Microalbuminuria: prognostic and therapeutic implications in diabetes mellitus

Comparison of Microalbuminuria Status in Type 2 Diabetes Mellitus Patients With Chronic Periodontitis: A Cross-Sectional Study

Background

Diabetes has increased the risk for various other ailments in various organs of the body. This can be contributing to periodontitis also as it is the sixth complication related to diabetes mellitus. There is a bidirectional relationship between both. Given the high global prevalence of type-2 diabetes mellitus (T2DM) with periodontitis, it is of great importance to determine the link between periodontitis and microalbuminuria in T2DM patients, which shows early renal disease.

Methodology

In the present study, a total of 500 patients having T2DM were assessed for periodontitis using Community Periodontal Index (CPI). Anthropometric and biochemical measurements were obtained. Blood samples were estimated for glycemic control tests such as fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), and lipid profile. The subjects who participated in the study were categorized into three groups depending on the albuminuria level. The data were tabulated and analyzed using SPSS Statistics software (IBM Corp., Armonk, USA).

Results

Out of 500 T2DM subjects, 342 subjects had periodontitis. A statistically significant difference was found in FPG, HbA1c, total cholesterol (TC), triglycerides, and low-density lipoprotein (LDL) between subjects with periodontitis and without periodontitis using a t-test (p = <0.001). The prevalence of normoalbuminuria, micro-, and macroalbuminuria among periodontitis patients was 24.6%, 72.8%, and 2.6% respectively, and the Chi-square analysis revealed that was highly significant. In terms of albuminuria, one-way analysis of variance (ANOVA) revealed statistically significant differences among the periodontitis subjects for the following variables: inputs such as the number of teeth, diabetes mellitus (DM) duration, the level of LDL, and also the depth of the pocket. Intergroup comparison of variables among subjects with albuminuria using the statistical test of Tukey Post Hoc found that there is a significant difference between normoalbuminuria and microalbuminuria. CPI score, tooth mobility, smoking, education level, family income, tooth brushing duration, along with the use of other dental hygiene aids was also found to be statistically significant among subjects with periodontitis.

Conclusion

The study concluded that T2DM patients had a higher incidence of microalbuminuria among individuals with periodontitis. These subjects also had significantly higher HbA1c and FPG levels than subjects with normoalbuminuria. In addition, subjects with periodontitis exhibited a significant reduction in the total teeth numbers present in the case of albuminuria. The longitudinal correlation between DM, microalbuminuria, and periodontitis could be further investigated in detail to explore possible pathways.

High normal urine albumin-to-creatinine ratio predicts development of hypertension in Korean men

BACKGROUND

Microalbuminuria is known as a risk factor for hypertension. Recently it was suggested that urine albumin-to-creatinine ratio (UACR), even within the normal range, can be associated with hypertension, but the temporal relationship between normal range UACR and hypertension was not confirmed. Therefore the aim of this study was to verify an association between normal range UACR and the development of hypertension in Korean men.

METHODS AND RESULTS

This prospective cohort study was performed on 1,284 initially non-hypertensive Korean men. The total follow-up period was 4,109.5 person-years and the mean follow-up period was 3.2±1.51 years. Cox proportional hazards model was used to estimate the hazard ratios (HR) for the risk of hypertension development. After adjusting for multiple covariates, the HR (95% confidence interval [CI]) for incident hypertension, comparing the second to the fourth quartiles of UACR level to the first quartile, were 1.35 (95% CI: 0.93-1.97), 1.55 (95% CI: 1.07-2.25) and 1.89 (95% CI: 1.31-2.71), respectively (P for trend=0.001).

CONCLUSIONS

High UACR within the normal range was significantly associated with hypertension development. Furthermore, this association remained significant after adjusting for multiple baseline covariates. 

Evolution of β-Cell Replacement Therapy in Diabetes Mellitus: Pancreas Transplantation

Diabetes mellitus remains one of the leading causes of morbidity and mortality worldwide. According to the Centers for Disease Control and Prevention, approximately 23.6 million people in the United States are affected. Of these individuals, 5-10% have been diagnosed with type 1 diabetes mellitus (TIDM), an autoimmune disease. Although it often appears in childhood, T1DM may manifest at any age. The effects of T1DM can be devastating, as the disease often leads to significant secondary complications, morbidity, and decreased quality of life. Since the late 1960s, surgical treatment for diabetes mellitus has continued to evolve and has become a viable alternative to chronic insulin administration. In this review, the historical evolution, current status, graft efficacy, benefits, and complications of pancreas transplantation are explored.

Trends of type 1 diabetes in Karachi, Pakistan

OBJECTIVE

Our study aims to assess the presentation, prevalence, and associations of acute and chronic complications in subjects with type 1 diabetes mellitus (T1DM) at their first visit to outpatient departments.

STUDY DESIGN AND SETTING

Study was carried out at two centers, Diabetic Association of Pakistan and WHO Collaborating Centre and Baqai Institute of Diabetology and Endocrinology, Karachi. Records of 591 T1DM subjects divided into two groups were studied. Group 1 (62.1%, n = 367) includes patients with known T1DM and group 2 (n = 224, 37.9%), newly diagnosed T1DM. Clinical features [polyuria, polydipsia, polyphagia, history of weight loss, and history of diabetic ketoacidosis (DKA)] were recorded. Biochemical parameters including fasting plasma glucose, 2-h postprandial plasma glucose, hemoglobin A1c, urinary ketones, and proteinuria were recorded. Arterial blood gases was done in suspected cases of DKA.

