Renal functional reserve in IDDM patients

Summary The aim of this study was to determine whether renal functional reserve (RFR) is altered in insulin-dependent diabetic (IDDM) patients according to the stage of diabetic nephropathy. RFR was examined in 33 IDDM patients in similar glycaemic and metabolic control and compared to 12 healthy control subjects, during eight 1 h clearance periods prior to, during and after a 3-h stimulation by amino acid infusion (4.5 mg · kg⁻¹· min⁻¹). RFR was calculated as the difference between stimulated and baseline glomerular filtration rates (GFR). In 14 early normotensive diabetic patients with normal urinary albumin excretion, mean baseline GFR (133 ± 3 ml · min⁻¹· 1.73 m⁻²) was higher whereas RFR (10 ± 4 ml · min⁻¹· 1.73 m⁻²) was lower (p < 0.05) than in control subjects (113 ± 4 and 28 ± 2 ml · min⁻¹· 1.73 m⁻², respectively). In 10 normotensive patients who had lived with IDDM for 16 years and who had microalbuminuria, baseline GFR and RFR (109 ± 7 and 24 ± 6 ml · min⁻¹· 1.73 m⁻², respectively) were similar to those in control subjects. In 9 patients who had suffered IDDM for 23 years and had developed macroalbuminuria and hypertension, baseline GFR (78 ± 8 ml · min⁻¹· 1.73 m⁻²) was lower than in control subjects (p < 0.05) and RFR (8 ± 4 ml · min⁻¹· 1.73 m⁻²) was not significant. In addition, renal vascular resistance decreased significantly during infusion (p < 0.05) in microalbuminuric normotensive patients as well as in control subjects (by 9 ± 4 and 11 ± 4 mm Hg · l⁻¹· min⁻¹· 1.73 m⁻², respectively) but not in normoalbuminuric normotensive or macroalbuminuric hypertensive patients. These results indicate that microalbuminuric normotensive patients retain a normal RFR, whereas RFR is reduced or suppressed at two opposite stages of the disease: in normoalbuminuric normotensive patients with a high GFR and in macroalbuminuric hypertensive patients with a decreased GFR. This dissimilar impairment reveals permanent glomerular hyperfiltration in both early IDDM without nephropathy and IDDM with overt diabetic nephropathy, but not in IDDM with incipient nephropathy. [Diabetologia (1998) 41: 86–93] Received: 12 February 1997 and in final revised form: 28 August 1997     

Reduction in albuminuria predicts a beneficial effect on diminishing the progression of human diabetic nephropathy during antihypertensive treatment

Summary Diabetic nephropathy is the main cause of increased mortality and morbidity in IDDM patients. The effect of antihypertensive treatment on the progression of the nephropathy is highly variable. The aim of this study was to evaluate putative predictors of the progression in diabetic nephropathy during long-term antihypertensive treatment. Eighteen hypertensive IDDM patients with diabetic nephropathy, who had not been treated previously, were followed during 3 years of treatment with captopril and frusemide or bendrofluazide. Glomerular filtration rate, arterial blood pressure, albuminuria and adjusted albuminuria were used as putative predictors of rate of decline in glomerular filtration. Fall rate in glomerular filtration rate was 4.6 (4.0) ml·min^–1·year^–1 (mean (SD)) during treatment. Relative change in albuminuria (ratio of first year of treatment/baseline) and albuminuria during first year of treatment were significantly correlated to fall rate in glomerular filtration rate during 3 years of treatment (r =0.73, p<0.001) and (r =0.60, p<0.01), respectively. Arterial blood pressure and glomerular filtration rate measured at baseline, during first year of treatment or relative changes in these variables did not correlate with fall rate in glomerular filtration rate during 3 years of treatment. Haemoglobin A_{1 c}, serum-cholesterol, protein intake and sodium excretion remained unchanged during treatment, and were not correlated with loss of kidney function. Reduction in albuminuria during captopril treatment predicts an attenuated rate of decline in glomerular filtration rate in early diabetic nephropathy (glomerular filtration rate >70 ml· min^–1·1.73 m^–2). The finding suggests a clinical application in monitoring the efficacy of antihypertensive treatment in early diabetic nephropathy. [Diabetologia (1994) 37: 511–516] Received: 21 September 1993 and in revised form: 3 December 1993     

Urinary excretion of the carboxy terminal domain of type IV collagen is associated with kidney size and function in IDDM

We evaluated whether urinary excretion of the carboxy terminal domain (NC1) of Type IV collagen is associated with glomerular filtration rate and kidney size in Type I (insulin-dependent) diabetes mellitus (IDDM). Urinary excretion rate of NC1, glomerular filtration rate (GFR), and kidney size were measured in 16 men with Type I diabetes. Their mean age was 33.3 ± 6.1 years with a duration of diabetes of 14.9 ± 3.7 years (mean ± SD). The urinary excretion rate of NC1 was higher in the diabetic patients than in 18 healthy control subjects. Urinary excretion of NC1 was associated with both kidney size, parenchymal width, and GFR (r = 0.73, p = 0.001; r = 0.63, p = 0.009; r = 0.53, p = 0.04, respectively). The exact relationship between these factors and basement membrane turnover/synthesis remains to be elucidated.     

