Cholesterol: a renal risk factor in diabetic nephropathy?

Association between plasma oxidized low-density lipoprotein and diabetic nephropathy

To investigate the association of oxidized low-density lipoprotein (ox-LDL) with the development of diabetic nephropathy, plasma levels of ox-LDL were measured in 70 patients with type 2 diabetes mellitus. A sandwich enzyme-linked immunoadsorbent assay (ELISA) using the mouse monoclonal antibody FOH1a/DLH3, which specifically recognizes oxidized phosphatidylcholine, and a horseradish peroxidase (HRP)-labeled goat anti-human apolipoprotein B IgG was used to measure ox-LDL levels. The mean age of the patients was 57.0+/-1 3.4 years, and the mean duration of diabetes was 13.4+/-8.5 years. Plasma ox-LDL levels were similar in patients with normoalbuminuria (13.7+/-3.9 U/ml), patients with microalbuminuria (12.8+/-3.9 U/ml), and normal controls (12.5+/-4.2 U/ml). However, the plasma ox-LDL level in patients with macroalbuminuria (16.8+/-7.5 U/ml) was significantly higher than those in the other groups (P<0.05). Hemoglobin A1c (HbA1c) levels were similar in diabetic patients with normoalbuminuria (8.2+/-2.2%), microalbuminuria (7.8+/-1.3%), or macroalbuminuria (7.2+/-1.4%). There was no significant correlation between the ox-LDL level and the HbA1c level. The significantly elevated plasma ox-LDL levels in patients with macroalbuminuria suggest that ox-LDL may play an important role in the progression of diabetic nephropathy.

Association of C-reactive protein with coronary heart disease risk factors in patients with type 2 diabetes mellitus

The assessment of markers of systemic inflammation, such as C-reactive protein (CRP) and interleukin 6 (IL6), could be used to identify persons at high risk of coronary heart disease (CHD). This study evaluates the relationship of CRP and IL6 with CHD risk factors in patients with type 2 diabetes mellitus (DM) with CHD and age and sex matched type 2 DM controls without CHD. CRP, IL-6, total plasma homocysteine (tHcy), lipoprotein (a) [Lp(a)] and sialic acid (SA) were determined in 55 type 2 diabetic patients with CHD and 51 age- and sex-matched type 2 diabetic controls without CHD. Multivariate and logistic regression analyses were used to relate these markers with CHD risk factors. CRP (P=0.02) and tHcy (P=0.03) were significantly higher in patients with CHD compared with the control group even after correction for age and sex. IL6, Lp(a), SA and lipid parameters were not significantly different between the two groups of patients. After adjustment for potential confounders, the odds ratio (OR) for elevated CRP was 2.00 (95% confidence interval [CI], 1.12-3.58) (P=0.02) but the OR for IL6 was 3.41 95% CI, 0.70-17.17 (P=0.14). Partial correlation analyses of CRP and IL6 with other variables showed significant correlation of CRP with tHcy, and SA in patients with CHD only. Our results support the inclusion of CRP (high-sensitivity assay), in the risk assessment of diabetic subjects.

Can glomerular mRNAs in human type 1 diabetes be used to predict transition from normoalbuminuria to microalbuminuria?

BACKGROUND

mRNAs of pathogenetic importance in the development of diabetic nephropathy were measured in subjects with type 1 diabetes to determine whether these might be used to predict progression from normoalbuminuria to microalbuminuria. We proposed that conversion from normoalbuminuria to microalbuminuria would be most likely in subjects whose connective tissue growth factor (CTGF) and collagen mRNAs were above the 95% confidence interval (CI) for live renal donors and within the 95% CI for subjects with abnormal albuminuria.

METHODS

Glomerular CTGF, collagen alpha2(IV), and control glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNAs were measured in microdissected glomeruli from living renal donors (n = 10), and subjects with normoalbuminuria (n = 12), microalbuminuria (n = 5), and overt proteinuria (n = 6).

RESULTS

After 44 +/- 2 months of follow-up, one subject converted from normoalbuminuria to microalbuminuria. Although the data are limited, progression from normoalbuminuria to microalbuminuria occurred in the only normoalbuminuric subject whose mRNA levels were above the live renal donors' 95% CI for CTGF and collagen alpha2(IV) and within the 95% CI of subjects with abnormal albuminuria. No clinical or histopathologic finding distinguished the progressor from the nonprogressors at the time of biopsy.

