Factors associated with progression to macroalbuminuria in microalbuminuric Type 1 diabetic patients: the EURODIAB Prospective Complications Study

Aims/hypothesis Type 1 diabetic patients who develop microalbuminuria are clearly disadvantaged in terms of their risk of morbidity and mortality from renal and cardiovascular diseases. It is therefore important to identify potential factors that can predict progression to macroalbuminuria.Methods This is a 7-year follow-up study of 352 microalbuminuric Type 1 diabetic patients from 31 European centres. Risk factors at baseline were compared in patients who progressed to macroalbuminuria and in patients who remained microalbuminuric or reverted to normoalbuminuria. Risk factors and albumin excretion rate (AER) were measured centrally.Results Over 7.3 years, 13.9% of the microalbuminuric patients progressed to macroalbuminuria, 35.5% remained microalbuminuric and 50.6% reverted to normoalbuminuria. Independent baseline risk factors for progression to macroalbuminuria were HbA₁c (7.9% vs 6.8%, p=0.004), AER (64.4 vs 44.9 µg/min, p=0.0001) and—after adjusting for diabetes duration, HbA₁c and AER—body weight (72 vs 67 kg, p=0.05). Independent factors associated with regression to normoalbuminuria were diabetes duration (15 vs 18 years, p=0.004), AER (37.2 vs 44.9 µg/min, p=0.0001) and—after adjusting for diabetes duration, HbA₁c and AER—waist-to-hip ratio (0.83 vs 0.86, p=0.05) and incidence of peripheral neuropathy at baseline (24% vs 38%, p=0.001). Blood pressure and smoking did not emerge as risk factors at baseline for the outcome of microalbuminuria.Conclusions/interpretation A significant fraction of microalbuminuric Type 1 diabetic patients will progress to overt proteinuria. Patients with higher AER values, sub-optimal metabolic control, excess body fat and peripheral neuropathy may carry a particularly high risk of clinical nephropathy requiring aggressive therapeutic intervention.Abbreviations AER albumin excretion rate - CVD cardiovascular disease - Gamma GT gamma-glutamyltransferase - OR odds ratio - PCS Prospective Complications Study - RR relative risk - SERR standardised estimates of relative risk - SREs standardised regression effects - vWF von Willebrand Factor     

Prevalence of micro- and macroalbuminuria,arterial hypertension,retinopathy and large vessel disease in European Type 2 (non-insulin-dependent) diabetic patients

Summary The prevalence of micro- and macroalbuminuria was determined in Type 2 (non-insulin-dependent) diabetic patients, less than 76 years of age, attending a diabetic clinic during 1987. All eligible patients (n=557) were asked to collect a 24-h urine sample for quantitative albumin analysis. Urine collections were obtained in 296 males and 253 females (96%). Normoalbuminuria were defined as urinary albumin excretion30 mg/24 h (n=323), microalbuminuria as 31–299 mg/24 h (n=151), and macroalbuminuria as 300 mg/ 24 h (n=75). The prevalence of macroalbuminuria was significantly higher in males (20%) than in females (6%), while the prevalence of microalbuminuria was almost identical in males (26%) and females (29%). The prevalence of arterial hypertension increased with increased albuminuria, being 48%, 68%, and 85% in patients with normoalbuminuria, microalbuminuria, and macroalbuminuria respectively. Prevalence of proliferative retinopathy rose with increasing albuminuria, being 2%, 5% and 12% in patients with normoalbuminuria, microalbuminuria, and macroalbuminuria respectively. Prevalence of coronary heart disease, based on Minnesota coded electrocardiograms, was more frequent in patients with macroalbuminuria (46%) compared to patients with microalbuminuria (26%) and patients with normoalbuminuria (22%). Foot ulcers were more frequent in micro- and macroalbuminuric patients, being 13% and 25%, respectively, compared to 5% in patients with normoalbuminuria. This cross-sectional study has revealed a high prevalence of microalbuminuria (27%) and macroalbuminuria (14%) in Type 2 diabetic patients. Patients with raised urinary albumin excretion are characterized by obesity, elevated haemoglobin A_lc, increased frequency of arterial hypertension, proliferative retinopathy, coronary heart disease and foot ulcers. Thus, these findings suggest that urinary excretion of albumin should be monitored routinely in patients with Type 2 diabetes.     