Procoagulant activity and intimal dysfunction in IDDM

Summary The biological activity of thrombin and coagulation factor Xa was assessed in 62 insulin-dependent diabetic patients. A group of non-diabetic subjects of comparable age and urinary albumin excretion rate (<30 mg/24 h) served as control subjects (group 1,n=14). The patients were divided into three groups according to urinary albumin excretion rate. In group 2, albumin excretion rate was less than 30 mg/24 h (n=17), in group 3 albumin excretion rate was in the range 30–300 mg/24 h (n=20) and in group 4 albumin excretion rate was greater than 300 mg/24 h (n=25). Compared to non-diabetic control subjects an increase in the biological activity of factor Xa was observed in all groups of diabetic patients (prothrombin fragment 1+2 levels were 1.14±0.38 nmol/l in group 2,p<0.005; 1.06±0.45 nmol/l in group 3,p<0.05 and 1.03±0.31 nmol/l in group 4,p<0.05 vs 0.75±0.34 nmol/l in group 1). No difference in the level of antithrombin III was seen between the groups. We reconfirmed the presence of intimal dysfunction in diabetic nephropathy demonstrated by elevated transcapillary escape rate of albumin in group 4 compared with group 2 (8.9±2.0% vs 7.0±1.9%,p<0.05). An overall positive correlation between transcapillary escape rate and prothrombin fragment 1+2 was found (r=0.36,p<0.005). However, in the groups with elevated albumin excretion rate such a correlation was not significant (group 3:r=0.15,p=0.54; group 4:r=0.03,p=0.86) while it was sustained in the groups with albumin excretion rate of less than 300 mg/24 h (group 1:r=0.61,p<0.05; group 2:r=0.64,p<0.05). In conclusion, IDDM patients had elevated biological activity of factor Xa, demonstrated by elevated levels of prothrombin fragment 1+2. This increment could not be explained by a deficiency of antithrombin III. [Diabetologia (1995) 38: 73–78]     

Enhanced G protein activation in IDDM patients with diabetic nephropathy

Summary Genetic susceptibility contributes significantly to the risk of developing nephropathy in insulin-dependent diabetes mellitus (IDDM). The cellular substrate for this has remained enigmatic. We investigated whether afflicted IDDM patients display an enhanced activation of pertussis toxin (PTX)-sensitive G proteins, a phenomenon which has been demonstrated in patients with essential hypertension. We established immortalised B lymphoblast cell lines from 10 IDDM patients without nephropathy (DC) and 15 IDDM patients with nephropathy (DN). Nephropathy was defined as a persistent albumin excretion rate of more than 20 μg/min (DC 3.9 ± 5.8, DN 562.3 ± 539.0 μg/min, respectively). Subjects were matched with regard to age (DC 28.9 ± 6.5, DN 35.9 ± 9.9 years), diabetes duration (DC 19.3 ± 6.9, DN 22.7 ± 5.8 years) and HbA_{1 c} values (DC 8.5 ± 1.4, DN 8.8 ± 1.6 %). Reactivity of PTX-sensitive G proteins was quantified by measuring platelet-activating factor (PAF)-induced Ca^{2 +} mobilisation (fura 2 method) and by mastoparan-stimulated [³⁵S]GTPγS binding. Expression of Gα_i proteins was quantified by Western blot analysis. PAF-evoked Ca^{2 +} increases above baseline averaged 77.0 ± 52.5 nmol/l in DC and 150.7 ± 61.5 nmol/l in DN (p = 0.005). PAF-evoked Ca^{2 +} increases correlated with stimulated [³⁵S]GTPγS binding (r ² = 0.42, p = 0.012). From Western blot analysis an overexpression of Gα_i proteins could be excluded in DN. A consequence of the altered metabolic milieu in diabetes is the increased release of vasoactive and proliferative agonists which promote glomerular hyperfiltration, hypertrophy, enhanced matrix deposition, and, finally, glomerulosclerosis. Many of these auto- and paracrine agonists bind to G protein-coupled receptors. Therefore, their cellular effects are reinforced by the enhanced G protein reactivity and increase the propensity to nephropathy in IDDM. [Diabetologia (1998) 41: 94–100] Received: 9 May 1997 and in revised form: 3 September 1997     

