Course of renal function in type 2 diabetic patients with abnormalities of albumin excretion rate.

Heterogeneity in renal structure has been described in type 2 diabetic patients with both microalbuminuria and proteinuria; in fact, only a subset of type 2 diabetic patients have the typical diabetic glomerulopathy. However, it is currently unknown whether abnormalities in albumin excretion rate (AER) have a different renal prognostic value depending on the underlying renal structure. Aims of this study were: 1) to study the course of renal function in type 2 diabetic patients with altered AER; 2) to evaluate the relationship between the course of glomerular filtration rate (GFR) and renal structure; and 3) to evaluate the relationship between the course of GFR and baseline AER levels, metabolic control, and blood pressure levels during a follow-up period of 4 years. A total of 108 type 2 diabetic patients, 74 with microalbuminuria (MA) and 34 with proteinuria (P), were recruited into a prospective study that encompassed: 1) a baseline kidney biopsy with morphometric measurements of glomerular parameters; 2) intensified antihypertensive treatment for an average 4-year period (blood pressure target <140/90 mmHg); and 3) determinations of GFR at baseline and every 6 months. Mean (+/- SD) GFR significantly decreased from baseline in both MA (-1.3+/-9.4 [95% CI -3.51 to +0.86], P < 0.05) and P (-3.0+/-13.0 ml x min(-1) x 1.73 m(-2) per year [-7.71 to +1.61], P < 0.01). However, the changes in GFR were quite heterogeneous. Thus, on the basis of percent GFR change per year from baseline (delta%GFR), both MA and P patients were defined as progressors or nonprogressors when they were below or above the median, respectively. Baseline parameters of glomerular structure had a strong influence on the course of GFR. Indeed, the odds ratios of being progressors significantly increased across the quartiles of baseline glomerular basement membrane (GBM) width and mesangial fractional volume [Vv(mes/glom)], being 2.71 and 2.85 higher, respectively, in the fourth quartile than in the first quartile (P < 0.01 for both). Conversely, nonprogressors outnumbered progressors in the first quartile of GBM width (odds ratio: 2.14, P < 0.05) and in the first quartile of Vv(mes/glom) (odds ratio: 2.28, P < 0.01). Baseline albumin excretion rate (AER) did not influence delta%GFR; in fact, the number of progressors did not increase across quartiles of baseline AER among either MA or P. Similarly, mean blood pressure levels during follow-up (and intensified antihypertensive therapy) did not affect the course of GFR: the number of progressors and nonprogressors did not change across quartiles of mean blood pressure. In contrast, HbA1c during follow-up had an impact on delta%GFR: the odds ratio for being a progressor increased across quartiles of HbA1c, particularly for the highest quartile (HbA1c >9.0%). In conclusion, the course of renal function is heterogeneous in type 2 diabetic patients with microalbuminuria or proteinuria. In fact, a subset of patients has a rapid decline in GFR over a 4-year follow-up period; these patients have more advanced diabetic glomerulopathy and worse metabolic control than the remaining patients, whose GFR remains stable. These two cohorts are otherwise undistinguishable as regards the degree of AER at baseline and tight blood pressure control. Kidney biopsy has an important prognostic role in these patients. Thus, tight blood pressure control, when not associated with satisfactory glycemic control, is unable to prevent rapid GFR decline in type 2 diabetic patients with typical diabetic glomerulopathy.

Patterns of renal injury in NIDDM patients with microalbuminuria.

