Glomerular size-and charge selectivity in Type 2 (non-insulin-dependent) diabetic patients with diabetic nephropathy

Summary In an attempt to evaluate the mechanisms of proteinuria in diabetic kidney disease, we measured the renal clearances of albumin, total IgG, and IgG4 in 20 male Type 2 (non-insulin-dependent) diabetic patients with diabetic glomerulosclerosis (biopsy proven), in 10 male Type 2 diabetic patients without nephropathy (urinary albumin excretion rate ≤ 30 mg/24 h), and in 10 healthy male subjects. The fractional clearance of albumin was increased in patients with nephropathy: 659 (42–4355) · 10^–6 (median (range)), compared to 2.6 (0.2–14.2) · 10^–6 in patients without nephropathy, and 2.3 (0.4–4.2) · 10^–6 in healthy subjects. The fractional clearance of total IgG (neutral) and of IgG4 (anionic) was 40–50 times higher in patients with nephropathy compared to the two other groups. The IgG/IgG4 selectivity index was not significantly different in the three groups, being: 1.12 (0.06–5.65), 1.16 (0.45–3.72) and 1.35 (0.65–3.34) in patients with nephropathy, patients without nephropathy, and healthy subjects, respectively. The IgG/albumin selectivity index was decreased in patients with nephropathy: 0.27 (0.01–1.26) compared to 1.29 (0.07–2.67) (p<0.05) and 1.23 (0.76–7.84) (p<0.001) in patients without nephropathy and healthy subjects, respectively. No significant change in IgG/albumin selectivity index was observed between patients without nephropathy and healthy subjects. The systolic blood pressure was elevated in the patients with nephropathy: 164±21 mm Hg (mean ± SD) compared to patients without nephropathy: 145±20 mm Hg (p<0.05) and to healthy subjects: 133±19 mm Hg (p<0.005). The diastolic blood pressure was higher in patients with and without nephropathy: 92±7 vs 90±10 mm Hg compared to 79±8 mm Hg (p<0.005) in healthy subjects. Our cross-sectional study suggests that impaired barrier size selectivity, probably due to an increase in large pore area (“shunt pathway”) in the glomerular capillary wall and systemic hypertension are the major pathogenic mechanisms of proteinuria in Type 2 diabetic patients with diabetic nephropathy. [Diabetologia (1994) 37: 195–201] Received: 7 June 1993 and in revised form: 25 August 1993     

Glomerular hypertension as one cause of albuminuria in Type II diabetic patients

Aims/hypothesis. Results from animal models of glomerular hypertension have suggested that this disorder is one cause of albuminuria in diabetic nephropathy. We evaluated this hypothesis clinically. Methods. The subjects were 20 patients with Type II (non-insulin-dependent) diabetes mellitus but without uraemia or hypertension: 8 had normoalbuminuria and 12 had albuminuria ( ≥ 20 μg/min). In the 2-week study, patients were on a diet with ordinary amounts of sodium for 1 week and on a sodium-restricted diet for 1 week. Urinary excretion of sodium and albumin and the systemic blood pressure were measured daily. Intrarenal haemodynamics, in terms of the glomerular pressure and resistance of afferent and efferent arterioles, were calculated from renal clearance, the plasma total protein concentration, and the pressure-natriuresis relation. In 8 of the 12 patients with albuminuria, an angiotensin-converting enzyme inhibitor, cilazapril, was given orally (2 mg/day) and the 2-week study was repeated. Results. In patients with albuminuria, resistance of efferent arterioles and the glomerular pressure were higher than in patients with normoalbuminuria (glomerular pressure, 53 ± 5 vs 43 ± 5 mmHg, means ± SD, p < 0.001). Urinary excretion of albumin correlated (n = 20, r = 0.675, p < 0.001) with the glomerular pressure but not with systemic pressure. The increased glomerular pressure and the albuminuria were decreased by cilazapril but systemic pressure was not. Conclusion/interpretation. These findings are consistent with the hypothesis that glomerular hypertension is present in Type II diabetic patients with early nephropathy and can cause albuminuria. [Diabetologia (1999) 42: 999–1005] Received: 25 January 1999 and in revised form: 15 March 1999     

Plasma lipoproteins and renal function during simvastatin treatment in diabetic nephropathy

Summary The aim of this study was to assess the effect of simvastatin on plasma lipoproteins and renal function in hypercholesterolaemic Type 1 (insulin-dependent) diabetic patients with diabetic nephropathy. Twenty-six hypercholesterolaemic (total cholesterol ≽ 5.5 mmol/l) Type 1 diabetic patients with nephropathy were enrolled in a double-blind randomized placebo-controlled study for 12 weeks. The active treatment group (n -14) received simvastatin (10–20 mg/day) for 12 weeks while the remaining 12 patients received treatment with placebo. The results during simvastatin treatment (baseline vs 12 weeks): total cholesterol 6.6 vs 4.8 mmol/1 (p < 0.01), LDL-cholesterol 4.25 vs 2.57 mmol/l (p < 0.01) and apolipoprotein B 1.37 vs 1.06 mmol/l (p < 0.01). HDL-cholesterol, and apolipoprotein A-I remained unchanged. Total cholesterol, LDL-cholesterol, HDL-cholesterol, apolipoprotein A–I, apolipoprotein B remained unchanged during placebo treatment. Albuminuria measured during the simvastatin and the placebo treatment (baseline vs 12 weeks) (the data are logarithmically transformed before analysis because of their positively skewed transformation; geometric mean (×/÷ antilog SE) is indicated) was 458 (×/÷ 1.58) vs 393 (×/÷ 1.61) and 481 (×/÷ 1.62) vs 368 (×/÷ 1.78 μg/min (NS). Glomerular filtration rate during simvastatin and placebo treatment (baseline vs 12 weeks) was 64 vs 63 and 72 vs 74 ml·min⁻¹·1.73 m⁻², respectively. Two patients receiving simvastatin treatment were withdrawn, one due to gastrointestinal side effects and one due to myalgia. In conclusion, our short-term study in Type 1 diabetic patients with diabetic nephropathy did not reveal any beneficial effect on albuminuria despite a striking lipid-lowering effect of simvastatin in diabetic nephropathy.     