Arteriolar hyalinosis is related to rapid GFR decline and long-standing GFR changes observed on renal biopsies in normo-microalbuminuric type 2 diabetic patients

AimsWhether or not renal structural changes, especially arteriolar hyalinosis, are related to the rate of renal functional decline and increase in urinary albumin excretion (UAE) at the early stage of diabetic nephropathy in patients with type 2 diabetes is still unknown. Our previous study determined that arteriolar hyalinosis is an independent risk factor for low GFR. We sought to determine whether arteriolar hyalinosis is also a risk factor for rapidly progressive decline in GFR.MethodsWe evaluated 22 type 2 diabetic patients with normo- or microalbuminuria who took part in the previous study, to clarify which renal histological factors were associated with changes in UAE and the glomerular filtration rate (GFR) during 11.0 ± 3.0 years of follow-up. Light and electron microscopy-based morphometric analyses were performed to quantitatively evaluate the glomerular and interstitial structural changes.ResultsIn all 22 patients, the GFR was significantly decreased from baseline to follow-up, while the UAE did not change markedly between the 2 periods. After 11 ± 3 years of follow-up, the GFR was significantly lower in the rapid decliner group (annual rate of GFR decline ≥3.0%) than in the non-rapid decliner group (p = 0.017). The index of arteriolar hyalinosis (IAH) at baseline in the rapid decliners was significantly larger than in the non-rapid decliners (p = 0.015). The IAH showed a significant negative correlation with the GFR at follow-up (r = 0.50, p = 0.018) and the annual rate in the GFR decline (r = 0.47, p = 0.027) and significant positive correlations with UAE at follow-up (r = 0.46, p = 0.034) and the annual rate in the UAE increase (r = 0.57, p = 0.005). The GFR at follow-up in patients with IAH ≥2.0 was significantly decreased from baseline (p = 0.042) and significantly lower than that of the patients with IAH <2.0 (p = 0.026), which did not decrease significantly from baseline. The frequency of rapid decliners was larger in the IAH ≥2.0 than in the IAH <2.0 patients (p = 0.037).ConclusionsAggravated arteriolar hyalinosis was a risk factor for a rapid GFR decline. This finding might reflect initial changes in early diabetic nephropathy.     

Glomerular hyperfiltration in microalbuminuric NIDDM patients

Summary Glomerular hyperfiltration and microalbuminuria are both regarded as risk factors for the development of diabetic nephropathy in insulin-dependent diabetic patients. Information on glomerular hyperfiltration is scarse in microalbuminuric non-insulin-dependent diabetic (NIDDM) patients. Therefore, we performed a cross-sectional study of glomerular filtration rate (single i. v. bolus injection of ⁵¹Cr-EDTA, plasma clearance for 4 h) in 158 microalbuminuric NIDDM patients compared to 39 normoalbuminuric NIDDM patients and 20 non-diabetic control subjects. The groups were well-matched with regard to sex, age and body mass index. The uncorrected (ml/min) and the adjusted (ml · min^–1· 1.73 m^–2) glomerular filtration rate were both clearly elevated in the microalbuminuric patients: 139 ± 29 and 117 ± 24 as compared to 115 ± 19 and 99 ± 15; 111 ± 23 and 98 ± 21 in normoalbuminuric NIDDM patients and control subjects, respectively (p < 0.001). The glomerular filtration rate (ml · min^–1· 1.73 m^–2) in NIDDM patients who had never received antihypertensive treatment was also clearly elevated in the microalbuminuric patients (n = 96): 119 ± 22 as compared to 100 ± 14 and 98 ± 21 in normoalbuminuric NIDDM patients (n = 27) and control subjects (n = 20), respectively (p < 0.001). Glomerular hyperfiltration (elevation above mean glomerular filtration rate plus 2 SD in normoalbuminuric NIDDM patients) was demonstrated in 37 (95 % confidence interval 30–45)% of the microalbuminuric patients. Multiple regression analysis revealed that HbA_{1 c}, 24-h urinary sodium excretion, age and known duration of diabetes were correlated with glomerular filtration rate in microalbuminuric NIDDM patients (r ² = 0.21, p < 0.01). Our cross-sectional study indicates that NIDDM patients at high risk of developing diabetic nephropathy are also characterized by an additional putative risk factor for progression, glomerular hyperfiltration. [Diabetologia (1996) 39: 1584–1589]     

Prevalence of left ventricular hypertrophy in Type I diabetic patients with diabetic nephropathy

