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

Poor Glycemic Control Is Associated With More Rapid Kidney Function Decline After the Onset of Diabetic Kidney Disease

BACKGROUND

The role of glycemic control and its variability on the rate of kidney function decline after the onset of diabetic kidney disease (DKD) remains unclear.

METHODS

The association between baseline glycated hemoglobin (HbA1c) and rates of estimated glomerular filtration rate (eGFR) loss during follow-up was examined by mixed-effects linear regression in 530 individuals with type 1 diabetes and early-to-moderate DKD from the Preventing Early Renal Loss (PERL) trial and 2378 individuals with type 2 diabetes and established DKD from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. The benefit of intensive vs standard glycemic control in slowing eGFR decline was examined in ACCORD. The associations between continuous glucose monitoring-derived short-term glycemic variability indices and rate of eGFR decline were also evaluated in PERL.

RESULTS

A higher baseline HbA1c was associated with a more negative eGFR slope in both PERL and ACCORD (-0.87 and -0.27 mL/min/1.73 m2/year per Hba1c unit increment, P < .0001 and P = .0002, respectively). In both studies, the strength of this association progressively increased with increasing levels of albuminuria (P for interaction <.05). Consistent with this, the benefit of intensive glycemic control on eGFR decline was greater in ACCORD participants with severe rather than moderate albuminuria (+1.13 vs + 0.26 mL/min/1.73 m2/year, P = .01). No independent associations were found in PERL between short-term glycemic variability indices and rate of eGFR decline.

CONCLUSION

In both type 1 and type 2 diabetes, poor glycemic control is associated with a more rapid rate of glomerular filtration rate decline after DKD onset, especially in persons with severe albuminuria.

Lipid mediators in diabetic nephropathy

The implications of lipid lowering drugs in the treatment of diabetic nephropathy have been considered. At the same time, the clinical efficacy of lipid lowering drugs has resulted in improvement in the cardiovascular functions of chronic kidney disease (CKD) patients with or without diabetes, but no remarkable improvement has been observed in the kidney outcome. Earlier lipid mediators have been shown to cause accumulative effects in diabetic nephropathy (DN). Here, we attempt to analyze the involvement of lipid mediators in DN. The hyperglycemia-induced overproduction of diacyglycerol (DAG) is one of the causes for the activation of protein kinase C (PKCs), which is responsible for the activation of pathways, including the production of VEGF, TGFβ1, PAI-1, NADPH oxidases, and NFҟB signaling, accelerating the development of DN. Additionally, current studies on the role of ceramide are one of the major fields of study in DN. Researchers have reported excessive ceramide formation in the pathobiological conditions of DN. There is less report on the effect of lipid lowering drugs on the reduction of PKC activation and ceramide synthesis. Regulating PKC activation and ceramide biosynthesis could be a protective measure in the therapeutic potential of DN. Lipid lowering drugs also upregulate anti-fibrotic microRNAs, which could hint at the effects of lipid lowering drugs in DN.

Is diabetic nephropathy reversible?

The lesions of diabetic nephropathy have been considered to be irreversible. Pancreas transplantation is the only available treatment able to restore long-term normoglycemia without exposing the patients to the risks of severe hypoglycemia; thus allowing testing the effects of very long-term euglycemia in preventing, halting and reversing diabetic nephropathy. Pancreas transplantation, performed simultaneously or shortly after kidney transplantation in patients with type 1 diabetes prevents the recurrence of diabetic glomerulopathy lesions. To test whether diabetic nephropathy lesions are reversible in humans, we studied renal structure before and 5 and 10 years after pancreas transplantation alone in eight non-uremic patients with long-term type 1 diabetes, who had mild to advanced diabetic nephropathy lesions at the time of transplantation. We observed that, despite prolonged normoglycemia, diabetic glomerular lesions were not significantly changed at 5 years post pancreas transplantation. In contrast, glomerular lesions were markedly improved after 10 years; indeed in most patients glomerular structure was normal at 10-year follow-up. We reported similar findings also for tubular and interstitial lesions. Thus this study demonstrated, for the first time in humans, that the lesions of diabetic nephropathy are reversible and that the kidney can undergo substantial architectural remodeling upon long-term normalization of the diabetic milieu.

KDOQI Clinical Practice Guideline for Diabetes and CKD: 2012 Update

The 2012 update of the Kidney Disease Outcomes Quality Initiative (KDOQI) Clinical Practice Guideline for Diabetes and Chronic Kidney Disease (CKD) is intended to assist the practitioner caring for patients with diabetes and CKD. Substantial high-quality new evidence has emerged since the original 2007 KDOQI guideline that could significantly change recommendations for clinical practice. As such, revisions of prior guidelines are offered that specifically address hemoglobin A(1c) (HbA(1c)) targets, treatments to lower low-density lipoprotein cholesterol (LDL-C) levels, and use of angiotensin-converting enzyme inhibitor (ACE-I) and angiotensin receptor blocker (ARB) treatment in diabetic patients with and without albuminuria. Treatment approaches are addressed in each section and the stated guideline recommendations are based on systematic reviews of relevant trials. Appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Limitations of the evidence are discussed and specific suggestions are provided for future research.

Predicting diabetic nephropathy using a multifactorial genetic model

Aims

The tendency to develop diabetic nephropathy is, in part, genetically determined, however this genetic risk is largely undefined. In this proof-of-concept study, we tested the hypothesis that combined analysis of multiple genetic variants can improve prediction.

Methods

Based on previous reports, we selected 27 SNPs in 15 genes from metabolic pathways involved in the pathogenesis of diabetic nephropathy and genotyped them in 1274 Ashkenazi or Sephardic Jewish patients with Type 1 or Type 2 diabetes of >10 years duration. A logistic regression model was built using a backward selection algorithm and SNPs nominally associated with nephropathy in our population. The model was validated by using random “training” (75%) and “test” (25%) subgroups of the original population and by applying the model to an independent dataset of 848 Ashkenazi patients.

Results

The logistic model based on 5 SNPs in 5 genes (HSPG2, NOS3, ADIPOR2, AGER, and CCL5) and 5 conventional variables (age, sex, ethnicity, diabetes type and duration), and allowing for all possible two-way interactions, predicted nephropathy in our initial population (C-statistic = 0.672) better than a model based on conventional variables only (C = 0.569). In the independent replication dataset, although the C-statistic of the genetic model decreased (0.576), it remained highly associated with diabetic nephropathy (χ² = 17.79, p<0.0001). In the replication dataset, the model based on conventional variables only was not associated with nephropathy (χ² = 3.2673, p = 0.07).

Conclusion

In this proof-of-concept study, we developed and validated a genetic model in the Ashkenazi/Sephardic population predicting nephropathy more effectively than a similarly constructed non-genetic model. Further testing is required to determine if this modeling approach, using an optimally selected panel of genetic markers, can provide clinically useful prediction and if generic models can be developed for use across multiple ethnic groups or if population-specific models are required.

What do we know about chronic renal failure in young adults? II. Adult outcome of pediatric renal disease

Congenital abnormalities of the kidney and urinary tract (CAKUT) account for more than half of all renal failure in children. For young adults with CAKUT two questions are paramount: what is the prognosis and what is the best management to improve outcome? The paediatric literature shows that prognostic factors are glomerular filtration rate (GFR) and the presence of proteinuria. We reviewed data from 101 young adult patients with either primary vesico-ureteric reflux and renal dysplasia or obstructive uropathy. Patients had an estimated GFR (eGFR) of <or=60 ml/min per 1.73 m(2) body surface area and had had at least 5 years of follow up (median 162 months). There was a strong correlation between the amount of proteinuria at the start and overall rate of decline. Angiotensin-converting enzyme inhibitors (ACEIs) slowed declining renal function at all levels of function, but this only had a significant effect on renal outcome when eGFR was >35 ml/min. The ACEI benefit increased with time. Rate of decline was slower than reported for other diseases and was only -2.4 ml/min per year for those reaching the start of dialysis. Outcome is predictable by the level of residual renal function (GFR). Nevertheless, function remains stable while proteinuria is minimal. Short-term studies overestimate rates of deterioration.