Microalbuminuria predicts overt nephropathy in non-insulin-dependent diabetic (NIDDM) patients; however, the structural basis for this functional abnormality is unknown. In this study we evaluated renal structure and function in a cohort of 34 unselected microalbuminuric NIDDM patients (26 male/8 female, age: 58 +/- 7 years, known diabetes duration: 11 +/- 6 years, HbA1c: 8.5 +/- 1.6%). Systemic hypertension was present in all but 3. Glomerular filtration rate (GFR) was 101 +/- 27 ml.min-1.1.73 m-2 and albumin excretion rate (AER) 44 (20-199) micrograms/ min. Light microscopic slides were categorized as: C I) normal or near normal renal structure; C II) changes "typical" of diabetic nephropathology in insulin-dependent diabetes (IDDM) (glomerular, tubulo-interstitial and arteriolar changes occurring in parallel); C III) "atypical" patterns of injury, with absent or only mild diabetic glomerular changes associated with disproportionately severe renal structural changes including: important tubulo-interstitial with or without arteriolar hyalinosis with or without global glomerular sclerosis. Ten patients (29.4%) were classified as C I, 10 as C II (29.4%) and 14 as C III (41.2%); none of these patients had any definable non-diabetic renal disease. GFR, AER and blood pressure were similar in the three groups, while HbA1c was higher in C II and C III than in C I patients. Diabetic retinopathy was present in all C II patients (background in 50% and proliferative in 50%). None of the patients in C I and C III had proliferative retinopathy, while background retinopathy was observed in 50% of C I and 57% of C III patients. In summary, microalbuminuric NIDDM patients are structurally heterogeneous with less than one third having "typical" diabetic nephropathology. The presence of both "typical" and "atypical" patterns of renal pathology was associated with worse metabolic control, suggesting that hyperglycaemia may cause different patterns of renal injury in older NIDDM compared to younger IDDM patients.

Effects of cilazapril and amlodipine on kidney function in hypertensive NIDDM patients.

Contrasting information has been reported concerning the course of renal function in NIDDM with hypertension alone or in association with renal damage. The aim of the present study was to elucidate the course of the glomerular filtration rate (GFR) in hypertensive NIDDM patients during antihypertensive therapy. Furthermore, we compared the effects of ACE inhibitors (cilazapril, Inibace, Roche, Milan, Italy) and Ca(2+)-channel blockers (amlodipine, Norvasc, Pfizer, Rome, Italy). Of the hypertensive NIDDM patients attending the outpatient's clinic of the internal medicine departments of the University of Padova and Sassari, 44 participated in the present study. Of these patients, 26 were normoalbuminuric and 18 microalbuminuric. They were randomly treated with either cilazapril or amlodipine. The target of antihypertensive treatment was a value < 140 mmHg for systolic and 85 mmHg for diastolic blood pressure (BP). Microalbuminuria was defined as an albumin excretion rate (AER) between 20 and 200 micrograms/min. GFR was measured by plasma clearance of 51Cr-labeled EDTA at baseline and every 6-12 months during a 3-year follow-up interval. A significant decrease was observed in the values of GFR, AER, and systolic and diastolic BP in normoalbuminuric and microalbuminuric patients during antihypertensive therapy. The GFR fall in the overall population of NIDDM patients was significantly and inversely related to the decrease of mean BP (diastolic + 1/3 pulse pressure) (r = -0.80, P < 0.0001) but not to that of HbA1c, triglycerides, and BMI. The GFR decline (mean +/- SE) per year in the normoalbuminuric patient was 2.03 +/- 0.66 ml.min-1 x 1.73 m-2 (95% CI 0.92-3.17) during cilazapril and 2.01 +/- 0.71 ml.min-1 x 1.73 m-2 (95% CI 0.82-3.11) during amlodipine therapy. The GFR decline per year in the microalbuminuric patient was 2.15 +/- 0.69 ml.min-1 x 1.73 m-2 (95% CI 0.86-3.89) during cilazapril and 2.33 +/- 0.83 ml.min-1 x 1.73 m-2 per year (95% CI 1.03-3.67) during amlodipine therapy. Cilazapril and amlodipine lowered AER to a similar extent in normoalbuminuric and microalbuminuric patients. No significant changes were observed concerning other clinical and biochemical features between the two antihypertensive therapies and particularly HbA1c, BMI, triglycerides, and cholesterol plasma values. These results support the tenet that arterial hypertension plays a pivotal role in contributing to renal damage in NIDDM, even when AER is normal. However, the degree of BP control, with both cilazapril and amlodipine, can successfully delay the slope of GFR decline in hypertensive NIDDM patients with or without incipient nephropathy.

