Prevention of diabetic nephropathy with enalapril in normotensive diabetics with microalbuminuria

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Clinical trials with reno-vascular end points in patients with diabetes: Changing the scenario over the past 20 years

Major clinical advances over the last 20 years in the area of diabetic kidney disease (DKD) have been confirmed in large seminal clinical trials. These findings add to the previously identified benefits resulting from intensive glucose and blood pressure control therapies. Furthermore, newer glucose lowering treatments such as SGLT2 inhibitors and GLP-1 agonists appear very promising and are likely to transform the management and outlook of DKD over the next decade. In addition, novel mineralocorticoid receptor antagonists and a recently reported trial with an endothelin receptor blocker also have the potential to change clinical practice.

Recent advances in the pharmacotherapeutic management of diabetic kidney disease

INTRODUCTION

Diabetic kidney disease (DKD) remains a major cause of morbidity and mortality in diabetes and is a key cause of end-stage kidney disease (ESKD) worldwide. Major clinical advances have been confirmed in large trials demonstrating renoprotection, adding to the benefits of existing intensive glucose and blood pressure control therapies. Furthermore, there are exciting new treatments predominantly at an experimental and early clinical phase which appear promising.

AREAS COVERED

The authors review DKD in the context of existing and emerging therapies affording cardiorenal benefits including SGLT2 inhibitors and GLP-1 receptor agonists. They explore novel therapies demonstrating potential including a newly developed mineralocorticoid receptor antagonist and endothelin receptor blockade, while evaluating the utility of DPP4 inhibitors in current clinical practice. They also consider the recent evidence of emerging therapies targeting metabolic pathways with enzyme inhibitors, anti-fibrotic agents, and agents modulating transcription factors.

EXPERT OPINION

Significant improvements have been made in the management of DKD with SGLT2i and GLP-1 agonists providing impressive renoprotection, with novel progress in renin-angiotensin-aldosterone system (RAAS) blockade with finerenone. There is also great potential for several new experimental therapies. These advances provide us with optimism that the outlook of this devastating condition will continue to improve.

Management of hypertension and renin-angiotensin-aldosterone system blockade in adults with diabetic kidney disease: Association of British Clinical Diabetologists and the Renal Association UK guideline update 2021

People with type 1 and type 2 diabetes are at risk of developing progressive chronic kidney disease (CKD) and end-stage kidney failure. Hypertension is a major, reversible risk factor in people with diabetes for development of albuminuria, impaired kidney function, end-stage kidney disease and cardiovascular disease. Blood pressure control has been shown to be beneficial in people with diabetes in slowing progression of kidney disease and reducing cardiovascular events. However, randomised controlled trial evidence differs in type 1 and type 2 diabetes and different stages of CKD in terms of target blood pressure. Activation of the renin-angiotensin-aldosterone system (RAAS) is an important mechanism for the development and progression of CKD and cardiovascular disease. Randomised trials demonstrate that RAAS blockade is effective in preventing/ slowing progression of CKD and reducing cardiovascular events in people with type 1 and type 2 diabetes, albeit differently according to the stage of CKD. Emerging therapy with sodium glucose cotransporter-2 (SGLT-2) inhibitors, non-steroidal selective mineralocorticoid antagonists and endothelin-A receptor antagonists have been shown in randomised trials to lower blood pressure and further reduce the risk of progression of CKD and cardiovascular disease in people with type 2 diabetes. This guideline reviews the current evidence and makes recommendations about blood pressure control and the use of RAAS-blocking agents in different stages of CKD in people with both type 1 and type 2 diabetes.

Glycosuria amount in response to hyperglycaemia and risk for diabetic kidney disease and related events in Type 1 diabetic patients

BACKGROUND

Hyperglycaemia impairs tubulo-glomerular feedback. We tested whether variable tubulo-glomerular feedback during hyperglycaemia contributes to renal risk heterogeneity seen in Type 1 diabetes.

METHODS

During the period 1990-92, we studied the tubulo-glomerular feedback in Type 1 diabetic patients at high or low renal risk [21 of 54 with glomerular hyperfiltration and/or microalbuminuria against 11 of 55 with normal glomerular filtration rate (GFR) and urinary albumin despite uncontrolled diabetes]. The GFR, effective renal plasma flow, mean arterial pressure and fractional reabsorptions of glucose, osmols, sodium and lithium were measured sequentially during normo- and hyperglycaemia. All patients were followed up until 2016 for incident proteinuria, estimated GFR <60 mL/min/1.73 m2, doubling of serum creatinine, end-stage renal disease or all-cause death.