Regression of microalbuminuria in type 1 diabetic patients: results of a sequential intervention with improved metabolic control and ACE inhibitors

Abstract The objective was to evaluate the effect of improved metabolic control and ACE inhibition used sequentially in the treatment of type 1 diabetic patients with microalbuminuria. We studied 44 consecutive type 1 diabetic patients with microalbuminuria not previously treated with ACE inhibitors. Improved metabolic control (optimisation period) was attempted for 6–12 months and patients with persistent microalbuminuria were subsequently treated with ACE inhibitors. Stepwise logistic regression analysis included the variables age, age at diabetes onset, duration of diabetes, HbA1c, initial albumin excretion rate (AER) and mean blood pressure as predictors of final AER. Thirty per cent of patients regressed to normoalbuminuria after the optimisation period, and 58% of them maintained normal AER 4.5±1.3 years later (3–7 years). Patients achieving normoalbuminuria had lower baseline AER (53±22 vs. 94±63 mg/24 h, p=0.012). The initial AER level was the only factor associated with final AER (r=0.58, p=0.021). Thirty patients with persistent microalbuminuria were treated with ACE inhibitors for two years, 35.5% of whom regressed to normal AER. Patients achieving normoalbuminuria after ACE inhibitor treatment had lower baseline AER (55±24 vs. 132±75 mg/24 h, p=0.03). The initial AER was the sole predictor of final AER (r=0.51, p<0.013). Overall, the sequential use of improved metabolic control and ACE inhibitor therapy resulted in long-term normalisation of AER in 47.4% of patients. The sequential implementation of improved metabolic control and ACE inhibitor therapy had a long-term beneficial effect in type 1 diabetic patients with microalbuminuria. We propose that type 1 diabetic patients with microalbuminuria could benefit from a period of metabolic improvement before the initiation of ACE inhibitor therapy.     

Transcapillary escape rate and relative metabolic clearance of glycated and non-glycated albumin in Type 1 (insulin-dependent) diabetes mellitus

Summary The transcapillary escape rate and relative plasma disappearance of glycated and non-glycated albumin were measured in 25 male Type 1 (insulin-dependent) diabetic patients using a double tracer technique. The patients were divided into three groups on the basis of their urinary albumin excretion: group 1, normal albumin excretion (<30 mg/24h) (n=8); group 2, microalbuminuria (30–300 mg/24 h) (n=9); and group 3, clinical nephropathy (>300 mg/24 h) (n=8). Six male age-matched non-diabetic persons served as control subjects. The transcapillary escape rate of glycated albumin was similar in group 1 and control subjects (4.7±2.1 versus 5.1±1.7%), but significantly increased in group2 (7.0±1.7%,p<0.05) and in group 3 (7.9±3.1%,p<0.05). The transcapillary escape rate of glycated albumin was slightly lower than that of non-glycated albumin in all groups, but significant only in normal control subjects. No difference in the catabolic rate of glycated and non-glycated albumin was found. We conclude that the in vivo effects of glycation on the clearance and transcapillary passage of albumin are small and not likely to play any significant role in the development of late diabetic microvascular complications.     

Magnetic resonance imaging of the kidney in Type 1 (insulin-dependent) diabetes mellitus

Summary Reductions in the physiological cortical to medullary signal intensity ratio are found in magnetic resonance scans of the kidney in non-diabetic glomerular disease. Whether this abnormality can also characterise patients with Type 1 (insulin-dependent) diabetes mellitus and nephropathy is not known. We measured the cortical to medullary signal intensity ratio in magnetic resonance images of the kidney in 34 patients with Type 1 diabetes (ten with either clinical proteinuria or raised serum creatinine or both, nine with microalbuminuria, seven with normal urinary albumin excretion and long duration of diabetes and eight with Type 1 diabetes of short duration). The cortical to medullary signal intensity ratio showed a trend to cluster at lower values in the normoalbuminuric patients with normal serum creatinine rather than in the nine healthy individuals, independent of Type 1 diabetes duration (1.47 ± 0.06 and 1.41 ± 0.13 vs 1.63 ± 0.16; five groups-Scheffé F-test p = 0.05–0.1). Among the Type 1 diabetic patients, significant reductions in the cortical to medullary signal intensity ratio characterised overt nephropathy (1.19 ± 0.15, p <0.05 vs all groups), but not microalbuminuria (1.47 ± 0.13, p = NS), concomitantly with low glomerular filtration rate and elevated fractional excretion of uric acid, but independent of glycaemic control. The determinants of the renal cortical to medullary signal intensity ratio in Type 1 diabetes are uncertain. Reductions in the cortical to medullary signal intensity ratio may be a late finding in diabetic nephropathy, and parallel the accompanying impairment in kidney haemodynamics. Magnetic resonance imaging of the kidney may not offer clues in the early diagnosis of diabetic nephropathy.     