Longitudinal ultrasound evaluation of carotid atherosclerosis in one, two and three dimensions

The aim of this study was to compare the sensitivity of three ultrasound phenotypes of carotid atherosclerosis in a longitudinal study of patients with diabetic nephropathy. B-mode ultrasound-derived intima-media thickness (IMT), total plaque area (TPA) as well as three-dimensional ultrasound (3DUS) vessel wall volume (VWV) of the common carotid artery (CCA) (VWV(CCA)) and internal carotid artery (ICA). (VWV(CCA+ICA)) were all evaluated in subjects enrolled in a randomized placebo-controlled double blind study of vitamin B therapy. Of 106 subjects randomized, 77 subjects were scanned at baseline and 2.3 +/- 1 y later (range: 0.5 to 4.5 y); of these subjects, 71 had images of sufficient quality for complete analysis of all three measurements. Subjects were analyzed according to the two treatment groups (A and B) and the analysis was performed blinded to treatment group description to prevent any potential for bias in future analyses. There were differences in sensitivity to longitudinal changes observed in all the ultrasound measurements. Specifically, there was no difference in IMT change between treatment groups (0.02 +/- 0.07 mm/y and 0.02 +/- 0.1 mm/y p = 0.15, group A and B, respectively, rates not different from zero [p > 0.05]) or TPA rate between treatment groups (0.09 +/- 0.2 cm(2)/y, significantly different from 0, p = 0.013 and -0.02 +/- 0.3 cm(2)/y in group A and B, respectively). However, the VWV(CCA+ICA) rate of change was significantly greater than 0 for group B (53 +/- 110 mm(3)/y) (p = 0.008), which was significantly (p = 0.034) higher than the rate of change of VWV(CCA+ICA) (nonsignificant, p = 0.6) for group A (-12 +/- 137 mm(3)/y). The relationship between DeltaVWV and DeltaIMT was significant, such that in group A, DeltaVWV(CCA) was positively associated with DeltaIMT (r = 0.44, p < 0.05), and in group B, DeltaVWV(CCA) was negatively correlated with DeltaIMT (r = -0.44, p < 0.01). These results suggest that 3DUS-derived VWV provides necessary and sufficient sensitivity and specificity to measure longitudinal changes in small numbers of carotid atherosclerosis patients at risk of disease progression and over short periods of time.

Cardiorenal syndrome at different stages of chronic kidney disease

The central concept of the cardiorenal syndrome (CRS) is that the heart and the kidney should be regarded not solely as individual organs but rather as a dipole with multiple interconnections. The interplay between the heart and the kidney seems complex and multifactorial: cardiac output, regulation of extracellular volume, blood pressure and renal sodium handling are the major parameters that determine the crosstalk between the 2 organs. These basic parameters are controlled through mediators (renin-angiotensin system, endothelin) and the relevant antagonists (natriuretic peptides). Recently, it has been shown that the nitric oxide / reactive oxygen species balance, sympathetic nervous system activation and the presence of systemic inflammation aggravate atherosclerosis, promote structural alterations in left ventricular geometry and favor progression of renal disease. Although the prevalence of the CRS is high, major clinical trials for heart failure have only partially addressed this issue. The present review tries to dissect the role of various components of the CRS in a way that could potentially facilitate the implementation of specific therapeutic strategies. The multiple factors that participate in the pathogenesis of this syndrome are studied in detail in an effort to better understand this syndrome and address effectively its various components, since a holistic approach could (ideally) alter the syndrome's course and hence ameliorate the prognosis of the CRS.

Effects of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and their combination on microalbuminuria in normotensive patients with type 2 diabetes

The goal of this study was to compare the effects of lisinopril, losartan, and their combination on microalbuminuria in normotensive patients with type 2 diabetes mellitus. Patients were randomly assigned to 3 groups: group 1 (n=9), group 2 (n=9), and group 3 (n=8) received 10 mg lisinopril, 50 mg losartan, and 10 mg lisinopril plus 50 mg losartan, respectively, each day. For 12 mo, the 24-h urine albumin excretion rate was assessed at 3-mo intervals. At study completion, the urine albumin excretion rate had been reduced significantly in each group (P=.001); however, no significant differences were noted among groups (P=.587). Investigators in the present study have concluded that lisinopril, losartan, and their combination have similar effects on microalbuminuria in normotensive patients with type 2 diabetes mellitus, and that combination therapy does not provide additional benefit.

Lipids and diabetic renal disease

Diabetic nephropathy is commonly associated with dyslipidemia, but the role of lipids in the progression of this disorder remains unresolved. In particular, the role of lipid-lowering drugs, such as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and fibrates, as renoprotective agents is not clarified. Experimental studies have demonstrated that dietary lipids promote renal injury and that statins, independent of their lipid-lowering effects, confer renoprotection via effects on intrarenal hemodynamics and renal cytokine and chemokine expression. Clinical studies have in general been underpowered, but a recent meta-analysis and findings from the Heart Protection Study suggest that statins may be renoprotective. Nevertheless, with the convincing antiatherosclerotic effects of these agents, including in the setting of diabetes, they should be widely administered in the diabetic population with or at risk for nephropathy.

Independent and additive impact of blood pressure control and angiotensin II receptor blockade on renal outcomes in the irbesartan diabetic nephropathy trial: clinical implications and limitations

Elevated arterial pressure is a major risk factor for progression to ESRD in diabetic nephropathy. However, the component of arterial pressure and level of BP control for optimal renal outcomes are disputed. Data from 1590 hypertensive patients with type 2 diabetes in the Irbesartan Diabetic Nephropathy Trial (IDNT), a randomized, double-blind, placebo-controlled trial performed in 209 clinics worldwide, were examined, and the effects of baseline and mean follow-up systolic BP (SBP) and diastolic BP and the interaction of assigned study medications (irbesartan, amlodipine, and placebo) on progressive renal failure and all-cause mortality were assessed. Other antihypertensive agents were added to achieve predetermined BP goals. Entry criteria included elevated baseline serum creatinine concentration up to 266 micromol/L (3.0 mg/dl) and urine protein excretion >900 mg/d. Baseline BP averaged 159/87 +/- 20/11 mmHg. Median patient follow-up was 2.6 yr. Follow-up achieved SBP most strongly predicted renal outcomes. SBP >149 mmHg was associated with a 2.2-fold increase in the risk for doubling serum creatinine or ESRD compared with SBP <134 mmHg. Progressive lowering of SBP to 120 mmHg was associated with improved renal and patient survival, an effect independent of baseline renal function. Below this threshold, all-cause mortality increased. An additional renoprotective effect of irbesartan, independent of achieved SBP, was observed down to 120 mmHg. There was no correlation between diastolic BP and renal outcomes. We recommend a SBP target between 120 and 130 mmHg, in conjunction with blockade of the renin-angiotensin system, in patients with type 2 diabetic nephropathy.