RESULTS

In group 1, male predominance was seen (57.8 vs. 42.2%). Mean age at presentation was 19.1 +/- 10 yr. Mean duration of diabetes was 16 +/- 9 yr. Two percent subjects presented with DKA, while 21% had a history of DKA. Among the subjects with >10 yr of diabetes, 20.1% had hypertension, 5.5% had nephropathy, 2.9% had neuropathy, and 7.7% had retinopathy. In group 2, 224 T1DM subjects were identified, with mean age of 17 +/- 11 yr. Equal number of males (50.9%) and females (49.1%) were diagnosed at their first presentation. Most subjects (40.8%, n = 91) diagnosed between 11 and 20 yr of age presented with polyuria (81.3%), polydipsia (77.2%), polyphagia (56.7%), and weight loss (79.5%). Ketonuria was positive in 4.9%, while 5.8% presented with DKA.

CONCLUSIONS

This is the first study in Pakistan to assess the mode of presentation and prevalence of acute and chronic complications in T1DM. Larger scale prospective studies are needed to have more detailed informative data.

A rapid and sensitive immunoresonance scattering spectral assay for microalbumin

BACKGROUND

Microalbuminuria (MAU) is the earliest clinical finding for renal disease and a risk factor for hypertensive cardiovascular disease. Several methods, including enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA), immunoturbidimetry (IT), immunonephelometry (IN), chemiluminescence immunoassay (CLIA), fluorescence immunoassay (FIA) and time-resolved fluorescence (TRF) have been applied for detection of MAU. However, the resonance scattering (RS) spectral assay, based on the immunoreaction and its resonance scattering effect, has not been reported.

METHOD

In the presence of 75 mg/l polyethylene glycol (PEG), the immunoreaction of microalbumin (Malb) and its goat anti-human Malb antibody took place specifically in pH 4.4 buffer solution and aggregated to form immunocomplex particles that exhibit a strongest resonance scattering peak at 488 nm, and it was used to assay of Malb.

RESULTS

The RS intensity at 488 nm (DeltaI) was proportional to the Malb concentration (C) in the range of 0.03-0.96 mg/l, the regression equation was DeltaI=116.0C-2.1, the detection limit was 0.02 mg/l. Urine samples from 20 healthy subjects were assayed by this assay. The results were in agreement with those obtained with IT.

CONCLUSION

This assay has been applied to detection of Malb in real samples, with simplicity, rapidity, high sensitivity and good selectivity.

Comparison of Commonly Used Assays for the Detection of Microalbuminuria

There are a variety of methods for assessing urinary albumin excretion, extending from the very low-range microalbuminuria to higher ranges extending into macroalbuminuria or proteinuria. The recommendation for the initial screening of a new patient is to use a urine dipstick to assess for microalbuminuria. If positive, a spot urine for albumin:creatinine should be measured and reassessed annually. All patients with kidney disease, diabetes, or hypertension and metabolic syndrome should be screened for albuminuria. New methodologies using high-performance liquid chromatography are much more sensitive and specific when compared with older methods of detection and may prove very useful for earlier identification of high-risk patients. This is important since studies have shown that albuminuria levels below the microalbuminuria range, determined by conventional methodologies in uncomplicated essential hypertensive men, are associated with an adverse cardiovascular and metabolic risk profile. High performance liquid chromatography methodology, in contrast to older studies, detects all intact albumin and enables clinicians to assess disease severity and monitor therapeutic effectiveness with confidence in the accuracy of the microalbuminuria data reported to them.

Effect of tranilast in early-stage diabetic nephropathy

BACKGROUND

Tranilast is an antifibrotic drug known to suppress collagen synthesis by fibroblasts by interfering with the effects of TGF-beta. We recently reported that it slowed the progression rate of advanced diabetic nephropathy (DN) by reducing the accumulation of collagens in renal tissue. The present study was undertaken to examine the effect of tranilast on early-stage DN.

METHODS

Among out-patients with diabetes mellitus, we selected patients with (i) urinary albumin excretion of 30-1000 mg/g creatinine (/gCr) in the first morning urine, (ii) serum creatinine (SCr) < or =1.2 mg/dl and no haematuria and (iii) currently taking an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker. Twenty patients fulfilled the criteria, of whom 10 were selected at random and commenced on tranilast [100 mg, 3 times daily; T(+) group]. The remaining 10 patients comprised the T(-) group. Excretion of both urinary type IV collagen (U-IV) and albumin (U-A) in the first morning urine was measured every 3 months. The follow-up period was 1 year.

RESULTS

At baseline, no significant differences were observed in SCr, HbA(1c), blood pressure and U-A excretion between the T(+) and T(-) groups, but U-IV excretion in the T(+) group was higher than in the T(-) group (6.4 +/- 0.66 vs 3.7 +/- 0.36 microg/gCr, mean +/- SEM, P < 0.01). At 1 year, SCr was not different from the baseline in either group. In the T(+) group, however, excretion rates of both U-IV and U-A tended to decrease with time, and after 1 year, were significantly decreased compared with excretion at baseline (U-A: 279 +/- 78 to 191 +/- 62 mg/gCr; P = 0.049, U-IV: 6.4 +/- 0.66 to 4.4 +/- 0.99 microg/gCr; P = 0.02). In contrast, in the T(-) group, excretion of both U-A and U-IV tended to increase with time. The changes of both U-A and U-IV excretions in the two groups took statistically different trends through tranilast treatment (P = 0.01 and P = 0.04, respectively).

CONCLUSIONS

Our results suggest that tranilast could be therapeutically beneficial in early-stage DN.