Summary The increased mortality of patients with diabetic nephropathy is mainly due to cardiovascular disease and end stage renal failure. Left ventricular hypertrophy is an independent risk factor for myocardial ischaemia and sudden death. The aim of our cross-sectional study was to evaluate left ventricular structure and function in Type I (insulin-dependent) diabetic patients with diabetic nephropathy. M-mode and Doppler echocardiography were done on 105 Type I diabetic patients with diabetic nephropathy [61 men, age (means ± SD) 44 ± 9 years, and albuminuria [median(range)] 567(10–8188) mg/24 h, serum creatinine 109 (53–558) μmol/l], and 140 Type I diabetic patients with persistent normoalbuminuria [79 men, 47 ± 10 years, urinary albumin excretion rate 8 (0–30) mg/24 h, and serum creatinine 81 (55–121) μmol/l]. Patients with and without nephropathy were comparable with respect to sex, body mass index, and duration of diabetes. Arterial blood pressure was slightly higher in patients with nephropathy: 140/79 ± 17/9 mm Hg vs 134/78 ± 15/8 mm Hg, p < 0.01, and the majority of proteinuric patients received antihypertensive drugs, 84 vs 17 %, respectively, p < 0.001. Left ventricular mass index was increased in the nephropathic group (means ± SD) 100.6 ± 23.9 g/m² compared with the normoalbuminuric group 91.4 ± 21.9 g/m², p = 0.002. Left ventricular hypertrophy was found more often in patients with nephropathy 23 (14–31)% compared with patients with normoalbuminuria 9 (5–14)%, p < 0.005. Diastolic function, assessed by the ratio between the peak diastolic velocity and the peak atrial systolic velocity (E/A ratio) and isovolumic relaxation time, was reduced in patients with vs without nephropathy: 1.17 ± 0.29 vs 1.34 ± 0.32, and 81.7 ± 16.5 vs 74.6 ± 14.5, p < 0.001 and p = 0.002, respectively. Systolic function was about the same and normal in both groups. Our study suggests that an increase in left ventricular mass index and a decrease in diastolic function occurs early in the course of diabetic nephropathy. [Diabetologia (1999) 42: 76–80] Received: 16 April 1998 and in final revised form: 5 August 1998     

Renal autoregulation is normal in newly diagnosed, normotensive, NIDDM patients

Summary Abnormalities of renal autoregulation with glomerular hyperfiltration and raised intraglomerular pressure have been suggested as important factors in the initiation and development of diabetic nephropathy. Angiotensin converting enzyme (ACE) inhibition appears to have a specific reno-protective role in diabetic nephropathy, possibly by reducing intraglomerular pressure. The acute effects of ACE inhibition on renal haemodynamics in normotensive, non-insulin-dependent diabetes mellitus (NIDDM) have not been previously reported. We measured simultaneous glomerular filtration rate (GFR) and renal plasma flow (RPF) in 29 (4 female) subjects, mean age 52 years (range 27–70), using ⁵¹Cr EDTA and ¹²⁵I Hippuran. Clearances were corrected to 1.73 m^–2. All patients were normotensive (blood pressure < 75^th centile for age and sex), newly diagnosed ( < 30 days), taking no antihypertensive or hypoglycaemic medication. Subjects were randomly allocated (double blind) to receive the ACE inhibitor trandolapril 4 mg day^–1 (H) (hypotensive dose), trandolapril 0.5 mg day^–1 (L) (non-hypotensive dose) or placebo (P) for 10 days after which renal haemodynamics were remeasured. For all subjects baseline GFR, RPF and filtration fraction (FF) were 97 ± 21 ml min^–1 mean ± SD, 439 ± 120 ml min^–1 and 22.3 ± 2.9 % respectively. Glomerular hyperfiltration (GFR > 120 ml min^–1) was only demonstrated in 3 subjects (10.3 %). In group H mean arterial pressure (103 ± 8 vs 93 ± 9 mmHg, p < 0.001) and FF (23.8 ± 2.3 vs 20.0 ± 4.0 %, p = 0.03) fell while RPF increased (376 ± 111 vs 426 ± 60 ml min^–1, p = 0.02), there was no significant change in GFR. No significant change in mean arterial pressure, GFR, RPF or FF occurred in groups P and L. These studies suggest that in newly diagnosed normotensive NIDDM subjects normal renal autoregulation occurs and glomerular hyperfiltration is uncommon. [Diabetologia (1998) 41: 206–211] Received: 2 July 1997 and in revised form: 16 September 1997     

Serum sialic acid concentration is elevated in IDDM especially in early diabetic nephropathy