Role of lipid control in diabetic nephropathy

Patients with diabetic nephropathy are known to be associated with many lipoprotein abnormalities, including higher plasma levels of very low-density lipoprotein, low-density lipoprotein and triglycerides, and lower levels of high-density lipoprotein. Many studies have reported that lipids may induce both glomerular and tubulointerstitial injury through mediators such as cytokines, reactive oxygen species, chemokines, and through hemodynamic changes. Clinical studies in patients with diabetic nephropathy showed that lipid control can be associated with an additional effect of reduction in proteinuria. Experimental studies demonstrated that lipid-lowering agents exerted a certain degree of renoprotection, through both indirect effects from lipid lowering and a direct effect on cell protection. Therefore, lipid control appears to be important in the prevention and treatment of diabetic nephropathy. Diabetic nephropathy has become the leading cause of end-stage renal failure in many countries, including Taiwan. One of the major risk factors for the development and progression of diabetic nephropathy is dyslipidemia. In this paper we will review the role of lipid in mediating renal injury and the beneficial effects of lipid control in diabetic nephropathy.

Outcome studies in diabetic nephropathy

Outcome studies in diabetic nephropathy have focused on strategies to prevent progression of diabetic nephropathy, the leading cause of ESRD in the United States. Once diabetics develop overt nephropathy, prognosis is poor. Risk factors for diabetic nephropathy are discussed, and include hyperglycemia, hypertension, angiotensin II, proteinuria, dyslipidemia, smoking, and anemia. Major outcomes as well as outcome studies in diabetic nephropathy for patients with microalbuminuria and macroalbuminuria are reviewed. Furthermore, the role of therapy with angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, and mineralocorticoid receptor antagonists as well as selected combination therapy are discussed. Recommendations for therapy with ace inhibitors and angiotensin II receptor blockers are made based on this evidence.

ACE inhibitor intervention in Type 1 diabetes with low grade microalbuminuria

Several clinical trials have consistently shown that antihypertensive treatment, particularly with angiotensin-converting enzyme inhibitors (ACE-I) reduces albuminuria in Type 1 diabetic patients. More recently, data on the beneficial effects of ACE-I on the preservation of glomerular filtration rate and renal ultrastructure have emerged. However, in general, these trials have recruited a wide spectrum of diabetics, including some patients with severe albuminuria. Thus, the question of the ideal stage at which to instigate what is likely to be lifelong therapy in young people still remains unanswered. Exercise is known to significantly increase both blood pressure (BP) and urinary albumin excretion (UAE), both of which are important determinants of progression of nephropathy in diabetes. Thus, it is possible that exercise may have an adverse effect on diabetic renal disease. The effects of ACE-I on exercise-BP and exercise-UAE in microalbuminuric Type 1 diabetic patients has not been examined in long-term placebo-controlled studies. In the second part of this two-part review, we examine the effects of the ACE-I, lisinopril, 20 mg o.d. for two years, in comparison with placebo, on UAE, 24-hour ambulatory BP, exercise-BP, exercise-UAE and renal haemodynamics in 22 patients with Type 1 diabetes and low-grade microalbuminuria. We further discuss the effects of ACE-I on nephropathy and other complications of diabetes.

Treatment of diabetic nephropathy in its early stages

Diabetic nephropathy is one of the most frequent causes of end-stage renal disease (ESRD), and, in recent years, the number of diabetic patients entering renal replacement therapy has dramatically increased. The magnitude of the problem has led to numerous efforts to identify preventive and therapeutic strategies. In normoalbuminuric patients, optimal glycemic control (HbA(1c) lower than 7.5%) plays a fundamental role in the primary prevention of ESRD [weighted mean relative risk reduction (RRR) approximately 37% for metabolic control versus trivial renoprotection for intensive anti-hypertensive therapy or ACE-inhibitors (ACE-I)]. In the microalbuminuric stage, strict glycemic control probably reduces the incidence of overt nephropathy (weighted mean RRR approximately 50%), while blood pressure levels below 130/80 mmHg are recommended according to the average blood pressure levels obtained in various studies. In normotensive patients, ACE-I markedly reduce the development of overt nephropathy almost regardless of blood pressure levels; in hypertensive patients, ACE-I are less clearly active (weighted mean RRR approximately 23% versus other drugs), whereas angiotensin-receptor blockers (ARB) appear strikingly renoprotective. Once overt proteinuria appears, it is uncertain whether glycemic control affects the progression of nephropathy. In type 1 diabetes, various anti-hypertensive treatments, mainly ACE-I, are effective in slowing down the progression of nephropathy; in type 2 diabetes, two recent studies demonstrate that ARB are superior to conventional therapy or calcium channel blockers (CCB). In clinical practice, pharmacological tools are not always used to the best benefit of the patients. Therefore, clinicians and patients need to be educated regarding the renoprotection of drugs inhibiting the renin-angiotensin system (RAS) and the overwhelming importance of achieving target blood pressure.

The relationship between glucose control and the development and progression of diabetic nephropathy

Diabetic nephropathy is a major cause of morbidity and mortality in patients with diabetes; it occurs in about one third of such patients. The course of nephropathy is better defined and similar for both type 1 and type 2 diabetes. Patients initially develop microalbuminuria (albumin excretion rates [AERs] between 20 and 200 micrograms/min), then overt nephropathy (AER > or = 200 micrograms/min), and finally a decline in glomerular filtration rate (GFR) eventuating in end-stage renal disease. Although metabolic control has long been hypothesized as a contributor to the development of nephropathy, it is only in recent years that this hypothesis has been proven. A number of observational studies have shown correlations between glycemic control and the development of various levels of albuminuria and also declines in GFR. However, large long-term prospective, randomized, interventional studies have now definitely proven that improved metabolic control that achieves near-normoglycemia can significantly decrease the development and progression of diabetic nephropathy as well as other long-term complications of diabetes, including retinopathy and neuropathy. It is now conceivable that the achievement of near-normoglycemia, plus medications that inhibit the renin-angiotensin system if microalbuminuria develops, may greatly decrease the numbers of patients eventually requiring renal replacement therapy.

Appropriate drug therapy for improving outcomes in diabetic nephropathy

Diabetic nephropathy is the leading cause of end-stage kidney disease in the United States. The majority of these cases are attributed to those with type 2 diabetes. Elevated blood pressure, proteinuria, and increased activity of the renin-angiotensin-aldosterone system (RAAS) play a major role in the development and progression of chronic kidney disease attributed to diabetes mellitus. Moreover, drugs that inhibit angiotensin II synthesis or block the angiotensin II type I receptor lower blood pressure, reduce proteinuria, and improve outcomes in patients with chronic kidney disease caused by diabetes. This article highlights improvements in the current management of diabetic nephropathy afforded by agents that inhibit the RAAS, discusses their limitations, and considers novel strategies to prevent onset and progression of diabetic nephropathy. Current opinions concerning combination drug therapy with agents that block the RAAS at multiple sites, as well as combining calcium channel blockers with either angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists, are also discussed.