RESULTS

Glycaemia increased from 6.1 ± 1.3 to 15.1 ± 1.9 mmol/L in both high-risk and low-risk patients. Glycosuria was lower in the high- versus low-risk patients: 0.34 ± 0.25 versus 0.64 ± 0.44 mmol/min (P = 0.03). Both groups displayed similar kidney function during normoglycaemia. Hyperglycaemia increased more importantly GFR and fractional reabsorptions, and pre-glomerular vasodilatation in the high- than in the low-risk patients (all P < 0.05). Over 21 years, 31.5% high- versus 12.7% low-risk patients developed endpoints (adjusted P = 0.006). In a multi-adjusted survival analysis of patients having undergone renal tests, each 0.10 mmol/min glycosuria during hyperglycaemia reduced the outcome risk by 0.72 (95% confidence interval 0.49-0.97, P = 0.03).

CONCLUSIONS

Reduced tubulo-glomerular feedback and glycosuria during hyperglycaemia indicate high renal risk for Type 1 diabetic patients. Inter-individual variability in tubulo-glomerular feedback activity determines renal risk in Type 1 diabetes.

Importance of intensive blood pressure control in type 2 diabetes: Mechanisms, treatments and current guidelines

Observational and interventional studies have shown that intensified blood pressure (BP) reduction can benefit people with diabetes. Because of their special haemodynamic properties, renin-angiotensin-aldosterone system (RAAS) blockers are recommended. The results of the BP arm of the ADVANCE study strongly support the recently updated European Society of Cardiology/European Association of Diabetes recommendations for the treatment of BP in people with diabetes, which recommend a target systolic/diastolic BP of 130/80 mmHg with few exceptions, and a fixed combination of an RAAS blocker with a diuretic or a calcium channel blocker as first-line treatment.

Chinese herbal medicine Tangshen Formula treatment for type 2 diabetic kidney disease in the early stage: study protocol for a randomized controlled trial

BACKGROUND

Diabetic kidney disease (DKD) is the main cause of end-stage kidney disease and has become a heavy economic and social burden due to its high prevalence and morbidity. The most effective strategy is that patients with DKD should be diagnosed and treated early. Preliminary studies showed that the Chinese herbal Tangshen Formula (TSF) may delay the progression of DKD, reducing microalbuminuria and macroalbuminuria and improving renal function. We designed a randomized, double-blind, placebo-controlled trial to evaluate the efficacy of TSF in patients with DKD.

METHODS/DESIGN

This trial is a 13-center, randomized, double-blind, placebo-controlled study. A total of 632 participants will be randomized in a 1:1 ratio to an experiment group (TSF plus losartan) and a control group (placebo plus losartan). The trial cycle will last 24 weeks. The primary outcome will be the change in the urine microalbumin-creatinine ratio from baseline to week 24. The secondary outcome will be the change in the rate of progression to the clinical proteinuria period after intervention, the rate of urine microalbumin negative conversion, the rate of normal urinary microalbumin, the doubling rate of the baseline creatinine value and the glomerular filtration rate between the two groups. Safety in medication will also be evaluated.

DISCUSSION

We hypothesize that patients with type 2 diabetes in the early stage of DKD will benefit from TSF. If successful, this study will provide evidence-based recommendations for clinicians.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03009864. Registered January 2017.

Effect of ACE-inhibition on coronary microvascular function and symptoms in normotensive women with microvascular angina: A randomized placebo-controlled trial

Objective

Studies have suggested a beneficial effect of angiotensin-converting enzyme (ACE) inhibition. To explore whether the ACE inhibitor ramipril has a direct effect on the microvasculature beyond the blood pressure (BP) lowering effect, we investigated whether ramipril improved coronary microvascular function in normotensive women with coronary microvascular dysfunction (CMD).

