glycated haemoglobin and microvascular complications: is there a natural cut-off point for the diagnosis of diabetes?

AIMS/HYPOTHESIS

This study was designed to determine whether the relationship of glycated haemoglobin to diabetic microvascular complications shows any natural thresholds that could be useful in diagnosing diabetes.

METHODS

We examined a population-based sample of 3,190 Malay adults aged 40-80 years in Singapore. The microvascular outcomes of interest were: (1) any retinopathy, defined from fundus photographs; (2) mild retinopathy, defined as in (1); (3) moderate retinopathy, defined as in (1); (4) chronic kidney disease, defined from estimated glomerular filtration rate; (5) micro- or macroalbuminuria, defined from urinary albumin to creatinine ratio; and (6) peripheral neuropathy, defined from neurothesiometer or monofilament sensory testing.

RESULTS

Increasing HbA(1c) was associated with all microvascular complications. The optimal cut-off points for detecting mild and moderate retinopathy were 6.6% (87.0% sensitivity, 77.1% specificity and area under the receiver operating characteristics [ROC] curve 0.899) and 7.0% (82.9% sensitivity, 82.3% specificity and area under ROC curve 0.904). The prevalences of mild and moderate retinopathy were <1% below the optimal cut-off points. For other complications, the association with HbA(1c) was linear without evidence of a distinct threshold. Although ROC analysis for these other complications also suggested optimal cut-off points between 6.6% and 7.0%, the sensitivity at these cut-off points was considerably lower than for mild and moderate retinopathy, ranging from 31.8% to 66.5%.

CONCLUSIONS/INTERPRETATION

Higher levels of HbA(1c) were associated with microvascular complications. Our data support use of an HbA(1c) cut-off point of between 6.6 and 7.0% in diagnosing diabetes. Cut-off points in this range were best for the identification of individuals with mild and moderate retinopathy. Any retinopathy, chronic kidney disease, albuminuria and peripheral neuropathy are less well detected at these cut-off points.

Pro's and con's of the early use of insulin in the management of type 2 diabetes: a clinical evaluation

PURPOSE OF REVIEW

Recently, there have been increasing calls for insulin to be used as the initial treatment of type 2 diabetes, and if not then, soon after its onset. The underlying reason given is that insulin will slow down the apoptosis of pancreatic beta-cells, which is increased in type 2 diabetes. This review will examine the clinical evidence supporting this recommendation.

RECENT FINDINGS

Several observational studies in which newly diagnosed type 2 diabetic patients are intensively treated for a short time with insulin, which is then stopped, have shown that approximately half of these patients retain good control without pharmacological therapy for up to a year. However, HbA1c levels in patients who have to be started on oral antidiabetic drugs are similar to the values in those who do not. HbA1c levels are similar in patients randomized to initial therapy with insulin or oral antidiabetic drug. There is no clinical evidence yet for an effect of insulin on beta-cell apoptosis.

SUMMARY

The primary goal is to achieve and maintain HbA1c levels of less than 7.0%. Given the extra demands on both patients and physicians when starting insulin compared with oral antidiabetic drug and the many subsequent years in which patients have diabetes, the arguments for using insulin initially, or in patients who have achieved the target HbA1c level, are not convincing. However, as soon as oral antidiabetic drug therapy cannot meet this goal, insulin must be introduced.

Detailed treatment algorithms for effective nurse- and pharmacist-directed diabetes care: a personal approach

The purpose of this article is to provide treatment algorithms proven to be effective in meeting the standards of care of the American Diabetes Association to nurses and pharmacists who are given the authority to make independent clinical decisions (under the overall supervision of a physician).

Importance of glycemic control on the course of glomerular filtration rate in type 2 diabetes with hypertension and microalbuminuria under tight blood pressure control

BACKGROUND AND AIMS

To evaluate the role of glycemic control on the evolution of glomerular filtration rate (GFR) in type 2 diabetes (T2DM) with mild-moderate hypertension under tight blood pressure control, and to address the current controversy whether diabetic nephropathy worsens, independently of blood pressure, proportionally to HbA1c at any physiological level or only when HbA1c is above a 7.5-8% threshold.

