Kidney function and glomerulopathy over 8 years in young patients with Type I (insulin-dependent) diabetes mellitus and microalbuminuria.

AIMS/HYPOTHESIS: We aimed to investigate prospectively the interrelation between kidney function and glomerular morphological changes over 8 years in young patients with Type I (insulin-dependent) diabetes mellitus and microalbuminuria. METHODS: Kidney biopsies were taken at baseline and after 8 years in 18 subjects who were 20 years of age (19-29 mean and range), had duration of diabetes for 11 years (7-18), and who had an albumin excretion rate of 45 microg/min (15-194). The glomerular ultrastructural parameters were analysed using stereological methods. RESULTS: At the end of the study three patients had an increased albumin excretion rate of more than 25 % a year, two of whom developed overt nephropathy. Glomerular filtration rate declined 2.3 ml/min x 1.73 m(-2) x yr(-1). Glomerular volume, volume fractions of matrix and mesangium, and basement membrane thickness showed an increase over the 8 years. Multiple regression analysis showed that mean 8-years HbA(1 c), matrix volume fraction(baseline) and basement membrane thickness BMT(baseline) accounted for 70 % of the variation in AER at the end of the study. Mesangial volume fraction(baseline,) glomerular filtration fraction(baseline,) and mean 8-year HbA(1 c) accounted for 73 % of the change in glomerular filtration rate from baseline. Smoking was strongly associated with the glomerular filtration rate at baseline ( r = 0.65). When glomerular filtration rate(baseline) was omitted from the equation, smoking was the only significant parameter linked to the change in glomerular filtration rate from the baseline. CONCLUSION/INTERPRETATION: In patients who had diabetes for 20 years, long-term hyperglycaemia and glomerulopathy found 8 years prior to the study, and possibly smoking, affected renal function (i. e. albumin excretion rate and glomerular filtration rate).

The juxtaglomerular apparatus in young type-1 diabetic patients with microalbuminuria. Effect of antihypertensive treatment.

BACKGROUND: Our goal was to investigate the effect of antihypertensive drugs on the juxtaglomerular apparatus (JGA) in young type-1 diabetic patients with microalbuminuria. METHODS: Twelve patients were allocated to treatment with either an angiotensin-converting enzyme inhibitor (group 1, six subjects) or a beta-receptor blocker (group 2, six subjects). A comparable group of nine patients without antihypertensive treatment provided reference values (group 3, nine subjects). Renal biopsies were taken at baseline and after a median of 40 months (groups 1 and 2) and 30 months (group 3). Using light microscopy with 1microm serial sections of the plastic-embedded biopsies, volumes of the JGA and glomerulus and areas of the macula densa and lumina of the afferent and efferent arterioles were obtained. RESULTS: A significant decrease of the volume of the JGA (P=0.026) and of the volume of the JGA relative to that of its corresponding glomerulus (P=0.0005) was noted in the reference group only. Negative correlations existed between the increase in the luminal area of the afferent arteriole and mean diastolic blood pressure in the study period in group 1 (P=0.024) and group 2 (P=0.032). CONCLUSIONS: Our results showed that a decrease in the size of the JGA is offset by antihypertensives. The negative correlation between the change in the luminal area of the afferent arteriole and mean diastolic blood pressure in groups 1 and 2 suggest that renal protection in antihypertensive treatment may be through a better constriction of the afferent arteriole protecting the glomerulus from systemic blood pressure.

Urinary albumin excretion rate and glomerular filtration rate in the prediction of diabetic nephropathy; a long-term follow-up study of childhood onset type-1 diabetic patients.