CONCLUSION

This case report provides proof-of-principle that a panel of glomerular mRNA markers chosen because of their pathogenetic relevance may be useful adjuncts to albuminuria and histology in predicting clinical stability or clinical progression in diabetic nephropathy.

Serum lipoprotein(a) concentration as a cardiovascular risk factor in Kuwaiti type 2 diabetic patients

Serum lipoprotein(a) [Lp(a)], a risk factor for coronary heart disease (CHD) in some nondiabetic populations, is largely under genetic control and varies among ethnic and racial groups. We evaluated serum Lp(a) concentration and its relationship with traditional CHD risk factors (age, sex, smoking, hypertension, dyslipidemia) as well as stage of diabetic nephropathy in 345 type 2 diabetic patients. Lp(a) concentration was skewed with median (2.5th, 97.5th percentiles) of 25.0 (8.1, 75.7) mg/dl. Twenty-three of 55 (41.8%) patients with CHD had increased (>30 mg/dl) Lp(a) compared with 102 of 290 (35.1%) patients without CHD (P=.35). Twelve of 27 (44.4%) female patients with CHD had increased Lp(a) compared to 11 of 28 (39.3%) males (P=.70). Lp(a) was significantly (P<.05) higher in females than males, but the logistic regression analysis showed significant association of Lp(a), LDL-C, and duration of diabetes mellitus (DM) with CHD in male patients only. Although female patients with CHD and macroalbuminuria had significantly (P<.05) higher Lp(a) than normoalbuminuric female patients without CHD, no such association was found in males and no significant association was found between Lp(a) and the degree of albuminuria. Partial correlation analysis controlling for age, sex, and BMI showed significant correlation of Lp(a) with total cholesterol only (P=.03) and no correlation was found with other lipid parameters. Multiple regression analysis did not show significant associations of Lp(a) with standard CHD risk factors, HbA(1c), and plasma creatinine. This study is in agreement with studies in other populations, which showed that Lp(a) may not be an independent risk factor for CHD in patients with DM. However, as Lp(a) could promote atherogenesis via several mechanisms, follow-up studies in our patients will confirm if increased Lp(a) concentration can partly account for the poorer prognosis when diabetic patients develop CHD.

Progression, remission, regression of chronic renal diseases

The prevalence of chronic renal disease is increasing worldwide. Most chronic nephropathies lack a specific treatment and progress relentlessly to end-stage renal disease. However, research in animals and people has helped our understanding of the mechanisms of this progression and has indicated possible preventive methods. The notion of renoprotection is developing into a combined approach to renal diseases, the main measures being pharmacological control of blood pressure and reduction of proteinuria. Lowering of blood lipids, smoking cessation, and tight glucose control for diabetes also form part of the multimodal protocol for management of renal patients. With available treatments, dialysis can be postponed for many patients with chronic nephropathies, but the real goal has to be less dialysis-in other words remission of disease and regression of structural damage to the kidney. Experimental and clinical data lend support to the notion that less dialysis (and maybe none for some patients) is at least possible.

Low-density lipoprotein apheresis in the treatment of atherosclerosis and other potential uses

This review concerns the clinical impact of low-density lipoprotein (LDL) apheresis for patients with refractory hypercholesterolemia. We examine and provide examples of investigations that have demonstrated the clinical benefits of LDL apheresis. In addition to benefits derived from the stabilization or regression of arterial lesions, we highlight other possible mechanisms related to clinical improvement. We also discuss the potential advantages of lipid apheresis for the treatment of patient populations other than those characterized by severe hypercholesterolemia and premature coronary heart disease.

The short-term effect of a switch from glibenclamide to metformin on blood pressure and microalbuminuria in patients with type 2 diabetes mellitus

BACKGROUND

Renal hyperfiltration and albuminuria have a deleterious effect on kidney function. Therefore, we studied the effect of metformin on blood pressure, renal hemodynamics, and microalbuminuria in type 2 diabetic patients.

METHODS

A clinical trial was designed in type 2 diabetic patients with incipient nephropathy. All patients were below the age of 65, normotensive, and without evidence of malignant, hepatic, or cardiovascular disorders. They were randomly allocated to receive glibenclamide or metformin. At baseline and 12 weeks thereafter we measured body mass index (BMI), serum insulin, blood glucose, lipid profile, glycosylated hemoglobin, blood pressure, glomerular filtration rate, renal plasma flow, and urine albumin.