Physical training decreases plasma thrombomodulin in Type I and Type II diabetic patients

Aims/hypothesis. Endothelial damage is an early step in the pathogenesis of atherosclerosis and its improvement through physical training can contribute to the known reduction of cardiovascular risk associated with exercise. An increase in some endothelium-dependent haemostatic parameters, considered as markers of endothelial damage, has been observed in diabetic patients. Methods. The effect of a three-month physical exercise programme on thrombomodulin, tissue factor pathway inhibitor, plasminogen activator inhibitor, tissue-type plasminogen activator and von-Willebrand factor was evaluated in 14 well-controlled patients with Type I (insulin-dependent) diabetes mellitus and 13 patients with Type II (non-insulin-dependent) diabetes mellitus (HbA_{1 c} 6.5 ± 0.8 and 7.4 ± 0.8 %, respectively). A matched control group was also studied. Results. Thrombomodulin at baseline was higher in both Type I and Type II diabetic patients than in their respective matched control subjects (50.0 ± 16 vs 31.1 ± 8.7 μg/l, p < 0.05; 51.0 ± 10 vs 28.5 ± 11 μg/l, p < 0.05, respectively). After the exercise programme, thrombomodulin plasma concentrations had decreased (p < 0.05) in both groups of patients, with final thrombomodulin values being similar to those observed in their control groups (38.2 ± 11 μg/l for Type I and 34.6 ± 12 μg/l for Type II patients). The thrombomodulin decrement correlated with baseline thrombomodulin and VO_2max increase in Type I diabetic patients. A decrease in tissue factor pathway inhibitor was also observed in Type II diabetic patients. Conclusion/interpretation. We conclude that the normalisation of plasma thrombomodulin concentrations in Type I and Type II diabetic patients after physical training might reflect the improvement in endothelial function associated with physical exercise. [Diabetologia (2001) 44: 693–699]     

Renal kallikrein in diabetic patients with hypertension accompanied by nephropathy

Summary We measured the 24-h excretion of urinary kallikrein in 27 patients with Type 2 (non-insulin-dependent) diabetes and in 10 normal control subjects. Mean (± SD) kallikrein excretion in diabetic patients with nephropathy (6.2±2.4 naphthyl units (NU)/day,n=13) was significantly lower than in control subjects (12.8±3.4NU/day,p<0.01) and in diabetic patients without nephropathy (9.4±3.4NU/day,n=14,p<0.05). Kallikrein excretion in hypertensive diabetic patients with nephropathy (5.1±1.6 NU/day,n=8) was significantly lower (p<0.05) than in normotensive patients with nephropathy (8.3±2.1 NU/day,n=5). There were no significant differences in kallikrein excretion rate (24-h excretion of urinary kallikrein/24-h creatinine clearance) among control subjects (9.9±4.3 NU/ml), diabetic patients with (9.0±3.2 NU/ml) and without (9.3±3.5 NU/ml) nephropathy. However, kallikrein excretion rate in hypertensive diabetic patients with nephropathy (7.7±3.3 NU/ml) was significantly lower (p<0.05) than in normotensive diabetic patients with nephropathy (11.8 ±2.0 NU/ml,n=10). Respective basal and post-stimulated (with intravenous furosemide 40 mg plus 60 min ambulation) plasma aldosterone concentrations measured in control subjects and in hypertensive diabetic patients with nephropathy were similar and increased to the same extent in the 2 groups (5.5±3.2 versus 5.3±3.2 and 9.3±2.6 versus 10.5±3.4 ng/ml), although the respective plasma renin activity tended to be lower in diabetic patients than in control subjects (0.7±0.6 versus 1.3±0.9 and 1.8±1.8 versus 3.0±2.6 ng⁻¹ · ml⁻¹ · h⁻¹). The results indicate that urinary kallikrein excretion is decreased in hypertensive diabetic patients with nephropathy, and that the decrease might not be attributable to an altered renin-aldosterone system.     