BACKGROUND: Predictors of diabetic nephropathy are only partly known. The role of glomerular hyperfiltration is much discussed. We have studied the cumulative incidence of micro and macroalbuminuria and the predictive value of glomerular filtration rate (GFR) and screening value of albumin excretion rate (AER) in type-1 diabetes. METHODS: A cohort of diabetic children was followed up at a mean duration of 29+/-3 years. All 75 children treated in one hospital with diabetes duration > or =8 years were prospectively followed for 8 years examining GFR, AER, blood pressure and HbA1c. After another 8-10 years, 60 of them were traced for endpoint follow-up. RESULTS: Seven patients (12%) developed macroalbuminuria, i.e. persistent overnight AER>200 mg/min, 12 (20%) developed persistent microalbuminuria (AER 15-200 mg/min) and 17 (28%) transient microalbuminuria (>15 mg/min on two consecutive occasions, normalized at endpoint). One baseline screening value of 24-h AER>15 mg/min predicted 93% of patients with persistent micro or macroalbuminuria. The negative predictive value was 78%. Six of seven macroalbuminuric and 10 of 12 microalbuminuric patients had a baseline GFR above the normal limit of the method (> or =125 ml/min/1.73 m(2)). When adjusted for diabetes duration, increased GFR predicted macro or microalbuminuria (odds ratios=5.44, P=0.04). The positive predictive value for having an increased baseline GFR was 53%. The negative predictive value was 77%. Stratification for HbA1c did not change the effect of an increased GFR. CONCLUSIONS: At a mean diabetes duration of 29 years the cumulative incidence of macroalbuminuria was 12%; however, another 20% had persistent microalbuminuria. A screening value of 24-h AER >15 mg/min was a strong predictor, whereas increased GFR was a weaker but significant predictor for micro and macroalbuminuria.

Higher intakes of fish protein are related to a lower risk of microalbuminuria in young Swedish type 1 diabetic patients.

OBJECTIVE: To examine the influence of dietary intake from various protein and fat sources on the occurrence of microalbuminuria in type 1 diabetic patients. RESEARCH DESIGN AND METHODS: In this nested case control study, 1,150 patients with diabetes duration >5 years reported dietary habits for the previous 12 months and submitted urinary samples for the analysis of albumin excretion rate (AER). A total of 75 cases of albuminuria (overnight AER > or = 15 microg/min) were identified and compared with 225 duration-matched control subjects. RESULTS: Neither mean protein, fat intake, average fish protein intake (control subjects 4.56 +/- 3.83 g/day and cases 3.82 +/- 2.87 g/day; P = 0.12), nor intake of meat and vegetable protein differed between the cases of albuminuria and the control subjects. High consumers of fish protein (greater than the 75th percentile) (12 cases and 63 control subjects, mean intake 9.35 g fish protein/day, i.e., approximately 53 g fish/day) had lower odds ratios (ORs) for microalbuminuria than individuals consuming less fish protein (mean 2.72 g/day) (crude OR 0.49 and 95% CI 0.25-0.97). When adjusted for known confounding factors, such as HbA1c, mean arterial pressure, diabetes duration, age, sex, smoking, BMI, country region, and total energy, individuals with a high intake of fish protein and fish fat showed a reduction in the risk for microalbuminuria (OR 0.22 and 0.31, respectively; 95% CI 0.09-0.56 and 0.13-0.76, respectively). When fish protein and fat were adjusted for each other, a high intake of fish protein but not of fish fat was still significantly associated with a decrease in the risk for microalbuminuria. CONCLUSIONS: Total protein and fat intake were not associated with the presence of microalbuminuria, but a diet including a high amount of fish protein seemed to lessen the risk.

On glomerular structural alterations in type-1 diabetes. Companions of early diabetic glomerulopathy.