RESULTS

We studied 23 patients in the glibenclamide group and 28 in the metformin group. There was no difference in baseline variables between the groups. Metabolic control was obtained in both groups. In the metformin group, all the following variables decreased: microalbuminuria was reduced by a mean of 24.2 mg/day (p = 0.008); systolic and diastolic blood pressure by a mean of 5.3 mmHg (p = 0.002) and 3.93 mmHg (p = 0.009), respectively; insulin levels by an average of 11.8 microIU/mL (p = 0.001), and total cholesterol levels and triglycerides by an average of 0.45 and 0.18 mmol/L, respectively. Insulin resistance measured by the homeostasis model decreased more in the metformin group than in the glibenclamide group. Patients treated with glibenclamide had an increase in HDL cholesterol of 0.082 mmol/L (p = 0.01).

CONCLUSIONS

Metformin significantly decreased the urine albumin excretion rate with none of the expected changes in renal hemodynamics, probably due to its favorable effects on blood pressure, lipid profile, metabolic control, and insulin resistance.

Diabetes, hemoglobin A(1c), cholesterol, and the risk of moderate chronic renal insufficiency in an ambulatory population

Moderate chronic renal insufficiency is common, with 12.5 million individuals in the United States estimated to have a creatinine clearance less than 50 mL/min/1.73 m(2). Little is known about the risk factors for moderate chronic renal insufficiency. We studied 1, 428 subjects with Cockcroft-Gault-estimated creatinine clearances greater than 70 mL/min in a hospital-based ambulatory population. Over a mean of 5.7 +/- 1.3 years, 86 subjects developed moderate chronic renal insufficiency, defined as a decrease in creatinine clearance to less than 60 mL/min (1.1 case/100 person-years). Risk factors for moderate chronic renal insufficiency were identified using a proportional hazards model controlling for age, sex, race, systolic blood pressure, and angiotensin-converting enzyme (ACE) inhibitor use. The risk for developing moderate chronic renal insufficiency was associated with diabetes mellitus (relative risk, 2.1; 95% confidence interval [CI], 1.3 to 3.3) and elevated hemoglobin A(1c) levels. Compared with subjects with normoglycemia (hemoglobin A(1c) </= 5.7%), the relative risk for moderate chronic renal insufficiency for patients in the upper quartile of hemoglobin A(1c) (>9.0%) was 2.7 (95% CI, 1.4 to 5.1). The development of moderate chronic renal insufficiency was also independently predicted by elevated maximum serum cholesterol level. Compared with subjects with maximum cholesterol levels of 250 mg/dL or less, the relative risk for those with maximum cholesterol levels greater than 350 mg/dL was 2.4 (95% CI, 1.1 to 5.2). Similar relative risks were obtained when moderate chronic renal insufficiency was defined by the development of an increase in serum creatinine level. Hypercholesterolemia was also associated with moderate chronic renal insufficiency among persons without diabetes. In conclusion, the risk for developing moderate chronic renal insufficiency is increased by diabetes and elevated hemoglobin A(1c) and serum cholesterol levels. Modification of these risk factors may decrease the incidence of moderate chronic renal insufficiency.

Factors associated with microalbuminuria in type 1 diabetes mellitus: a cross-sectional study

In order to determine the prevalence of microalbuminuria in people with Type 1 diabetes mellitus (Type 1 DM) and identify factors associated with microalbuminuria, we studied 312 Type 1 DM patients attending in three hospitals in two Spanish regions over 6 months. Clinical characteristics, micro- and macro-vascular complications, blood pressure, 24-h urine albumin excretion, lipid profile, HbA1(c) levels, smoking habits, and family history of hypertension and diabetic nephropathy were recorded. Univariate analysis and multiple logistic regression were used to examine associations between these variables and the prevalence of microalbuminuria. We detected microalbuminuria in 29% of the patients. The prevalence of microalbuminuria was high during the second decade of diabetes and declined thereafter. Univariate analysis showed dyslipidaemia (P<0. 002), previously diagnosed hypertension (P<0.001), family history of hypertension (sibling alone P<0.006; mother alone P<0.05), family history of diabetic nephropathy (P<0.001), and laser-treated retinopathy (P<0.03) to be factors associated with the presence of microalbuminuria. Multiple logistic regression revealed an association between microalbuminuria and family history of nephropathy (OR 7.6, 3.6-16). In conclusion, in our sample the frequency of microalbuminuria seems to be related to the presence of dyslipidaemia, hypertension, and to a family history of hypertension or nephropathy.