Serum amyloid A and C-reactive protein levels may predict microalbuminuria and macroalbuminuria in newly diagnosed type 1 diabetic patients

BackgroundIn this study we evaluated the association of baseline levels of six different candidate proteins for the development of microalbuminuria and macroalbuminuria in type 1 diabetic patients, who were followed for approximately 30 years. Two of the proteins are markers of inflammation: serum amyloid A (SAA) and C-reactive protein (CRP), three are involved in lipid metabolism: apolipoprotein A1, apolipoprotein E and adiponectin and the last protein, fibronectin, is related to structural changes.MethodsA nested case control study population of 60 patients from an inception cohort of type 1 diabetic patients where 20 developed microalbuminuria followed by macroalbuminuria and 40 stayed normoalbuminuric during approximately 30 years of follow-up time was used to evaluate baseline levels of the six candidate biomarkers. The proteins were quantified by multiplexed immunoassays.ResultsLog SAA levels were borderline predictor of microalbuminuria, HR 2.31 (1–5.4) p = 0.053 in a univariate Cox regression model and predicted the development of macroalbuminuria HR 2.432 (1–6) p = 0.049, also univariate. When adjusting for covariates, log SAA predicted the development of microalbuminuria with an HR 4.131 (1.1–15) p = 0.03. Log CRP predicted the development of microalbuminuria, HR 2.928 (1.4–6.1) p = 0.004, and macroalbuminuria, HR 2.785 (1.3–5.8) p = 0.007 in univariate models. When adjusting for covariates, log CRP predicted the development of microalbuminuria with an HR 5.882 (1.7–20.9) p = 0.006 and macroalbuminuria with an HR 3.233 (1.1–9.8) p = 0.038. Apolipoprotein A1, apolipoprotein E, fibronectin and adiponectin were not associated with development of elevated albumin excretion rate.ConclusionsSAA and CRP baseline levels predicted development of micro- and macroalbuminuria during 30 years of follow up, supporting the theory that inflammation is involved in the progression of diabetic nephropathy. Further studies are needed to fully establish the two proteins’ potential as additional biomarkers for the development of diabetic nephropathy.     

Increased levels of mannan-binding lectin in type 1 diabetic patients with incipient and overt nephropathy

Aims/hypothesis Diabetic nephropathy is associated with insulin resistance, and low-grade inflammation and activation of the complement system may contribute to this cascade. Mannan-binding lectin (MBL) activates the complement system, and elevated MBL concentrations have been observed in normoalbuminuric type 1 diabetic patients. The aim of this study was to assess whether MBL is associated with diabetic nephropathy in type 1 diabetes, and whether there is an association between MBL and low-grade inflammatory markers or insulin resistance.Methods A total of 191 type 1 diabetic patients from the Finnish Diabetic Nephropathy Study were divided into three groups based upon their AER. Patients with normal AER (n=67) did not take antihypertensive medication, while patients with microalbuminuria (n=62) or macroalbuminuria (n=62) were all treated with an ACE inhibitor. As a measure of insulin sensitivity we used estimated glucose disposal rate. MBL was measured by an immunofluorometric assay, C-reactive protein by a radioimmunoassay and IL-6 by high-sensitivity enzyme immunoassay.Results Patients with normal AER (median [interquartile range]: 1,154 g/l [180–2,202 g/l]) had lower levels of MBL than patients with microalbuminuria (1,713 g/l [724–2,760 g/l]; p=0.029) or macroalbuminuria (1,648 g/l [568–3,394 g/l]; p=0.019). There was a significant correlation between MBL and estimated glucose disposal rate, but not between MBL and C-reactive protein or IL-6 levels in univariate analysis. However, in a multiple regression analysis, HbA1c was the single variable independently associated with MBL (±SEM: 0.26±0.08; p=0.003).Conclusions/interpretation MBL concentrations are increased in type 1 diabetic patients with diabetic nephropathy. MBL was not associated with low-grade inflammatory markers.     

Prevalence of hypertension in Type 1 (insulin-dependent) diabetes mellitus

Summary The prevalence of hypertension in a representative sample (n=10202) of the Danish general population aged 16–59 years was assessed to 4.4% based on three blood pressure readings. In Type 1 (insulin-dependent) diabetic patients of similar age (n=1703) the prevalence was determined in a similar way to 14.7% (p<0.00001). The excess prevalence in Type 1 diabetic patients was due to hypertension in patients with incipient and clinical nephropathy as the prevalence of hypertension among diabetic patients with normal urinary albumin excretion (essential hypertension) was 3.9%, similar to that observed in the general population. The patients with Type 1 diabetes and essential hypertension had higher systolic (146±19 vs 133±18 mmHg, p<0.00001) and diastolic blood pressure (87±12 vs 79±7mmHg, p<0.00001), but less changes in the eye background than patients with incipient nephropathy (urinary albumin excretion 30–300 mg/24 h) (p<0.03), indicating that the two groups were also different with respect to other microangiopathic lesions. Patients with essential hypertension were defined as having a normal urinary albumin excretion before and during antihypertensive treatment (if any). They were followed-up for a 58 (6–234) month period. We confirmed that hypertension is more common among Type 1 diabetic patients than in the general population and found the prevalence of essential hypertension similar in Type 1 diabetic patients to the non-diabetic population. This supports our hypothesis that hypertension is very unlikely to be the cause of diabetic nephropathy.     