Glomerular structural modifications were measured in kidney biopsies from two follow-up studies in type-1 diabetic patients with microalbuminuria and in kidney donors. Stereologic methods were used to obtain data on glomerular composition and absolute quantities per glomerulus to supplement data on diabetic glomerulopathy previously published. Diabetic patients at baseline (n=37) showed significant changes compared with controls (n=11). The volume fraction of tuft/glomerulus was increased, the proportion of capillary surface facing peripheral basement membrane was decreased (0.72+/-0.04 vs 0.77+/-0.03, P=0.0008), the ratio of mesangial surfaces, urinary/capillary, was decreased (0.67+/-0.17 vs 1.11+/-0.28, P<10(-4)), and the average capillary diameter was increased (8.9+/-0.9 microm vs 7.5+/-1.0 microm, P=0.0002). The total volume of mesangial extracellular material per glomerulus was increased (P=0.01), whereas glomerular volume was not significantly different from controls. Follow-up biopsies after antihypertensive treatment with ACE-inhibitor (n=7) or beta-blocker (n=6; 36-48 months) and after intensive insulin treatment (n=7; 24-33 months) showed no change. In a conventionally treated group (n=9), the glomerular volume, the volume of extracellular material/glomerulus, and the capillary length increased. The mean capillary diameter did not correlate with the glomerular volume. In conclusion, the development of diabetic glomerulopathy entails structural modifications of the glomerular tuft. Antihypertensive and intensified insulin treatment seem to slow the progression of ultrastructural changes.

Follow-up study of glomerular dimensions and cortical interstitium in microalbuminuric type 1 diabetic patients with or without antihypertensive treatment.

BACKGROUND: A decrease in urinary albumin excretion is regularly seen with antihypertensive treatment in patients with diabetic nephropathy. Our study concerns structural data obtained by light microscopy in baseline and follow-up biopsies in antihypertensive treated patients and in a reference group. METHODS: Microalbuminuric type 1 diabetic patients with diabetes duration of 6-16 years were studied. Two groups, allocated to treatment with either angiotensin-converting enzyme-inhibitor (group 1, n=6) or beta-blocker (group 2, n=6) after the baseline biopsy, were studied in parallel, whereas the reference group (group 3, n=9), without antihypertensive treatment, was part of a previously completed study. The renal plastic-embedded biopsies were serially sectioned (1 microm), the sections being used for determining glomerular volume, vascular pole area, and interstitial space expressed as fraction of tubular cortex. RESULTS: A significant increase in glomerular volume (P=0.04) was seen in group 3 only. Vascular pole area (VPA) and VPA relative to calculated glomerular surface did not show significant changes in any of the groups, only a tendency to increase in VPA in group 3 (P=0.051). The increase in VPA correlated with systolic blood pressure during the study period (r=0.49, P=0.03). Glomerular volume did not correlate with HbA(1C), current diabetic glomerulopathy, or ensuing worsening of glomerulopathy. In group 3 every case showed an increase in interstitium (P=0.0009), group 2 showed a decrease (P=0.03), and group 1 showed no change. Increase in interstitial fractional volume correlated with diastolic blood pressure during the study (r=0.54, P=0.01). CONCLUSIONS: In early microalbuminuria, type 1 diabetic patients show glomerular growth, probably compensatory to the developing glomerulopathy. The increase in interstitial volume fraction, demonstrable in early nephropathy, is further augmented over a few years, but is arrested by antihypertensive treatment.

Influence of insertion/deletion polymorphism in the ACE-I gene on the progression of diabetic glomerulopathy in type 1 diabetic patients with microalbuminuria.

OBJECTIVE: To investigate the influence of the insertion/deletion polymorphism of the ACE gene on the progression of early diabetic glomerulopathy in patients with and without antihypertensive treatment (AHT). RESEARCH DESIGN AND METHODS: There were 30 microalbuminuric patients with >5 years of type 1 diabetes who had renal biopsies taken at baseline and after 26-48 months of follow-up. Of the 30 patients, 13 (4 with II genotype and 9 with ID and DD genotypes) were randomized to AHT (enalapril or metoprolol) during the study. The ACE genotype was determined by a polymerase chain reaction. Glomerular structural changes were measured by stereological methods. RESULTS: Of the patients, 8 had the II genotype, 19 had ID genotype, and 3 had DD genotype. During the study, basement membrane thickness, matrix star volume, and the overall diabetic glomerulopathy index were increased in patients with ID and DD genotypes only (P < 0.001, P = 0.01, P < 0.001, respectively). Among those with ID and DD genotypes, progression of basement membrane thickening and diabetic glomerulopathy index were increased in those without AHT, as compared with the antihypertensive treated patients (P < 0.001, P = 0.02, respectively). In multivariate analysis, the ACE genotype had an independent influence on the progression of basement membrane thickening (P = 0.01), when AHT (P < 0.001) and the mean HbAlc during the study (P < 0.001) were also taken into account. ACE genotype tended to be independently associated with the diabetic glomerulopathy index (P = 0.05). CONCLUSIONS: Microalbuminuric type 1 diabetic patients carrying the D-allele have an increased progression of diabetic glomerulopathy. Presence of this allele and no AHT seems to enhance this process. Larger studies are needed to confirm the clinical significance of our findings.