Hypertriglyceridaemia and hyperuricaemia are risk factors for progression of IgA nephropathy

BACKGROUND

The prognosis of IgA nephropathy (IgAN) is variable and about 10-20% of patients progress to end-stage renal disease (ESRD) in 10 years. Hypertension, proteinuria and renal insufficiency at the time of diagnosis are risk factors associated with poor prognosis. Lipid abnormalities may have a role in the progression of glomerulonephritides, and glomerulosclerosis and atherosclerosis may have similar pathophysiological mechanisms. We therefore evaluated factors associated with cardiovascular diseases, especially hypercholesterolaemia, hypertriglyceridaemia, and hyperuricaemia, as predictors of the progression of IgAN.

METHODS

A total of 223 patients with IgAN (141 men, 82 women; median age 41 years, range 8-78 years) were studied. The following parameters were recorded at the time of renal biopsy: presence of hypertension or diabetes, smoking habits, body mass index (BMI), serum creatinine, total and HDL-cholesterol, triglycerides, and urate and 24-h urinary protein excretion. The patients were followed up for 0.2-17 years (median 10 years) with respect to progression of renal disease defined as elevation of serum creatinine above 125 micromol/l in men or 105 micromol/l in women, and over 20% elevation from baseline.

RESULTS

Forty-one patients (18%) showed progression. Hypertriglyceridaemia and hyperuricaemia were significantly more common at the time of renal biopsy in patients with progressive than in those with stable disease. In patients with normal renal function at the time of diagnosis initial hypertriglyceridaemia, hyperuricaemia, hypertension and proteinuria were independent risk factors for progression of IgAN in the Cox regression hazard model.

CONCLUSIONS

Our results show that hypertriglyceridaemia and hyperuricaemia at the time of diagnosis are important, previously underestimated predictors of poor outcome in IgAN, although causality between these factors and progression cannot be inferred from the present study.

Clinical management of diabetic nephropathy

From the viewpoint of nephrologists dealing with diabetic patients with ESRD and the associated complications and devastating prognosis, the need to reduce the incidence, and delay the rate of progression of diabetic nephropathy is obvious. Studies published within the last year have provided support for views that seem intuitively obvious; that improved glycaemic control and reduced blood pressure are associated with delayed onset and delayed progression of diabetic nephropathy. These reports have also demonstrated the difficulty of achieving ideal blood pressure targets and glycaemic control in diabetic patients. Thus, even with available therapy it is likely that improved compliance and achieving targets will have a major impact on disease outcome. There is evidence in several subgroups that ACEi are beneficial over other agents and the favourable side-effect and efficacy profile of these agents makes it reasonable to suggest that they should be used 'first line' in all patients with diabetes unless specifically contra-indicated. However, the failure to readily achieve blood pressure targets and the need for polypharmacy suggest that novel agents are required. We believe that statin therapy will have a major impact on CVD in diabetic patients and is also likely to delay progression; studies assessing the combined affect of anti-hypertensive and statin therapy specifically on the development and progression of diabetic nephropathy will be necessary before evidence-based recommendations can be made. The role for newer agents and targeting high risk groups using genetic markers remains uncertain but we await there development with interest. The future can only get better for patients with DN.

Urinary albumin and insulin as predictors of coronary artery disease: An angiographic study

Microalbuminuria has been associated with cardiovascular risk factors, events, and mortality. It also clusters with hyperinsulinemia and the metabolic syndrome. How urinary albumin excretion and the fasting serum insulin level relate to coronary artery disease (CAD) has not been previously determined. In 308 patients undergoing elective coronary angiography, the albumin to creatinine ratio was measured in urine from an early morning void. The fasting serum insulin level was also determined. CAD was assessed by angiography. Urinary albumin excretion was 28 +/- 5 mg/g (mean +/- SE) in patients with CAD and 10 +/- 1 mg/g in those without CAD (P < 0.001). Fasting serum insulin levels were also greater in patients with CAD compared with those without CAD; 20 +/- 3 and 13 +/- 1 microU/mL, respectively (P = 0.016). Urinary albumin excretion and fasting serum insulin levels increased progressively with severity of CAD. In patients without diabetes (n = 255), significant relationships of urinary albumin excretion and the fasting serum insulin levels to CAD were observed, but they were more pronounced when patients with diabetes (n = 53) were included. In multiple regression analysis, the odds ratios for severe CAD were 2.2 (95% confidence interval, 1.1 to 4.5) for microalbuminuria and 2. 2 (95% confidence interval, 1.3 to 3.8) for hyperinsulinemia. In summary, urinary albumin excretion and the fasting serum insulin levels were directly related to angiographic evidence of CAD. Microalbuminuria and hyperinsulinemia predict a significantly elevated risk for coronary atherosclerosis.