Effect of sodium intake on blood pressure and albuminuria in Type 2 diabetic patients: the role of insulin resistance

Aims/hypothesis This study was done to measure the effect of Na⁺ intake on blood pressure and albuminuria, in relation with insulin sensitivity and kidney haemodynamics, in Type 2 diabetic patients with and without microalbuminuria.Methods Type 2 diabetic patients, 20 with microalbuminuria, 21 without, spent two consecutive 7-day periods, one on a high (250 mmol), the other on a low-Na⁺ (20 mmol) diet. Body weight, 24-h blood pressure and albuminuria were measured at the end of each period. At the end of high-Na⁺ diet insulin sensitivity (euglycaemic insulin clamp; 2 mU·kg^–1·min^–1) and kidney haemodynamics were measured in nine patients from each group.Results Switching from low to high-Na⁺ diet resulted in an increase in blood pressure (7.4±4.7 mmHg; p<0.001), body weight (1.9±0.4 kg; p<0.05) and albuminuria [from 80 (31–183) µg/min to 101 (27–965) µg/min; p<0.01) in patients with microalbuminuria. No changes occurred in patients without microalbuminuria. Patients with microalbuminuria also had greater intraglomerular pressure (44±1 mmHg vs 36±1; p<0.001), calculated from glomerular filtration rate, renal plasma flow, plasma protein concentration and the relationship between pressure and natriuresis. In these patients insulin sensitivity was lower (5.16±49 vs 7.36±0.63 mg·kg^–1·min^–1; p=0.007). Urinary albumin excretion (r=0.40; p=0.009) and insulin sensitivity (r=–0.59; p=0.01) were correlated with intraglomerular pressure.Conclusion/interpretation High salt intake increases blood pressure and albuminuria in Type 2 diabetic patients with microalbuminuria. These responses are associated with insulin resistance and increased glomerular pressure. Insulin resistance could contribute to greater salt sensitivity, increased glomerular pressure and albuminuria.Abbreviations GFR Glomerular filtration rate - PGC intraglomerular pressure - AER albumin excretion rate     

Glomerular Charge Selectivity in Type 1 (Insulin-dependent) Diabetes Mellitus

Glomerular charge selectivity was assessed using the ratio of the clearance of pancreatic isoamylase to the clearance of the more anionic salivary isoamylase (C_PAm/C_SAm) in 12 normal subjects and 50 patients with Type 1 diabetes: 13 with normal albumin excretion and short duration of diabetes (<5 years), 15 with normal albumin excretion and long duration of diabetes (>15 years), 13 with microalbuminuria, and 9 with clinical nephropathy. None had serum creatinine >200 μmol I^?1. There were no significant differences in C_PAm/C_SAm between the normal subjects and the two groups of normoalbuminuric patients with Type 1 diabetes. C_PAm/C_SAm was significantly lower in diabetic patients with microalbuminuria or clinical nephropathy than in normoalbuminuric patients with Type 1 diabetes. When the 37 patients with normoalbuminuria and long-standing diabetes, microalbuminuria, and nephropathy were considered together, there was a significant negative correlation between C_PAm/C_SAm and albumin excretion rate (r_s = 0.71, p < 0.001). Progressive impairment of glomerular charge selectivity at the molecular size of amylase (molecular mass 56 kDa) accompanies increasing albuminuria in Type 1 diabetes.     

Association of monocyte chemoattractant protein-1 with renal tubular damage in diabetic nephropathy

Monocyte chemoattractant protein-1 (MCP-1), is a chemokine that mediates renal interstitial inflammation, tubular atrophy, and interstitial fibrosis by recruiting monocytes/macrophages into renal tubulointerstitium. Recent studies have demonstrated that protein overload in renal tubular cells up-regulates MCP-1 gene and its protein expression. Therefore, we hypothesized that increased expression of MCP-1 in renal tubuli, probably triggered by an increase in the leakage of plasma protein from glomerular capillary to tubular fluid, may contribute to renal tubular damage and accelerate the progression of diabetic nephropathy. To test this hypothesis, we examined urinary excretion levels of MCP-1 and N-acetylglucosaminidase (NAG), a sensitive marker of renal tubular damage, in Japanese Type II diabetic patients with normoalbuminuria (n=29), microalbuminuria (n=25), and macroalbuminuria (n=18). The median urinary excretion level of MCP-1 in patients with macroalbuminuria (394.4 ng/g creatinine) was significantly elevated compared to the levels in patients with normoalbuminuria and microalbuminuria (159.6 and 193.9 ng/g creatinine, respectively). Furthermore, the urinary MCP-1 excretion level was positively correlated with urinary excretion levels of albumin (r=.816, P<.001) and NAG (r=.569, P<.001) in all subjects. These results suggest that MCP-1 is produced in renal tubular cells and released into urine in proportion to the degree of proteinuria (albuminuria), and that increased MCP-1 expression in renal tubuli contributes to renal tubular damage. Therefore, we conclude that heavy proteinuria itself may accelerate the progression of diabetic nephropathy by increasing the MCP-1 expression in renal tubuli.     