Abstract. Objectives. Elevated serum sialic acid concentration is a strong predictor of cardiovascular mortality in non-diabetic subjects. Because patients with insulin-dependent diabetes mellitus (IDDM) and albuminuria have a highly increased cardiovascular morbidity and mortality, we hypothesized that IDDM patients with albuminuria would have an increased concentration of serum sialic acid. Design. Cross-sectional study. Setting. Outpatient clinic at Steno Diabetes Centre, Gentofte, Denmark. Subjects. Twenty-six non-diabetic controls and 74 IDDM patients with normoalbuminuria (urinary albumin excretion [UAE] < 30 mg 24 h^?1; n = 37), incipient nephropathy (UAE 30–300 mg 24 h^?1; n = 20) and clinical nephropathy (UAE > 300 mg 24 h^?1; n = 17), matched for sex, age and body mass index (BMI). Main outcome measures. Serum sialic acid concentration, concurrent fasting blood glucose, glycated haemoglobin (HbA1c), serum creatinine, plasma fibrinogen and erythrocyte sedimentation rate. Results. Normoalbuminuric patients had a higher serum sialic acid concentration (mmol L^?1) than non-diabetic controls (1.83 ± 0.24 vs. 1.67 ± 0.26; P < 0.02). Serum sialic acid concentration was further increased in patients with incipient nephropathy (2.02 ± 0.37; P < 0.03) and in patients with clinical nephropathy (2.13 ± 0.33; P < 0.002) compared with normoalbuminuric IDDM patients. Serum sialic acid correlated strongly with plasma fibrinogen (r = 0.78; P < 0.0001) and erythrocyte sedimentation rate (r = 0.62; P < 0.0001). In a multiple regression analysis including UAE, retinopathy status, fasting blood glucose, HbA1c, mean blood pressure, serum creatinine, age, BMI, duration and smoking, UAE and fasting blood glucose were the independent variables which correlated significantly with serum sialic acid concentration (P < 0.0001 and P < 0.05, respectively). Conclusion. Serum sialic acid is elevated in IDDM especially in albuminuric patients. Whether elevated serum sialic acid is predictive for early diabetic nephropathy and cardiovascular disease in IDDM has to be shown in the future.     

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     

Morphometric documentation of abnormal intramyocellular fat storage and reduced glycogen in obese patients with Type II diabetes

Aims/hypothesis. Insulin resistance of skeletal muscle has been associated with increased lipid availability. This study aimed to estimate volume fractions of intramyocellular triglyceride droplets and glycogen granules in skeletal muscle using electron microscopy and furthermore, relate these findings to insulin sensitivity and the level of circulating lipids. Methods. We compared 11 obese patients with Type II (non-insulin-dependent) diabetes mellitus and 11 obese normoglycaemic subjects matched for age and sex. Glucose metabolism was determined using the euglycaemic hyperinsulinaemic clamp technique (40 mU · m^–2· min^–1) coupled with indirect calorimetry and tritiated glucose. On the second day, using an automatic procedure, a fasting muscle biopsy was carried out and processed for electron microscopy. Volume fractions of intramyocellular structures were estimated by pointcounting on photographic pictures in a blinded manner. Results. Insulin-stimulated total glucose disposal rate was lower in the Type II diabetic subjects compared with the obese normoglycaemic subjects (4.96 ± 049 vs 10.35 ± 0.89 mg · min^–1· kg ffm^–1, p < 0.001) as was glucose storage (2.03 ± 0.50 vs 6.59 ± 0.83, p < 0.001). The electron microscopy study revealed that the diabetic subjects had higher intramyocellular amounts of triglyceride (1.43 ± 0.21 vs 0.39 ± 0.07 %, p < 0.001) and lower amounts of glycogen (3.53 ± 0.33 vs 6.94 ± 0.54 %, p < 0.001). Mitochondrial volume was identical indicating equal aerobic capacity. The fractional intramyocellular lipid volume was found to be positively associated with fasting NEFA (r = 0.63, p = < 0.05 and r = 0.79, p = < 0.05) and triglyceride (r = 0.74, p = 0.01 and r = 0.62, p < 0.05) in the obese diabetic and normoglycaemic cohorts respectively. Intramyocellular lipid content was negatively correlated to insulin sensitivity (r = –0.71, p < 0.02) in the obese diabetic group whereas no significant association was found in the obese normoglycaemic group. Conclusion/interpretation. This study shows that fat accumulates intramyocellulary while glycogen stores are simultaneously reduced in obese subjects with Type II (non-insulin-dependent) diabetes mellitus. Quantitatively, a major component of the excessive lipid accumulation could be secondary in origin, related to the diabetic state in itself, although a contribution from the altered insulin action cascade of obesity and diabetes cannot be excluded. In both groups significant positive relations were found between circulating and intramyocellular lipid. [Diabetologia (2001) 44: 824–833] Received: 6 December 2000 and in revised form: 16 March 2001     

The JEVIN trial: A population-based survey on the quality of diabetes care in Germany: 1994/1995 compared to 1989/1990