Methods

We included 63 normotensive women with angina, no epicardial stenosis>50% and CMD defined as a coronary flow velocity reserve (CFVR)<2.2 assessed by adenosine stress-echocardiography in a randomized double-blinded, superiority trial with 1:1 allocation to placebo or ramipril (maximum dose 10 mg depending on blood pressure) for 24±6 weeks. Primary outcome was CFVR. Secondary outcomes were left ventricular systolic and diastolic function and symptoms evaluated by Seattle Angina Questionnaire (clinicaltrials.gov, NCT02525081).

Results

Follow-up was available on 55 patients. BP remained unchanged during treatment in both groups. CFVR improved in both the ramipril (p = 0.004) and placebo group (p = 0.026) with no difference between groups (p = 0.63). Symptoms improved in both groups with no significant between-group differences. No changes were detected in parameters of systolic and diastolic function. No serious adverse reactions were reported.

Conclusions

In normotensive women with angina and CMD, treatment with ramipril had no significant effect on CFVR or symptoms compared with placebo. The effect of ACE inhibition previously reported may be mediated by blood pressure reduction.

Dietary Apostichopus japonicus Alleviates Diabetes Symptoms and Modulates Genes Expression in Kidney Tissues of db/db Mice

The effects of Apostichopus japonicus enzymatic hydrolysate on the regulation of dyslipidemia, pathoglycemia, and transcription changes in kidney tissues of db/db mice were evaluated. In this study, the symptoms of diabetes in db/db mice were alleviated after 10 weeks of treatments with low (db/db + LD group) and high dose (db/db + HD group) of Apostichopus japonicus enzymatic hydrolysate, and the high dose treatment showed a better antidiabetic effect. Compared with the db/db group, the fasting blood glucose levels (36.84 ± 7.82 vs 25.18 ± 6.84 mmol/L, P < 0.01), the urine glucose levels (45.44 ± 3.93 vs 22.66 ± 5.58 mmol/L, P < 0.01), and the serum insulin sensitivity index (-4.65 ± 0.43 vs -4.74 ± 0.75, P > 0.05) in the db/db + HD group were decreased, whereas the fasting plasma insulin (3.12 ± 1.08 vs 5.54 ± 1.82 μg/L, P < 0.01) and the serum insulin resistance index (5.01 ± 2.02 vs 5.96 ± 2.49, P < 0.05) were increased. Subsequently, the kidney transcription profiles were measured in the db/db group and db/db + HD group via microarray, and the results show that Apostichopus japonicus hydrolysate induced differential expression of 77 genes. Among these genes, the down-regulation of genes ntrK1 and ptpN5 played vital roles, as this effect induced the further down-regulation of neurotrophin tyrosine kinase, protein tyrosine phosphatase, and other transcription factors, which are involved in the classical mitogen-activated protein kinases (MAPK) and p38MAPK signaling pathways. The inhibited MAPK and p38MAPK signaling pathways are involved in glycometabolism and the control of lipid metabolism, and they regulate the occurrence and development of diabetic nephropathy.

Levels of NT-proBNP, markers of low-grade inflammation, and endothelial dysfunction during spironolactone treatment in patients with diabetic kidney disease

Renin-angiotensin-aldosterone system (RAAS) blockade may reduce levels of biomarkers of chronic low-grade inflammation and endothelial dysfunction. We investigated the effect of spironolactone added to standard RAAS blockade on these biomarkers in an analysis of four original studies.

MATERIALS AND METHODS

The studies were double-blind, randomised, placebo-controlled studies in 46 type 1 and 23 type 2 diabetic patients with micro- or macroalbuminuria treated with angiotensin-converting enzyme inhibitor (ACE inhibitor) or angiotensin receptor blocker (ARB), and randomised to additional treatment with spironolactone 25 mg and placebo daily for 60 days.

OUTCOME MEASURES

Changes in inflammatory (hsCRP, s-ICAM, TNFα, IL-6, IL-8, Serum amyloid A, IL1β), endothelial dysfunction (sE-selectin, s-ICAM1, s-VCAM1, VWF, p-selectin, s-thrombomodulin) and NT-proBNP after each treatment period.

RESULTS

During spironolactone treatment, u-albumin excretion rate was reduced from 605 (411-890) to 433 (295-636) mg/24 h, as previously reported. Markers of inflammation and endothelial dysfunction did not change; only changes in NT-proBNP (reduced by 14%, p=0.05) and serum amyloid A (reduced by 62%, p=0.10) were borderline significant.