Coelution of other proteins with albumin during size-exclusion HPLC: Implications for analysis of urinary albumin

BACKGROUND

Size-exclusion HPLC has been used as an alternative to immunoassays for quantifying urinary albumin (microalbumin). Systematically higher values for the HPLC method have been proposed to result from nonimmunoreactive albumin.

METHODS

We evaluated separation of purified proteins and urinary components by size-exclusion HPLC using a Zorbax Bio Series GF-250 column eluted with phosphate-buffered saline. Urinary components eluting in the "albumin" peak were analyzed by mass spectrometry and reversed-phase HPLC.

RESULTS

Several proteins, such as transferrin, alpha1-proteinase inhibitor, alpha1-acid glycoprotein, and alpha2-HS glycoprotein, analyzed as purified components, were not resolved from albumin by size-exclusion HPLC. Peaks for other proteins, such as IgG and urinary components identified as dimers of alpha1-microglobulin and immunoglobulin light chains, overlapped with the albumin peak. Profiles of urine specimens showed variable amounts of components overlapping with albumin. Furthermore, the albumin peak obtained by size-exclusion HPLC was found by mass spectrometry and reversed-phase HPLC to contain multiple components in addition to albumin.

CONCLUSIONS

Size-exclusion HPLC does not resolve albumin from several other proteins in urine. The albumin peak resolved by this technique, although predominantly composed of albumin, contains several coeluting globulins that would contribute to overestimation of albumin concentration by size-exclusion HPLC.

The Role of Glycosaminoglycans and Sulodexide in the Treatment of Diabetic Nephropathy

Diabetic nephropathy occurs in 20-40% of diabetic patients, making it one of the most important causes of end-stage renal disease (ESRD). It has a large impact in terms of associated morbidity and mortality for the individual patient and in terms of costs for healthcare. Several studies have demonstrated that micro- and macroalbuminuria predict cardiovascular morbidity and mortality in patients with diabetes mellitus.Current nephroprotective therapies for diabetic nephropathy include the pursuit of normoglycemia and normotension, and a consensus is emerging that there is a necessity to also achieve as low a level of albuminuria as possible. However, the search for innovative and ancillary approaches to the prevention and treatment of this diabetic complication is warranted since strict metabolic control can be difficult, and sometimes dangerous, to achieve and even diabetic patients responding to ACE inhibitors (ACEIs) or angiotensin II receptor antagonists (angiotensin receptor blockers; ARBs) and metabolic control show progressive renal damage and eventually ESRD. A number of drugs are currently being investigated; glycosaminoglycans are particularly interesting since, in theory, they target the generalized endothelial dysfunction and metabolic defect in matrix and basement membrane synthesis which, according to the Steno hypothesis, are responsible for diabetic nephropathy and macroangiopathy.Treatment with glycosaminoglycans, and with sulodexide in particular, significantly improves albuminuria in type 1 and type 2 diabetic patients with micro- or macroalbuminuria. The albuminuria-lowering effect of sulodexide enhances the effect of ACEI/ARB therapy. Most studies have shown that the effect of sulodexide on albuminuria is sustained, strongly suggesting that favorable chemical and anatomic remodeling is induced by exogenous glycosaminoglycans in renal tisues, as observed in the experimental model.

The beneficial effects of pancreas transplant alone on diabetic nephropathy

OBJECTIVE

Pancreas transplant alone can be effective in significantly improving the quality of life of type 1 diabetic patients, and it can also eliminate acute diabetes complications, such as hypoglycemic and/or hyperglycemic episodes. The effects of pancreas transplant alone on long-term complications of diabetes, including nephropathy, are still not settled. We evaluated whether restoration of long-lasting normoglycemia by pancreas transplant alone might have beneficial action on diabetic nephropathy.

RESEARCH DESIGN AND METHODS

A total of 32 type 1 diabetic patients were evaluated before and 1 year after successful pancreas transplant alone, together with 30 matched nontransplanted type 1 diabetic subjects. Several metabolic and kidney function parameters were measured, including plasma glucose, glycohemoglobin (A1C), C-peptide, plasma lipids, blood pressure, creatinine, creatinine clearance, and urinary protein excretion.

RESULTS

Pancreas transplant alone restored sustained normoglycemia, without exogenous insulin administration, and improved plasma lipid levels. Blood pressure decreased significantly. Creatinine concentrations and clearances did not differ before and after transplantation. Urinary protein excretion decreased significantly after pancreas transplant alone, with four microalbuminuric and three macroalbuminuric patients who became normoalbuminuric. None of these changes occurred in the nontransplanted group.

CONCLUSIONS

Successful pancreas transplant alone, through restoration of sustained normoglycemia, improves diabetic nephropathy in type 1 diabetic patients.

Ramipril prevents microtubular changes in proximal tubules from streptozotocin diabetic rats