Dyslipidaemia and the progression of renal disease in chronic renal failure patients

BACKGROUND

Dyslipidaemia is common in patients with chronic renal failure (CRF), and there is increasing evidence to support the role of dyslipidaemia as a contributing factor in the progression of chronic renal disease. However, few prospective studies have been carried out which address the possible relationship between dyslipidaemia and the rate of progression of renal disease in patients with renal failure.

METHODS

Between January 1985 and December 1997, we prospectively assessed the risk of CRF progression to dialysis in a cohort of 138 patients. Forty CRF patients reached end-stage renal disease (ESRD) and had to start supportive therapy during the follow-up period [group ESRD(+)]. The remaining 98 CRF patients served as controls [group ESRD(-)]. Potential clinical and laboratory risk factors for more rapid CRF decline to dialysis, including lipid abnormalities and baseline creatinine clearance were determined at the start of the follow-up period.

RESULTS

Several significant differences were found in univariate analysis between the two groups of CRF, ESRD(+) and ESRD(-), namely a shorter follow-up period, a lower level of baseline creatinine clearance, a faster rate of creatinine clearance decline, a higher level of serum triglycerides, fibrinogen, total homocyst(e)ine and proteinuria, and a lower level of serum high-density lipoprotein in the ESRD(+) group than in the ESRD(-) group. However, by multivariate Cox analysis proteinuria [relative risk (95% confidence interval) 1.32 (1.16-1.50) for each g/day P = 0.001], baseline creatinine clearance [0.53 (0.40-0.70) for each 10 ml/min, P = 0.001] and chronic interstitial nephritis and hypertensive nephrosclerosis [0.38 (0.17-0.84) for presence, P = 0.005] were the only significant risk factors for CRF progression to dialysis. Hypertriglyceridaemia and male gender were selected in the final model, but were of borderline significance.

CONCLUSIONS

These results suggest a limited role for dyslipidaemia in the progression of chronic renal disease to dialysis in CRF patients, in contrast with the powerful influence of proteinuria, baseline creatinine clearance and nephropathy type in predicting this progression.

Hyperlipidaemia and the progression of nephropathy in OLETF rats: effect of angiotensin-converting enzyme inhibitor, enalapril

1. The influence of angiotensin-converting enzyme (ACE) inhibitor is investigated in enalapril on renal function in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of spontaneously non-insulin-dependent diabetes (NIDDM). 2. Enalapril (5 mg/kg) or vehicle was administered once daily by gastric gavage to 22-week-old male OLETF rats for 32 weeks. Blood pressure, albuminuria, creatinine clearance, plasma glucose, serum insulin and lipids were determined before and during the treatment. Renal haemodynamics was examined at the end of the treatment. 3. Enalapril lowered blood pressure mildly but significantly. In the vehicle-treated rats, urinary albumin excretion increased from 0.75 +/- 0.16 mg/mg creatinine (Cr) to 8.65 +/- 0.78 mg/mg Cr. Enalapril significantly blunted the development of albuminuria from 0.66 +/- 0.12 mg/mg Cr to 5.19 +/- 0.67 mg/mg Cr (P < 0.008) without significant influence on creatinine clearances. Enalapril also significantly blunted the rise in serum cholesterol and triglyceride prior to the development of massive albuminuria. Enalapril did not affect bodyweight, plasma glucose or insulin levels. Renal haemodynamics assessed by inulin and p-aminohippuric acid clearances were similar in both groups at the end of the treatment. 4. These results reconfirmed that the ACE inhibitor has protective effects on nephropathy in NIDDM. Massive albuminuria was preceded by increase in serum lipids in OLETF rats, which supports the view that hyperlipidaemia exacerbates glomerular injury in chronic renal disease. Enalapril attenuated the rise in serum lipids, suggesting that the beneficial effects of the compound on renal injury in OLETF rats might also be mediated through the action of affecting serum lipids.