METHODS AND RESULTS

T2DM (N=127) during early stage diabetic nephropathy characterized by microalbuminuria were followed during a 2 year multicenter study. Individual GFR profiles were accurately obtained by (51)Cr - EDTA bolus injections and analyzed with linear statistical mixed-effects models. GFR at baseline was significantly negatively correlated with age and plasma creatinine concentration (P<or=0.0001), and GFR declined, on average, by 4.0 ml/min 1.73 m(2)/year (P=0.001). A significant correlation was found between individual GFR decline rate and average systolic (SBP) and diastolic (DBP) blood pressures (-0.254 (0.736) ml/min 1.73 m(2)/year per mmHg increase in SBP (DBP), P=0.041 (0.014)) and % of glycated hemoglobin (HbA1c) (-1.78 ml/min 1.73 m(2)/year per % increase in HbA1c, P=0.048). This implies a 44% increase/reduction in GFR decline rate for 1% HbA1c increase/reduction around 7.0% (i.e. 5.79 and 2.24 ml/min 1.73 m(2)/year at 8% and 6% HbA1c, respectively).

CONCLUSIONS

This study demonstrates that, despite tight blood pressure control, an accurate glycemic control till very low patterns of HbA1c (from 10-11% to 5-6%) is needed to delay the progression of GFR decay in Mediterranean T2DM in south Europe with microalbuminuria.

Long-term prevention of diabetic nephropathy: an audit

AIMS/HYPOTHESIS

In type 1 diabetic patients with microalbuminuria not receiving antihypertensive treatment, an increase in urinary AER (UAER) of 6-14%/year and a risk of developing diabetic nephropathy (DN) of 3-30%/year have been reported. We audited the long-term effect of blocking the renin-angiotensin-aldosterone system (RAAS) with an ACE inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in microalbuminuric type 1 diabetic patients on progression of microalbuminuria and development of DN.

METHODS

All patients with type 1 diabetes and persistent microalbuminuria (30-300 mg/24 h) were identified (n=227) in 1995 at Steno Diabetes Center and followed for 11 years. Development of DN was defined as a UAER of >300 mg/24 h in two of three consecutive urine samples.

RESULTS

Age and duration of diabetes at baseline (mean+/-SD) were 46+/-15 and 28+/-13 years, respectively. During follow-up 14 patients emigrated and 58 (26%) died. Over the same period 79% were treated with an ACEI or ARB. There was a mean decline in UAER of 4%/year. Sixty-five patients (29%) progressed to overt DN, corresponding to 3.1%/year. However, 29 of them regressed to normo- or microalbuminuria on intensified antihypertensive treatment. Glycaemic control and blood pressure remained nearly unchanged.

CONCLUSIONS/INTERPRETATION

In our outpatient clinic, the implementation of RAAS-blocking treatment in type 1 diabetic patients with microalbuminuria successfully reduced long-term progression to overt DN to a rate similar to those previously reported in randomised, double-blind intervention trials of shorter duration using RAAS blockade.

Risk of microalbuminuria and progression to macroalbuminuria in a cohort with childhood onset type 1 diabetes: prospective observational study

OBJECTIVES

To describe independent predictors for the development of microalbuminuria and progression to macroalbuminuria in those with childhood onset type 1 diabetes.

DESIGN

Prospective observational study with follow-up for 9.8 (SD 3.8) years.

SETTING

Oxford regional prospective study.

PARTICIPANTS

527 participants with a diagnosis of type 1 diabetes at mean age 8.8 (SD 4.0) years.

MAIN OUTCOME MEASURES

Annual measurement of glycated haemoglobin (HbA1c) and assessment of urinary albumin:creatinine ratio.