This study has investigated the microtubular cytoskeleton in rat glomerular and proximal tubule cells in experimental diabetes. The effect of treatment with ramipril on the relationship between microtubule organization and albuminuria in diabetes has also been examined. Diabetes was induced in male Sprague-Dawley rats by administration of streptozotocin (50 mg/kg, i.v.). Rats were treated with or without ramipril in their drinking water for 12 weeks. Diabetes was characterized by an increase in blood glucose level, glomerular filtration rate, and albumin excretion rate. Treatment of diabetic rats with ramipril did not affect glycaemic control, but reduced systolic blood pressure and prevented the rise in albuminuria and glomerular filtration rate. Immunohistochemistry was performed by using the ARK Peroxidase method with alpha-tubulin antibody. The regular, grainy staining pattern of the microtubules present in the renal proximal tubules from control kidneys was altered in diabetic animals, and appeared fragmented and striated. This was prevented by treatment with ramipril. Quantitative morphometric analysis revealed an increase in the percent proportional staining for alpha-tubulin in the proximal tubules of untreated diabetic rats (33.3 +/- 3.3%, n = 8, P < 0.05 vs control) compared with control rats (11.7 +/- 1.7%, n = 6), which was reduced by ramipril treatment (26.7 +/- 2.1%, n = 6, P < 0.05 vs untreated diabetic). Staining for alpha-tubulin in glomerular cells was unchanged in all groups. There was no significant difference in renal alpha-tubulin expression among all groups, as determined by real-time reverse transcription-polymerase chain reaction. These results raise the possibility that diabetes-induced changes in microtubules in the renal proximal tubules may contribute, in part, to the increase in albuminuria observed in diabetes.

Differences in urinary albumin detected by four immunoassays and high-performance liquid chromatography

OBJECTIVES

To compare the analysis of urinary albumin from diabetic patients by four conventional immunoassays including radioimmunoassay (RIA), immunonephelometry (IN), and two different methods of immunoturbidimetry (IT), as well as by high-performance liquid chromatography (HPLC).

DESIGN AND METHODS

Urines were collected over a 24-h period and stored at -20 degrees C until assay. Urinary albumin concentration was determined by an in-house RIA, by IN using a Beckman Array Analyser with reagents from Beckman Diagnostics (Sydney, Australia), by IT using a Dade-Behring Turbitimer with reagents from Dade-Behring (Marburg, Germany), by IT using a Dade-Behring Dimension R x L Chemistry Analyser with reagents from DiaSorin (Stillwater, OK, USA), and by HPLC using a Zorbax Bio series preparative GF-250 column. Regression lines were calculated using a least squares method to determine the correlation between the assays studied. Bland-Altman bias plots including limits of agreement were also calculated.

RESULTS

The correlation coefficients calculated were high (>0.85) indicating a strong linear relationship between all assays studied. The slopes calculated for the comparisons demonstrate that each assay can vary from one another (up to threefold) and have a slope significantly different from an ideal slope of 1 (P < 0.001). These results were confirmed by Bland-Altman bias plots and calculation of the limits of agreement that were all large.

CONCLUSIONS

At this time, there is no global standard by which urinary albumin assays may be standardized. This study suggests the need for such standards.

Cost-effective strategies in the prevention of diabetic nephropathy

A significant subgroup of patients with diabetes mellitus are predisposed to developing diabetic nephropathy and it is in this subgroup that other diabetes- related complications, and in particular greatly increased cardiovascular disease risk, are concentrated. The high personal, social and financial costs of managing end-stage renal failure and the other complications associated with diabetic nephropathy make a powerful case for screening and effective intervention programmes to prevent the condition or retard its progression. As major breakthroughs in finding genetic susceptibility factors remain elusive, screening efforts continue to be based on microalbuminuria testing, despite increasing recognition of its limitations as a positive predictor of nephropathy. Interventions have been extensively studied, but results remain conflicting. Economic evaluations of such screening and intervention programmes are essential for health planners, yet models of the cost/benefit ratio of such interventions often rely on a rather slim evidence base. Where economic models are developed, they are frequently based on those papers that propound the greatest clinical benefits of a given intervention, leading to a possible over-estimation of the advantages of the chosen approach. Furthermore, the benefits of even such generally accepted interventions as ACE inhibitor treatment are less firmly established than generally appreciated. Lifestyle interventions are instinctively attractive, but are by no means a low-cost option (as is often assumed by both medical professionals and politicians). This review critically assesses the evidence for clinical efficacy and economic benefit of microalbuminuria screening and interventions such as intensive glycaemic control, antihypertensive treatment, ACE inhibition and angiotensin receptor blockade, dietary protein restriction and lipid-modifying therapy. The various costs associated with diabetic nephropathy are so great that even expensive interventions may have a favourable cost/benefit ratio, provided they are truly effective.

Introducing practice-based learning and improvement ACGME core competencies into a family medicine residency curriculum

BACKGROUND

The Accreditation Council for Graduate Medical Education (ACGME) recommends integrating improvement activities into residency training. A curricular change was designed at the Department of Family and Community Medicine, University of Louisville, to address selected ACGME competencies by incorporating practice-based improvement activities into the routine clinical work of family medicine residents.

METHODS

Teams of residents, faculty, and office staff completed clinical improvement projects at three ambulatory care training sites. Residents were given academic credit for participation in team meetings. After 6 months, residents presented results to faculty, medical students, other residents, and staff from all three training sites. Residents, staff, and faculty were recognized for their participation.

PROGRAM EVALUATION

Resident teams demonstrated ACGME competencies in practice-based improvement: Chart audits indicated improvement in clinical projects; quality improvement tools demonstrated analysis of root causes and understanding of the process; plan-do-study-act cycle worksheets demonstrated the change process.

CONCLUSIONS

Improvement activities that affect patient care and demonstrate selected ACGME competencies can be successfully incorporated into the daily work of family medicine residents.

Nitric oxide synthase gene polymorphisms and diabetic nephropathy

AIMS/HYPOTHESIS

Susceptibility to diabetic nephropathy in subjects with Type 1 diabetes is mainly genetically determined. Excess cardiovascular risk associated with diabetes is overwhelmingly concentrated in patients with nephropathy. Endothelial dysfunction is a feature of cardiovascular disease, hypertension, dyslipidaemia and smoking, all of which are associated with diabetic nephropathy. Nitric oxide regulates endothelial function and so genes encoding nitric oxide synthases could confer susceptibility to nephropathy. Recently positive associations have been reported. We examined polymorphisms within NOS3 and NOS2A, the genes encoding endothelial- and inducible nitric oxide synthase, for association with nephropathy.