DISCUSSIONS

Our results indicate that the renoprotective effect of spironolactone when added to RAAS blockade is not mediated through anti-inflammatory pathways since markers of inflammation and endothelial dysfunction are not affected during treatment.

Spironolactone diminishes urinary albumin excretion in patients with type 1 diabetes and microalbuminuria: a randomized placebo-controlled crossover study

AIMS

Adding aldosterone receptor blockade to standard renoprotective treatment may provide additional renoprotection in patients with overt nephropathy. We expected an impact of spironolactone in early diabetic nephropathy, and for this hypothesis we studied the effect on markers of glomerular and tubular damage in patients with Type 1 diabetes and persistent microalbuminuria.

METHODS

A double-blind, randomized, placebo-controlled crossover study in 21 patients with Type 1 diabetes and microalbuminuria using spironolactone 25 mg or placebo once daily, for 60 days added to standard antihypertensive treatment. After each treatment period, the primary endpoint were evaluated: urinary(u)-albumin excretion/24 hour(h) and secondary endpoints; 24 h blood pressure, glomerular filtration rate (GFR) and markers of tubular damage: urinary liver-type fatty-acid binding protein (LFABP), neutrophil gelatinase associated lipocalin (NGAL) and kidney injury molecule 1 (KIM1).

RESULTS

All patients completed the study. During spironolactone treatment, urinary albumin excretion rate was reduced by 60% (range 21-80%), from 90 mg/24 h to 35 mg/24 h (P=0.01). Blood pressure (24 h) did not change during spironolactone treatment (P>0.2 for all comparisons). The GFR (SD) decreased from 78 (6) mL/min/1.73 m(2) to 72 (6) mL/min/1.73 m(2) (P=0.003). Urinary liver-type fatty-acid binding protein, neutrophil gelatinase-associated lipocalin and kidney injury molecule 1 did not change during treatment (P>0.3 for all comparisons). Treatment was well-tolerated, but two patients had severe hyperkalaemia (plasma potassium = 5.7 mmol/l), which was sufficiently treated with diuretics and dietary intervention.

CONCLUSIONS

Spironolactone treatment in addition to standard renoprotective treatment lowers urinary albumin excretion in microalbuminuric patients with Type 1 diabetes, and thus may offer additional renoprotection independent of blood pressure.

Adding a statin to a combination of ACE inhibitor and ARB normalizes proteinuria in experimental diabetes, which translates into full renoprotection

The capacity of renin-angiotensin system (RAS) inhibitors to delay progression of diabetic nephropathy depends on the time at which therapy is started. A multimodal intervention is required to afford renoprotection in overt diabetic nephropathy. Here we assessed the effects of maximal RAS inhibition by angiotensin-converting enzyme (ACE) inhibitor plus angiotensin II type 1 receptor blocker (ARB) in combination with statin in rats with overt diabetic nephropathy. Uninephrectomized rats made diabetic by streptozotocin were orally treated from 4 (when proteinuria and renal lesions had developed) to 8 mo with vehicle, lisinopril plus candesartan, lisinopril plus candesartan plus rosuvastatin, or rosuvastatin alone. Systolic blood pressure increased in diabetic rats and was significantly lowered by combined therapies. Dual RAS blockade significantly reduced proteinuria compared with vehicle. Addition of statin further lowered proteinuria to control levels. Glomerulosclerosis was ameliorated by RAS inhibitors or statin, and regression was achieved by the addition of statin. Loss of podocytes of diabetic rats was limited by ACE inhibitor plus ARB while normalized by the three drugs. Defective nephrin expression of diabetes was increased by dual RAS blockade or statin and restored by the triple therapy. Tubular damage, interstitial inflammation, and expression of the fibrotic markers transforming growth factor (TGF)-β1 and phosphorylated Smad 2/3 in tubuli were significantly reduced by the triple regimen. These data suggest a strategy to target proteinuria to try to achieve regression of renal disease in diabetic patients who do not fully benefit from RAS inhibition alone.