Long-term glycemic control measurements in diabetic patients receiving hemodialysis

Cardiovascular morbidity is increased in patients with diabetes mellitus and there is a great prevalence of diabetes and cardiovascular disease among patients with end-stage renal disease (ESRD). Control of glycemia can decrease cardiovascular and end-organ damage. Because the validity of glycemic control tests have not been rigorously studied in patients with ESRD, we evaluated the value of various measures in these patients. The overall clinical goal was to investigate whether hemoglobin A1C (A1C) accurately reflects actual glycemic control as compared with other measures in light of the importance of attaining appropriately controlled blood glucose (BG). The commonly used tests of total glycated hemoglobin (GHb) and A1C may be unreliable in patients with ESRD because of the presence of anemia, shortened red blood cell (RBC) survival, and assay interferences from uremia. The primary aim of this study was to assess the relationship of capillary BG measurements to A1C, GHb, total glycated plasma proteins (GPP), and fructosamine (Fr) in diabetic patients receiving hemodialysis. Twenty-three patients were instructed to obtain BG evaluations twice daily for 7 days by using the Elite glucometer (Bayer Corporation, Elkhart, IN). These determinations included 6 fasting, 6 preprandial, and 3 separate 2-hour postprandial levels. Blood was obtained on day 7 for measurement of A1C, GHb, GPP, and Fr. A1C was analyzed by an immunoassay, GPP and GHb were assayed by affinity high-performance liquid chromatography (HPLC), and Fr by automated nitroblue colorimetric assay. Scatter plots were generated by plotting the average BG versus A1C, GHb, GPP, or Fr. Linear regression was performed for each plot showing the following relationships: A1C = 0.0174 (BG) + 4.76 (r = 0.58; P < 0.05): GHb = 0.0371 (BG) + 3.57 (r = 0.584; P < 0.05): GPP = 0.0083 (BG) + 26.13 (r = 0.065; P = 0.77): Fr = 0.6865 (BG) + 250 (r = 0.345; P = 0.11). Despite anemia and shortened RBC lifespan in patients with ESRD, A1C in the range of 6% to 7% estimates glycemic control similarly to patients without severe renal impairment. A1C values above 7.5% may overestimate hyperglycemia in patients with ESRD. Thus, diabetic patients receiving hemodialysis may have long-term BG that are more properly controlled than previously determined, reducing their risks of the macro- and microvascular complications of diabetes mellitus.

Effect of captopril or imidapril on the progression of diabetic nephropathy in Japanese with type 1 diabetes mellitus: a randomized controlled study (JAPAN-IDDM)

OBJECTIVE

to clarify and confirm the renoprotective effects of ACEIs in Japanese type 1 diabetics.

RESEARCH DESIGN AND METHODS

a double-blind randomized study using two ACEIs, imidapril (a prodrug of imdaprilat without an SH-residue) and captopril as well as placebo was performed. Seventy-nine eligible cases were randomized to receive captopril 37.5 mg (n=26), imidapril 5 mg (n=26) or their placebos (n=27) daily in a double-blind manner.

RESULTS

urinary albumin excretion (UAE), determined every half year, was significantly decreased by the ACEIs (placebo vs. ACEIs F=11.316, P=0.001, placebo vs. captopril F=4.260, P=0.043, placebo vs. imidapril F=14.341, P<0.001) during the study period (the mean; 1.48 years). Although the HbA(1C) levels and systolic blood pressure (BP) between the three groups were not different, glycemic and BP control significantly affected UAE. Systolic BP in the placebo group tended to be higher by 7-10 mmHg throughout the study.

CONCLUSIONS

these results suggest that the ACE inhibitors, imidapril and captopril, prevent the increase in UAE in micro and macroalbuminuric patients with type 1 diabetes mellitus and that the target BP might be less than 130/80 mmHg.

Savings in dialysis treatment?

The steadily increasing number of dialysis patients prompts considerations on possibilities for budget reductions with maintenance of treatment quality. A literature survey is presented concerning trends of population increase, individual treatment costs, rationing of patient intake, and consequences of delayed progress of renal insufficiency as well as of savings during both the initial and the later phases of regular dialysis therapy. Cost reduction in one area may well induce rising total budgets and influence clinical outcome. A multidisciplinary approach is suggested to obtain answers to several questions: Can the economic burden of the changing patient demography be counterbalanced by a reorganized staff structure? Will early referral, good predialysis control, and incremental dialysis start imply longer survival? Will increased dialysis doses be economically neutralized by less staff requirements, drug consumption, and patient morbidity? Should dialyzer reuse be abandoned? Can pretransplant dialysis periods be reduced or omitted by improved planning?

Renal function and structure in albuminuric type 2 diabetic patients without retinopathy

BACKGROUND

In type 2 diabetic patients without retinopathy the cause of albuminuria is heterogeneous and our knowledge of the relationship between kidney structure and function in these patients is limited. Therefore, a long-term study evaluating the structural-functional relationship in albuminuric type 2 diabetic patients without retinopathy was performed.

METHODS

Mesangial volume of total glomerular volume (Vv (mes/glom)), fractional area of focal interstitial fibrosis and tubular atrophy of cortical area (FF) and percentage of sclerosed glomeruli (S/G) were measured on kidney biopsies from 49 type 2 diabetic patients without retinopathy. Glomerular filtration rate (GFR) was determined at least 3 times (median 8 (range 3-20)) in each patient. Patients were followed for 7.0 (1.1-17) years. Albuminuria and blood pressure were measured every 3-6 months.

RESULTS

Biopsies revealed diabetic glomerulopathy (DG-group) in 69% of the patients (27 male/7 female) and normal glomerular structure (n=9) or glomerulonephritis (n=6) were found in 31% (13 male/2 female) (NDG-group). In the DG-group GFR decreased from 97+/-5 to 66+/-5 ml/min/1.73 m(2) (mean+/-SE) (P<0.001), with a rate of decline in GFR of 5.3+/-0.8 ml/min/year and in the NDG-group from 93+/-7 to 74+/-11 ml/min/1.73 m(2) (P<0.01), with a rate of decline in GFR of 3.2+/-0.9 ml/min/year, P=0.09 between groups. Mean arterial blood pressure decreased from 109+/-2 to 100+/-2 mm Hg (P<0.001) (DG-group) and remained unchanged in the NDG-group. An association between Vv (mes/glom) and rate of decline in GFR was revealed mainly in the NDG-group (DG-group; r=0.31, P=0.07 and NDG-group; r=0.74, P<0.01). Furthermore, the rate of decline in GFR seemed to be associated with FF in the NDG group (r=0.48, P=0.07). Percentage of S/G was not associated with the rate of decline in GFR. Vv (mes/glom) was associated with mean albuminuria during follow-up in the DG group; r=0.38, P<0.03 (NDG group; r=0.51, P=0.09). Albuminuria was an independent predictor of the rate of decline in GFR in both groups (DG-group; r=0.40, P<0.05 and NDG-group; r=0.61, P<0.01).

CONCLUSIONS

Our study revealed a tendency to a faster rate of decline in GFR in the DG-group compared to the much smaller NDG-group, characterized by marked heterogeneity of the underlying kidney lesions and rate of GFR loss. A large mesangial volume fraction was associated with increased albuminuria and loss in GFR. Albuminuria acted as a progression promoter in both groups.

Drug treatment effects on disease progression

Degenerative diseases are characterized by a worsening of disease status over time. The rate of deterioration is determined by the natural rate of progression of the disease and by the effect of drug treatments. A goal of drug treatment is to slow disease progression. Drug treatments can be categorized as symptomatic or protective. Symptomatic treatments do not affect the rate of disease progression whereas protective treatments have the ability to slow disease progression down. Many current methods for describing disease progression have two common drawbacks: a linear relationship between time and disease status is assumed, and within- and between-subject variability is ignored. Disease progress models combined with pharmacokinetic pharmacodynamic models and hierarchical random effects statistical models provide insights into understanding the time course and management of degenerative disease.

Lisinopril reduces albuminuria during exercise in low grade microalbuminuric type 1 diabetic patients: a double blind randomized study

BACKGROUND

Antihypertensive treatment is presently recommended in most type 1 diabetic patients with microalbuminuria. The long-term effect of angiotensin converting enzymes (ACE) inhibitor (ACE-i) treatment on exercise urinary albumin excretion (E-UAE) and exercise blood pressure (E-BP) in type 1 diabetic patients with low grade microalbuminuria is not well documented. In addition, the possible predictive effect of baseline E-UAE on the progression of overnight UAE remains to be clarified.