[Perinatal factors can be risk factors of diabetic nephropathy]. / Perinatala faktorer kan utgöra risk för diabetesnefropati.

This article discusses the association of perinatal risk determinants and the future development of diabetic nephropathy. A low birth-weight seems to increase the risk for future cardiovascular disease, hypertension and insulin resistance, all of which are features of diabetic nephropathy. In a nation-wide case-controlled study we found that smoking during pregnancy and low maternal education, rather than low birth weight per se increase the risk of developing incipient nephropathy in offspring with type-1 diabetes. These factors are in addition to, and independent of, a familial disposition for cardiovascular disease and hypertension. Persistent hyperglycaemia is a prerequisite for the influence of these factors. Our findings support the hypothesis of a multifactorial aetiology of diabetic nephropathy.

Renal arterioles in patients with type I diabetes and microalbuminuria before and after treatment with antihypertensive drugs.

Antihypertensive drugs can slow or even reverse the progression of diabetic nephropathy at the microalbuminuric stage. This study was performed to obtain quantitative data on changes in the renal arterioles in a follow-up study. Twelve patients with type I diabetes and with microalbuminuria were allocated to treatment for 3 years with either an ACE inhibitor (group I, 6 patients) or a beta blocker (group II, 6 patients). Baseline and follow-up renal needle biopsy specimens were taken and serially sectioned at 1 microm for light microscopy, enabling identification of arterioles as afferent or efferent. Thin sections for electron microscopy were made at 50-microm intervals, and micrographs were taken of arteriolar profiles. Matrix volume fraction of the media and a calculated matrix thickness were obtained. At baseline, structural parameters were higher than normal values. At follow-up all patients were normoalbuminuric. Both groups showed only minor changes in arteriolar structures over 3 years. In the afferent arterioles in group II there was a significant increase in the matrix volume fraction of the media, and there was a tendency to an increase in matrix thickness in both groups. In the efferent arterioles there were no significant changes in parameters. There were no differences between the two groups in arteriolar structural changes from baseline to follow-up. Thus, this study shows a slight but significant matrix accumulation in the afferent arterioles during treatment with antihypertensive drugs. This may have implications for the progression to overt nephropathy, which indicates a need for more long-term studies of treatment with antihypertensive drugs in incipient nephropathy in type I diabetes.

Effect of angiotensin converting enzyme inhibitor or beta blocker on glomerular structural changes in young microalbuminuric patients with Type I (insulin-dependent) diabetes mellitus.