High prevalence of risk factors for cardiovascular disease in parents of IDDM patients with albuminuria

Summary Life expectancy is shorter in the subset of insulin-dependent diabetic (IDDM) patients who are susceptible to kidney disease. Familial factors may be important. In this study the prevalence of cardiovascular disease mortality and morbidity and of risk factors for cardiovascular disease was compared in the parents of 31 IDDM patients with elevated albumin excretion rate (AER > 45 μg/min; group A) with that of parents of 31 insulin-dependent diabetic patients with normoalbuminuria (AER < 20 μg/min; group B). The two diabetic patient groups were matched for age and duration of disease. Information on deceased parents was obtained from death certificates and clinical records and morbidity for cardiovascular disease was ascertained using the World Health Organization questionnaire and Minnesota coded ECG. Hyperlipidaemia was defined as serum cholesterol higher than 6 mmol/l and/or plasma triglycerides higher than 2.3 mmol/l and/or lipid lowering therapy; arterial hypertension as systolic blood pressure higher than 140 mmHg and/or diastolic blood pressure higher than 90 mmHg and/or antihypertensive treatment. The percentage of dead parents was similar in the two groups (26 vs 20 % for parents of group A vs group B, respectively), but the parents of the diabetic patients with elevated AER had died at a younger age (58 ± 10 vs 70 ± 14 years; p < 0.05). Parents of diabetic patients with nephropathy had a more than three times greater frequency of combined mortality and morbidity for cardiovascular disease than that of the parents of diabetic patients without nephropathy (26 vs 8 %; odds ratio 3.96, 95 % CI 1.3 to 12.2; p < 0.02). Living parents of group A had a higher prevalence of arterial hypertension (42 vs 14 % p < 0.01) and hyperlipidaemia (49 vs 26 % p < 0.05) as well as higher levels of lipoprotein (a) [median (range) 27.2 (1–107) vs 15.6 (0.2–98) mg/dl; p < 0.05]. They also had reduced insulin sensitivity [insulin tolerance test: median (range) K_itt index: 3.7 (0.7–6.2) vs 4.8 (0.7–6.7)% per min; p < 0.05]. In the families of IDDM patients with elevated AER there was a higher frequency of risk factors for cardiovascular disease as well as a predisposition to cardiovascular disease events. This may help explain, in part, the high prevalence of cardiovascular disease mortality and morbidity in those IDDM patients who develop nephropathy. [Diabetologia (1997) 40: 1191–1196] Received: 4 March 1997 and in revised form: 9 May 1997     

Insertion/deletion polymorphism in the angiotensin-l-converting enzyme gene is associated with coronary heart disease in IDDM patients with diabetic nephropathy

Summary Insulin-dependent diabetic (IDDM) patients with diabetic nephropathy have a highly increased morbidity and mortality from coronary heart disease. An insertion (I) /deletion (D) polymorphism in the angiotensin-I-converting enzyme (ACE) gene has been shown to be associated with coronary heart disease. Therefore, we have investigated the role of this ACE/ID polymorphism in 198 IDDM patients with diabetic nephropathy and 190 normoalbuminuric IDDM patients. The prevalence of myocardial infarction and other coronary heart disease was significantly elevated in patients with nephropathy, 19 % (38/198) vs 8 % (15/190), p < 0.001. In the nephropathic group 12 of 63 (19 %), 23 of 95 (24 %), and 3 of 40 (7.5 %) patients with the DD, ID and II genotypes, respectively had a history of coronary heart disease, II vs DD and ID, p < 0.05 when compared to nephropathic patients without coronary heart disease. Multiple logistic regression analysis of the risk factors associated with coronary heart disease in univariate analysis revealed that the II genotype acts as an independent protective factor against coronary heart disease, odds ratio II/DD + ID 0.27 (95 % confidence interval 0.07–0.97, p < 0.05). There was no difference in genotype or allele frequency (D/I) between patients with and without nephropathy, 0.56/0.44 in both groups, but plasma ACE concentration was elevated in patients with nephropathy 609 (151–1504) ng/ml as compared to patients with normoalbuminuria, 428 (55–1630) ng/ml, p < 0.001. We suggest that ACE/ID polymorphism may influence the frequency of life-threatening cardiac complications in IDDM patients suffering from diabetic nephropathy, a condition characterized by increased plasma ACE concentration. [Diabetologia (1995) 38: 798–803] Received: 10 October 1994 and in revised form: 20 December 1994     

Association between serum levels of soluble receptor for advanced glycation end products and circulating advanced glycation end products in type 2 diabetes

Aims/hypothesis Activation of the receptor for advanced glycation end products (RAGE, also known as AGE-specific receptor [AGER]) has been implicated in the development of diabetic vascular complications. Blockade of RAGE using a soluble form of the receptor (sRAGE) suppressed vascular hyperpermeability and atherosclerosis in animal models. Since little is known about the regulation of endogenous sRAGE levels, we determined whether serum sRAGE is influenced by circulating AGEs and the severity of nephropathy in type 2 diabetic patients.Materials and methods We recruited 150 healthy control and 318 diabetic subjects. Diabetic subjects were subdivided into those with proteinuria, microalbuminuria or normoalbuminuria. Serum sRAGE was assayed by ELISA and serum AGEs by competitive ELISA using a polyclonal rabbit antiserum raised against AGE-RNase.Results Diabetic subjects had higher sRAGE (1,029.5 pg/ml [766.1–1,423.0] interquartile range vs 1,002.6 [726.5–1,345.3], p<0.05) and AGEs (4.07±1.13, SD, unit/ml vs 3.39±1.05, p<0.01) than controls. Proteinuric subjects had the highest sRAGE levels and there was a significant trend between the severity of nephropathy and sRAGE (p=0.01). In diabetic subjects, serum log(sRAGE) correlated with AGEs (r=0.27, p<0.001), log(plasma creatinine) (r=0.31, p<0.001), log(urine AER) (r=0.24, p<0.01) and log(triglycerides) (r=0.15, p<0.01). On stepwise linear regression analysis, AGEs and creatinine levels were the main independent determinants of sRAGE concentration.Conclusions/interpretation Serum sRAGE levels and circulating AGEs are associated with the severity of nephropathy in type 2 diabetic patients. Prospective studies are required to determine whether endogenous sRAGE potentially influences the development of diabetic vascular complications.     

