Evidence of Impaired Glomerular Charge Selectivity in Nondiabetic Subjects With Microalbuminuria

Microvascular complications of diabetes: the role of angiotensin converting enzyme inhibitors Proceedings of a Round Table Meeting, June 1999, San Diego, USA

Objective To investigate the serum cystatin C (Cys C) level in patients with diabetes mellitus(DM), and analyzed the relationship between Cys C and the course of DM with normal urinary albumin excretion rate (UAER). Then analyzed the relationship of the Cys C level between patients of DM with normal UAER and patients of diabetic nephropathy phase Ⅲ. Methods The serum Cys C levels of 120 DM patients with normal UAER and 40 DM patients of diabetic nephropathy phase Ⅲ were detected. One hurdred and twenty cases of DM patients with normal UAER were divided into group A(the course of DM 10 years, 40 cases)according to their course of DM. Take the 40 cases of diabetic nephropathy phase Ⅲ patients as group D. Results Cys-C levels were highest in group C (0.96±0.18)mg/L,followed by group B (0.84±0.19)mg/L, and group A (0.73±0.20)mg/L(P 0.05). Conclusions When UAER is normal, renal function damage is aggravated gradually with the increasing course of DM; and when the course of DM more than 10 years, the renal function damage degree just as the diabetic nephropathy phase Ⅲ. Key words: Diabetes mellitus; Diabetic nephropathy; Course; Cystatin C

In order to evaluate tubular damage in diabetic patients, the activity of renal proximal tubule derived enzymes excreted in 24-hour urine were recorded in 5 groups as follows: (i) 48 noninsulin-independent diabetic patients with normal renal function and a urinary albumin excretion rate within the normal range; (ii) 45 noninsulin-dependent diabetic patients with normal renal function and a high urinary albumin level; (iii) 26 noninsulin-dependent diabetic patients with renal failure; (iv) 40 patients with essential hypertension and normal renal function, and (v) 48 normal control subjects. Regardless of whether cases were noninsulin-dependent diabetics with normal or high urinary albumin excretion rate or cases with renal dysfunction, urinary dipeptidyl aminopeptidase IV and N-acetyl-beta-D-glucosaminidase excretions were significantly higher than in healthy subjects, and urinary gamma-glutamyl transpeptidase excretion was significantly lower than in healthy subjects. No significant changes in urinary enzyme excretions showed specific variations in the essential hypertensive patients. These results suggest that there is tubular damage in the early stages of noninsulin-dependent diabetic patients with normal renal function and normal urinary albumin excretion rate. Detection of urinary excretion of dipeptidyl aminopeptidase IV, N-acetyl-beta-D-glucosaminidase and gamma-glutamyl transpeptidase may be especially useful for the early diagnosis of diabetic nephropathy.

Urinary orosomucoid excretion rate is increased in a substantial proportion of patients with Type II (non-insulin-dependent) diabetes mellitus and normal urinary albumin excretion rate. The aim of this study was to determine whether increased urinary orosomucoid excretion rate is predictive of increased mortality in patients with Type II diabetes. In a cohort study including 430 patients with Type II diabetes, baseline urinary samples were analysed for orosomucoid and albumin. Mean follow-up was 2.4 years. We found that 188 (44 %) patients had normal and 242 (56 %) patients had increased urinary orosomucoid excretion rates. During the study period 41 patients died; out of these 23 patients died of cardiovascular diseases. Odds ratio for all-cause mortality was 2.50 (95 % CI 1.00-6.22) and odds ratio for cardiovascular mortality was 9.81 (1.31-73.6) having increased urinary orosomucoid excretion rate at baseline (odds ratios adjusted for age, sex, duration of diabetes, cardiovascular diseases, weight, medication, HbA1 c, plasma creatinine and urinary albumin excretion rate). Urinary albumin excretion rate was an independent predictor of all-cause mortality when urinary orosomucoid excretion rate was not included in the analysis. Subgroup analysis revealed that 39 % of the patients with normal urinary albumin excretion rate (n = 251) had increased urinary orosomucoid excretion rates and that these patients had a higher cardiovascular mortality (p = 0.007) than patients with normal urinary albumin excretion rate and normal urinary orosomucoid excretion rates. We found that urinary orosomucoid excretion rate predicted all-cause and cardiovascular mortality in patients with Type II diabetes independently from other risk factors.