DESIGN AND METHODS

In a randomized placebo controlled double blind study the effects of 2 years treatment with either lisinopril (20 mg o.d.) or placebo was evaluated in 21 normotensive type 1 diabetic patients with overnight UAE between 20 and 70 microg min-1. Determinations of E-UAE and E-BP were performed after exercise on an ergometercycle with a load of 70% of estimated maximal VO2 for 20 min. Patients in the placebo and lisinopril groups were similar with regard to age (35.8 +/- 11.3 vs. 29.3 +/- 8.6 years), duration of diabetes (19.4 +/- 8.2 vs. 16.8 +/- 5.3 years), and HbA1c (9.0 +/- 1.0 vs. 9.4 +/- 1.7%).

RESULTS

At baseline, E-UAE was similar in the two groups (placebo: 150.1 x or divide 3.7, lisinopril: 96.8 x or divide 1.8 microg min-1 (geometric mean x or divide tolerance factor)). After 2 years treatment E-UAE had increased in the placebo group, whereas E-UAE was reduced in the lisinopril treated patients (placebo: 213.6 x or divide 6.9, lisinopril: 48.3 x or divide 3.1 microg min-1, P = 0.04). The relative increase in E-UAE (E-UAE/Pre-exercise UAE) was similar at baseline in both groups (3.7 x or divide 2.3 vs. 2.8 x or divide 2.0) but significantly higher in the placebo group after 2 years (4.4 x or divide 2.4 compared with 1.6 x or divide 1.7 in the lisinopril group, P < 0.01) These changes over two years in relative increase in E-UAE were significantly different (P = 0.03). Exercise blood pressure was similar in both groups at baseline and over 2 years increased in the placebo group (from 166.5 +/- 15.1-179.9 +/- 35.6 mmHg), in contrast to the lisinopril group where E-BP was slightly reduced (from 168.5 +/- 20.6-165.1 +/- 16.6 mmHg) but the difference in blood pressure over the 2 years did not reach statistical significance. Exercise urinary albumin excretion and E-BP were closely associated (correlation for year 2: r = 0.734, P < 0.001), and also changes over the 2 years in E-UAE and E-BP were positively correlated (r = 0.53, P = 0.01). At year 2, overnight UAE, pre-exercise UAE (pre-E-UAE), E-UAE and E-BP were all closely linked (r-values between 0.6 and 0.9, P-values < 0.01). In the prediction of changes in overnight UAE over 2 years, neither baseline E-UAE nor baseline E-BP conveyed explanatory information in comparison with baseline overnight UAE and HbA1c.

CONCLUSIONS

In type 1 diabetic patients with low-grade microalbuminuria, 2 years of ACE-i treatment with lisinopril significantly reduced E-UAE. Strong correlations were found between E-UAE and E-BP and also changes over 2 years in these parameters were significantly associated.

Determination of optimal protein contents for a protein restriction diet in type 2 diabetic patients with microalbuminuria

To establish the method by which the optimal dietary protein content for type 2 diabetic patients with nephropathy could be determined, dietary protein content was reduced in gradated steps and renal function was evaluated at the completion of each diet. Eight type 2 diabetic patients with microalbuminuria were examined in this study. Renal function, urinary albumin excretion rate (AER) and urinary excretion rates of prostaglandins were evaluated at the completion of each of three consecutive one-week dietary periods where the protein content was 1.2, 0.8 and 0.6 g x kg Body Weight (BW)(-1) x day(-1) on the first, second and third week, respectively. Filtration fraction (FF), AER and urinary excretion rates of prostaglandin E2 and 6-keto-prostaglandin F1alpha significantly decreased in response to reduced dietary protein content from 1.2 to 0.8 g x kg BW(-1) x day(-1). No additional decreases in FF, AER and urinary excretion rates of these two prostaglandins were obtained after the 0.6 g x kg BW(-1) x day(-1) low protein diet period. The method evaluating renal hemodynamics at the completion of several consecutive one-week dietary periods was confirmed to be useful to determine the optimal protein contents in type 2 diabetic patients with nephropathy. The result showed that the optimal protein content in type 2 diabetic patients with microalbuminuria was 0.8 g x kg BW(-1) x day(-1) and protein restriction of less than 0.8 g x kg BW(-1) x day(-1) was not necessary for patients with this stage of diabetic nephropathy. A part of reasons in which FF decreased after reduced protein content in diet may be due to decreased prostaglandins production in the kidneys.

Insertion/deletion polymorphism in ACE gene is not associated with renal progression in Japanese patients with IgA nephropathy

We determined the relationship between the gene polymorphism of angiotensin I-converting enzyme (ACE) and the progression of immunoglobulin A (IgA) nephropathy in a large cohort in a multicenter trial of ethnically homogeneous Japanese patients (n = 527). Patients with biopsy-proven IgA nephropathy were recruited from several clinics in Japan. The mean observation period was 8.4 +/- 4.7 years. ACE insertion/deletion (I/D) genotype was determined by polymerase chain reaction amplification using allele-specific primers. Clinical factors investigated in all patients were date of birth, sex, levels of urinary protein excretion, duration of observation, serum creatinine (sCr) level, and creatinine clearance (CCr). ACE genotype distribution did not differ between patients who maintained normal renal function (II, 41%; ID, 44.7%; DD, 14.3%) and those who progressed to renal impairment (II, 41.7%; ID, 40.4%; DD, 17.9%). Kaplan-Meier analysis did not show a significant difference in renal survival rate among the three groups of each genotype. In multivariate analysis, only two variables, proteinuria greater than 1.0 g/d of protein and impaired renal function (sCr >1.2 mg/dL or CCr <70 mL/min) at the time of renal biopsy, were found to be risk factors for disease progression leading to a poor outcome. No association was observed between these variables and ACE genotype. It appears that ACE I/D polymorphism may not affect the progressive deterioration of renal function in patients with IgA nephropathy from our multicenter trial.

Pancreas transplantation for the prevention of diabetic nephropathy

Diabetic nephropathy is the leading cause of kidney failure in the United States. Poor glycemic control, hypertension, and smoking have been implicated as risk factors for the development and progression of diabetic nephropathy in patients with type 1 diabetes mellitus. Improved medical therapy including angiotensin-converting enzyme inhibitors and tight glycemic control with use of intensive insulin therapy have been shown to reduce the progression of diabetic nephropathy substantially based on albumin excretion rates. Despite these improvements in medical management, many patients still experience progression from early diabetic nephropathy to end-stage renal disease. Successful pancreas transplantation leads to normal glycemic control in patients with type 1 diabetes, but historically it has generally been limited to patients with both kidney failure and diabetes. In this review of the current treatment of diabetic nephropathy, we examine the potential role of preemptive pancreas transplantation in patients with diabetic nephropathy.

The cost-effectiveness of treating all patients with type 2 diabetes with angiotensin-converting enzyme inhibitors

BACKGROUND

Although guidelines recommend angiotensin-converting enzyme inhibitors for diabetic patients with microalbuminuria, this strategy requires that providers adhere to screening recommendations. In addition, the benefit of angiotensin-converting enzyme inhibitors in normoalbuminuric patients was recently demonstrated.

OBJECTIVE

To evaluate the cost-effectiveness of treating all patients with type 2 diabetes.

DESIGN

Markov model simulating the progression of diabetic nephropathy.