Low-density lipoprotein apheresis retards the progression of hyperlipidemic overt diabetic nephropathy

BACKGROUND

Hyperlipidemia has recently received attention as being involved in the progression of diabetic nephropathy (DN). Low-density lipoprotein apheresis (LDL-A) can remove a large amount of plasma lipid directly from the patients in a short time.

METHODS

Fifteen type 2 diabetic patients with overt nephropathy received LDL-A in two different manners: short-term intensive therapy (SIT) for nine patients and long-term intermittent therapy (LIT) for six patients.

RESULTS

The changes in the monthly decline rates of reciprocal serum creatinine (1/Cr) were -0.035 +/- 0.020 in the three-month period before SIT, 0.047 +/- 0.041 during and until two weeks after SIT, and -0.035 +/- 0.015 after a period of two weeks from the therapy. The mean duration of LIT in six patients was 8.2 +/- 7.4 months, and the mean monthly decline rates of 1/Cr significantly decreased during the period of LIT as compared with the six-month period before the treatment.

CONCLUSION

LDL-A can retard the progression of overt DN, especially when it is performed repeatedly for a long period at two-week intervals.

Role of hyperlipidemia in progressive renal disease: focus on diabetic nephropathy

BACKGROUND

It has been suggested that lipids promote renal injury and that 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors confer renoprotection in certain renal diseases, including diabetic nephropathy.

METHODS

Sprague-Dawley rats were randomized to sham, subtotal nephrectomy (STNx) or STNx + atorvastatin groups. After 12 weeks, proteinuria, renal function, glomerular injury, renal transforming growth factor-beta (TGF-beta) gene expression and macrophage (ED1-positive cells) accumulation were assessed. In addition, the effects of HMG CoA reductase in human diabetic nephropathy were reviewed.

RESULTS

Atorvastatin therapy was associated with a modest reduction in proteinuria and glomerulosclerosis without influencing lipid levels or renal function in STNx rats. These effects were associated with decreased renal TGF-beta 1 gene expression and less glomerular and tubulointerstitial macrophage accumulation. The renoprotective effects of HMG CoA reductase inhibitors in both insulin- and non-insulin-dependent diabetic subjects with either incipient or overt nephropathy appear to be highly variable.

CONCLUSIONS

HMG CoA reductase inhibition appears to confer renoprotection via effects on prosclerotic cytokines such as TGF-beta and macrophage accumulation, independent of their lipid-lowering properties. The role of lipid-lowering agents in early or overt diabetic nephropathy remains to be fully ascertained.

Coronary artery disease and diabetes

The increased risk of cardiovascular disease in diabetic patients is well documented. A greater appreciation for the importance of this fact and regular use of secondary prevention strategies, including aggressive use of HMG-CoA reductase inhibitors or other lipid-lowering agents to reduce cholesterol levels, are clearly indicated for diabetic patients with CAD. If no contraindications exist, ACE inhibitors, beta blockers, and aspirin also should be considered for these high-risk patients.

Diabetic hypertensive patients: improving their prognosis

Diabetes is a devastating disease with multiple adverse effects on the vasculature. Moreover, hypertension is a prerequisite for patients with diabetes to progress to end-stage renal disease and to develop cardiovascular complications. Adequate control of blood glucose and blood pressure are the two most important factors that predict a favorable renal outcome. Recent studies have also shown that some classes of antihypertensive medications, such as the angiotensin-converting enzyme (ACE) inhibitors, may be ideal initial agents to control blood pressure in the hypertensive diabetic patient and thus to preserve renal function. In addition, nondihydropyridine calcium-channel blockers have been shown to retard the decline in renal function in patients with non-insulin-dependent diabetes mellitus (NIDDM) nephropathy who have lost at least 50% of their renal function. Retrospective analyses demonstrate that a reduction in blood pressure, especially to levels of <130/85 mg Hg in diabetic patients, retards the progression of renal disease. Reduction in arterial pressure to these low levels is probably more important than the agents used to achieve this goal. Because many of these patients require more than one medication to achieve these lower levels of arterial pressure, it is clear that fixed-dose combinations of such agents will both improve the likelihood of achieving a given blood pressure goal as well as medication compliance.