Reduced bone mineral density (BMD), termed diabetic osteopenia, has been reported in patients with insulin-dependent (Type 1) diabetes mellitus (IDDM). To examine BMD in long-term IDDM patients with normal kidney function, but with different degrees of urinary albumin excretion rate (UAER), compared to that of patients with elevated plasma creatinine, 36 IDDM male patients (mean duration 27 years) were subdivided according to UAER (<30, 30-300, >300, >300 mg 24 h(-1) and plasma creatinine 0.120-0.350 mmol l(-1)) and 15 controls were recruited. BMD was measured by dual energy X-ray absorptiometry and UAER by enzyme linked immunosorbent assay. BMD was normal in IDDM patients with normal UAER and reduced in the femoral neck, the trochanter major, and the Wards triangle in patients with increased UAER (p < 0.01, p < 0.05, p < 0.02). BMD correlated to creatinine clearance in both cortical and cancellous bone sites (p < 0.001, p < 0.0001), and inversely to the levels of plasma PTH (p < 0.0005). We conclude that BMD is normal in long-term IDDM male patients with normal kidney function and normal UAER and reduced in patients with increased UAER. Diabetic osteopenia seems to be a progressive phenomenon related to diabetic nephropathy and associated with the decrease in creatinine clearance and with the resulting rise in plasma PTH.

The present study was undertaken to clarify the progression of urinary albumin excretion rate (UAER) in non-insulin-dependent diabetic (NIDD) patients 6 years after diagnosis, and to elucidate the risk factors of nephropathy. This is a population-based controlled (baseline) cohort study. The prospective evaluation utilized the diabetic patients as internal controls. The setting was an urban primary health care centre. Main outcome measures were the UAER-24 h and fractional urinary albumin excretion rate (FAC) and their relation to mean blood pressure, haemoglobin Alc, fasting serum insulin and cholesterol and renal size. UAER (mg/24 h) was increased (geometric mean, quartile 1 and 3) in the diabetic patients at baseline, compared to the non-diabetic control subjects; 21 (10 and 33) versus 12 (8 and 15), P = 0.0001 (Wilcoxon's rank test). The UAER-24 h was not increased in diabetic subjects at follow-up; 24 (7 and 49) P = 0.3791 versus diabetic subjects at baseline. Eighteen per cent of normoalbuminuric (UAER < 30mg/24 h) patients developed microalbuminuria (UAER = 30-300 mg/24 h) and 3% clinical nephropathy (UAER > 300 mg/24 h). Of the microalbuminuric subjects 19% progressed to clinical nephropathy, 46% remained microalbuminuric and 35% remitted to normoalbuminuria. Serum insulin concentration, after assessment of confounding factors, measured at the baseline predicted the UAER for all diabetic subjects at follow-up in multiple linear regression analysis in an independent and significant way (P = 0.01). Serum insulin concentration (P = 0.034) and diuretic therapy (P = 0.050) at baseline independently predicted the outcome of the categorical variable progressor/nonprogressor (n = 22/86) based on the UAER-24 h at baseline and at follow-up. Progression of the UAER during the first 6 years is found among approximately every fifth NIDD subject who develops either microalbuminuria (from normoalbuminuria) or clinical nephropathy (from microalbuminuria). The role of serum insulin (insulin resistance) or some factor associated with it, is suggestive in the genesis of kidney disease.