DATA SOURCES

Randomized trials estimating the progression of diabetic nephropathy with and without angiotensin-converting enzyme inhibitors.

TARGET POPULATION

Patients 50 years of age with newly diagnosed type 2 diabetes (fasting plasma glucose level > or = 7.8 mmol/L [140 mg/dL]).

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTIONS

Patients received angiotensin-converting enzyme inhibitors, screening for microalbuminuria, or screening for gross proteinuria.

OUTCOME MEASURES

Lifetime cost, quality-adjusted life expectancy, and marginal cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS

Screening for gross proteinuria had the highest cost and the lowest benefit. Compared with screening for microalbuminuria, treating all patients was more expensive ($15240 and $14940 per patient) but was associated with increased quality-adjusted life expectancy (11.82 and 11.78 quality-adjusted life-years). The marginal cost-effectiveness ratio was $7500 per quality-adjusted life-year gained.

RESULTS OF SENSITIVITY ANALYSIS

Results were sensitive to the cost, effectiveness, and quality of life associated with angiotensin-converting enzyme inhibitor therapy, as well as age at diagnosis. The model was relatively insensitive to adherence with screening and costs of treating end-stage renal disease.

CONCLUSIONS

Treating all middle-aged diabetic patients with angiotensin-converting enzyme inhibitors is a simple strategy that provides additional benefit at modest additional cost. The strategy assumes that patients meet the older diagnostic criteria for diabetes and makes sense only for those who are not bothered by treatment.

Evaluation and treatment of hypertension

Hypertension is a significant and prevalent risk factor for the development of cardiovascular disease and target organ damage. The urgency of treatment of high blood pressure depends on the level of blood pressure elevation and the presence of coexistent risk factors for cardiovascular disease. Likewise, the level to which blood pressure is reduced is not restricted to the definition of high blood pressure but instead depends on the underlying disease. Diabetes and renal insufficiency, for example, require blood pressure goals below those that are traditionally defined. In the absence of contraindications, beta-blockers and diuretics are still recommended as first-line agents for treatment of uncomplicated hypertension. Calcium channel antagonists also may reduce mortality. In patients with diabetes, ACE inhibitors are effective first-line agents in type 1 and type 2 diabetic patients who are hypertensive or have microalbuminuria. ACE inhibitors may be beneficial in patients with nondiabetic renal insufficiency as well. Calcium channel antagonists may have some effect in retarding progression of diabetic nephropathy although a recent trial found a higher incidence of death as a secondary endpoint in hypertensive diabetic patients who were treated with calcium channel antagonists. Beta-blockers seem to be safe and well tolerated in patients with mild to moderate intermittent claudication, although patients with rest pain or limb ischemia have not been studied. Beta-blockers should not be used in patients with asthma. Dihydropyridine calcium channel antagonists are the preferred treatment of hypertension in patients with Raynaud's but should be avoided in patients with severe gastroesophageal reflux disease. NSAIDs, particularly piroxicam and indomethacin, raise mean blood pressure by approximately 5 mm Hg, enough to consider a change of either NSAID or antihypertensive to one that is not as affected by NSAIDs. Cyclosporine A can induce hypertension by its vasoconstrictive effects, particularly on the kidney. Calcium channel antagonists may antagonize this vasoconstriction while allowing the clinician to reduce the dose of cyclosporine A required to achieve its immunosuppressive effect.

Progression of diabetic nephropathy in normotensive type 1 diabetic patients

BACKGROUND

The first aim of our long-term study was to describe the natural history of diabetic nephropathy in 59 normotensive type 1 diabetic patients. Secondly, we evaluated genetic and nongenetic progression promoters.

METHODS

The following progression promoters were determined: the insertion/deletion polymorphism in the angiotensin converting enzyme (ACE) gene, blood pressure, albuminuria, hemoglobin A1c, cholesterol, smoking, height, and gender. We studied the natural history by measuring 51Cr-EDTA plasma clearance at yearly intervals at least three times during [median (range)] 5.5 (2.2 to 18.3) years.

RESULTS

At baseline the three groups (II, N = 11; ID, N = 25, and DD, N = 23) had comparable GFR (103 +/- 16; 99 +/- 19; 113 +/- 22 ml/min/1.73 m2, respectively; mean +/- SD), arterial blood pressure, albuminuria, and hemoglobin A1c. During the follow-up there was a median rate of decline in GFR in all 59 patients of 1.2 (range 12.9 to -4.4) ml/min/year. During the study period no significant differences were observed in: the rate of decline in glomerular filtration rate [median (range) 0.9 (10.6 to -1.9); 2.5 (12.9 to -4.4); 1.4 (10.8 to -1.9 ml/min/year)], arterial blood pressure, albuminuria, hemoglobin A1c or cholesterol between the three groups (II, ID and DD), respectively. At baseline, multiple linear regression analysis including the above-mentioned putative risk factors revealed that albuminuria, short stature, and male gender independently predict an enhanced decline in GFR [R2 (adjusted) = 0.33; P < 0.002]. During the follow-up period, only albuminuria acted as an independent progression promoter [R2 (adjusted) = 0.37; P < 0.0001].

CONCLUSIONS

Our study revealed a rather slow progression of kidney disease in normotensive type 1 diabetic patients with diabetic nephropathy. Albuminuria, short stature, and male gender act as progression promoters in such patients.

Increased bradykinin and "normal" angiotensin peptide levels in diabetic Sprague-Dawley and transgenic (mRen-2)27 rats

BACKGROUND

The transgenic (mRen-2)27 rat (TGR) is a high tissue renin, high angiotensin (Ang) II model of hypertension. When administered streptozotocin (STZ), TGRs develop a rapidly progressive diabetic nephropathy with renal failure over 12 weeks. Bradykinin (BK) and Ang II are potent vasoactive peptides that may participate in the vascular and metabolic abnormalities of diabetes.

METHODS

TGR and Sprague-Dawley (SD) rats were administered STZ (diabetic) or citrate buffer (nondiabetic) at six weeks of age. Diabetic rats received daily ultralente insulin to maintain moderate hyperglycemia ( approximately 18 mM). Rats were sacrificed four- and eight-weeks post-STZ or vehicle.

RESULTS

Diabetes did not modify the blood pressure of either SD rats or TGRs. Diabetes increased levels of BK-(1-9) and its metabolite BK-(1-7) in kidney, aorta, and heart of both SD rats and TGRs. Diabetes did not influence Ang II levels in plasma, kidney, aorta, heart, or adrenal gland of SD rats, but reduced to normal the elevated Ang II levels in plasma, kidney, aorta, and adrenal gland of TGRs.

CONCLUSIONS

STZ-induced diabetes was associated with elevated tissue levels of BK-(1-9) and "normal" circulating and tissue levels of Ang II. The increased BK-(1-9) levels were consistent with the participation of this peptide in the vascular and metabolic abnormalities of diabetes. However, the rapidly progressive nephropathy of diabetic TGRs was not associated with BK-(1-9) and Ang II levels in target organs that differed from those of diabetic SD rats.

Natural course of kidney function in Type 2 diabetic patients with diabetic nephropathy

AIMS

To determine the natural course of kidney function and to evaluate the impact of putative progression promoters in Caucasian Type 2 diabetes mellitus (DM) patients with diabetic nephropathy who had never received any antihypertensive treatment.

METHODS

A long-term observational study of 13 normotensive to borderline hypertensive Type 2 DM patients with diabetic nephropathy. Glomerular filtration rate (GFR) was measured approximately every year (51Cr-EDTA plasma clearance technique). Albuminuria, blood pressure (BP) and haemoglobin A1c (HbA1c) was determined 2-4 times per year and serum cholesterol every second year.