RESULTS

Cumulative prevalence of microalbuminuria was 25.7% (95% confidence interval 21.3% to 30.1%) after 10 years of diabetes and 50.7% (40.5% to 60.9%) after 19 years of diabetes and 5182 patient years of follow-up. The only modifiable adjusted predictor for microalbuminuria was high HbA1c concentrations (hazard ratio per 1% rise in HbA1c 1.39, 1.27 to 1.52). Blood pressure and history of smoking were not predictors. Microalbuminuria was persistent in 48% of patients. Cumulative prevalence of progression from microalbuminuria to macroalbuminuria was 13.9% (12.9% to 14.9%); progression occurred at a mean age of 18.5 (5.8) years. Although the sample size was small, modifiable predictors of macroalbuminuria were higher HbA(1c) levels and both persistent and intermittent microalbuminuria (hazard ratios 1.42 (1.22 to 1.78), 27.72 (7.99 to 96.12), and 8.76 (2.44 to 31.44), respectively).

CONCLUSION

In childhood onset type 1 diabetes, the only modifiable predictors were poor glycaemic control for the development of microalbuminuria and poor control and microalbuminuria (both persistent and intermittent) for progression to macroalbuminuria. Risk for macroalbuminuria is similar to that observed in cohorts with adult onset disease but as it occurs in young adult life early intervention in normotensive adolescents might be needed to improve prognosis.

The effect of medical therapy and islet cell transplantation on diabetic nephropathy: an interim report

BACKGROUND

The effect of islet cell transplantation (ICT) on renal function in type 1 diabetes is uncertain and some recent studies report a significant decline in estimated glomerular filtration rate (GFR) and worsening of albuminuria.

METHODS

We are conducting a prospective crossover study comparing medical treatment with islet transplantation on the progression of diabetic complications, including renal function. The primary endpoint is change in GFR measured by Tc-diethylenetriaminepentaacetate with secondary endpoints including estimated GFR and albumin excretion.

RESULTS

We have followed 21 patients after islet transplantation a median of 29 months (range 13-45) and compared their results with medically treated patients followed a median 29.5 months (range 13-56). There is no difference in the rate of decline in measured GFR between medically treated patients (-0.35+/-0.89; 95% CI: -0.57 to -0.13 mL/min/month/1.73 m) and those after ICT (-0.31+/-1.18; 95% CI: -0.61 to -0.01) and neither is significantly different from that expected for the general population. The rate of decline in our estimated GFR results is lower than that reported in other studies and we did not find any worsening of albuminuria.

CONCLUSIONS

We do not find evidence of worsening of renal function after islet transplantation compared with medically treated patients.

Protektion der Nierenfunktion bei Diabetikern

The course of diabetic nephropathy is affected by several factors that can be manipulated. In primary prevention, near normal metabolic control beginning at the time of the diagnosis of diabetes diminishes the risk of microalbuminuria to an extent depending on the HbA1c level attained. Hypertensive diabetics should be consistently treated with renin-angiotensin system (RAS)-blocking agents. In secondary prevention, a multifactorial therapy is able to stop or retard further progression. Its components are a sustained decrease of blood pressure in the normotensive range using RAS-blocking agents (normotensive patients should also be treated) as well as near normal metabolic control that takes into account the changing pharmacokinetic and pharmacodynamic properties of blood glucose-lowering drugs in renal insufficiency. Consideration of further factors (smoking, protein intake, anemia) and several general nephroprotective measures complete the treatment spectrum. Therapy for dyslipidemia and the administration of aspirin are important in view of the high cardiovascular morbidity. It is essential to monitor kidney function and the therapeutic components at short intervals.

Determinants of progression from microalbuminuria to proteinuria in patients who have type 1 diabetes and are treated with angiotensin-converting enzyme inhibitors

The aims of this study were to assess the frequency and determinants of (1) treatment with angiotensin-converting enzyme inhibitors (ACE-I) and (2) progression to proteinuria in the presence of ACE-I treatment in patients with type 1 diabetes and microalbuminuria. A clinic-based cohort study of patients with type 1 diabetes was begun in 1991. The patients who were included in this study (n = 373) are the cohort members who received a diagnosis of microalbuminuria during a 2-yr baseline observation and were followed for 10 yr with frequent assessments of urinary albumin excretion and biennial examinations. Progression to proteinuria occurred when the median urinary albumin excretion during a 2-yr interval exceeded 299 mug/min. During the decade-long study, the proportion of patients who had a history of microalbuminuria and were treated with ACE-I rose from 17 to 67%. Patients who started this treatment had (on average) higher BP, higher urinary albumin excretion, and longer diabetes duration than those who did not. Microalbuminuria often progressed to proteinuria (6.3/100 person-years) in those who were treated. Poor glycemic control and elevated serum cholesterol were the major determinants/predictors of this progression. Although treatment with ACE-I increased during the past decade, it was not completely effective, because microalbuminuria progressed to proteinuria in many treated patients. Poor glycemic control and elevated serum cholesterol were the major determinants/predictors for progression while on ACE-I treatment. The mechanisms that are responsible for the frequent failure of ACE-I to prevent progression of microalbuminuria to proteinuria in a clinical setting are not clear.