AIMS/HYPOTHESIS: To investigate the influence of angiotensin converting enzyme inhibitors and beta blockers on the progression of early diabetic glomerulopathy. METHODS: Thirteen patients with Type I (insulin-dependent) diabetes mellitus (mean age 18.8 years) with microalbuminuria 31 (19-160) microg/min were randomised to treatment with enalapril (group 1, n = 7) or metoprolol (group 2, n = 6). Renal biopsies were taken before and after 38 (36-48) months of treatment. Albumin excretion rate, blood pressure and HbA1c were measured every third month. A reference group without antihypertensive treatment (group 3, n = 9), with similar age, diabetes duration and degree of microalbuminuria as group 1 and 2, had baseline and follow-up renal biopsies taken previously with an interval of 26-34 months, analysed at the same laboratory. Glomerular structures were measured by stereological methods. RESULTS: Measurements of basement membrane thickness, mesangial and matrix volume fractions were similar among groups at baseline. Structural variables were only increased in group 3 at follow-up. Delta values in basement membrane thickness and diabetic glomerulopathy index per 24 months were lower in group 1 and 2 than in group 3 (p < 0.05). Microalbuminuria returned to normal in group 1 and 2 only. Decreased albumin excretion rate tended to inversely correlate with increased basement membrane thickness (p = 0.08) and diabetic glomerulopathy index (p = 0.05). Mean HbA1c was similar between groups. Mean diastolic blood pressure was lower in group 1 and 2 than in group 3 (p < 0.01). Mean HbA1c and mean diastolic blood pressure correlated to changes in basement membrane thickness, mesangial volume fraction and diabetic glomerulopathy index (p < 0.05). CONCLUSION/INTERPRETATION: Contrary to findings in the group without antihypertensive treatment, no progression of glomerulopathy was seen in those treated with enalapril or metoprolol.

Neovascularization at the vascular pole region in diabetic glomerulopathy.

BACKGROUND: Diabetic nephropathy is associated with renal structural changes involving all of the compartments. Most characteristic is the diabetic glomerulopathy. Studies of the histological changes during the early phases of nephropathy have included the glomerulopathy and also the juxtaglomerular structures. Neovascularization, well-known in diabetic retinopathy, has also been observed in the kidney. The present study concerns estimates of frequency of neovascularization at the vascular pole region in early stages of diabetic nephropathy. METHODS: Extra efferent arterioles at the glomerular vascular pole were detected during measurements of the vascular pole area applying 1-microm serial sections through kidney biopsies. It was observed that more than one efferent arteriole existed occasionally. The present study was carried out with the aim of estimating the frequency of this phenomenon in diabetic patients and in non-diabetic controls, the diabetic patients categorized according to the level of albumin excretion rate. RESULTS: Neovascularization was first observed in IDDM patients with microalbuminuria. Some of the cases presented the phenomenon in all of the glomeruli studied. As the examinations of many kidney biopsies continued the phenomenon was observed also in the non-diabetic control group and in one IDDM patient with normoalbuminuria. However, the frequency was statistically highly significantly increased in patients with elevated albumin-excretion. Within this group a strong correlation between frequency of neovascularization and the severity of diabetic glomerulopathy is seen. CONCLUSIONS: The vascular abnormality localized to the vascular pole region is observed occasionally in the normal kidney, but the frequency is increased in patients with diabetic glomerulopathy. The abnormality may develop as a consequence of a long-standing diabetic glomerulopathy and might lead to less pronounced elevation of albumin excretion.

Enlargement of the juxtaglomerular apparatus in insulin-dependent diabetes mellitus patients with microalbuminuria.

Kidney biopsies from 15 insulin-dependent diabetes mellitus (IDDM) patients with microalbuminuria were investigated to obtain quantitative data on the juxtaglomerular apparatus. The IDDM patients were young and normotensive with a mean duration of microalbuminuria of 2 years. Eight healthy kidney donors served as controls. Measurements taken by light microscopy, using 1-microm serial sections of epon blocks, included volumes of the juxtaglomerular apparatus and of glomeruli, areas of the macula densa and luminal area of the juxtaglomerular (afferent and efferent) arterioles at the level of the glomerular vascular pole. The volume of the juxtaglomerular apparatus was significantly larger in the IDDM group than in controls [6.08 (2.96-18.8) 10(4) microm3 vs 3.48 (1.84-5.21) 10(4) microm3, P=0.003, median and (range)], as was the volume of the juxtaglomerular apparatus relative to glomerular volume [1.89(1.28-4.21)% vs 1.48 (1.13-1.71)%, P=0.004]. The area of the macula densa was also larger in the IDDM patients (1370 microm2 vs 937 microm2, P=0.03). Luminal areas of the afferent and efferent arterioles and the ratio between them did not differ significantly between the two groups. In conclusion, the juxtaglomerular apparatus is enlarged more than would be expected from the glomerular hypertrophy in IDDM patients with microalbuminuria.