Summary Since 1990 in most Eastern European countries health care systems have been decentralized or are undergoing the processes of decentralization. Increasingly, diabetic patients are no longer treated by diabetologists but by non-specialized physicians. During the same period structured treatment and teaching programmes have been introduced and health care is increasingly influenced by the St. Vincent declaration. To show the effect of these changes on the quality of diabetes care 90 % (n = 244) of all insulin-treated diabetic patients aged 16 to 60 years and living in the city of Jena (100 247 inhabitants) were studied in 1994/1995. The results were compared with the baseline examination of 1989/1990 (n = 190). HbA_1c (HbA_1c/mean normal) in IDDM patients under specialized care was similar in 1994/1995 (1.54 ± 0.27, n = 47) to 1989/1990 (1.52 ± 0.31, n = 131, p = 0.0018), but higher under non-specialized care (1.71 ± 0.38, n = 80, p = 0.0087). In the total group of NIDDM patients there was no significant change in HbA_1c (1994/1995: 1.75 ± 0.4, n = 117, vs 1989/1990: 1.78 ± 0.4, n = 59, p = 0.67), but with a tendency to higher HbA_1c under non-specialized (1.81 ± 0.4, n = 79) compared to specialized care (1.66 ± 0.39, n = 38, p = 0.06). Incidence of severe hypoglycaemia (IDDM 0.13; NIDDM 0.04), ketoacidosis (0.02; 0.01) and the prevalence of nephropathy (21 %; 35 %) and neuropathy (24 %; 38 %) remained unchanged in comparison to 1989/1990, whereas there was an increase in the prevalence of diabetic retinopathy. Specialized care is mandatory for patients with IDDM. [Diabetologia (1997) 40: 1350–1357] Received: 3 April 1997 and in revised form: 18 June 1997     

Plasma homocysteine is related to albumin excretion rate in patients with diabetes mellitus: a new link between diabetic nephropathy and cardiovascular disease?

Summary The high risk of cardiovascular disease in patients with diabetes mellitus, particularly in those with nephropathy, is not completely explained by classical risk factors. A high plasma homocysteine concentration is an independent risk factor for cardiovascular disease but information on its association with diabetes is limited. Fasting homocysteine concentrations were measured in the plasma of 165 diabetic patients (75 with insulin-dependent [IDDM]; 90 with non-insulin-dependent diabetes [NIDDM]) and 56 non-diabetic control subjects. Other measurements included the prevalence of diabetic complications, glycaemic control, lipid and lipoprotein levels, vitamin status and renal function tests. Patients with NIDDM had higher homocysteine levels than control subjects, whereas IDDM patients did not (9.2 ± 4.5 vs 7.7 ± 2 μmol/l, p < 0.01; and 7.0 ± 3 vs 7.4 ± 2 μmol/l, NS). Univariate correlations and multiple regression analysis showed albumin excretion rate to be the parameter with the strongest independent association with homocysteine. Patients with both types of diabetes and nephropathy had higher plasma homocysteine concentrations than those without nephropathy. Increases of homocysteine in plasma were related to increases in the severity of the nephropathy. Fasting hyperhomocysteinaemia was considered as the mean of the plasma homocysteine for all control subjects (7.5 ± 2.1 μmol/l) + 2 SD (cut-off =11.7 μmol/l). Nephropathy was present in 80 % of diabetic patients with fasting hyperhomocysteinaemia. In conclusion, increases in fasting homocysteine in diabetic patients are associated with increased albumin excretion rate, especially in those with NIDDM, thus providing a potential new link between microalbuminuria, diabetic nephropathy and cardiovascular disease. [Diabetologia (1998) 41: 684–693] Received: 4 August 1997 and in final revised form: 4 February 1998     

Structural changes in renal arterioles in Type I diabetic patients

Aims/hypothesis. We aimed to obtain data on arteriolar structure in a follow-up study of microalbuminuric diabetic patients. Methods. Kidney biopsies were obtained at baseline and after 8 years in 18 Type I (insulin-dependent) diabetic patients. Albumin excretion rate, blood pressure and HbA_1C were measured regularly, and the glomerular filtration rate (GFR) was measured at the time of the kidney biopsy. The biopsy was embedded into plastic blocks and serially sectioned with 1 μm sections. In levels 25 μm apart, afferent and efferent arteriolar profiles were identified and digitised in the electron microscope. The extra-cellular matrix as volume fraction of the media was measured, and estimates of thickness of matrix, media, endothelium and lumen were obtained. Baseline and follow-up biopsies were studied concomitantly. Results. A large increase was seen in matrix volume fraction in afferent (p = 0.0001) and in efferent arterioles (p = 0.0004). Estimated thickness of media and matrix increased, whereas endothelial cell thickness decreased, over the 8 years. There was a correlation between the parameters of diabetic glomerulopathy and arteriolar parameters in the biopsies done at 8 years, basement membrane thickness compared with afferent matrix volume fraction: r = 0.74, p = 0.0005. Also aggravation of glomerulopathy and arteriolar structure over 8 years showed positive correlation. Arteriolar parameters correlated with the albumin excretion rate (AER) and inversely with GFR. Conclusion/interpretation. The arteriolar accumulation of matrix parallels that taking place in glomeruli and shows association with functional parameters over 8 years in Type I diabetic patients with microalbuminuria. These changes are considered an important part of the structural lesions in the diabetic kidney underlying the development of diabetic nephropathy. [Diabetologia (2002) 45: ▪–▪] Received: 9 October 2001 and in revised form: 29 November 2001     