Gluconeogenic Substrates and Hepatic Gluconeogenic Enzymes in Streptozotocin-Diabetic Rats: Effect of Mulberry (Morus indicaL.) Leaves

Mulberry (Morus indica L.) leaves, the sole food of the silk worm, were evaluated for antidiabetic effects in streptozotocin (STZ)-diabetic rats. Treatment with dried mulberry leaf powder at 25% of the diet for a period of 8 weeks was found to be remarkably beneficial to STZ-diabetic rats as evidenced by controlled hyperglycemia and glycosuria. In addition, mulberry leaves countered (reversed) the alterations in gluconeogenic substrates in STZ-diabetic rats as indicated by significant reduction in serum pyruvic and lactic acid levels, a significant increase in proteins and a significant decrease in free amino acid, urea, and creatinine levels in blood, and a decreased urinary excretion of urea and creatinine. Anomalies in the activities of hepatic gluconeogenic enzymes associated with impaired glucose homeostasis in STZ-diabetic rats were ameliorated by feeding the mulberry leaf-supplemented diet, indicating that control over hyperglycemia and associated complications in the diabetic state by mulberry leaves is by way of regulation of gluconeogenesis. With respect to all the parameters, mulberry leaves were more effective than the oral hypoglycemic drug glibenclamide.

Microalbuminuria and the risk for early progressive renal function decline in type 1 diabetes

This study aimed to establish the time of initiation and the determinants of renal function decline in type 1 diabetes. Until now, such decline has been assumed to be a late-occurring event associated with proteinuria. A total of 267 patients with normoalbuminuria and 301 patients with microalbuminuria were followed for 8 to 12 yr. Linear trends (slopes) in GFR were estimated by serial measurement of serum cystatin C. Cases of early renal function decline were defined by loss in cystatin C GFR that exceeded -3.3%/yr, a threshold that corresponds to the 2.5th percentile of the distribution of GFR slopes in an independent nondiabetic normotensive population. Cases of early renal function decline occurred in 9% (mean slope -4.4; range -5.9 to -3.3%/yr) of the normoalbuminuria group and 31% (mean slope -7.1; range -23.8 to -3.3%/yr) of the microalbuminuria group (P < 0.001). Risk for early renal function decline depended on whether microalbuminuria regressed, remained stable, or progressed, rising from 16 to 32 and 68%, respectively (P < 0.001). In multivariate analysis, risk for decline was higher after age 35 yr or when glycosylated hemoglobin exceeded 9% but did not vary with diabetes duration, smoking, BP, or angiotensin-converting enzyme inhibitor treatment. Contrary to the existing paradigm of diabetic nephropathy, progressive renal function decline in type 1 diabetes is an early event that occurs in a large proportion of patients with microalbuminuria. Together with testing for microalbuminuria, clinical protocols using cystatin C to diagnose early renal function decline and track response to therapeutic interventions should be developed.

What predicts progression and regression of urinary albumin excretion in the nondiabetic population?