RESULTS

The patients (12 males/one female), age 56+/-9 (mean +/- SD) years, with a known duration of diabetes of 10+/-6 years, were followed for 55 (24-105) (median (range)) months. GFR decreased from 104 (50-126) to 80 (39-112) ml x min(-1) x 1.73 m(-2) (P = 0.002) with a median rate of decline of 4.5 (-0.4 to 12) ml x min(-1) x year(-1). During follow-up, albuminuria rose from 494 (301-1868) to 908 (108-2169) mg/24 h (P = 0.25), while BP, HbA1c and serum cholesterol remained essentially unchanged. In univariate analysis the rate of decline in GFR did not correlate significantly with neither baseline nor mean values during follow-up of BP, albuminuria, HbA1c and serum cholesterol.

CONCLUSIONS

Our study suggests that normotensive to borderline hypertensive Type 2 DM patients with diabetic nephropathy have a rather slow decline in kidney function, but we did not unravel the putative progression promoters responsible for the variation in rate of decline in GFR.

Value of blood pressure self-monitoring as a predictor of progression of diabetic nephropathy

OBJECTIVE

To determine the impact of self-monitoring of blood pressure values (BP(S)) as compared with office blood pressure measurements (BP(O)) on the progression of diabetic nephropathy.

DESIGN

Long-term, follow-up cohort study.

SUBJECTS AND METHODS

Hypertensive, type 1 diabetic patients with overt diabetic nephropathy were investigated. Patients initially participated in a hypertension treatment and teaching programme including extensive advice on blood pressure self-monitoring. Self-monitoring and office blood pressure values were continuously assessed during the entire follow-up period. Progression of diabetic nephropathy over the study period was individually assessed as the mean decline of glomerular filtration rate (GFR) per patient per year. Baseline and follow-up parameters were included in stepwise multiple regression analyses with the decline of GFR per year as the dependent variable.

RESULTS

Seventy-seven type 1 diabetic patients (37 women, 40 men) were followed for a mean period of 6.2 +/- 2.8 years (mean +/- SD; range 2-12) resulting in a total of 481 patient-years. During the follow-up period, mean BP(O) decreased from 166/95 at baseline to 154/89 mmHg during follow-up, and mean BP(S) fell from 159/93 to 138/83 mmHg. The mean decline of GFR was 4.1 +/- 5.6 ml/min per year. Loss of kidney function was significantly correlated with proteinuria, blood pressure and glycosylated haemoglobin values. In the multiple regression analyses, BP(S) predicted the loss of renal function better than BP(O) (R2 = 0.52 versus 0.42). The simple correlation between BP(S) and GFR decline was higher compared to BP(O) and GFR (r = -0.42; P < 0.0001 versus -0.33; P < 0.004).

CONCLUSION

Blood pressure self-monitoring values are a better predictor of progression of diabetic nephropathy when compared with office blood pressure measurements.

AT1 receptor antagonists: a challenge for ACE inhibitors in diabetic nephropathy

Due to its hemodynamic, metabolic and growth promoting effects, angiotensin II (AII) may play an important role in the pathogenesis of diabetic kidney disease. Consequently, decreasing the production or cellular action of AII is a rational target for therapeutic attempts aimed at slowing the progression of diabetic nephropathy. Based on their superior renoprotective performance in recent landmark studies, currently ACE inhibitors are the drugs of choice in diabetic patients with microalbuminuria or overt proteinuria. A new class of antihypertensive medications, the AT1 receptor antagonists may represent an alternative to ACE inhibitors in the treatment of diabetic nephropathy. They provide a more complete blockade of the renal renin-angiotensin system and are generally better tolerated than ACE inhibitors. On the other hand, AT1 receptor antagonists do not increase bradykinin levels, an effect that may contribute to the high level of renoprotection achieved by ACE inhibitors. Although human data are not available at this point, ACE inhibitors and AT1 receptor antagonists have similar beneficial effects on proteinuria, renal hypertrophy and glomerulosclerosis in animal models of diabetic kidney disease. Currently several prospective studies are being conducted to compare the efficacy of ACE inhibitors and AT1 receptor antagonists in the treatment of human diabetic nephropathy.

Progression of renal failure and hypertensive nephrosclerosis

Data provided by end-stage renal disease (ESRD) registries document a progressive and striking increase in the incidence of hypertension-related ESRD over the years, and its prevalence supports the classic statement that the kidney may be a victim of hypertension. Two clinical conditions should be considered separately when the role of hypertension in progressive renal disease is discussed: (a) hypertension and primary renal disease and (b) progressive renal disease in essential hypertension. The appearance of systemic hypertension is one of the major risk factors for the progressive deterioration of primary renal disease both in experimental models and in humans. Strict blood pressure control is able to significantly reduce the disease progression to renal failure. Angiotensin-converting enzyme inhibitors probably show a better nephroprotective action than other antihypertensive agents. Long-lasting hypertension may induce ESRD in some patients through hypertensive nephrosclerosis. In many cases of progressive renal disease associated with essential hypertension, particularly in elderly Caucasians, atheromatous renovascular disease via renal artery stenosis and/or cholesterol microembolization represent the main cause of ESRD.

Effects of antihypertensive therapy on progression of diabetic nephropathy

There is a clear relationship between hypertension and the microvascular complications of diabetes. Genetic predisposition to hypertension has been correlated to the risk of diabetic nephropathy in type I diabetes, and hypertension is a well known risk factor for developing nephropathy in patients with type II diabetes. Multiple studies have emphasized the importance of hypertension on renal disease progression, and blood pressure control with conventional antihypertensive drugs slows the rate of renal function loss in diabetic nephropathy. Furthermore, evidence of the role of renin-angiotensin system (RAS) on progression of renal damage has focused much interest on the therapeutic action of the RAS blockade. In patients with type I diabetes, blocking the RAS with angiotensin converting enzyme (ACE) inhibitors prevents progression from microalbuminuria to overt nephropathy, and in overt nephropathy decreases the gradual loss of renal function beyond its blood pressure lowering effect. Less clinical information is available in type II diabetic nephropathy, but our experience and some recent studies suggest that ACE inhibitors also have a renoprotective action in type II diabetes. The role of calcium channel blockers in diabetic nephropathy is not clear. Several short-term studies with the first generation dihydropyridine calcium antagonists showed a lower effect on urinary albumin excretion and a more rapid progression to renal failure than with ACE inhibitors. However, other calcium channel blockers, particularly of the non-dihydropyridine type, have been shown to have a beneficial effect on diabetic nephropathy, decreasing proteinuria and slowing progression.

Antihypertensive therapy in type 2 diabetes: implications of the appropriate blood pressure control in diabetes (ABCD) trial

As the population ages, the incidence of type 2 diabetes will increase as will the incidence of concomitant vascular complications. Hypertension substantially increases the risk of cardiovascular disease in patients with diabetes. Results from the recent Appropriate Blood Pressure Control in Diabetes (ABCD) trial demonstrated an advantage of an angiotensin-converting enzyme (ACE) inhibitor (enalapril) over a long-acting calcium antagonist (nisoldipine) with regard to the incidence of cardiovascular events over a 5-year follow-up period in hypertensive persons with type 2 diabetes. This trial was a prospective, randomized, blinded study comparing the effects of moderate blood pressure control (target diastolic pressure 80-89 mm Hg) with those of intensive control (target diastolic pressure 75 mm Hg) on the incidence and progression of diabetic vascular complications. The study also compared nisoldipine with enalapril as first-line antihypertensive therapy in terms of prevention and progression of complications of diabetes. In 470 hypertensive patients, the incidence of fatal and nonfatal myocardial infarctions was significantly (p = 0.001) higher among those receiving nisoldipine (n = 25) compared with those receiving enalapril (n = 5). Comparison with previous studies suggests that the difference observed between nisoldipine and enalapril resulted from a beneficial effect of enalapril rather than a deleterious effect from nisoldipine. Since these findings in the ABCD trial are based on a secondary endpoint, they require confirmation. Nevertheless, they suggest that ACE inhibitors should be the initial antihypertensive medication used in patients with type 2 diabetes and hypertension.