Familial and perinatal risk factors for micro- and macroalbuminuria in young IDDM patients.

It has been suggested that hereditary risk for hypertension and cardiovascular disease (CVD) as well as intrauterine growth may be involved in the pathogenesis of diabetic nephropathy. In the present study, we investigated the influence of familial and perinatal risk factors on the occurrence of micro- and macroalbuminuria in young IDDM patients. A cohort of 1,150 young patients with > or =5 years' duration of IDDM was screened for microalbuminuria. Data on family history of hypertension, CVD, IDDM, and NIDDM; perinatal factors such as birth weight, gestational age, and duration of breastfeeding; and maternal education, smoking, hypertension, and proteinuria during pregnancy were collected. We identified 75 patients with an albumin excretion rate > or =15 microg/min in more than two overnight urinary samples and compared them in a nested case-control study with three normoalbuminuric control subjects per patient from the same cohort, matched for diabetes duration. Perinatal factors were analyzed in all patients born at term (+/- 2 weeks), 59 of the 75 patients and 155 of the 225 control subjects. In univariate analysis, hypertension in parents (odds ratio [OR] 4.21), CVD in parents and grandparents (OR 1.26), maternal smoking during pregnancy (OR 3.21), and a low level of maternal education (OR 2.33) were significantly associated with the development of micro- and macroalbuminuria. When adjusted for other familial and perinatal factors, current mean blood pressure, HbA1c, smoking, BMI, sex, age, and postpubertal diabetes duration, using logistic regression analyses, only parental hypertension in all patients and maternal smoking during pregnancy and low level of maternal education in full-term patients were independent risk factors. When patients with poor glycemic control were analyzed separately, familial CVD, poor metabolic control, parental hypertension, maternal smoking during pregnancy, and level of maternal education were independent risk factors, with the adjusted OR markedly increased, compared with the matched subgroup with better HbA1c. In conclusion, familial hypertension and CVD, maternal smoking during pregnancy, and low level of maternal education may independently increase the risk for incipient nephropathy in full-term offspring who later develop IDDM. Current poor glycemic control seemed to increase the effect of these risk factors.

Diabetic glomerulopathy in young IDDM patients. Preventive and diagnostic aspects.

The clinical course of diabetic nephropathy may be described in stages; the normo-, micro- and macroalbuminuric stage. The basis for its development is the diabetic glomerulopathy in which accumulation of basement membrane (BM) material is pivotal. Normoalbuminuric patients have normal or slightly increased BM thickness; microalbuminuric patients show further BM thickening and mesangial expansion, formation of new capillaries, arteriolar and interstitial changes. The degree of diabetic glomerulopathy may be predicted by long-term glycemic control, diabetes duration and glomerular filtration rate (GFR). A slight decline in GFR in microalbuminuric patients is associated with increases in BM thickness, capillary diameter and interstitial volume fraction. In turn, the degree of early diabetic glomerulopathy may predict the level of microalbuminuria several years later. Improved metabolic control, even to not normal levels, retards the increase of BM thickness and matrix volume in microalbuminuric adolescents. If matrix accumulation may be prevented diabetic nephropathy will not develop. Morphometric analyses may thus be useful in evaluating the effect of intervention, also during shorter periods and at early stages.

Serum leptin levels in young females with insulin-dependent diabetes and the relationship to hyperandrogenicity and microalbuminuria.