Diabetic nephropathy is associated with low-grade inflammation in Type 1 diabetic patients

Aims/hypothesis Increased concentrations of C-reactive protein and interleukin-6, a finding suggestive of the presence of inflammation, have been observed in Type 2 diabetes. In such patients, C-reactive protein was predictive of diabetic nephropathy. Studies on low-grade inflammatory markers and nephropathy in Type 1 diabetic patients have shown conflicting results. Therefore we studied whether low-grade inflammation is associated with diabetic nephropathy in Type 1 diabetic patients.Methods We divided 194 Type 1 diabetic patients into three groups from the Finnish Diabetic Nephropathy Study based upon their albumin excretion rate. Patients with normoalbuminuria (n=67) had no antihypertensive medication or signs of cardiovascular disease, while patients with microalbuminuria (n=64) or macroalbuminuria (n=63) were all treated with an angiotensin-converting enzyme inhibitor, a drug that could attenuate low-grade inflammation. As a measure of insulin sensitivity we used estimated glucose disposal rate. C-reactive protein was measured by radioimmunoassay and interleukin-6 by high sensitivity enzyme immunoassay.Results C-reactive protein was higher in micro- and macroalbuminuric patients compared to normoalbuminuric patients (normoalbuminuria 2.0±1.7, microalbuminuria 2.6±1.7, macroalbuminuria 2.9±2.5 mg/l; p=0.016), while interleukin-6 increased in parallel with the severity of the renal disease (1.9±1.5, 2.9±3.3, 3.6±3.1 ng/l; p<0.0001). In multiple regression analysis albumin excretion rate was the only variable independently associated with C-reactive protein (p=0.03), whereas albumin excretion rate (p=0.0003), HDL-cholesterol (p=0.0135) and duration of diabetes (p=0.0176) were independently associated with interleukin-6.Conclusions/interpretation Low-grade inflammatory markers are associated with diabetic nephropathy in Type 1 diabetic patients. The predictive value needs to be assessed.Abbreviations DN diabetic nephropathy - CRP C-reactive protein - eGDR estimated glucose disposal rate - FinnDiane finnish diabetic nephropathy study - MDRD modification of diet in renal disease     

The course of kidney function in Type 2 (non-insulin-dependent) diabetic patients with diabetic nephropathy

Summary We evaluated the impact of some putative progression promoters on kidney function in albuminuric Type 2 (non-insulin-dependent) diabetic patients with biopsyproven diabetic glomerulosclerosis. Twenty-six patients (1 female) with a mean age of 52 (standard error 2) years and a known mean duration of diabetes of 9 (1) years were followed-up prospectively for a mean of 5.2 (range 1.0–7.0) years. Twenty-one patients received antihypertensive treatment. During the observation period the glomerular filtration rate decreased from 83 (24–146) to 58 (2–145) ml·min⁻¹·1.73 m⁻² (mean (range)) (p<0.001). The mean rate of decline in glomerular filtration rate was 5.7 (−3.5 to 22.0) ml/min per year. Albuminuria increased from 1.2 (0.3–7.2) to 2.3 (0.4–8.0) g/24 h (geometric mean (range)) (p<0.001). Arterial blood pressure remained unchanged: 162/93 (SE 4/3) and 161/89 (4/2) mm Hg. Univariate analysis showed the rate of decline in glomerular filtration rate to correlate with systolic blood pressure (r=0.71,p<0.001), mean blood pressure (r=0.56,p<0.005), albuminuria (r=0.58,p<0.005) and the initial glomerular filtration rate (r=−0.49,p<0.02). The rate of decline in glomerular filtration rate did not correlate significantly with dietary protein intake, total cholesterol, high-density lipoprotein cholesterol or HbA_1c. Three patients died from uraemia and four patients died from cardiovascular disease. Two patients required renal replacement therapy at the end of the observation period. Our prospective observational study revealed that one-fifth of the patients developed end-stage renal failure during the 5-year observation period. The decline in glomerular filtration rate varied considerably between patients. Increase in arterial blood pressure to a hypertensive level is an early feature of diabetic nephropathy. Elevated systolic blood pressure accelerates the progression of diabetic nephropathy in Type 2 diabetic patients.     