When to initiate ACEI/ARB therapy in patients with type 1 and 2 diabetes

Angiotensin converting enzyme inhibitors (ACEI) and angiotensin 2 receptor blockers (ARB) have become a mainstay of adjunctive therapy for the prevention and amelioration of diabetic nephropathy. Although ACEI were shown over 20 years ago to slow the rate of loss of renal function in diabetic subjects with decreased renal function, the question of how early in the course of diabetes to introduce them remains unresolved. Recent studies suggest that very early initiation of ACEI/ARB therapy may not have demonstrable beneficial effects even over a period of years.

Evidence-based guide to slowing the progression of early renal insufficiency

Early renal insufficiency (ERI), defined as a calculated or measured glomerular filtration rate (GFR) between 30 and 60 mL/min per 1.73 m2, is present in more than 10% of the adult Australian population. This pernicious condition is frequently unrecognised, progressive and accompanied by multiple associated comorbidities, including hypertension, renal osteodystrophy, anaemia, sleep apnoea, cardiovascular disease, hyperparathyroidism and malnutrition. Several treatments have been suggested to retard GFR decline in ERI, including blood pressure reduction, angiotensin-converting enzyme inhibition, angiotensin receptor antagonism, calcium channel blockade, cholesterol reduction, smoking cessation, erythropoietin therapy, dietary protein restriction, intensive glycaemic control and early intensive multidisciplinary patient education within a renal unit. In addition, specific interventions have been reported to be renoprotective in atherosclerotic renal artery stenosis, diabetic nephropathy, lupus nephritis and certain forms of primary glomerulonephritis. The present paper reviews the available published randomised controlled clinical trials and meta-analyses supporting (or refuting) a role for each of these therapeutic manoeuvres.

Long-term prevention of diabetic nephropathy: an audit

AIMS/HYPOTHESIS

In type 1 diabetic patients with microalbuminuria not receiving antihypertensive treatment, an increase in urinary AER (UAER) of 6-14%/year and a risk of developing diabetic nephropathy (DN) of 3-30%/year have been reported. We audited the long-term effect of blocking the renin-angiotensin-aldosterone system (RAAS) with an ACE inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in microalbuminuric type 1 diabetic patients on progression of microalbuminuria and development of DN.

METHODS

All patients with type 1 diabetes and persistent microalbuminuria (30-300 mg/24 h) were identified (n=227) in 1995 at Steno Diabetes Center and followed for 11 years. Development of DN was defined as a UAER of >300 mg/24 h in two of three consecutive urine samples.

RESULTS

Age and duration of diabetes at baseline (mean+/-SD) were 46+/-15 and 28+/-13 years, respectively. During follow-up 14 patients emigrated and 58 (26%) died. Over the same period 79% were treated with an ACEI or ARB. There was a mean decline in UAER of 4%/year. Sixty-five patients (29%) progressed to overt DN, corresponding to 3.1%/year. However, 29 of them regressed to normo- or microalbuminuria on intensified antihypertensive treatment. Glycaemic control and blood pressure remained nearly unchanged.

CONCLUSIONS/INTERPRETATION

In our outpatient clinic, the implementation of RAAS-blocking treatment in type 1 diabetic patients with microalbuminuria successfully reduced long-term progression to overt DN to a rate similar to those previously reported in randomised, double-blind intervention trials of shorter duration using RAAS blockade.

Lack of association between the angiotensin-converting enzyme gene (I/D) polymorphism and diabetic nephropathy in Tunisian type 2 diabetic patients

Objective. The aim of the present study was to investigate whether the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism is associated with diabetic nephropathy and type 2 diabetes in the Tunisian population.

Design. A case-control study was conducted among 141 unrelated type 2 diabetic patients with (90 patients) or without nephropathy (51 patients) and 103 non-diabetic controls with normal fasting blood glucose. Genotyping was performed using a nested polymerase chain reaction amplification in order to identify correctly heterozygous individuals.

Results. The distribution of DD, ID and II genotypes did not significantly differ between type 2 diabetic patients with or without nephropathy (DD: 44%; ID: 46%; II: 10% vs. DD: 41%; ID: 47 %; II: 12%, respectively).There was also no significant statistical difference between the genotype distribution and allele frequencies of the (I/D) polymorphism in all type 2 diabetic subjects compared to non-diabetic controls with normal fasting blood glucose (DD: 43%; ID: 46%; II: 11% vs. DD: 37%; ID: 48% ;II: 15%, respectively).