To investigate the relationship between leptin levels and IDDM with and without microalbuminuria, fasting serum levels of leptin, insulin, insulin-like growth factor-1 (IGF-1), sex hormone-binding globulin (SHBG), testosterone (SHBG) ratio, blood pressure and body mass index (BMI) were measured in 18 normo- and 11 microalbuminuric females with >5 years of IDDM, and 24 healthy controls in late puberty. Leptin levels were higher in micro- than normoalbuminuric IDDM patients, and lower in healthy controls than in both IDDM groups (p < 0.05, respectively). In multiple regression analysis, presence of IDDM and BMI independently contributed to increased leptin values (R2 = 0.34, p < 0.001). Including IDDM females only, solely low IGF-1 and high testosterone/SHBG were associated with leptin (R2 = 0.39, p = 0.009). Albumin excretion rate (AER) was correlated to leptin (r = 0.48, p = 0.01). With AER as the dependent variable only serum leptin and diastolic blood pressure added to the regression (R2 = 0.59, p < 0.001). In conclusion, serum leptin, independently of BMI, is: (1) increased in IDDM females of late puberty; (2) associated with low IGF-1 and hyperandrogenemia, and (3) related to increased albumin excretion rate in IDDM females.

Decreasing glomerular filtration rate--an indicator of more advanced diabetic glomerulopathy in the early course of microalbuminuria in IDDM adolescents?

BACKGROUND: Overt diabetic nephropathy is accompanied by a progressive decline in glomerular filtration rate (GFR). In this study we have investigated if a reduction of GFR already during the transition from normo- to microalbuminuria is associated with glomerular structural changes. METHODS: Seventeen adolescents (11 girls/6 boys) with 10.5 (3.3) (mean, SD) years of IDDM were studied. GFR was previously measured in the normoalbuminuric stage 2-5 years prior to the renal biopsy, and measured again at the time for the biopsy, after in mean 1.8 years of microalbuminuria (15-200 micrograms/min). HbAlc and albumin excretion rate were measured 3 or 4 times yearly and blood pressure 1-4 times yearly between the GFR examinations. The associations between the yearly rate of fall in GFR and basement membrane (BM) thickness, mesangial and matrix volume fractions, matrix star volume, mean capillary diameter (CAPD), area of filtration surface (peripheral BM) per glomerulus, total capillary length per glomerulus, the ratio of peripheral BM to capillary surface, glomerular volume, and interstitial volume fraction were analysed. RESULTS: BM thickness and matrix star volume were increased in patients with, as compared to those without, a decline in GFR > or = 6 ml/min per year (P < 0.005 respectively). Patients with previous glomerular hyperfiltration (> or = 135 ml/min per 1.73 m2) showed the steepest decline in GFR; 11 ml/min per year versus -0.8 ml/min per year in previously normofiltering patients, P < 0.001. The rate of fall in GFR was positively correlated to BM thickness (P < 0.001), interstitial volume fraction (P = 0.02) and CAPD (P = 0.04), mean HbAlc (P = 0.01), but not to the change in HbAlc between GFR examinations. CONCLUSION: A decreasing glomerular filtration rate in the early stage of microalbuminuria may be due to more advanced diabetic glomerulopathy than in IDDM patients with stable GFR.

The dopaminuric response to high salt diet in insulin-dependent diabetes mellitus and in family history of hypertension.

Alterations in the renal dopamine [DA] system have been suggested to contribute to the development of hypertension and diabetic nephropathy. To identify early abnormalities in renal handling of DA and sodium we challenged 16 normotensive patients with uncomplicated insulin-dependent diabetes (IDDM), 18 normotensive nondiabetic subjects with familial borderline hypertension, and 16 healthy controls, 14-29 years old, with a high-sodium diet (HSD). Systolic blood pressure was slightly higher in subjects with familial borderline hypertension than in the other groups on a normal sodium diet (NSD) (P < 0.05). Blood pressure and 24-h urinary measurements were performed on a NSD and after 3 days on a HSD. Twenty-four-hour urinary DA excretion was similar in all groups on NSD. A significant rise in DA excretion was noted after HSD in control subjects (P < 0.01), but not in subjects with a family history of hypertension or with IDDM. Urinary sodium excretion increased in all groups. A correlation between the change in DA and sodium/creatinine ratio after HSD was seen in healthy controls (r = 0.57, P = 0.02) but not in those with familial borderline hypertension (r = 0.18, P = 0.47) or with IDDM (r = 0.40, P = 0.15). A rise in systolic (but not diastolic) pressure was noted only in the IDDM group after HSD (P = 0.02). In conclusion, an impairment in the renal DA and sodium system can be detected early in IDDM and in individuals with familial hypertension. We speculate that this impairment may contribute to the development of hypertension and microvascular disease in both conditions.