Background: Expression of angiotensin-II type 1 receptor (AT1R) play a role in angiotensin-II (Ang-II) mechanism of action. Angiotensin-II also have a role on urinary albumin excretion (UAE) incidence in hypertensive subjects. Objective: Understanding the role of A1166C AT1R gene polymorphism on UAE rate in hypertensive subjects. Method: This is an observational study with cross-sectional approach, conducted in 2014 at Dr. Wahidin Sudirohusodo Hospital Makassar. We included both hypertensive and controlled hypertensive subjects, eGFRMDRD ≥60 ml/menit/.73 m2, no evidence of urinary tract infection, no diabetes mellitus, not on period of menstruation or hematuria. Based on ACR, subjects were classified into A1 (ACR <30 mg/g), A2 (ACR 30–300 mg/g) and A3 (ACR >300 mg/g). A1 group was categorized as normal, while A2 and A3 group as abnormal. A1166C AT1R gene polymorphism detected by PCR examination if we found genotype: AT1R 1166AA, AT1R 1166AC and AT1R 1166CC. Non-AA genotype are AT1R 1166AC and AT1R 1166CC, and AA genotype is AT1R 1166AA. Result: From 71 subjects, 20 subjects (28.2%) are non-AA genotype and 51 subjects (71.8%) are AA genotype. From 20 non-AA genotype subjects, 4 subjects (20%) with abnormal UAE rate and 16 subjects (80%) with normal UAE rate. While from 51 subjects with AA genotype, 6 subjects (11,8%) with abnormal UAE rate and 45 subjects (88.2%) with normal UAE rate. The risk of non-AA genotype to have UAE rate increment is 1.9 times compared with AA genotype, but statistically not significant (CI: 0,47–7,51; p = 0.452). Conclusion: We found that C allele of the A1166C AT1R gene polymorphism is not a risk factor for UAE rate increment in hypertensive subjects.

Although cardiovascular and cerebrovascular morbidity and mortality in type 2 diabetic patients is closely related to urinary albumin excretion rate (UAER), the causative mechanisms are not yet identified. The aim of our study was to define the circadian variation of blood pressure (BP) in 72 type 2 diabetic patients (mean age 60 years, mean diabetes mellitus duration: 12 years) in comparison with 41 nondiabetic controls with essential hypertension (mean age 58 years) by using ambulatory blood pressure measurement. Thirty diabetic patients had normal UAER (< 30 mg/24 h), 27 had microalbuminuria (30 to 300 mg/24 h), and 15 had persistent proteinuria (> 300 mg/24 h). Systolic blood pressure during both nighttime and daytime was significantly elevated in type 2 diabetic patients with macroalbuminuria compared to controls and patients with normal UAER. During nighttime even type 2 diabetic patients with microalbuminuria had significantly elevated systolic blood pressure compared to controls with essential hypertension. We also observed a correlation of nocturnal blood pressure to UAER (systolic: r = 0.32, P < .007 and diastolic: r = 0.24, P < .04). Nondipping (defined as a reduction of nocturnal BP < 10%) was observed in 80% of the macroalbuminuric, 74% of the microalbuminuric, but only in 43% of the normoalbuminuric type 2 diabetic patients and in 37% of the controls (P < .04). Since a loss of circadian variation of BP is closely related to vascular complications in nondiabetics, our findings may indicate an important relationship between nondipping of BP and the high morbidity and mortality rate in diabetic patients with increased UAER.