Macro-microangiopathy and endothelial dysfunction in NIDDM patients with and without diabetic nephropathy

Summary The Steno hypothesis suggests that albuminuria reflects widespread vascular damage (proliferative retinopathy and severe macroangiopathy) due to a generalized vascular (endothelial) dysfunction. We assessed this concept in NIDDM (non-insulin-dependent diabetic) patients with (13 female/39 male, age 60 ± 7 years, group 1) and without (12 female/41 male, age 61 ± 7 years, group 2) diabetic nephropathy compared to matched non-diabetic subjects (7 female/15 male, age 58 ± 8 years, group 3). A 12-lead ECG was recorded and coded blindly using the Minnesota Rating Scale; the World Health Organization cardiovascular questionnaire was used to assess past and present evidence of myocardial infarction, angina pectoris, stroke, and peripheral vascular disease (digital systolic blood pressure determination). The degree of diabetic retinopathy was scored from fundus photography. The following variables were measured: transcapillary escape rate of albumin (initial disappearance of intravenously injected ¹²⁵I-labelled human serum albumin), plasma concentrations of prorenin (radioimmunoassay) and serum concentrations of von Willebrand factor (enzyme-linked immunoadsorbent assay). Prevalence of ischaemic heart disease (ECG reading) (49/20/5)% and peripheral vascular disease as indicated by reduced systolic blood pressure on big toe (69/30/14)% was significantly higher in group 1 vs group 2 (p < 0.01) and in group 2 vs group 3 (p < 0.01), respectively. The prevalence and severity of retinopathy was higher in group 1 vs 2 (p < 0.01). Transcapillary escape rate of albumin (%/h) was elevated in group 1 and 2 as compared to control subjects: 7.9 (4.3–13.7); 7.4 (3.7–16.4) vs 6.0 (3.4–8.7), (p < 0.005), respectively. Plasma prorenin activity (IU/ml) was raised in group 1 and group 2 as compared to group 3: 272 (59–2405); 192 (18–813), and 85 (28–246), p < 0.001, respectively. Serum von Willebrand factor (IU/ml)was elevated in group 1 as compared to group 2 and 3: 2.07 (0.83–4.34); 1.60 (0.30–2.99) and 1.50 (1.00–2.38), p < 0.001, respectively. Our study demonstrated that NIDDM patients with and without albuminuria had increased transcapillary escape of albumin and raised prorenin activity, whereas only those with albuminuria had increased von Willebrand factor. Patients with NIDDM may have abnormal endothelial function in the absence of albuminuria. [Diabetologia (1996) 39: 1590–1597]     

Erythrocyte Na/K ATPase activity and diabetes: relationship with C-peptide level

Summary Erythrocyte Na/K ATPase activity is decreased in Type I diabetic patients; for Type II diabetic patients, literature data are controversial. Therefore, we have compared this enzymatic activity in 81 patients with Type I diabetes mellitus, 87 with Type II diabetes mellitus and 75 control subjects. Mean erythrocyte Na/K ATPase activity was lower in the Type I diabetic patients (285 ± 8 nmol Pi · mg protein^–1· h^–1) than in the control subjects (395 ± 9 nmol Pi · mg protein^–1· h^–1) whereas that of the Type II diabetic patients did not differ from that of control subjects. Sex, age, body mass index, and HbA_{1 c} levels did not influence erythrocyte Na/K ATPase activity. The 25 Type II diabetic patients treated with insulin, however, had lower Na/K ATPase activity than the 62 on oral treatment (264 ± 18 vs 364 ± 16 nmol Pi · mg protein^–1· h^–1, p < 0.001) but similar to that of Type I diabetic patients. Among the Type II diabetic patients, stepwise regression analysis showed that fasting C-peptide level was the only factor independently correlated with Na/K ATPase activity; it explained 23 % of its variance. In fact, in the insulin-treated patients, those with almost total endogenous insulin deficiency (C-peptide < 0.2 nmol · l^–1) had the lower Na/K ATPase activity (181 ± 21 vs 334 ± 17 nmol Pi · mg protein^–1· h^–1, p < 0.0001). The biological effects of treatment with C-peptide have recently led to the suggestion that this peptide could have a physiological role through the same signalling pathway as insulin, involving G-protein and calcium phosphatase and thus restoring Na/K ATPase activity. The relationship we describe between endogenous C-peptide and this activity is a strong argument for this physiological role. [Diabetologia (1998) 41: 1080–1084] Received: 6 November 1997 and in final revised form: 10 April 1998     

Plasma concentration of C-reactive protein is increased in Type I diabetic patients without clinical macroangiopathy and correlates with markers of endothelial dysfunction: evidence for chronic inflammation

Summary Moderately increased plasma concentrations of C-reactive protein are associated with an increased risk of cardiovascular disease. C-reactive protein, its relation to a low degree of inflammatory activation and its association with activation of the endothelium have not been systematically investigated in Type I (insulin-dependent) diabetes mellitus. C-reactive protein concentrations were measured in 40 non-smoking patients with Type I diabetes without symptoms of macrovascular disease and in healthy control subjects, and in a second group of Type I diabetic patients (n = 60) with normo- (n = 20), micro- (n = 20) or macroalbuminuria (n = 20). Differences in glycosylation of α₁-acid glycoprotein were assayed by crossed affinity immunoelectrophoresis. Activation of the endothelium was measured with plasma concentrations of endothelial cell markers. The median plasma concentration of C-reactive protein was higher in Type I diabetic patients compared with healthy control subjects [1.20 (0.06–21.64) vs 0.51 (0.04–9.44) mg/l; p < 0.02]. The Type I diabetic subjects had a significantly increased relative amount of fucosylated α₁-acid glycoprotein (79 ± 12 % vs 69 ± 14 % in the healthy control subjects; p < 0.005), indicating a chronic hepatic inflammatory response. In the Type I diabetic group, log(C-reactive protein) correlated significantly with von Willebrand factor (r = 0.439, p < 0.005) and vascular cell adhesion molecule-1 (r = 0.384, p < 0.02), but not with sE-selectin (r = 0.008, p = 0.96). In the second group of Type I diabetic patients, increased urinary albumin excretion was associated with a significant increase of von Willebrand factor (p < 0.0005) and C-reactive protein (p = 0.003), which were strongly correlated (r = 0.53, p < 0.0005). Plasma concentrations of C-reactive protein were higher in Type I diabetic patients without (clinical) macroangiopathy than in control subjects, probably due to a chronic hepatic inflammatory response. The correlation of C-reactive protein with markers of endothelial dysfunction suggests a relation between activation of the endothelium and chronic inflammation. [Diabetologia (1999) 42: 351–357] Received: 4 September 1998 and in final revised form: 24 November 1998     