METHODS

Large case-control studies of patients with Type 1 diabetes and overt nephropathy who had hypertension and diabetic retinopathy. The control group comprised Type 1 diabetic subjects who have been on insulin for 50 or more years and have an extremely low risk of nephropathy. Genotyping was by PCR and agarose- or automated polyacrylamide gel electrophoresis using fluorescence-labelled primers.

RESULTS

NOS3 intron 4 genotype frequencies (n=860: 464 cases, 396 control subjects) were 2.6%, 23.3%, 74.1% and 2.3%, 22.7%, 75.0% for aa, ab and bb genotypes; p=0.935. NOS2A promoter genotype frequencies (n=715: 358 cases, 357 control subjects) were 0.3%, 16.8%, 83.0% and 0.3% 17.6% and 82.1% for +/+, +/- and -/- genotypes (p=0.952).

CONCLUSION/INTERPRETATION

In our cohort of Caucasian subjects with Type 1 diabetes there is no association between either of the polymorphisms studied and diabetic nephropathy. The previous suggestion from smaller studies that the intron 4 polymorphism in NOS3 could play a role in susceptibility to the disease is not confirmed.

Microalbuminúria em pacientes diabéticos tipo 1: prevalência e fatores associados

Para avaliar a freqüência da microalbuminúria e fatores clínicos e metabólicos associados, estudamos 72 pacientes com diabetes tipo 1 [DM1, 38F/34M, sendo 6 crianças, 17 adolescentes e 49 adultos, com 22,7±9,5 anos e 7 anos (0,1-37,5) de duração da doença]. A taxa de excreção de albumina (EUA) foi determinada em amostra noturna de urina de 10h. Microalbuminúria foi definida como EUA > ou = 20 e <200mig/min em pelo menos 2 de 3 amostras de urina, 25% mostraram-se microalbuminúricos (16 adultos e 2 adolescentes) e tinham maiores médias de idade (27,3±5,8 vs 20,9±10,1 anos, p<0,001), duração do DM [11,0 (0,1-17,0) vs 5,9 (1,0-37,5) anos, p<0,05], índice de massa corporal (22,7±2,6 vs 20,7±3,1, p<0,05), uréia (32,4±7,8 vs 28,3±5,9mg/dl, p<0,05), creatinina [0,7 (0,6-1,2) vs 0,6 (0,4-1,1) mg/dl, p<0,05] e maior freqüência de retinopatia (33% vs 9,4%, p<0,05) quando comparados aos normoalbuminúricos. Na regressão linear múltipla em stepwise, tendo a EUA como variável dependente, a única variável independente associada e preditora foi a idade (r²= 0,13, p<0,05). Concluímos que a idade foi um fator determinante no surgimento da microalbuminúria. Apesar de não termos observado microalbuminúria em crianças sugerimos que a triagem nesta faixa etária deve ser discutida no contexto específico de cada serviço de atendimento ao diabetes.

Immuno-unreactive albumin excretion increases in streptozotocin diabetic rats

We previously showed that albumin is fragmented (>90%) during renal passage to low-molecular-weight (<10 kd) peptides. The aim of the present study was to document the renal handling of albumin in experimental diabetes. Tritium-labeled albumin was infused into control and streptozotocin (STZ) diabetic rats during 7 days. Urinary radioactivity, assessed by size exclusion chromatography, revealed a major peak corresponding to low-molecular-weight, albumin-derived fragments and a minor peak corresponding to intact albumin or high-molecular-weight, albumin-derived protein. The fractional clearance of albumin, calculated from total radioactivity measurements, was at least 100-fold greater than the fractional clearance of albumin determined by radioimmunoassay (RIA) for control and diabetic rats. This result was mainly because low-molecular-weight, albumin-derived fragments were not detected by RIA. The fractional clearance of high-molecular-weight, albumin-derived protein was 2- to 10-fold greater than the fractional clearance determined by RIA. The immuno-unreactive high-molecular-weight, albumin-derived protein (called ghost albumin), characterized by size exclusion chromatography and high-performance liquid chromatography, was present in control and diabetic rat urine. Ghost albumin excretion rate was enhanced 11-fold after 8 weeks of STZ diabetes as compared with aged-matched controls. This study shows that renal modification resulting in low-molecular-weight and high-molecular-weight components of albumin is a major contributor to the renal handling of albumin. The results indicate that excretion of modified albumin is increased in STZ rats as compared with albumin detected by conventional RIA. Long-term studies are necessary to evaluate the potential of ghost albumin as a new marker for the assessment of urinary albumin in diabetes.

Heart rate elevation and diabetic retinopathy in patients with type 2 diabetes mellitus and normoalbuminuria

To investigate the role of heart rate (HR) and blood pressure (BP) for diabetic retinopathy, 24-h ambulatory HR and BP were monitored for 162 in patients with type 2 diabetes and normoalbuminuria. The fundus was assessed as no retinopathy, simple diabetic retinopathy (SDR) and proliferative retinopathy (PDR). Comparing the highest with the lowest quartile of diabetic duration, the relative risk for retinopathy was 9.3 and for nocturnal HR, it was 3.6. Comparison among three retinopathy groups (no retinopathy, group 1, n=122; SDR, group 2, n=24; Pre-PDR or PDR, group 3, n=16) showed that 24-h and nocturnal HR were significantly higher in group 3 (80+/-9 and 71+/-9 beats per min) than in group 2 (73+/-8 and 64+/-8) and group 1 (72+/-7 and 60+/-7). In multiple logistic analysis, the odds ratio of diabetic duration and nocturnal HR to the existence of retinopathy was 1.17 (95% CI, 1.10-1.25, P=0.00001) and 1.11 (95% CI, 1.05-1.17, P=0.0002). We concluded that diabetic retinopathy is related to diabetic duration and high heart rate in type 2 diabetes mellitus with normoalbuminuria. Heart rate elevation may be a predictor of advanced retinopathy.