To examine the relationship between increased urinary albumin excretion rate and fasting plasma lipids among male and female respondents to the EURODIAB IDDM Complications Study, and attempt to explain inconsistencies in previous reports. A cross-sectional study of 3250 randomly selected Type 1 diabetic patients from 31 diabetes clinics in 16 European countries was carried out between 1989 and 1990. Plasma lipids and urinary albumin were measured centrally. The present analysis was confined to the subgroup of 2205 patients attending after a 10-12 h overnight fast. Mean age was 33 years (SD 10) and mean duration of Type 1 diabetes mellitus was 15 years (SD 9). The prevalence of microalbuminuria (24-h urinary albumin excretion rate 20-200 microg/min) was 21.7% (95% confidence interval 19.9-23.5) and macroalbuminuria (24-h urinary albumin excretion rate > 200 microg/min) 7.8% (6.6-9.0). In comparison to patients with normal urinary albumin excretion rate (< 20 microg/min), and after controlling for age, sex, glycaemic control, duration of diabetes and current smoking, macroalbuminuria was associated with significantly (P<0.01) increased fasting plasma triglycerides, cholesterol, LDL-cholesterol, cholesterol:HDL-cholesterol ratio and, in women, reduced HDL-cholesterol. In men and women with microalbuminuria, the only significant association was with increased plasma triglycerides. These data confirm that there is an association between fasting plasma lipids and increasing urinary albumin excretion rate in European Type 1 diabetic patients. In microalbuminuric patients, however, the association was weaker than previously reported and partly explained by confounding factors.

The urinary excretion of retinol-binding protein (RBP) was studied in 101 insulin-dependent diabetic patients allocated to three groups according to 24-h urinary albumin excretion rate (UAE) (median of three urine collections): group 1 (n = 45), normal UAE less than 30 mg/24 h; group 2 (n = 27), microalbuminuria (UAE 30-300 mg/24 h); and group 3 (n = 29), clinical diabetic nephropathy (UAE greater than 300 mg/24 h). We used 23 healthy subjects as controls. Fractional clearance of RBP (FC-RBP) and its 24-h urinary excretion rate (URBP) were higher in each diabetic group than in healthy subjects, the highest values being found in group 3. Groups 1 and 2 did not differ in URBP and FC-RBP. There was a correlation between FC-RBP and haemoglobin A1c in both the total diabetic cohort (P less than 0.001) and in diabetic patients in groups 1 and 2 with a glomerular filtration rate of more than 90 ml/min (P less than 0.05). No correlation was found between FC-RBP and UAE and/or duration of diabetes in any of the diabetic groups. We conclude that the increased urinary excretion of RBP, indicating proximal tubular dysfunction, is already present in normoalbuminuric insulin-dependent diabetic patients and correlates with metabolic control. Further deterioration in proximal tubular function was not observed in microalbuminuric patients, but is a late event in clinical diabetic nephropathy.

To compare the efficacy of pentoxifylline and captopril on urinary albumin excretion (UAE) rate in non-hypertensive diabetic patients with microalbuminuria. 450 subjects were screened; of these 130 eligible, non-hypertensive, type 2 diabetic subjects were enrolled and randomly allocated to receive either pentoxifylline 400 mg t.i.d. (n = 65) or captopril 25 mg t.i.d. (n = 65) for six months in a randomized equivalent trial design study. Patients were eligible to participate if they had microalbuminuria, defined by UAE rate of 20-200 microg/min, and systolic/diastolic blood pressure lower than 140/85 mmHg. Diagnosis of high blood pressure and renal failure were exclusion criteria. In addition, subjects receiving ACE inhibitors or pentoxifylline were not included. Both treatments were well tolerated, without serious adverse events; nonetheless, one subject (1.6%) in the group with pentoxifylline had severe headache, and three (4.7%) subjects in the group with captopril had intense dry cough and nasal congestion that required stopping pentoxifylline and captopril. In addition, slight headache and mild dry cough that did not require specific treatment or interruption of medication were present in two (3.2%) and five (7.8%) subjects treated with pentoxifylline and captopril. Four subjects dropped-out (one in the pentoxifylline group and three in the captopril group). Blood pressure and fasting glucose levels were similar between the two groups throughout the study. The UAE rate decreased from the first month of treatment in the subjects of both groups, a reduction that was sustained in the following months. At the end of the study, the average UAE rate in the subjects of both groups was lower than 25 microg/min. Pentoxifylline showed to be an effective alternative to ACE inhibitors in reducing UAE in non-hypertensive diabetic patients with microalbuminuria.