Polymorphism of the solute carrier family 12 (sodium/chloride transporters) member 3, SLC12A3, gene at exon 23 (+78G/A: Arg913Gln) is associated with elevation of urinary albumin excretion in Japanese patients with type 2 diabetes: a 10-year longitudinal study

Aims/hypothesis We have shown previously that the SLC12A3 +78G/A polymorphism in exon 23 (Arg913Gln) was a new candidate for conferring susceptibility to diabetic nephropathy. The aim of this study was to confirm the effect of this polymorphism on the elevation of urinary albumin excretion in type 2 diabetic patients.Methods We retrospectively studied 264 Japanese patients with type 2 diabetes over a ten-year period. The subjects were classified into two groups: (1) persistent normoalbuminuria or microalbuminuria, or improvement from microalbuminuria to normoalbuminuria (group N); and (2) progression from normoalbuminuria to microalbuminuria or overt proteinuria, or progression from microalbuminuria to overt proteinuria (group P). They were assessed for association with the +78G/A polymorphism.Results The frequency of the +78A allele was significantly higher in group N than in group P (10% vs 1%, p=0.021). By logistic regression analysis and discriminant analysis, the substituted allele was shown to be an independent factor correlating negatively to the elevation of albumin excretion (p=0.043 and 0.022, respectively).Conclusions/interpretation The SLC12A3 +78A(+) genotype may have a protective effect against the development and/or progression of diabetic nephropathy in Japanese type 2 diabetic patients.     

Sustained reduction of proteinuria in Type 2 (non-insulin-dependent) diabetes following diet-induced reduction of hyperglycaemia

Summary To determine whether sustained control of hyperglycaemia in Type 2 (non-insulin-dependent) diabetic patients would diminish proteinuria, the effect of hypocaloric diet therapy (500 kcal/day) on proteinuria was assessed in obese, Type 2 diabetic patients (n=24) and compared with results obtained for obese subjects with normal glucose tolerance (n=7) and impaired glucose tolerance (n=6). Diet therapy of similar mean duration resulted in similar percentage weight loss (mean percentage of original weight ±SEM) in diabetic (13.6±1.6%), glucose intolerant (16.4±3.3%) and obese nondiabetic (11.0±1.0%) subjects. Following therapy, plasma glucose concentrations 2h after an oral glucose load declined in the diabetic (18.34±0.81 to 10.67±0.50 mmol/1, mean ±SEM; p<0.001) and in the glucose intolerant subjects (10.2±0.3 to 7.3±0.4 mmol/l, p<0.01) while remaining unchanged in the obese non-diabetic subjects (7.09±0.23 to 6.77±0.32 mmol/l, NS). Concentrations of total protein of plasma origin and albumin in 24-h urine collections were quantified by a sensitive immunonephelometric assay using specific antisera. Initially, 24-h excretion of total protein and albumin were elevated in the diabetic [mg protein/24 h; (median±95% confidence limits): 63 (42–138), p<0.05; albumin: 26 (14–56), p<0.05] and glucose intolerant subjects [protein:52 (13–92), NS; albumin: 24 (3–61), NS] compared with the non-diabetic subjects [protein: 20 (5–38); albumin: 6.2 (3.5–9.5)]. Following diet therapy, both total protein and albumin excretion were reduced significantly in diabetic subjects (p<0.001) and similar decreases were observed in clearance rates of protein and albumin. Initially, 11 out of the 24 diabetic subjects had 24-h albumin excretion in the subclinical range (>30, < 500 mg/24h), whereas following diet therapy, only three out of the 11 had subclinical albuminuria. For all subjects, the decrease in albumin excretion following diet therapy was significantly correlated with the initial albumin excretion (r=0.63, p<0.0001). In one diabetic subject, whose glucose tolerance and albumin excretion were sequentially monitored for 14 months, the decreases in glycaemia and proteinuria observed in the first month of therapy persisted after discontinuation of diet therapy. Thus, metabolic control of Type2 diabetes by a hypocaloric diet produced significant sustained reductions in proteinuria. The question remains whether or not this retards the development of clinical nephropathy or end stage renal disease.     