Retinopathy and microalbuminuria in type 2 diabetes: determinants and time-dependency of the association

Background: The aim of this study was to identify the independent determinants of diabetic retinopathy (RET) and microalbuminuria (MA) and to assess the time-dependency of the association of RET with MA. Methods: In 668 out-patients with type 2 diabetes, RET was assessed by stereoscopic fundoscopy and by measuring the level of MA in untimed, triplicate urine collections on at least two and four separate visits, respectively, during a period of at least 24 months. RET was defined as RET of any type and MA as a urinary albumin-to-creatinine ratio (ACR) between 2 and 30 mg/mmol. Multiple logistic regression analysis was used to determine odds ratios (OR) and 95% confidence intervals (CI). The extent of the association (OR(assoc)) was estimated by the odds that a patient with RET has MA divided by the odds that a patient without RET has MA. Results: Common determinants of RET and MA were: systolic BP, HbA(1c), and triglycerides. Age, non-Caucasian ethnicity, and RET were associated with MA, whereas duration of diabetes and ACR were associated with RET. We estimated an overall OR(assoc) of 2.36 (95% CI, 1.72-3.24). The time-dependency of OR(assoc) showed a hyperbolically shaped curve, reaching a maximum value of 2.5 at 9.8 years after the diagnosis of type 2 diabetes. Conclusions: Our study, which supports what is currently known about independent determinants of diabetic RET and MA, suggests a drastic increase in clustering of RET and MA over the first 5 years before the diagnosis of type 2 diabetes.

Prevalence of abnormal urinary albumin excretion in adolescents and children with insulin dependent diabetes: the MIDAC study. Microalbinuria in Diabetic Adolescents and Children (MIDAC) research group

OBJECTIVE

To examine the prevalence of microalbuminuria, defined as an albumin to creatinine ratio (UAC) equal to or greater than 2 mg/mmol in at least two of three early morning urine samples, in adolescents and children with insulin dependent diabetes mellitus.

DESIGN

Centrally coordinated, cross sectional, multicentre study in paediatric diabetes outpatient clinics in the United Kingdom and Republic of Ireland.

METHODS

Blood and urine samples collected between July 1997 and July 1998 were analysed at a central reference laboratory for HbA(1C) using high performance liquid chromatography, and for urinary albumin and creatinine concentrations from which the UAC was derived (mg/mmol). Clinical data were collected locally and coordinated centrally.

SUBJECTS

Patients, aged between 10 and 20 years, with insulin dependent diabetes mellitus for more than a year, attending diabetes outpatient clinics.

RESULTS

A total of 1007 patients, comprising 69% of the eligible population of 1451, provided three early morning urine samples. Ninety eight (9.7%) had microalbuminuria using the currently accepted screening cut off of UAC >/= 2 mg/mmol in at least two of three early morning urine samples. Significantly more girls than boys and significantly more pubertal and postpubertal patients had abnormal albumin excretion. Microalbuminuria was not associated with raised blood pressure.

CONCLUSIONS

A prevalence of 9.7% for abnormal UAC was found in a cohort of 1007 children and adolescents aged 10-20 years. Thus a tenth of this national sample of young people were identified as being at particular risk of microvascular and later macrovascular disease.

Premature cardiovascular disease in chronic renal failure

There is a remarkable lack of reliable information about the determinants of risk of cardiovascular disease (CVD) among patients with chronic renal failure. Indeed, such patients have often been deliberately excluded from randomised trials of treatments of CVD, perhaps because of concerns about drug safety. But the absolute risk of CVD among them may be large, so the potential absolute benefits of treatments may also be large, and may well exceed any increased hazards. Hence, as well as further investigation of the underlying mechanisms of cardiac disease, it would be helpful to have some large-scale randomised trials in a wide range of renal patients of interventions (such as cholesterol-lowering drugs, antihypertensives, aspirin, B-vitamins, and antioxidant vitamins) that are of proven or suspected benefit in other settings. If safe and effective treatments can be identified, and started early in the natural history of renal failure, the exceptionally high risk of CVD experienced by these patients could be decreased before and after end-stage renal failure has occurred.

Lisinopril. A review of its pharmacology and use in the management of the complications of diabetes mellitus