Uptake mechanisms for ascorbate and dehydroascorbate in lymphoblasts from diabetic nephropathy and hypertensive patients

Summary In diabetic nephropathy and hypertension, a major cause of mortality is from cardiovascular disease. Since low levels of antioxidants such as vitamin C have been associated with such complications, we have examined the uptake mechanisms for ascorbic acid (AA) and dehydroascorbic acid (DHA) in lymphoblasts from normal control subjects (CON), normoalbuminuric insulin-dependent diabetic (IDDM) patients (DCON), patients with IDDM and nephropathy (DN) and hypertensive patients (HT) using mass assays of uptake and measuring AA using high-performance liquid chromatography. Precautions were taken to prevent oxidation of AA and to take into account the instability of DHA in buffers. DHA uptake was the major mechanism in all four groups of subjects, and the V_max (maximal uptake rate) was significantly lower in the DN cells (24.7 ± 1.0 nmol [95 % confidence intervals CI 22.5, 26.3] 10⁶ cells^–1 h^–1) compared to CON and DCON cells (33.9 ± 2.1 [95 % CI 29.4, 38.4] and 37.0 ± 2.2 [95 % CI 32.2, 41.8] nmol 10⁶ cells^–1 h^–1, respectively, p < 0.001 for both). DHA V_max was also lower in the HT group (23.2 ± 1.1 [95 % CI 20.7, 25.7] nmol 10⁶ cells^–1 h^–1) compared to the CON group (p < 0.001). There were no significant differences in the K_m or passive membrane permeability for DHA or the AA uptake. DHA uptake showed a negative correlation to systolic blood pressure (r _s = –0.49, p < 0.001). These findings suggest that impaired DHA uptake may be one component of the phenotype expressed by DN cells that may persist in culture. Impaired DHA uptake in vivo, especially in the presence of hyperglycaemia, leads to impaired regeneration of AA and depletion of anti-oxidant defences, exposing such individuals to increased risk of cardiovascular disease. [Diabetologia (1998) 41: 435–442] Received: 10 July 1997 and in final revised form: 24 November 1997     

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     

Assessment of baroreceptor-cardiac reflex sensitivity using time domain analysis in patients with IDDM and the relation to left ventricular mass index

Summary Autonomic dysfunction in insulin-dependent diabetic (IDDM) patients has been associated with abnormalities of left ventricular function and an increased risk of sudden death. A group of 30 patients with IDDM and 30 age, sex and blood pressure matched control subjects underwent traditional tests of autonomic function. In addition, baroreceptor-cardiac reflex sensitivity (BRS) was assessed using time domain (sequence) analysis of systolic blood pressure and pulse interval data recorded non-invasively using the Finapres beat-to-beat blood pressure recording system. ’Up BRS' sequences–increases in systolic blood pressure associated with lengthening of R-R interval, and ’down BRS' sequences–decreases in systolic blood pressure associated with shortening of R-R interval were identified and BRS calculated from the regression of systolic blood pressure on R-R interval for all sequences. We also assessed heart rate variability using power spectral analysis and, after expressing components of the spectrum in normalised units, assessed sympathovagal balance from the ratio of low to high frequency powers. IDDM subjects underwent 2-D echocardiography to assess left ventricular mass index. Standard tests of autonomic function revealed no differences between IDDM patients and control subjects, but dramatic reductions in baroreceptor-cardiac reflex sensitivity were detected in IDDM patients. ’Up BRS' when supine was 11.2 ± 1.5 ms/mmHg (mean ± SEM) compared with 20.4 ± 1.95 in control subjects (p < 0.003) and when standing was 4.1 ± 1.9 vs 7.6 ± 2.7 ms/mmHg (p < 0.001). Down BRS when supine was 11.5 ± 1.2 vs 22 ± 2.6 (p < 0.001) and standing was 4.4 ± 1.9 vs 7.3 ± 2.5 ms/mmHg (p < 0.003). There were significant relations between impairment of the baroreflex and duration of diabetes (p < 0.001) and poor glycaemic control (p < 0.001). From a fast Fourier transformation of supine heart rate data and using a band width of 0.05–0.15 Hz as low-frequency and 0.2–0.35 Hz as high frequency total spectral power of R-R interval variability was significantly reduced in the IDDM group for both low-frequency (473 ± 62.8 vs 746.6 ± 77.6 ms² p = 0.002) and high frequency bands 125.2 ± 12.9 vs 459.3 ± 89.8 ms² p < 0.0001. When the absolute powers were expressed in normalised units the ratio of low frequency to high frequency power (a measure of sympathovagal balance) was significantly increased in the IDDM group (2.9 ± 0.53 vs 4.6 ± 0.55, p < 0.002 supine: 3.8 ± 0.49 vs 6.6 ± 0.55, p < 0.001 standing). Thus, time domain analysis of baroreceptor-cardiac reflex sensitivity detects autonomic dysfunction more frequently in IDDM patients than conventional tests. Impaired BRS is associated with an increased left ventricular mass index and this abnormality may have a role in the increased incidence of sudden death seen in young IDDM patients. [Diabetologia (1996) 39: 1385–1391] Received: 9 April 1996 and in revised form: 19 July 1996     