Increased transcapillary escape rate of albumin in Type 1 (insulin-dependent) diabetic patients with microalbuminuria

Summary The transcapillary escape rate, intravascular mass and outflux of albumin were measured in 75 Type 1 (insulin-dependent) diabetic patients. The groups were defined as: group 1: normal urinary albumin excretion, <30 mg/24 h (n=21); group 2: microalbuminuria, 30–300 mg/24 h (n=36); group 3: diabeticnephropathy, <300 mg/24 h (n=18). Fifteen sex- and age-matched non-diabetic persons served as control subjects. The diabetes duration was: group 1: 20±9 years, group 2: 17±5 years, group 3: 19±7 years. The transcapillary escape rate of albumin was similar in controls and group 1 (5.0±1.8 versus 5.2±1.5%) and was significantly higher in the microalbuminuric group 2 and group 3 (8.1±2.2 versus 8.1±2.3 %). The differences were not explained by differences in metabolic control or blood pressure at the time of investigation. The outflux of albumin was also higher in group 2 than in group 1 and controls (7.1 ± 2.0 versus 5.3±1.5 and 5.1±2.0 g/h × 1.73 m²). It was indistinguishable from controls in group 3 (5.8±1.5 g/h × 1.73 m²) because of a reduced intravascular mass of albumin (p<0.01) in group 3. In conclusion, a universal vascular leakage of albumin is an early event in the development of diabetic nephropathy, with the leakage of albumin being fully developed in the microalbuminuric patient. In contrast, long-term diabetic patients with normal urinary albumin excretion have a normal transcapillary escape rate of albumin.     

Plasma disappearance of glycated and non-glycated albumin in Type 1 (insulin-dependent) diabetes mellitus: evidence for charge dependent alterations of the plasma to lymph pathway

Summary The fractional plasma escape rates of glycated and non-glycated albumin have earlier been measured in groups of Type 1 (insulin-dependent) diabetic patients and control subjects. The escape of non-glycated albumin was similar in control subjects and normoalbuminuric patients, but elevated in patients with micro or macroalbuminuria. In all groups the escape rate of glycated albumin was lower than that of non-glycated albumin. Glycation increases the anionic charge of albumin. To assay for charge-dependent alterations of transport a selectivity index (non-glycated albumin/glycated albumin transport ratio) was determined from the disappearance data. The index was high in control subjects (1.021±0.0057 (SEM)). This reflects a mean difference between the two escape rates of 2.1% per hour (for comparison the mean of the fractional escape rate of non-glycated albumin of the normal control subjects was 4.7% per hour). The index was numerically even higher in normoalbuminuric patients (1.031±0.0047 (SEM)), but reached significantly lower levels in patients with microalbuminuria (1.013±0.0030 (SEM), p<0.02). Patients with clinical nephropathy had very low levels indicating loss of selectivity (1.002±0.0068 (SEM), p<0.001). This pattern accords well with measurements of renal clearance selectivity indices, suggesting a general, progressive deterioration of anionic perivascular barrier components in diabetic microangiopathy. The structural target for these changes is likely to be the glycosaminoglycans of the glomerular basal membrane and the interstitial matrix.     

Apolipoprotein(a) and cardiovascular disease in Type 2 (non-insulin-dependent) diabetic patients with and without diabetic nephropathy

Summary The relative mortality from cardiovascular disease is on average increased five-fold in Type 2 (non-insulin-dependent) diabetic patients with diabetic nephropathy compared to non-diabetic subjects. We assessed the possible contribution of dyslipidaemia in general and elevated serum apolipoprotein(a) (apo(a)) in particular. Type 2 diabetic patients with normo-, micro- and macroalbuminuria were compared with healthy subjects. Each group consisted of 37 subjects matched for age, sex and diabetes duration. Serum creatinine in the nephropathy group was 105 (54–740) mol/l. The prevalence of ischaemic heart disease (resting ECG, Minnesota, Rating Scale) was 57, 35, 19 and 2% in macro-, micro- and normoalbuminuric diabetic patients and healthy subjects, respectively. The prevalence of ischaemic heart disease was higher in all diabetic groups as compared to healthy subjects (p<0.05), and higher in macroalbuminuric as compared to normoalbuminuric diabetic patients (p<0.01). There was no significant difference between apo(a) in the four groups: 161 (10–1370), 191 (10–2080), 147 (10–942), 102 (10–1440) U/l (median (range)) in macro-, micro- and normoalbuminuric groups and healthy subjects. Serum total-cholesterol, HDL-cholesterol and LDL-cholesterol were not significantly different when comparing healthy subjects and each diabetic group. Apolipoprotein A-I was lower (p<0.05) in all diabetic groups as compared to healthy subjects (nephropathy vs healthy subjects): 1.50±0.25 vs 1.69±0.32 g/l (mean ± SD). Triglyceride was higher (p<0.05) in patients with nephropathy and microalbuminuria as compared to healthy subjects (nephropathy vs healthy subjects): 2.01 (0.66–14.7) vs 1.09 (0.41–2.75) mmol/l (median (range)). Apolipoprotein B was higher (p<0.02) in patients with nephropathy as compared to the other three groups (nephropathy vs healthy subjects): 1.54±0.47 vs 1.33±0.30 g/l. In conclusion, our case-control study has confirmed that Type 2 diabetic patients with increased urinary albumin excretion frequently suffer from dyslipidaemia and cardiovascular disease. However, our study revealed no significant elevation in serum concentration of apo(a) in patients with diabetic nephropathy, but numbers were small.     