Protective effects of a small dose of captopril on the reduction of glomerular basement membrane anionic sites in spontaneously hypertensive rats with streptozotocin-induced diabetes

Angiotensin-converting enzyme (ACE) inhibitors have been used in several clinical trials to slow a progressive decline in glomerular function in patients with diabetic nephropathy independent of their effects on blood pressure. The purpose of this study was to clarify the mechanisms(s) through which an ACE inhibitor, captopril, exerts its protective effect on renal function using spontaneously hypertensive rats (SHR) with streptozotocin (STZ)-induced diabetes. Male SHRs were made diabetic by intravenous injection of STZ (45 mg/kg). One hundred or 25 mg/kg of captopril was administered daily for 4 weeks to them. Urine albumin excretion (UAE) rate was markedly increased in diabetic SHRs, while captopril treatment resulted in a significant suppression of UAE in diabetic SHRs, independent of both its daily dose and effects on blood pressure as well as glycemic control. Examination by electron microscope revealed that the number of anionic sites (AS) in the lamina rara externa per 1000 nm of glomerular basement membrane (GBM) was significantly decreased (22.9+/-0.2 to 16.1+/-0.3, p < 0.001), after induction of diabetes, whereas, significant recovery (18.2+/-0.1, p < 0.001) could be obtained even by the smaller dose (25 mg/kg) of captopril which did not exert either antihypertensive or antidiabetic effect on diabetic SHRs. Thus, we demonstrate here the direct evidence that captopril, an ACE inhibitor, can protect against damage on GBM of diabetic SHR without controlling blood pressure as well as blood glucose level.

Effect of enalapril on endothelial function in young insulin-dependent diabetic patients: a randomized, double-blind study

OBJECTIVES

We sought to determine whether 6 months of treatment with the angiotensin-converting enzyme (ACE) inhibitor enalapril can improve conduit artery endothelial function in young subjects with insulin-dependent diabetes mellitus (IDDM).

BACKGROUND

Endothelial dysfunction is an early event in atherogenesis and has been demonstrated in young subjects with IDDM. ACE inhibitors have been shown to enhance conduit artery endothelial function in animal experiments and in patients with established coronary atherosclerosis, although their effect in IDDM is not known.

METHODS

Ninety-one subjects (mean age 30.9 years, range 18 to 44) with stable IDDM but no clinical evidence of vascular disease were randomized to receive enalapril (20 mg once daily) (46 subjects) or placebo (45 subjects) in a randomized, double-blind, parallel-group study. Brachial artery flow-mediated dilation (FMD), an endothelium-dependent stimulus, and response to glyceryl trinitrate (GTN), which acts directly on vascular smooth muscle, were assessed noninvasively by means of high resolution external vascular ultrasound at baseline and after 12 and 24 weeks of treatment.

RESULTS

FMD was inversely correlated with total cholesterol (r=0.22, p=0.041) but not with any diabetic variables. Treatment with enalapril had no significant effect on FMD (p=0.67) or response to the endothelial-independent dilator GTN (p=0.45).

CONCLUSIONS

These data suggest that impairment of endothelial-dependent dilation in young subjects with IDDM is not improved by treatment with the ACE inhibitor enalapril. This lack of improvement may reflect the complex nature of vascular disease in IDDM, which can affect both endothelial and smooth muscle function.

The effect of nisoldipine as compared with enalapril on cardiovascular outcomes in patients with non-insulin-dependent diabetes and hypertension

BACKGROUND

It has recently been reported that the use of calcium-channel blockers for hypertension may be associated with an increased risk of cardiovascular complications. Because this issue remains controversial, we studied the incidence of such complications in patients with non-insulin-dependent diabetes mellitus and hypertension who were randomly assigned to treatment with either the calcium-channel blocker nisoldipine or the angiotensin-converting-enzyme inhibitor enalapril as part of a larger study.

METHODS

The Appropriate Blood Pressure Control in Diabetes (ABCD) Trial is a prospective, randomized, blinded trial comparing the effects of moderate control of blood pressure (target diastolic pressure, 80 to 89 mm Hg) with those of intensive control of blood pressure (diastolic pressure, 75 mm Hg) on the incidence and progression of complications of diabetes. The study also compared nisoldipine with enalapril as a first-line antihypertensive agent in terms of the prevention and progression of complications of diabetes. In the current study, we analyzed data on a secondary end point (the incidence of myocardial infarction) in the subgroup of patients in the ABCD Trial who had hypertension.

RESULTS

Analysis of the 470 patients in the trial who had hypertension (base-line diastolic blood pressure, > or = 90 mm Hg) showed similar control of blood pressure, blood glucose and lipid concentrations, and smoking behavior in the nisoldipine group (237 patients) and the enalapril group (233 patients) throughout five years of follow-up. Using a multiple logistic-regression model with adjustment for cardiac risk factors, we found that nisoldipine was associated with a higher incidence of fatal and nonfatal myocardial infarctions (a total of 24) than enalapril (total, 4) (risk ratio, 9.5; 95 percent confidence interval, 2.7 to 33.8).

CONCLUSIONS

In this population of patients with diabetes and hypertension, we found a significantly higher incidence of fatal and nonfatal myocardial infarction among those assigned to therapy with the calcium-channel blocker nisoldipine than among those assigned to receive enalapril. Since our findings are based on a secondary end point, they will require confirmation.

Experimental diabetes is associated with functional activation of protein kinase C epsilon and phosphorylation of troponin I in the heart, which are prevented by angiotensin II receptor blockade

A cardiomyopathy that is characterized by an impairment in diastolic relaxation and a loss of calcium sensitivity of the isolated myofibril has been described in chronic diabetic animals and humans. To explore a possible role for protein kinase C (PKC)-mediated phosphorylation of myofibrillar proteins in this process, we characterized the subcellular distribution of the major PKC isoforms seen in the adult heart in cardiocytes isolated from diabetic rats and determined patterns of phosphorylation of the major regulatory proteins, including troponin I (TnI). Rats were made diabetic with a single injection of streptozotocin, and myocardiocytes were isolated and studied 3 to 4 weeks later. In nondiabetic animals, 76% of the PKC epsilon isoform was located in the cytosol and 24% was particulate, whereas in diabetic animals, 55% was cytosolic and 45% was particulate (P < .05). PKC delta, the other major PKC isoform seen in adult cardiocytes, did not show a change in subcellular localization. In parallel, TnI phosphorylation was increased 5-fold in cardiocytes isolated from the hearts of diabetic animals relative to control animals (P < .01). The change in PKC epsilon distribution and in TnI phosphorylation in diabetic animals was completely prevented by rendering the animals euglycemic with insulin or by concomitant treatment with a specific angiotensin II type-1 receptor (AT1) antagonist. Since PKC phosphorylation of TnI has been associated with a loss of calcium sensitivity of intact myofibrils, these data suggest that angiotensin II receptor-mediated activation of PKC may play a role in the contractile dysfunction seen in chronic diabetes.