Protein C activation in NIDDM patients

Summary Enhanced activation of the clotting system has been recently implicated in the pathogenesis of vascular complications in patients with diabetes mellitus. Abnormalities of the anticoagulant system may constitute a potential trigger factor for the haemostatic activation observed in diabetic subjects. The current study aimed to evaluate anticoagulant activity in diabetic patients by assessing the plasma levels of activated protein C-protein C inhibitor complex; and by measuring the anticoagulant response to exogenous thrombomodulin. This study comprised 61 patients (34 men, 27 women) with non-insulin-dependent diabetes mellitus (NIDDM) of whom 22 showed microalbuminuria and 39 normoalbuminuria. Data obtained in 31 non-obese and non-diabetic subjects were available for comparison. The plasma levels of fibrinogen (p < 0.02), prothrombin fragment 1 + 2 (p < 0.05), fibrin monomer (p < 0.0001), protein C antigen (p < 0.005), total protein S antigen (p < 0.02), soluble thrombomodulin (p < 0.005) and soluble E-selectin (p < 0.005) were significantly higher in diabetic patients than in healthy subjects. The plasma level of activated protein C-protein C inhibitor complex (7.4 ± 3.8 vs 3.0 ± 0.4 pmol/l) was significantly higher (p < 0.0001) and the anticoagulant response to exogenous thrombomodulin (23.4 ± 2.6 vs 35.3 ± 3.0 ng/ml) was markedly lower (p = 0.005) in all diabetic patients than in healthy subjects. Cases with microalbuminuria presented low plasma levels of activated protein C-protein C inhibitor complex (5.5 ± 0.6 vs 8.6 ± 0.7 pmol/l, p < 0.05) and significantly decreased values of the anticoagulant response to exogenous thrombomodulin (16.5 ± 2.9 vs 23.4 ± 2.6 %, p = 0.03) as compared to those with normoalbuminuria. The present study suggests that the hyper-coagulable state in NIDDM is associated with an increased activation of protein C but with a poor plasma reactivity to the anticoagulant effect of thrombomodulin. [Diabetologia (1996) 39: 1455–1461] Received: 27 February 1996 and in revised form: 3 June 1996     

Aortic pressure-diameter relation in patients with non-insulin dependent diabetes mellitus: new insights

Aims/hypothesis. Type II (non-insulin-dependent) diabetes mellitus is associated with macrovascular disease. Therefore, we investigated the aortic elastic properties by a new method in patients with diabetes and control patients matched with them. Methods. Patients with Type II diabetes (n = 20) and control patients without diabetes (n = 21) were enrolled in the study. All patients had coronary artery disease. Instantaneous aortic diameter was measured by an intravascular catheter developed in our institution. Instantaneous aortic pressure was measured simultaneously at the same aortic level with a catheter-tip micromanometer. Thus, aortic pressure-diameter loops were obtained and slope and intercept were calculated. Aortic distensibility, stiffness constant and energy loss were also calculated. Results. The mean age and the heart rate were similar in the two groups. The pulsatile changes in aortic diameter were greater in the control group (0.94 ± 0.4 vs 1.28 ± 0.4 mm, p < 0.01). The stiffness of the aortic wall was greater in diabetic patients as indicated from the following variables: the distensibility was less in patients with diabetes (1.16 ± 0.6 vs 1.95 ± 0.9 cm²· dyne^–1· 10^–6, p < 0.01); the slope was greater (113.4 ± 120.1 vs 51.61 ± 3.3 mmHg/mm, p < 0.01) and the intercept was less in diabetic patients (–2301.9 ± 2692.9 vs –1114.45 ± 295.6 mmHg, p < 0.01); the stiffness constant was greater in patients with diabetes (1.66 ± 1.8 vs 0.77 ± 0.8 mm^–1, p < 0.03). Aortic energy loss was, however, similar between the groups. Conclusion/interpretation. In patients with non-insulin dependent diabetes aortic elastic properties, evaluated by pressure-diameter relation, are impaired. This could play an important part in the development of vascular complications related to diabetes. [Diabetologia (2000) 43: 1070–1075] Received: 17 April 2000     