Physiological inhibitors of blood coagulation and prothrombin fragment F 1+2 in type 2 diabetic patients with normoalbuminuria and incipient nephropathy

Microalbuminuria and haemostasis derangements have been considered as independent risk factors for cardiovascular death in type 2 (non-insulin-dependent) diabetic patients. Few studies have assessed coagulation inhibitors in type 2 diabetic patients with normoalbuminuria and microalbuminuria. Therefore, 32 type 2 diabetic patients with normoalbuminuria (albumin excretion rate, AER<20 mg/min, mean 7±1) and 28 type 2 diabetic patients with microalbuminuria (AER 20–200 mg/min, mean 84±11) were studied. The patients were matched for age, sex, disease duration and treatment, body mass index (BMI), blood pressure and glycohaemoglobin. Protein C and S activity, antithrombin III, thrombomodulin and prothrombin fragments 1+2 (F 1+2) were assessed together with fibrinogen, triglycerides, total and high density lipoprotein (HDL)-cholesterol concentrations. Fibrinogen, total and low density lipoprotein (LDL) concentrations were similar in the two groups, while a significant difference was observed for triglycerides (normoalbuminuric group: 128±10 mg/dl, microalbuminuric group: 184.1±17 mg/dl;P<0.007) and HDL-cholesterol (normoalbuminuric group: 45±2 mg/dl, microalbuminuric group: 39±2 mg/dl;P<0.05). The coagulation parameters were as follows: normoalbuminuric group: protein C activity 109%±5%, protein S 95.4%±5%, thrombomodulin 49.3±3 ng/ml, antithrombin III 93.3%±3%, F 1+2 1.05±0.04 nmol/l; microalbuminuric group: protein C activity 107%±4%, protein S 98.4%±4%, thrombomodulin 64.4±4 ng/ml, antithrombin III 93.3%±3%, F 1+2 1.03±0.05 nmol/l. The difference was significant for thrombomodulin (P<0.007). A significant direct correlation was observed in the microalbuminuric group between AER and thrombomodulin (r=0.38,P<0.05). In conclusion, our data do not support the hypothesis that a reduction in the activity of anticoagulant physiological inhibitors (protein C, protein S, antithrombin III) could contribute to explain the higher cardiovascular risk in type 2 diabetic patients with microalbuminuria. The elevation of plasma thrombomodulin concentration in type 2 diabetic patients could be the consequence of widespread vascular damage in diabetic patients with incipient nephropathy.     

Plasma concentrations of VCAM-1 and ICAM-1 are elevated in patients with Type 1 diabetes mellitus with microalbuminuria and overt nephropathy.

AIMS: Elevated urinary albumin excretion is associated with macrovascular atherosclerotic complications in Type 1 diabetes mellitus. Adhesion molecules mediate leucocyte adhesion to the endothelium early in the atherosclerotic process. The present study tests the hypothesis that microalbuminuria and diabetic nephropathy are associated with elevated plasma concentrations of soluble vascular adhesion molecule (sVCAM)-1, soluble intercellular adhesion molecule (sICAM)-1, and soluble E-selectin (sE-selectin) aiming to illustrate factors of potential pathogenetic relevance for the excess cardiovascular disease in diabetic patients with renal complications. METHODS: Soluble adhesion molecule concentrations were measured by enzyme-linked immunosorbent assays (ELISA) in healthy controls (n = 16) and in 59 Type 1 diabetic patients: group 1-patients with normoalbuminuria (n = 16); group 2-patients with microalbuminuria (n = 15); group 3-patients with macroalbuminuria and normal serum creatinine (n = 15), group 4-patients with macroalbuminuria and moderately elevated serum creatinine (n = 13). RESULTS: Plasma concentrations of sVCAM-1 and sICAM-1 were similar in healthy controls and normoalbuminuric Type 1 diabetic patients, but the concentrations were increased by the presence of microalbuminuria and overt nephropathy (P < 0.001 and P < 0.0001, ANOVA). Concentrations of sE-selectin did not differ between diabetic patients and controls. CONCLUSIONS: Plasma concentration of sICAM-1 is elevated in Type 1 diabetic patients with microalbuminuria and the concentrations of sICAM-1 as well as sVCAM-1 are elevated in patients with macroalbuminuria and normal s-creatinine. The elevated plasma concentrations of these soluble adhesion molecule concentrations in patients with renal complication can be of pathogenetic importance for the development of atherosclerosis and plasma soluble adhesion molecule concentrations may provide additional information on cardiovascular risk.     