Impaired insulin-induced glucose uptake by extrahepatic tissue is hallmark of NIDDM patients who have or will develop hypertension and microalbuminuria.

Insulin resistance may be a mechanism linking non-insulin-dependent diabetes mellitus (NIDDM) to hypertension and cardiovascular mortality. Microalbuminuria also is an independent risk factor of cardiovascular mortality and of hypertension. Little information is available in the literature on the relationship between microalbuminuria and insulin action. This study investigated the relationships between blood pressure (BP) levels, microalbuminuria, and insulin resistance in NIDDM patients. Seventy-five NIDDM patients attending the outpatient clinic of the Department of Internal Medicine of the University Hospital in Padua, Italy participated in the cross-sectional part of our study. These subjects were divided into four groups on the basis of BP levels and albumin excretion rate (AER): 28 normotensive normoalbuminuric (NIDDM1), 19 hypertensive normoalbuminuric (NIDDM2), 15 normotensive microalbuminuric (NIDDM3), and 13 hypertensive microalbuminuric patients (NIDDM4). We defined microalbuminuria as an AER > 20 micrograms/min. Patients with BP levels > 145/90 mmHg were considered hypertensive. A group of 20 normal subjects served as control subjects. The results from the cross-sectional study indicate that the mean of insulin-induced whole-body glucose utilization, primarily an index of extrahepatic insulin action, was lower at all insulin infusion steps in the group of hypertensive and/or microalbuminuric patients than in the group of normotensive normoalbuminuric patients and control subjects. Hepatic glucose output, an index of insulin action in the liver, was on average less efficiently inhibited in all of the patients than in the control subjects, regardless of the BP levels or the AER.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of angiotensin converting enzyme inhibitors and calcium antagonists on atrial natriuretic peptide release and action and on albumin excretion rate in hypertensive insulin-dependent diabetic patients.

Abnormalities in sodium homeostasis and in atrial natriuretic peptide (ANP) behavior could play a role in determining and accelerating the development of glomerular hypertension, hypertension, and microalbuminuria in insulin-dependent diabetes. The aim of the present study was to investigate in 32 hypertensive insulin-dependent diabetic patients (HD) with an altered albumin excretion rate the natriuretic response and ANP release to saline load (2 mmol/kg 90 min, and the effects angiotensin converting enzyme inhibitor therapy 2.5 to 5.0 mg cilazapril, once daily), and calcium antagonists (sustained release verapamil: 120 to 240 mg Isoptin Press, once daily, and long acting nifedipine: 20 to 40 mg Adalat AR, twice daily) on sodium homeostasis and albumin excretion rate. Eight normal subjects matched for sex, age, and weight served as controls. The 32 HD patients showed a blunted response in ANP release and sodium excretion during saline infusion in comparison with controls. The cilazapril and verapamil treatments were tested in 16 of the 32 HD patients and were both effective in ameliorating natriuretic and ANP response to saline load and in decreasing albumin excretion rate. The combined cilazapril and verapamil treatment further improved both these parameters in these patients, although blood pressure levels were comparable. The other 16 HD patients underwent sequential verapamil and nifedipine treatment. Verapamil was more effective than nifedipine in improving natriuresis and ANP release to saline load and in lowering the albumin excretion rate. The results of the present study demonstrate that sodium homeostasis and ANP release are altered in hypertensive nephropathic patients, and both cilazapril and verapamil are more effective than nifedipine in ameliorating natriuresis, ANP release, and albumin excretion rate.

Close relationship between microalbuminuria and insulin resistance in essential hypertension and non-insulin dependent diabetes mellitus.