An increase or decrease in urinary albumin excretion (UAE) is associated with, respectively, a higher or lower risk for renal and cardiovascular disease, independent of widely known cardiovascular risk factors. This study aimed to identify factors that are associated with changes in UAE in the nondiabetic population using data of the Prevention of Renal and Vascular End stage Disease (PREVEND) Study, a community-based prospective cohort study. Data of the 6647 nondiabetic participants who completed the first (1997 through 2001) and second (2001 through 2003) screening were used. Change in UAE was categorized as regression (n = 650), stable (n = 5240), or progression (n = 757) on the basis of change in class during follow-up, with classes being a UAE <15, 15 to 30, 30 to 300, and >300 mg/24 h. With the use of stepwise forward multinomial regression analysis changes in BP, fasting glucose concentration, and start of antihypertensive drugs were found to be the most important modifiable variables associated with the risk for progression and regression (P < 0.01 for likelihood ratio test). The odds ratios to develop regression or progression of UAE during follow-up were 0.64 (95% confidence interval [CI] 0.57 to 0.73) and 1.91 (95% CI 1.72 to 2.12), respectively, per 10-mmHg increase in BP during follow-up, 0.89 (95% CI 0.80 to 0.98) and 1.09 (95% CI 1.01 to 1.17), respectively, per 1-mmol/L increase of fasting glucose levels during follow-up, and 1.57 (95% CI 1.21 to 2.06) and 0.70 (95% CI 0.51 to 0.95), respectively, for start of antihypertensive drugs during follow-up. These associations were independent of baseline BP, glucose, body mass index, estimated GFR, and UAE and changes in high-sensitivity C-reactive protein during follow-up. In conclusion, changes in glucose concentration and BP and start of antihypertensive drugs (angiotensin-converting enzyme inhibitors/angiotensin receptor blockers in >50% of cases) are associated with progression and regression of UAE in the nondiabetic population. Although associations do not necessarily suggest causality, it is hypothesized that in the general population, the most important ways to reduce UAE are by lowering glucose concentration and BP (including start of antihypertensive medication), even in normotensive, nondiabetic individuals.

Growth hormone hypothesis and development of diabetic nephropathy in Type 1 diabetes

In Type 1 diabetes, poor glycemic control is the key predictor for the development of microalbuminuria, an established early marker of overt nephropathy. However, the role of other pathways in the development of diabetic nephropathy may also be important. The growth hormone (GH) hypothesis suggests that the GH-insulin-like growth factor (IGF)-1 axis may play an important role in this disease process. In Type 1 diabetes, the characteristic pattern of GH hypersecretion and low circulating IGF-1 levels results from hepatic GH resistance owing to the lack of portal insulin. Clinical data indicate that high GH and low IGF-1 levels reduce insulin sensitivity and worsen glycemic control. Furthermore, despite hepatic GH resistance, GH receptors at the kidney remain intact. Experimental data show that excess GH stimulates renal GH receptors and, through paracrine IGF-1 production, results in pathophysiological changes consistent with diabetic nephropathy, namely nephromegaly, glomerular hyperfiltration and eventual proteinuria. These abnormalities are reversed by intervention to block or normalize the local effects of GH and IGF-1. Although such data in humans are limited, preliminary trials show that interventions to increase IGF-1 levels and reduce GH hypersecretion improve glycemic control and insulin sensitivity in the short term. However, their effects on early nephropathy and end points, such as the prevalence of end stage renal disease, have yet to be determined.

Prediction, progression and prevention of diabetic nephropathy. The Minkowski Lecture 2005

Diabetic nephropathy is a major problem for patients and health care systems. The costs of treatment remain high. To confront the ongoing challenge, we need to identify individuals at high risk for initiation and progression of this devastating complication. Risk factors include genetic markers; constitutional factors such as low birthweight; haemodynamic factors, including activation of the RAS system and hypertension; metabolic factors such as glycaemia; and additional factors such as urinary AER and smoking. Modifiable risk factors should be treated aggressively. Potential new markers of risk include indices of increased inflammation, changes in coagulation, endothelial dysfunction, growth factors and cytokines. Application of such markers may in time improve risk assessment and allow new treatment targets to be identified. Interventions that aim to achieve strict glycaemic control and blockade of the renin-angiotensin system have been shown to be effective in clinical trials and are feasible in clinical practice. The 'natural history' of diabetic nephropathy can be transformed if these strategies of intensive screening and care are applied, leading both to a lower incidence of diabetic nephropathy and to an improved outcome, with survival exceeding 20 years from onset of overt proteinuria.