Adiponectin, total antioxidant status, and urine albumin excretion in the low-risk “Golden Years” type 1 diabetes mellitus cohort

Adiponectin is associated with inflammation and oxidative stress. Levels are reduced in type 2 diabetes mellitus and coronary heart disease. Conversely, levels are elevated in type 1 diabetes mellitus (T1DM) and associated with microalbuminuria and diabetic nephropathy. An explanation may be that elevated adiponectin in T1DM represents a beneficial counterregulatory response to disease. Our aim was to examine adiponectin in relation to urinary albumin excretion and plasma total antioxidant status (TAOS) in subjects with long-standing T1DM. Serum adiponectin and plasma TAOS were measured in 338 samples from the Golden Years cohort. These subjects have T1DM for at least 50 years and are at low risk of complications. Subjects were divided into normoalbuminuria, microalbuminuria, and macroalbuminuria groups. Adiponectin was elevated in women (20.53 ± 5.94 vs 11.8 ± 3.6 mg/L, P < .001); therefore, the samples were sex stratified. Within men, adiponectin was higher in those with macroalbuminuria (normoalbuminuria vs microalbuminuria vs macroalbuminuria: 10.97 ± 3.26 vs 11.55 ± 3.50 vs 23.63 ± 7.07 mg/L, P = .002). In women, no difference was observed (20.48 ± 5.61 vs 20.75 ± 7.04 vs 29.62 ± 7.81 mg/L, respectively; P = .42). Plasma TAOS did not differ by groups. The correlation between adiponectin and TAOS showed a linear increase from normoalbuminuria, microalbuminuria, to macroalbuminuria in men (r = 0.33, P = .001; r = 0.48, P < .001; r = 0.59, P = .04) and women (r = 0.25, P = .01; r = 0.63, P < .001; r = 0.79, P = .08). Adiponectin was higher in women. Within men, levels were significantly higher in the presence of macroalbuminuria. In both sexes, adiponectin and TAOS were correlated, which was most marked with micro-/macroalbuminuria. The increase in adiponectin in the face of an insult may be a compensatory mechanism to reduce oxidative burden.     

Kidney function in newly diagnosed Type 2 (non-insulin-dependent) diabetic patients, before and during treatment

Summary Glomerular filtration rate, kidney volume, and urinary albumin excretion rate were studied in otherwise healthy newly diagnosed Type 2 (non-insulin-dependent) diabetic patients, untreated at diagnosis, after short-term treatment and after 3 months treatment. In 10 patients (Group A) glomerular filtration rate (measured by the plasma clearance of 51-Cr-EDTA) decreased from the time of diagnosis 106.2±14.6 ml·min^–1·1.73m^2–1 (mean±SD) to 95.9±13.7 ml·min^–1·1.73m^2–1 after 3 months treatment (p=0.049). At the same time, mean plasma glucose was reduced from 13.3±3.2 mmol/l to 6.5±1.1 mmol/l. The fall in mean plasma glucose was correlated to the reduction in glomerular filtration rate, r=0.76, p=0.011. Kidney volume as measured by ultrasonic scanning was reduced from 264.0±33.7 ml/l.73m² to 210.8±23.8 ml/l.73 m² (p<0.005). The relative decline in urinary albumin excretion rate was correlated to the fall in glomerular filtration rate, r=0.69, p=0.026. In 15 patients (Group B) 24-h urine collections were made during 9.5±3.2 days, urinary albumin excretion rate fell from the first to the last day in hospital from 14.0×/÷3.0 g/min (geometric mean ×/÷ tolerance factor) to 7.0×/÷2.7 g/min p=0.015. The relative decline was correlated to the change in mean plasma glucose, r=0.65, p=0.032.Thus, kidney function in Type 2 diabetic patients is influenced by metabolic control, although to a lesser extent than is seen in Type 1 (insulin-dependent) diabetic patients with comparable glycaemic control. Urinary albumin excretion is reduced by improvement in glycaemic control, to which it is significantly correlated. Long-term consequences of reduction in urinary albumin excretion on the development of diabetic nephropathy and on survival remains to be elucidated.