Improvement of blood glucose control in IDDM patients retards the progression of morphological changes in early diabetic nephropathy

Summary We investigated in a randomized, prospective study the influence of improved blood glucose control during 2–3 years in young insulin-dependent diabetic (IDDM) patients with microalbuminuria, which is indicative of early nephropathy. Patients were randomized either to intensive treatment by continuous subcutaneous insulin infusion (CSII) (n =9) or CT (n =9). Kidney biopsies were taken at baseline and after 26–34 months. End points were structural changes in the glomeruli. Sensitive, quantitative, morphometric methods were used. The blood glucose control improved significantly (p =0.01) during the study in the CSII-group as glycated haemoglobin (HbA_{1 c}) fell from 10.1 % ([95 % CI] 8.9–11.3) to 8.6 % (7.9–9.2), but not in the CT-group, 10.1 % (8.3–11.9) vs 9.7 % (8.7–10.8). Mean HbA_{1 c} during the study period was significantly lower in the CSII-group than in the CT-group, 8.7 % (8.1–9.3) vs 9.9 % (8.5–11.3), p =0.04. Basement membrane thickness (BMT) increased in both groups, most (CT vs CSII, p =0.03) in the CT-group: 140 nm (50–230) vs CSII: 56 nm (27–86). In the CT-group only an increase was seen in matrix/mesangial volume fraction (p =0.006) and matrix star volume (p =0.04). Furthermore, a positive correlation between mean HbA_{1 c} during the study and change from baseline in BMT (r =0.70, p =0.001) and matrix/glomerular volume fraction (r =0.33, p =0.09, NS) was demonstrated. Albumin excretion rate correlated significantly to BMT and most of the matrix parameters. The present study shows that during a period of only 2.5 years, a close relationship between the level of mean blood glucose and progression of glomerular morphological changes in early diabetic nephropathy can be demonstrated. [Diabetologia (1994) 37: 483–490] Received: 24 August 1993 and in revised form: 23 November 1993     

Genetic Variation of a Collagen IV α1-Chain Gene Polymorphism in Danish Insulin-dependent Diabetes Mellitus (IDDM) Patients: Lack of Association to Nephropathy and Proliferative Retinopathy

In insulin-dependent (Type 1) diabetes mellitus (IDDM) the development of nephropathy is partly due to genetic susceptibility. Previously one study has demonstrated a relationship between a HindIII restriction polymorphism of the collagen IV α1-chain gene and diabetic nephropathy. The aim of the present study was to evaluate such as association in a case–control study including 207 Danish IDDM patients: 116 with nephropathy (urinary albumin excretion rate (AER) > 300 mg 24 h⁻¹) and 91 without nephropathy (AER < 30 mg 24 h⁻¹). Using genomic DNA, HindIII restriction fragment length analysis revealed a bi allele polymorphism visualized by Southern hybridization with a cDNA probe recognizing the collagen IV α1-chain gene. No differences in genotype frequencies or allele frequencies were demonstrated comparing patients with and without nephropathy: p = 0.39 and p = 0.96, respectively. Neither were there any difference in genotype frequencies or allele frequencies when the patients were stratified according to the presence of proliferative retinopathy: p = 0.44 and p = 0.84, respectively. Pooling the diabetic groups revealed genotype frequencies and allele frequencies comparable to those found in 57 healthy unrelated Danish individuals. We conclude that in a Danish IDDM population a HindIII restriction polymorphism of the collagen IV α1-chain gene is not associated with diabetic nephropathy, diabetic retinopathy or with diabetes per se. © 1997 by John Wiley & Sons, Ltd.