Effect of ramipril on blood pressure and protein excretion rate in normotensive nondiabetic patients with proteinuria

Angiotensin-converting enzyme inhibitors reduce proteinuria in both normotensive and hypertensive patients with proteinuric renal disease. However, the mechanism of the antiproteinuric effect has not been clarified. We performed a prospective, double-blind, placebo-controlled, randomized crossover trial to test the hypothesis that the antiproteinuric effect of ramipril was due to an improvement in glomerular permselectivity independent of blood pressure and glomerular filtration rate. The effect of low-dose (1.25 mg/d) and high-dose (5 mg/d) ramipril was assessed in 15 normotensive nondiabetic patients with proteinuria (> 150 mg/d). The study was divided into four 12-week periods: placebo, high- or low-dose ramipril, crossover to low- or high-dose ramipril, and placebo. Blood pressure, glomerular filtration rate, renal plasma flow rate, urinary protein excretion rate, and plasma angiotensin II levels were measured at the end of each period. Mean arterial pressure, urine protein to creatinine ratio, and albumin excretion rate decreased significantly during low- and high-dose ramipril. Glomerular filtration rate and renal plasma flow rate were not changed significantly. Plasma angiotensin II levels decreased with both low- and high-dose ramipril. There were no episodes of hypotension and only one subject developed cough during ramipril that did not require discontinuation of the study drug. In conclusion, administration of ramipril in both low and high doses lowered blood pressure and reduced proteinuria in this cohort of normotensive patients with a variety of proteinuric renal diseases. The antiproteinuric effect of ramipril is probably mediated by a reduction in glomerular capillary pressure.

Predictors of the progression of renal insufficiency in patients with insulin-dependent diabetes and overt diabetic nephropathy. The Collaborative Study Group

We designed a prospective, double-blind controlled trial to determine predictors of loss of renal function in patients with insulin dependent diabetes and established nephropathy. A total of 409 insulin-dependent diabetic patients with established nephropathy enrolled in a trial on the effect of Captopril on the rate of progression of renal disease. Baseline demographic, clinical (history and physical) and laboratory parameters were analyzed as risk factors for time to progression. Dichotomous characteristics were compared by Fisher's exact test and continuous characteristics with the Wilcoxon rank-sum test. Univariate proportional hazards regression analysis was used to estimate relative risk of nephropathy progression, and bivariate proportional hazard regression to identify interactions with the treatment group assignment. Multivariate proportional hazard regression was employed to determine which characteristics were independent risk factors. We found that a number of demographic and clinical characteristics were significantly associated with nephropathy progression even after adjustment for treatment group. However, after multivariate analysis, the risk factors that independently predicted progression were onset of IDDM later in life, parental diagnosis of IDDM, the presence of edema, increased mean arterial pressure, and an abnormal electrocardiogram. Likewise, a number of laboratory characteristics were also predictive of nephropathy progression. A low hematocrit, high blood sugar, and higher protein excretion predicted nephropathy progression as did a higher serum creatinine, particularly in the face of a normal serum albumin. In conclusion, this study identifies a number of clinical and laboratory risk factors that can predict which patients with insulin-dependent diabetes with established nephropathy are more likely to sustain a clinically important decrease in renal function over a median follow-up of three years.

The effect of macrophage colony-stimulating factor (M-CSF) on the progression of lipid-induced nephrotoxicity in diabetic nephropathy

In order to elucidate the role of macrophage in lipid-induced nephrotoxicity in diabetic nephropathy, we examined the effect of macrophage colony-stimulating factor (M-CSF) on the progression of renal lesions in hypercholesterolemic steptozotocin (STZ)-diabetic rats fed with high cholesterol chow. Hypercholesterolemia aggravated albuminuria in diabetic rats accompanied by infiltration of macrophages in glomeruli. Treatment with M-CSF suppressed simultaneously infiltration of glomerular macrophages and urinary albumin excretion in hypercholesterolemic diabetic rats. These results suggest that infiltration of glomerular macrophage has a primary role in lipid-induced nephrotoxicity in diabetic nephropathy, and M-CSF is involved in this process as a preventive factor.

Angiotensin-converting enzyme inhibition in diabetic nephropathy: ten years' experience