The aim of this study was to investigate the relationships among insulin resistance and albumin excretion rate in 25 nondiabetic patients with essential hypertension and in 28 patients with non-insulin dependent diabetes mellitus (NIDDM). Two groups of healthy subjects matched for age, sex, and weight served as controls. Patients with essential hypertension were divided into two subgroups: without (H1) and with (H2) microalbuminuria. Diabetic patients were divided into four subgroups: those with normoalbuminuria without (NIDDM1) and with (NIDDM2) hypertension and those with microalbuminuria without (NIDDM3) and with (NIDDM4) hypertension. Whole-body glucose utilization during euglycemic hyperinsulinemic clamp (40 mU/m2/min insulin infusion) was calculated by tracer dilution techniques (6,6 2H2 glucose tracer continuous infusion) and was significantly lower in hypertensives with microalbuminuria than in those without (H2 versus H1 versus controls: 3.41 +/- 0.51 versus 6.52 +/- 0.62 versus 7.03 +/- 0.48 mg/kg/min; mean +/- SE). Whole-body glucose utilization in NIDDM patients--NIDDM4 versus NIDDM3 versus NIDDM2 versus NIDDM1 versus controls--was: 1.86 +/- 0.31 versus 2.21 +/- 0.39 versus 2.01 +/- 0.40 versus 5.98 +/- 0.77 versus 5.52 +/- 0.92 mg/kg/min (mean +/- SE). Whereas the first three subgroups did not differ among themselves, they had significantly lower glucose utilization than did the normotensive NIDDM1 patients without microalbuminuria and nondiabetic controls (P < 0.01). Hypertensives with microalbuminuria had higher Vmax of sodium-lithium countertransport (Na/Li CTT) in red blood cells than did both hypertensives without microalbuminuria and controls. It was also observed that NIDDM patients with microalbuminuria had higher Vmax of Na/Li CTT than did NIDDM patients without microalbuminuria and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships among natriuresis, atrial natriuretic peptide and insulin in insulin-dependent diabetes.

Insulin-dependent diabetic patients have a large exchangeable body sodium pool, secondary to sodium retention. The pathogenesis of impaired natriuresis in insulin dependent diabetes remains to be elucidated. The present study examines the role of hyperinsulinemia, impaired atrial natriuretic release, and resistance to atrial natriuretic peptide action in determining sodium retention in normotensive and hypertensive insulin-dependent diabetic patients. Eight insulin-dependent diabetic patients had significantly higher daily sodium excretion rate (147 +/- 16 mmol/day; mean +/- SE) during conventional insulin treatment (daily plasma glucose: 11.6 +/- 1.2 mmol/liter; daily plasma insulin: 27 +/- 3 microU/ml) than during intensified insulin treatment (daily sodium excretion rate: 91 +/- 12, P less than 0.01; daily plasma glucose: 6.8 +/- 0.7, P less than 0.01; daily plasma insulin: 44 +/- 4, P less than 0.01). Daily sodium excretion rate was also significantly lower (107 +/- 13, P less than 0.01) in the same diabetic patients during intensified insulin treatment along with hyperglycemic clamp (daily plasma glucose: 12.8 +/- 0.3, NS; plasma insulin 48 +/- 4, P less than 0.01). Seven control subjects had lower extracellular liquid volume than eight insulin-dependent diabetic patients (11.0 +/- 0.8 l/1.73 m2 vs. 14.8 +/- 0.9, P less than 0.05) and also had baseline plasma atrial natriuretic peptide concentrations (18 +/- 5 pg/ml vs. 37 +/- 4, P less than 0.05). Atrial natriuretic peptide response to saline challenge was blunted in insulin-dependent diabetic patients when saline was administered on the basis of body surface area (90 mmol/1.73 m2.90 min) but not when administered on the basis of extracellular liquid volume (ECV) (8.2 mmol/liter ECV.90 min).(ABSTRACT TRUNCATED AT 250 WORDS)