Predictors of renal morphological changes in the early stage of microalbuminuria in adolescents with IDDM.

OBJECTIVE: To evaluate the impact of glycemic control, blood pressure, lipid levels, glomerular filtration rate (GFR), age, and duration of IDDM on the degree of structural glomerular changes in the transitional stage of microalbuminuria. RESEARCH DESIGN AND METHODS: Fifteen adolescents (seven boys and eight girls) with > 5 years of duration of IDDM and with low-grade microalbuminuria (15-30 micrograms/min) participated. Seventeen living kidney donors served as healthy control subjects. Five-year mean HbA1c; 5-year mean systolic and diastolic blood pressure; GFR, cholesterol, and triglycerides 2-5 years before renal biopsy; age; and duration of IDDM were investigated and related to basement membrane thickness (BMT), mesangial and matrix volume fractions, and the overall glomerulopathy index [(BMT/10 + mat/glom, %) + matrix star volume]. RESULTS: BMT and the overall diabetic glomerulopathy were increased in diabetic patients as compared with control subjects (P < 0.001), whereas matrix volume fraction, but not mesangial volume fraction, tended to be increased (P = 0.11). In multivariate analysis, BMT was predicted by 5-year mean HbA1c, diabetes duration, and previous GFR (R2 = 0.71, P = 0.003). With matrix volume fraction as the dependent variable, BMT and diabetes duration were the only significant determinants (R2 = 0.63, P = 0.003). Diabetes duration, 5-year mean HbA1c, and GFR were the variables with an independent influence on the overall diabetic glomerulopathy index (R2 = 0.72, P = 0.003). Preceding blood pressure and lipid levels or age had no significant independent influence on these morphometric measures. CONCLUSIONS: In the very early stage of microalbuminuria in IDDM adolescents, a high percentage of the variation in BMT and overall severity of glomerulopathy is explained by prolonged hyperglycemia and diabetes duration. Previous glomerular hyperfiltration may also add to the prediction of these morphological changes.

Glomerular volume and the glomerular vascular pole area in patients with insulin-dependent diabetes mellitus.

The vascular pole area (VPA) and glomerular volume were measured in renal biopsies from 9 insulin-dependent diabetes mellitus (IDDM) patients with normal albumin excretion rate (IDDM group 1), 38 IDDM patients with albumin excretion rate > 15 micrograms/min (IDDM group 2) and 10 living kidney donors (ND). The volume of individual glomeruli was estimated as the sum of profile areas factored by the measured distance between levels, t approximately 10 microns, and VPA as the sum of chords multiplied by t. Mean glomerular volume was increased in IDDM patients but reached statistical significance only in IDDM group 2 (P = 0.002 vs ND). VPA was significantly different among the groups, mean (CV%) was 2036 (29) microns2 in ND, 3555 (34) micron2 in IDDM group 1, and 3528 (48) microns2 in IDDM group 2, p = 0.004 and 0.001, IDDM versus ND. VPA calculated as a percentage of the surface area of the corresponding glomerulus was 2.4 (23)% in ND, 3.4 (27)% in IDDM group 1, and 3.3 (42)% in IDDM group 2; P = 0.007 and 0.01, IDDM versus ND. The intra-biopsy coefficient of variation was high (20-35%) and of the same order in all groups for all three measurements. Glomerular volume and absolute as well as relative size of VPA showed a positive correlation with estimates of mesangial expansion in IDDM group 2 and the VPA showed a negative correlation with GFR. Thus, part of the enlargement may represent a compensatory phenomenon triggered by the development of structural and functional abnormalities in the diabetic kidney.