An elevated urinary albumin excretion rate (UAER) is associated with an increased risk of cardiovascular mortality, but the pathophysiological mechanism underlying this association is poorly understood. To investigate the role of endothelial dysfunction, leukocyte adhesion, and low-grade inflammation (1) in the development of elevated UAER (study I) and (2) in linking elevated UAER with risk of cardiovascular mortality (study II), we performed a prospective study in an age-, sex-, and glucose tolerance- stratified sample of a population-based cohort aged 50 to 75 years. High levels of von Willebrand factor, soluble vascular cell adhesion molecule-1 (sVCAM-1), and C-reactive protein (CRP) were used as markers of endothelial dysfunction, leukocyte adhesion, and low-grade inflammation, respectively. For study I, subjects who had normal UAER at baseline (n=316 subjects, 66 with type 2 diabetes) were reexamined after a mean follow-up of 6.1 years. The development of elevated UAER was defined as a mean albumin-to-creatinine ratio >2.0 mg/mmol at follow-up. Age-, sex-, and glucose tolerance- adjusted logistic regression analyses showed the development of elevated UAER to be significantly associated with levels of sVCAM-1 and CRP (odds ratio 1.14 [95% CI 1.02 to 1.27] per 10% increase of sVCAM-1 and odds ratio 1.17 [95% CI 1.04 to 1.32] per 50% increase of CRP). The results were not materially different after additional adjustment for hypertension, body mass index, cardiovascular disease, and creatinine clearance or stratification by the presence of diabetes. For study II, the vital status of all subjects (n= 575) was determined after a mean follow-up of 6.6 years. Eighty-one of 575 subjects died (30 died of cardiovascular disease). The presence of elevated UAER at baseline was associated with a 4.1-fold (1.94 to 8.73) increased risk of cardiovascular death after adjustment for age, sex, and glucose tolerance status. Adjustment for levels of von Willebrand factor, sVCAM-1, or CRP did not materially affect the results, nor did additional adjustment for the presence of hypertension, retinopathy, and cardiovascular disease and for levels of homocysteine, triglycerides, and high density lipoprotein cholesterol. Leukocyte adhesion (sVCAM-1) and low-grade inflammation (CRP) are determinants of the development of elevated UAER. However, these determinants do not explain the association between elevated UAER and cardiovascular mortality.

Patients with Type 1 (insulin-dependent) diabetes without proteinuria were studied to define those patients who will later develop persistent proteinuria (more than 0.5 g protein/24 h). Two investigations were performed; 71 patients were studied longitudinally for 6 years and another 227 patients were studied cross-sectionally. All were less than 50 years of age and had developed diabetes before the age of 40 years. At entry into the study they had no proteinuria (Albustix method), had normal blood pressure and urinary albumin excretion rates less than 200 micrograms/min (normal less than or equal to 20 micrograms/min). The best predictor of persistent proteinuria or an albumin excretion rate greater than 200 micrograms/min was the initial urinary albumin excretion rate. During the longitudinal study, seven patients with an urinary albumin excretion rate of more than 70 micrograms/min at the start of the study developed persistent proteinuria or an albumin excretion rate greater than 200 micrograms/min. In contrast, only three out of the remaining 64 patients with urinary albumin excretion rate less than or equal to 70 micrograms/min developed urinary albumin excretion rate greater than 200 micrograms/min. Patients with an urinary albumin excretion rate greater than 70 micrograms/min are thus at risk of developing diabetic nephropathy. We designate this stage of renal involvement incipient nephropathy. Patients with incipient nephropathy were further characterized in the cross-sectional study. Compared with normoalbuminuric patients, patients with incipient nephropathy had increased systolic and diastolic blood pressure, but normal serum creatinine. The glomerular filtration rate was higher than normal in patients with incipient nephropathy though not different from that of normoalbuminuric patients.