Lisinopril, like other ACE inhibitors, lowers blood pressure and preserves renal function in hypertensive patients with non-insulin-dependent or insulin-dependent diabetes mellitus (NIDDM or IDDM) and early or overt nephropathy, without adversely affecting glycaemic control or lipid profiles. On available evidence, renoprotective effects appear to be greater with lisinopril than with comparator calcium channel blockers, diuretics and beta-blockers, despite similar antihypertensive efficacy. As shown by the EUCLID (EUrodiab Controlled trial of Lisinopril in Insulin-Dependent Diabetes) trial, lisinopril is also renoprotective in normotensive patients with IDDM and microalbuminuria. The effect in normotensive patients with normoalbuminuria was smaller than in those with microalbuminuria, and no conclusions can yet be made about its use in patients with normoalbuminuria. In complications other than nephropathy, lisinopril has shown some benefit. Progression to retinopathy was slowed during 2 years' lisinopril therapy in the EUCLID study. Although not yet fully published, these results provide the most convincing evidence to date for an effect of an ACE inhibitor in retinopathy. The drug may also improve neurological function, but this finding is preliminary. Lastly, post hoc analysis of the GISSI-3 trial indicates that lisinopril reduces 6-week mortality rates in diabetic patients when begun as early treatment after an acute myocardial infarction. The tolerability profile of lisinopril is typical of ACE inhibitors and appears to be similar in diabetic and nondiabetic individuals. Hypoglycaemia has occurred at a similar frequency with lisinopril and placebo, as shown in the EUCLID trial. In addition, the GISSI-3 study indicates that the incidence of persistent hypotension and renal dysfunction is increased with lisinopril in general, but the presence of diabetes does not appear to confer additional risk of these events in diabetic patients with acute myocardial infarction receiving lisinopril. In summary, lisinopril lowers blood pressure and produces a renoprotective effect in patients with IDDM and NIDDM without detriment to glycaemic control or lipid profiles. Like other ACE inhibitors, lisinopril should thus be viewed as a first-line agent for reducing blood pressure and preventing or attenuating nephropathy in hypertensive diabetic patients with IDDM or NIDDM and microalbuminuria or overt renal disease. The EUCLID study, using lisinopril, provides new data supporting an additional place in managing normotensive patients with microalbuminuria and IDDM. These findings, together with some evidence for an effect of lisinopril in delaying progression of retinopathy and in reducing mortality, suggest a broader role for the drug in managing diabetic vascular complications.

Detection of microalbuminuria in diabetic patients by urinary dipstick

The present study was undertaken to determine the usefulness of a new, sensitive urinary dipstick, Micral-Test II (Boehringer-Mannheim, Mannheim, Germany) for the detection of microalbuminuria (urinary albumin concentration: 20-200 mg/l) in diabetic patients. four hundred and eleven consecutive outpatients with diabetes were screened for microalbuminuria. The diagnostic accuracy of Micral-Test II for the detection of urinary albumin excretion > 20 mg/l was assessed by comparing the urinary albumin concentration determined by Micral-Test II with radioimmunoassay (RIA). In comparison with radioimmunoassay, Micral-Test II had an overall sensitivity of 93%, specificity of 93% and positive predictive value of 89%. False negative results were found in 7% and false positives were obtained in 7% of specimens. These findings suggest that Micral-Test II may be a useful method for the screening of microalbuminuria. However, it should not be regarded as a diagnostic test and a positive result should be followed by measuring AER by a laboratory based method.

Progression of retinopathy is related to glycaemic control even in patients with mild diabetes mellitus

To study the progression of retinopathy in patients with mild diabetes mellitus, we examined, in a cohort study, 347 patients treated with diet alone at baseline. The patients participated in an ophthalmological screening and control programme, and diet-treated patients who were examined between January 1990 and July 1992 were included in the study and followed until October 1995. Mean follow-up was 3.4 +/- 1.1 years. The alternative classification of the Wisconsin study was used to classify retinopathy, and the mean HbA1c values for the study period, to estimate the level of glycaemic control. At baseline, 314 of the patients (90.5%) had no retinopathy, and 33 (9.5%) had mild non-proliferative diabetic retinopathy. In 296 patients there was no retinopathy progression, in 27 patients there was progression by 1 level in the retinopathy scale, and in 24 patients by 2 levels or more. In 2 patients there was progression to proliferative diabetic retinopathy. The mean HbA1c (%) was 6.5 +/- 1.3. Higher HbA1c correlated to increased progression (r = 0.16; p = 0.005), and in a multivariate analysis, HbA1c remained associated with a progression of retinopathy by 2 levels or more, with a relative risk of 1.4 per percent increase in HbA1c (95% CI 1.1-2.0; p = 0.02). Furthermore, the presence of any retinopathy at baseline was associated with progression with a relative risk of 1.7 (95% confidence interval 1.1-2.8; (p = 0.02). These data indicate that even slightly elevated levels of HbA1c might be associated with a risk of retinopathy progression.

Microalbuminuria in type 2 diabetes: an independent predictor of cardiovascular mortality

BACKGROUND

Microalbuminuria has been shown to be associated with cardiovascular mortality in type 2 diabetic subjects. It is unclear to what extent this is due to the increased prevalence of other cardiac risk factors.

AIMS

To examine the relationship of urine albumin excretion to cardiovascular mortality and to determine its status as an independent risk factor.

METHODS

In a prospective longitudinal study from 1986-1993 we followed 666 type 2 diabetic subjects from a diabetes outpatient service. Cardiovascular risk factors including urine albumin concentration were measured at study entry. Cox proportional hazards regression was used to determine risk factors for mortality. The hazard ratios of microalbuminuria and macroalbuminuria for all cause, cardiovascular and coronary heart disease mortality were determined after accounting for other cardiac risk factors including blood pressure, glycated haemoglobin, total cholesterol, HDL cholesterol, triglycerides, urea, smoking, body mass index, patient age and disease duration.

RESULTS

The prevalence of urine albumin of 30-300 mg/L at study entry was 31.7%. A total of 167 deaths occurred (80 from cardiovascular disease). Mortality hazard ratios in subjects with urine albumin of 30-300 mg/L as compared to < 30 mg/L, adjusted for age, sex and other cardiovascular risk factors were 1.77 (95% CI 1.22-2.57, p = 0.002) for all causes, 2.34 (95% CI 1.38-3.99, p = 0.002) for cardiovascular and 1.78 (95% CI 0.97-3.26, p = 0.061) for coronary heart disease (CHD) mortality. Other factors significantly associated with cardiovascular mortality included diastolic blood pressure, HDL cholesterol and glycated haemoglobin. Total cholesterol and log triglyceride were significantly associated with CHD mortality. Disease duration, age at diagnosis, smoking and body mass index were not related to cardiovascular or CHD mortality.