Early nephropathy in type 1 diabetes: a new perspective on who will and who will not progress

Impaired renal function and end-stage renal disease (ESRD) affect up to a third of patients with type 1 diabetes. Thus, strategies for early detection and for preventative interventions are of critical importance. A model of diabetic nephropathy was developed in the 1980s that placed paramount importance on the finding of microalbuminuria as an early marker of a committed process of progressive kidney disease in diabetes. However, recent studies have provided evidence that microalbuminuria is a marker of dynamic, rather than fixed, kidney injury. Preliminary studies into early renal function decline, a process measured in early nephropathy using a simple assay for cystatin C to calculate the slope of glomerular filtration rate change over time, suggest that it is a more proximal marker than microalbuminuria of a person's trajectory toward impaired renal function and ESRD. Therefore, early renal function decline, rather than microalbuminuria, may be considered as the early marker of the committed process underlying progressive diabetic nephropathy.

Novel predictors of overt nephropathy in subjects with type 1 diabetes. A nested case control study from the Pittsburgh Epidemiology of Diabetes Complications cohort

BACKGROUND

Predictors of diabetic nephropathy are only partly known and traditional risk factors do not adequately explain disease risk. We thus examined novel risk factors for overt nephropathy (ON) in type 1 diabetes.

METHODS

The EDC is a prospective study of childhood-onset type 1 diabetes. When first seen (1986-1988), mean age was 28 and diabetes duration 19 years. In the subsequent 10 years, 56 of 485 subjects without ON in 1986-88 developed ON. An age, duration (+/-3 years), and sex-matched control was identified for 47 cases. Forty-two matched pairs had available stored plasma samples obtained prior to ON onset in cases, and complete standard risk factor data.

RESULTS

Cases had a higher baseline albumin excretion rate (AER), HbA1, pulse rate, non-HDL cholesterol, fibrinogen, small LDL and lower eGDR and LDL particle size compared to controls (all P values<0.05). Multiple measures of immune complexes were increased in cases (P<0.05), whereas borderline elevations were seen for total antioxidant reserve (P=0.06) and retinol (P=0.08). Multivariably, other than AER, LDL particle size and IgG-IC were predictive beyond the standard predictors.

CONCLUSION

Besides AER, the immunecomplexes and lipoprotein subclasses may provide additional information in the assessment of ON risk in type 1 diabetes.

Using protein/creatinine ratios in random urine

We assessed the new test paper Multistix PRO IOLS, in which the +/-region of the conventional test for protein was altered so that creatinine correction became possible. Urinary samples from 235 patients with various renal diseases were obtained from the Juntendo University Hospital. We examined 1) the correlation between qualitatively measured values of urinary protein by the new test paper and the conventional test paper, and 2) the correlation between qualitative and quantitative values of protein (P), creatinine (C), and the P/C ratio measured by the new test paper. There was a good correlation between the P/C ratio observed with the new test paper and that observed by quantitative analysis. There was also a good correlation of the P/C ratio between 24-hr urine and urinary samples obtained at any time of day. Thus, it appears that the results obtained from urinary samples any time of day can predict the amount of protein excreted during the day.

Clinical characteristics of normotensive renal transplant recipients with microalbuminuria and effects of angiotensin II type I receptor antagonist on urinary albumin excretion

AIM

Microalbuminuria is typically observed in renal transplant recipients with systemic hypertension. The effects of angiotensin II type 1 receptor antagonist (losartan) on the hypertensive recipients have been evaluated. However, the clinical background of normotensive recipients with microalbuminuria and the effect of losartan administration in those subjects have not been clarified. One of the two purposes for the present study was to investigate the clinical characteristics of normotensive recipients with microalbuminuria. The other was to evaluate the effect of losartan on urinary excretion of albumin in these patients.

METHODS

The clinical data and the change of the single kidney glomerular filtration rate (GFR) for the graft by radionuclide study were assessed in 13 normotensive recipients with microalbuminuria. These were compared with the data of 13 normotensive patients without microalbuminuria. The 13 recipients with microalbuminuria were treated with losartan for one year and urine excretion of albumin, N-acetyl-beta-D-glucosaminidase (NAG) and serum creatinine (S-Cr) levels were measured.