The aim of this study was to examine the impact of parental type 2 diabetes on the autonomic nervous system and to determine whether autonomic neuropathy is present and associated with changes in 24-h ambulatory blood pressure (AMBP) and urinary albumin excretion rate (UAER) in nondiabetic subjects with parental type 2 diabetes. We examined 223 nondiabetic offspring of type 2 diabetic subjects and a control group of 258 offspring of nondiabetic subjects. The autonomic nervous system was assessed by three cardiovascular reflex tests, 24-h AMBP was measured with an oscillometric recorder (90207; Spacelabs, Redmond, WA), and UAER was determined through three overnight urine samples. The subjects with parental type 2 diabetes had significantly lower heart rate variation in all three bedside tests (P < 0.01) than subjects without parental diabetes. The prevalence of autonomic neuropathy in the nondiabetic offspring with parental type 2 diabetes (6.7%) was significantly (P < 0.01) higher compared with the control group (1.6%). Autonomic neuropathy was associated with a higher fasting insulin level (P < 0.05), higher UAER (P < 0.001), higher 24-h mean AMBP (P < 0.01), and reduced diurnal blood pressure variation (P < 0.001) after adjustment for age, sex, and BMI. In conclusion, parental type 2 diabetes was found to be associated with alterations in the autonomic nervous system in nondiabetic subjects. The presence of autonomic neuropathy in subjects with parental type 2 diabetes was associated with higher UAER, fasting insulin level, and 24-h AMBP and a reduced diurnal blood pressure variation. This study indicates that parental type 2 diabetes has an impact on the cardiac autonomic function in nondiabetic subjects.

To evaluate kidney function 7 years after the end of treatment with cyclosporine A (CsA) (initial dosage of 9.3 tapered off to 7.0 mg.kg-1.day-1) in young patients (mean age 20 years) with newly diagnosed type 1 diabetes participating in a randomized, double-blind, placebo-controlled CsA trial. In this study, 21 patients received CsA for 12.5 +/- 4.0 months (mean +/- SD) and 19 patients received placebo for 14.4 +/- 3.8 months. The two groups were similar with regard to mean arterial blood pressure (BP), urinary albumin excretion rate (UAER), serum creatinine, and estimated glomerular filtration rate (GFR [Cockcroft and Gault]) at initiation of CsA treatment (baseline). HbA1c (mean +/- SEM) during 7 years of follow-up was also the same: 8.7 +/- 0.4 vs. 8.3 +/- 0.4% in the CsA and placebo groups, respectively. During the 7 years after cessation of study medication, two CsA group patients and one control patient were lost to follow-up. One placebo-treated patient developed IgA nephropathy (biopsy proven) and was excluded. Four CsA-treated patients developed persistently elevated UAER > 30 mg/24 h (n = 3 with microalbuminuria), whereas all the 17 placebo-treated patients had normal UAER (< 30 mg/24 h) after 7 years of follow-up. At the end of follow-up, the CsA group had a more pronounced rise in UAER: 2.5-fold (95% CI 1.4-4.5) higher than baseline value vs. 1.1-fold (0.7-1.7) in the placebo-treated group (P < 0.05). Estimated GFR (ml.min-1.1.73 m-2) declined from baseline to end of follow-up (1994) by 6.3 +/- 6.0 in the former CsA group, whereas it rose by 7.4 +/- 5.0 in the placebo group (P = 0.05). In 1994, 24-h blood pressure was nearly the same: 131/77 +/- 4/2 vs. 127/75 +/- 2/2 mmHg (NS) in the CsA and placebo groups, respectively. Five randomly selected CsA-treated patients had a kidney biopsy performed shortly after the CsA treatment was stopped. Interstitial fibrosis/tubular atrophy and/or arteriolopathy were present in two subjects who both subsequently developed persistent microalbuminuria. The results of our 7-year follow-up study suggested that short-lasting CsA treatment in young, newly diagnosed type 1 diabetic patients accelerated the rate of progression in UAER and tended to induce a loss in kidney function. Longer term follow-up is mandatory to clarify whether CsA-treated patients are at increased risk of developing clinical nephropathy.