CONCLUSIONS

We confirm microalbuminuria as an independent predictor of mortality in type 2 diabetes despite its association with a number of conventional cardiovascular risk factors.

What happens to women with preeclampsia? Microalbuminuria and hypertension following preeclampsia

There is little published data on the incidence of remote hypertension, microalbuminuria (a possible marker of remote cardiovascular events) and diabetes following preeclampsia. This is of particular importance in Pacific Island populations as they have a high rate of preeclampsia, non-insulin dependent diabetes and cardiovascular related deaths. The aim of this study was to compare the rate of microalbuminuria and hypertension in 50 Samoan women with past preeclampsia (cases) with 50 Samoan women who did not have past preeclampsia (controls). Forty per cent of cases were hypertensive at follow-up compared to 2% in the control group (p < 0.0001). Microalbuminuria or proteinuria occurred in 40% of women with past preeclampsia and 18% of controls (p < 0.02). Half of the cases with microalbuminuria were hypertensive. No case or control had an elevated fructosamine, suggesting that current diabetes was an unlikely explanation for the microalbuminuria. We conclude that Samoan women with past preeclampsia are at increased risk of developing chronic hypertension and microalbuminuria. The significance of the microalbuminuria after preeclampsia is not known, but it may be a marker of either remote cardiovascular morbidity or non-insulin dependent diabetes. This study raises longterm health implications for women with preeclampsia.

Diabetic vascular injury and ACE. Potential for pharmacological prevention of complications of later life

Experimental studies have indicated that angiotensin converting enzyme (ACE) inhibitors have multiple actions on the kidney and blood vessels which include both haemodynamic and antitrophic effects. Inhibition of angiotensin II and potentiation of bradykinin have both been postulated to be major mechanisms in mediating the effects of ACE inhibitors. Clinical studies have indicated that these agents postpone end-stage renal failure in macroproteinuric patients with insulin-dependent diabetes mellitus (IDDM). Indeed, these drugs are useful in both hypertensive and normotensive diabetic patients with macroproteinuria. In IDDM patients with microalbuminuria, ACE inhibitors have been shown to decrease albuminuria and to retard the development of overt renal disease. The role of these agents in patients with non-insulin-dependent diabetes mellitus (NIDDM) and early or overt renal disease remains to be clearly delineated. However, preliminary studies suggest a similar beneficial renoprotective effect of ACE inhibitors in NIDDM. It should be appreciated that the presence of micro- or macroproteinuria in NIDDM is a predictor of cardiovascular rather than renal morbidity and mortality. The possibility of cardiovascular protection, in addition to renal protection, being conferred by these drugs needs to be considered in both IDDM and NIDDM, although this issue has not been evaluated in detail.

Diabetes and hypertension: prognostic and therapeutic considerations

Hypertension and diabetes are common disorders which frequently co-exist. Both are risk factors for atherosclerotic vascular disease and their combination is associated with an increased incidence of nephropathy, ischaemic heart disease, peripheral vascular disease, and stroke. Several trials such as the HDFP and SHEP studies that included diabetic patients have demonstrated the beneficial effects of antihypertensive therapy in reducing mortality. In diabetes, studies have focussed predominantly on the efficacy of antihypertensive therapy in reducing the progression of diabetic kidney disease. Such therapy has been shown to decrease albuminuria in the setting of "normal" and elevated blood pressure in both type I and type II diabetic patients. This reduction in albuminuria has been observed in microalbuminuric diabetic patients and also in those with overt renal disease. Recent studies in type I diabetic patients with overt nephropathy indicate that these effects on urinary albumin excretion are associated with reduction in the rate of decline in renal function and development of end-stage renal failure. Indeed, several groups have shown that the initiation of antihypertensive therapy improves the prognosis of type I diabetic patients with nephropathy. While certain classes of drugs may reduce the rate of progression of complications such as nephropathy, others have side effect profiles that are disadvantageous in patients with diabetes.

Screening for microalbuminuria in type 2 diabetic patients: the evaluation of a dipstick test in general practice

To evaluate the Micral test, a semiquantitative dipstick test, in a general practice setting, 317 Type 2 diabetic patients completed a screening for microalbuminuria by means of the Micral test as well as immuno-nephelometry with the Disc 120 immuno-nephelometer (Hyland, Nivelles, Belgium). Data were collected in 10 general practices performing the Nijmegen Monitoring Project. At a regular check-up each Type 2 diabetic patient was asked to collect first morning urine samples on three consecutive days. The sensitivity of the Micral test was 67%, the specificity 93%. Between the practices the sensitivity ranged from 58% to 81%, the specificity from 87% to 95%. Microalbuminuria, defined as a mean urine albumin concentration > or = 20 mg I-1 by nephelometry on three consecutive days, was found in 66 patients (21%). The first Micral test correctly picked out these patients with microalbuminuria in 70% of the cases and in 90% those patients without microalbuminuria. The diagnostic performance of the Micral test was further proved by a Receiver Operating Characteristic (ROC) curve. The Area Under the Curve (AUC) of the Micral test was 0.84 (95% CI 0.78-0.90). Micral test results of 0 and 10 should be regarded as negative.