Pregnancy and progression of diabetic nephropathy

Aims/hypothesis: Pregnancy could damage kidney function in diabetic nephropathy. We investigated the long-term impact of pregnancy on the progression of diabetic nephropathy. Methods: Our observational follow-up study included all women patients with Type I (insulin-dependent) diabetes mellitus who developed diabetic nephropathy between 1970 and 1989 at Steno Diabetes Center (n = 93). Follow-up lasted 16 years (range 3–28) from the onset of diabetic nephropathy until death or the year 2000. A total of 26 women became pregnant after the onset of diabetic nephropathy (group A). The remaining 67 served as control subjects (group B). All patients received aggressive antihypertensive treatment (blood pressure goal < 140/90 mmHg). Results: The two groups were comparable at onset of diabetic nephropathy regarding blood pressure, albuminuria, s-cholesterol, smoking, retinopathy and s-creatinine (mean 79(SD 23) μmol/l). The slopes of 1/s-creatinine (1000 · l ·μmol^–1· year^–1) during the whole observation period were –0.39(0.40) compared with –0.41(0.70) (group A vs B – NS). The slopes of 1/s-creatinine before and after pregnancy were similar. Decline in creatinine clearance (ml/min/yr) was 3.2 (3.4) compared with 3.2 (5.1) (group A vs B -NS). At the end of follow-up, 35 % (95 %-CI:17–53) of the pregnant women had died and 19 % (7–39) had reached end stage renal disease compared to 34 % (23–45) and 24 %(14–34) of the control subjects, respectively(NS). Group A and B had similar blood pressure levels during the whole observation period: 136(13)/83(7) vs 139 (14)/85(7) mmHg (NS). Conclusion/interpretation: Pregnancy has no adverse long-term impact on kidney function and survival in Type I diabetic patients with well-preserved kidney function (normal serum creatinine) suffering from diabetic nephropathy. [Diabetologia (2002) 45: 36–41] Received: 20 June 2001 and in revised form: 21 September 2001     

Detection of monocyte-derived microparticles in patients with Type II diabetes mellitus

Aims/hypothesis. The role of plasma monocyte-derived microparticles (MDMPs) and platelet-activation markers (platelet-derived microparticle [PDMP], platelet-bound CD62P [plt-CD62P], and platelet-bound CD63 [plt-CD63]) in diabetic vascular complications is not clear. We measured and compared plasma concentrations of MDMPs and the platelet-activation markers to investigate their possible contribution to diabetic vascular complications. Methods. Activated platelets and microparticles (PDMP and MDMP) were analysed by flow cytometry. Concentrations of serum sE-selectin were measured with enzyme-linked immunosorbent assay. Results. The concentration of MDMPs in diabetic patients was higher than in normal subjects. We found no differences in the binding of anti-GPIIb/IIIa and anti-GPIb monoclonal antibodies between groups. There were differences, however, in the concentrations of PDMPs, plt-CD62P, and plt-CD63 between Type II (non-insulin-dependent) diabetes mellitus patients and control subjects (PDMPs: 585 ± 25 vs 263 ± 9, p < 0.01; plt-CD62P: 28.1 % ± 1.4 % vs 9.4 % ± 0.6 %, p < 0.001; plt-CD63: 28.1 % ± 1.4 % vs 8.6 % ± 0.5 %, p < 0.001). Amounts of MDMPs correlated positively with these platelet activation markers, and the relation between PDMP and MDMP was the most significant. The concentration of MDMP in patients who had diabetes complicated with nephropathy, retinopathy, or neuropathy was higher than in those without diabetes-related complications. The increase in MDMP was particularly significant in patients with nephropathy. Concentrations of sE-selectin were higher in Type II diabetes patients than in control subjects, and correlated with MDMP, PDMP, plt-CD62P, and plt-CD63 levels in nephropathy patients. Conclusion/interpretation. In Type II diabetes patients, we detected increased activation of monocytes, which could have been stimulated by activated platelets and PDMPs. Because the activation of monocytes is associated with vascular endothelial damage, high concentrations of MDMPs could indicate vascular complications in diabetes patients, especially those who have diabetes-related nephropathy. [Diabetologia (2002) 45: ▪–▪] Received: 21 May 2001 and in revised form: 13 November 2001     

Structural basis of diabetic nephropathy in microalbuminuric NIDDM patients: a light microscopy study

Summary The objective of the study was to evaluate early structural changes occurring in patients with non-insulin-dependent diabetes mellitus (NIDDM) and microalbuminuria by light microscopy. Basal renal biopsy was performed in patients who were subsequently randomized to different antihypertensive treatments. Fourteen NIDDM patients aged 36–65 years (duration of diabetes 9 ± 7 years) with microalbuminuria (mean urinary albumin excretion 66 ± 49 μg/min) underwent percutaneous renal biopsy. Control biopsies were obtained from five patients of similar age undergoing nephrectomy for renal neoplasia with normal renal function and no history of renal disease. Control and diabetic biopsies were processed by light microscopy and stained with haematoxylin and eosin, periodic acid Schiff, Masson's trichrome and silver methenamine. The percentage of globally sclerotic glomeruli was evaluated. Glomerular volume was determined using perimeter analysis. A semiquantitative assessment (range 0 to 3 +) was made of mesangial sclerosis, interstitial fibrosis, tubular atrophy, arteriosclerosis and arteriolar hyalinosis. Glomerular volume was significantly increased in diabetic as compared to control glomeruli (3.2 ± 8 vs 1.8 ± 7, p < 0.01). Mesangial sclerosis (0.9 vs 0, p < 0.0001) and arteriolar hyalinosis (0.91 vs 0.2, p < 0.022) were significantly higher in diabetic compared to control subjects. No significant differences between diabetic and control subjects were found in the percentage of globally sclerotic glomeruli or in the extent of interstitial fibrosis, tubular atrophy and arteriosclerosis. Thus NIDDM patients with microalbuminuria show histological findings consistent with diabetic nephropathy characterized by glomerular hypertrophy, mesangial sclerosis and arteriolar hyalinosis. However, the renal histological changes are mild and appear less marked than in insulin-dependent diabetic patients. [Diabetologia (1996) 39: 1625–1628].     