RESULTS

The GFR of the grafts from donors to recipients significantly increased (30.9 to 55.2 mL/min) in microalbuminuric recipients, but did not significantly increase in the non-microalbuminuric recipients. Decreases of the urinary excretion rate of albumin (351 +/- 261 at baseline to 158 +/- 14 mg/gCr at 12 months), NAG (13 +/- 5 to 10 +/- 3 IU/gCr) and S-Cr (1.7 +/- 0.6 to 1.5 +/- 0.4 mg/DL) were observed in the microalbuminuric recipients with losartan administration.

CONCLUSIONS

The present study suggests that an increased single kidney GFR of the graft from the donor in situ to the recipient might be a cause of microalbuminuria in normotensive recipients. The one-year effects of losartan were observed in terms of the decrease in urinary excretion of albumin, NAG and S-Cr levels.

New insights into the significance of microalbuminuria

PURPOSE OF REVIEW

This review summarizes recent work that has explored the association between microalbuminuria and adverse clinical outcomes in the presence and absence of diabetes.

RECENT FINDINGS

Recent investigations have documented the prevalence of microalbuminuria in the general community and have also highlighted the continuous relationship between the level of urinary albumin excretion and clinical endpoints. Even below traditional microalbuminuria thresholds, urinary albumin levels appear to correlate with clinical outcomes. Microalbuminuria is becoming increasingly recognized as an independent risk factor for cardiovascular morbidity and mortality. At least for subjects with type 2 diabetes and microalbuminuria, intensive, multifactorial interventions can reduce the risk of cardiovascular events by about 50%. Although several studies have found an association between microalbuminuria and surrogate measurements of vascular disease, the exact molecular mechanisms linking an increase in urinary albumin excretion and vascular disease are still unknown. Microalbuminuria also has a well-documented association with progressive diabetic renal disease but recent studies have suggested that the prognostic significance of microalbuminuria in this regard may not be as powerful as originally reported.

SUMMARY

Aggressive, multifactorial interventions, including the use of drugs that interrupt the renin-angiotensin system are strongly recommended for patients with diabetes and micro-albuminuria to ameliorate the progression of renal and vascular complications. This approach should also possibly apply to microalbuminuric subjects without diabetes. The relationship between microalbuminuria and progressive diabetic renal disease requires re-evaluation given temporal trends in the prevention and treatment of diabetic complications.

Regression of microalbuminuria in type 1 diabetes

BACKGROUND

In the present study, we aimed to determine the frequency of a significant reduction in urinary albumin excretion and factors affecting such reduction in patients with type 1 diabetes and microalbuminuria.

METHODS

The study included 386 patients with persistent microalbuminuria, indicated by repeated measurements of urinary albumin excretion (estimated on the basis of albumin-to-creatinine ratios) in the range of 30 to 299 microg per minute during an initial two-year evaluation period. Subsequent measurements during the next six years were grouped into two-year periods, averaged, and analyzed for regression of microalbuminuria, which was defined as a 50 percent reduction in urinary albumin excretion from one two-year period to the next.

RESULTS

Regression of microalbuminuria was frequent, with a six-year cumulative incidence of 58 percent (95 percent confidence interval, 52 to 64 percent). The use of angiotensin-converting-enzyme inhibitors was not associated with the regression of microalbuminuria. However, microalbuminuria of short duration, salutary levels of glycosylated hemoglobin (less than 8 percent), low systolic blood pressure (less than 115 mm Hg), and low levels of both cholesterol and triglycerides (less than 198 mg per deciliter [5.12 mmol per liter] and 145 mg per deciliter [1.64 mmol per liter], respectively) were independently associated with the regression of microalbuminuria. Patients with salutary levels of all modifiable factors had a hazard ratio for regression of 3.0 (95 percent confidence interval, 1.5 to 6.0), as compared with patients with no salutary levels of any modifiable factor.

CONCLUSIONS

Frequent regression of microalbuminuria in patients with type 1 diabetes indicates that elevated urinary albumin excretion does not imply inexorably progressive nephropathy. Identification of the multiple determinants of the regression of microalbuminuria has implications for current theories about the mechanisms of early diabetic nephropathy.