The aim of our prospective study was to evaluate putative progression promoters, kidney function, and prognosis during long-term treatment with angiotensin-converting enzyme inhibition in insulin-dependent diabetes mellitus patients suffering from diabetic nephropathy. Eighteen consecutive hypertensive insulin-dependent diabetes patients with nephropathy (mean age, 33 years) who had not been treated previously were all treated with captopril in combination with frusemide or bendrofluazide. The four patients who were refractory to this regimen also received nifedipine. Treatment was continued for a median of 8.9 years (range, 6.3 to 9.8, years). Renal function was assessed every 6 months by measurement of glomerular filtration rate (GFR) (single-bolus 51Cr-EDTA technique) and albuminuria by radioimmunoassay. Baseline values (+/- SE) were mean arterial blood pressure 146/93 +/- 3/1 mm Hg, albuminuria (geometric mean +/- antilog SE) 982 +/- 1.2 micrograms/min, and GFR 98 +/- 5 mL/min/1.73 m2. Angiotensin-converting enzyme inhibition induced a significant reduction during the whole treatment period of blood pressure (137/85 +/- 3/1 mm Hg; P < 0.01) and albuminuria (392 +/- 1.4 microns/min; P < 0.01), and the rate of decline in GFR was 4.4 +/- 0.7 mL/min/yr, in contrast to previous reports of 10 to 14 mL/min/yr (natural history). Univariate analysis revealed a significant correlation between the rate of decline in GFR and mean arterial blood pressure (r = 0.58, P = 0.01), albuminuria (r = 0.67, P < 0.01), hemoglobin A1c (r = 0.69, P < 0.01), and serum total cholesterol concentration (r = 0.51, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma lipids and the progression of nephropathy in diabetes mellitus type II: effect of ACE inhibitors

Ninety-four normotensive type II diabetics with normal renal function and microalbuminuria were randomized to receive enalapril 10 mg/day or placebo and were followed for five years. In the patients treated by enalapril plasma creatinine values and albuminuria remained stable throughout the observation period. Their plasma total cholesterol decreased from an initial value of 245 +/- 27 mg/dl to mean study value of 236 +/- 29 mg/dl, and to a fifth year value of 232 +/- 27 mg/dl (P < 0.001). The changes in HDL cholesterol and triglyceride values were nonsignificant. In the placebo group there was a significant increase in albuminuria and a mean decline of 13% in reciprocal creatinine values during the five years. Plasma total cholesterol increased from an initial mean value of 246 +/- 24 to a mean study value of 252 +/- 25 mg/dl, and to a fifth year mean value of 259 +/- 32 mg/dl (P < 0.001). There was a significant correlation between both initial and mean plasma total cholesterol values, and the decline in renal function and the rise in albuminuria in the placebo treated patients. This correlation persisted after stratification for blood pressure. Treatment with enalapril did not eliminate these correlations. Cholesterol may be an additional risk factor for diabetic nephropathy. ACE inhibitors may have a modest cholesterol lowering effect in diabetic patients mediated, in part, through the decline in albuminuria.

Remission of nephrotic range proteinuria in type I diabetes. Collaborative Study Group

The present study assessed the extent to which remission of nephrotic-range proteinuria occurred in patients with Type I diabetes enrolled in the Captopril Study, a placebo controlled multicenter clinical trial of captopril therapy in diabetic nephropathy. Of the 409 patients recruited into the Captopril Study, 108 had nephrotic-range proteinuria (> 3.5 g/24 hr) at entry in the Study (baseline). This group was the subject of the present study. Remission of nephrotic-range proteinuria was defined as follows: (1) Onset of the remission was taken as the date when proteinuria was first noted to be < or = 1.0 g/24 hr. (2) The reduction in proteinuria had to be sustained for a minimum of six months and until the end of the Captopril Study. (3) During the remission, the average of all 24 hour proteinuria measurements could not exceed 1.5 g. (4) Decline in renal function could not explain the reduced proteinuria. That is, the patient's serum creatinine during the entire period of observation in the Captopril Study had to remain at less than a doubling of the baseline serum creatinine. Remission of nephrotic-range proteinuria occurred in 7 of 42 patients assigned to captopril (16.7%, mean follow-up 3.4 +/- 0.8 years) and in 1 of 66 patients assigned to placebo (1.5%, mean follow-up 2.3 +/- 1.1 years; P = 0.005, comparing remission rate in captopril vs. placebo-treated patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Low-density lipoprotein immunofluorescence at the site of renal injury in glomerulosclerosis: a potential pathogenetic role for lipids in renal disease

The role of lipids in the genesis of renal disease has received increased attention. We describe the presence of anti-low-density lipoprotein immunofluorescence at the site of renal injury found by light microscopy. This may offer immunohistologic evidence for a potential role of this atherogenic lipid in the genesis of renal disease and glomerulosclerosis. Furthermore, we describe the contribution of cholesterol in early renal disease and markers for malnutrition in the dialytic management of end-stage renal disease. Interventional strategies, including vasoactive agents present and future, are presented.