Effects of dietary protein restriction on albumin and fibrinogen synthesis in macroalbuminuric type 2 diabetic patients

Aims/hypothesis Diabetic nephropathy is associated with hypoalbuminaemia and hyperfibrinogenaemia. A low-protein diet has been recommended in patients with diabetic nephropathy, but its effects on albumin and fibrinogen synthesis are unknown. Methods We compared the effects of a normal (NPD; 1.38 ± 0.08 g kg⁻¹ day⁻¹) or low (LPD; 0.81 ± 0.04 g kg⁻¹ day⁻¹) -protein diet on endogenous leucine flux (ELF), albumin and fibrinogen synthesis (l-[5,5,5,-²H₃]leucine infusion), and markers of inflammation in nine type 2 diabetic patients with macroalbuminuria. Six healthy participants on NPD served as control participants. Results In comparison with healthy participants, type 2 diabetic patients on an NPD had similar ELF, reduced serum albumin (38 ± 1.1 vs 42 ± 0.8 g/l; p < 0.05), similar fractional synthesis rates (FSR) and absolute synthesis rates (ASR) of albumin, and both increased plasma fibrinogen concentration [10.7 ± 0.6 vs 7.2 ± 0.5 μmol/l (3.64 ± 0.22 vs 2.45 ± 0.18 g/l); p < 0.05] and fibrinogen ASR [11.03 ± 1.17 vs 6.0 ± 1.8 μmol 1.73 m⁻² day⁻¹ (3.7 ± 0.4 vs 1.9 ± 0.3 g 1.73 m⁻² day⁻¹); p < 0.01]. After LPD, type 2 diabetic patients had the following changes in comparison with NPD: reduced proteinuria (2.74 ± 0.4 vs 4.51 ± 0.8 g/day; p < 0.05), ELF (1.93 ± 0.08 vs 2.11 ± 0.08 μmol kg⁻¹ min⁻¹; p < 0.05) and total fibrinogen pool; increased serum albumin (42 ± 1 vs 38 ± 1 g/l; p < 0.01) and albumin ASR (14.1 ± 1 vs 9.9 ± 1 g 1.73 m⁻² day⁻¹; p < 0.05); and reduced plasma IL-6 levels, which were correlated with albumin ASR (r = −0.749; p < 0.05). Conclusions/interpretation LPD in type 2 diabetic patients with diabetic nephropathy reduces low-grade inflammatory state, proteinuria, albuminuria, whole-body proteolysis and ASR of fibrinogen, while increasing albumin FSR, ASR and serum concentration. ISRCTN ID no: CCT-NAPN-16911     

Left Ventricular Hypertrophy in Non-insulin-dependent Diabetic Patients With and Without Diabetic Nephropathy

The aim of our cross-sectional case–control study was to evaluate putative mechanisms of the increased cardiac morbidity and mortality in NIDDM patients with or without diabetic nephropathy. Fifty-one NIDDM patients with diabetic nephropathy (38 males, age 61 ± 8 years, group 1), 53 NIDDM patients with normoalbuminuria (42 males, 61 ± 7 years, group 2), and 22 non-diabetic control subjects (15 males, 58 ± 8 years, group 3) were investigated. Previous antihypertensive treatment was withdrawn 2 weeks before the study. Left ventricular mass index (LVMI) and systolic function were determined by echocardiography. LVMI was elevated, mean ± SE, in group 1: 157 ± 6 g m⁻², and in group 2: 139 ± 7 g m⁻², as compared with group 3: 95 ± 5 g m⁻² (p < 0.001, for both), and in group 1 as compared with group 2 (p = 0.05). The prevalence of left ventricular hypertrophy (LVH) (LVMI > 131 g m⁻² in men and > 100 g m⁻² in women) was much higher in group 1: 75 % (95 % CI, 60–86), and group 2: 51 % (95 % CI, 37–65), as compared with group 3: 9 % (95 % CI, 1–29) (p < 0.001, for both), and in group 1 as compared with group 2 (p < 0.01). Shortening fraction of the left ventricle, % ± SE, was relatively reduced in group 1: 32.5 ± 1.1 %, and group 2: 33.4 ± 1.1 %, as compared with group 3: 41.2 ± 1.2 % (p < 0.01, for both). In a subgroup of 26 normoalbuminuric normotensive NIDDM patients, LVMI was higher than in 14 normotensive non-diabetic control subjects: 137 ± 10 g m⁻² vs 96 ± 7 g m⁻², respectively (p < 0.005). The prevalence of LVH was 42 % (95 % CI, 23–63) and 14 % (95 % CI, 2–43) (p = 0.07) in these two groups, respectively. In conclusion, normotensive and hypertensive NIDDM patients with and without diabetic nephropathy frequently suffer from LVH and relatively reduced systolic function which may constitute independent risk factors for fatal and non-fatal cardiac events. © 1997 John Wiley & Sons, Ltd.