Conclusions. In the present preliminary study, the (I/D) polymorphis within the ACE gene is likely not associated with diabetic nephropathy nor with type 2 diabetes in the Tunisian studied population.

Rationale for Combining Blockers of the Renin-Angiotensin System

Blockade of the renin-angiotensin system (RAS) with angiotensin I-converting enzyme (ACE) inhibitors and AT1-receptor (AT1R) blockers has become one of the most successful therapeutic approaches in medicine. The question is no longer whether RAS inhibition helps, but rather how we can optimize inhibition to achieve optimal cardiovascular and renal protection. Indeed, numerous data have shown that the RAS is not blocked fully over 24 hours with current doses of RAS blockers because they trigger a counter-regulatory renin release that can offset pharmacologic inhibition of the RAS. This absence of full blockade may have clinical implications. Combination therapy with ACE inhibitors and AT1R antagonists thus has been proposed to inhibit the biological effects of the reactive renin release triggered by single-site RAS inhibition. By using this approach, numerous experimental and clinical studies have suggested that this combination therapy has additive or synergistic effects on blood pressure and on the prevention of cardiovascular and renal lesions. Although similar intensity of RAS blockade can be achieved by either combination therapy or by using high doses of an AT1-receptor antagonist given alone, the ACE inhibitor present in the combination interferes with the bradykinin-nitric oxide pathway and the N-acetyl-Ser-Asp-Lys-Pro metabolism, which both may have additional biological effects.

WITHDRAWN: Angiotensin converting enzyme inhibitors in normotensive diabetic patients with microalbuminuria

BACKGROUND

Renal disease is a serious complication of diabetes mellitus.

OBJECTIVES

To examine whether the progression of early diabetic renal disease to end-stage renal failure may be slowed by the use of angiotensin converting enzyme inhibitors for reasons other than their antihypertensive properties, so that they have value in the treatment of normotensive diabetics with microalbuminuria.

SEARCH STRATEGY

Medline was searched for English language reviews and randomised controlled trials. Personal reference lists, and reference lists of retrieved studies were also used.

SELECTION CRITERIA

Randomised controlled trials with separate identifiable results for initially normotensive diabetic patients, who received angiotensin converting enzyme inhibitors for at least one year and were compared with controls.

DATA COLLECTION AND ANALYSIS

Meta-analyses were performed on the results of 12 randomised controlled trials with a variety of patient inclusion and exclusion criteria. One further study met all conditions for inclusion but did not provide data in useable form for meta-analyses.

MAIN RESULTS

Albumin excretion rate fell for patients on angiotensin converting enzyme inhibition in 12 of the 13 studies but did so for only two of the 13 groups on placebo. Treatment provided a significant reduction in albumin excretion rate in both insulin dependent diabetes mellitus and non insulin dependent diabetes mellitus. Treatment with either captopril, enalapril or lisinopril reduced albumin excretion rate in comparison with control patients.A significantly greater lowering of blood pressure was experienced by initially normotensive patients in the angiotensin converting enzyme inhibitor than in the placebo group. Average glycosylated haemoglobin fell a little in the treated patients and rose in the controls, the difference being just significant. The difference in changes in glomerular filtration rate did not reach statistical significance.

AUTHORS' CONCLUSIONS

Inhibition of angiotensin converting enzyme can arrest or reduce the albumin excretion rate in microalbuminuric normotensive diabetics, as well as reduce or prevent an increase in blood pressure. But, given the drop in blood pressure in patients on angiotensin converting enzyme inhibitors, it is not certain that the reduction of albumin excretion rate is due to a separate renal effect. A direct link with postponement of end-stage renal failure has not been demonstrated. There appear to be no substantial side effects.

Relationship Between Low-Normal Blood Pressure and Kidney Disease in Type 1 Diabetes

Current recommendations, largely based on studies in type 2 diabetes, suggest lower target blood pressures (BPs) for individuals with diabetes than for the general population. However, the effect of lower BP on renal outcomes in type 1 diabetes is uncertain. In a population-based cohort of type 1 diabetes adults (mean age: 33.1 years) based in Wisconsin, of which the distribution of baseline BP was in the low-normal range, we examined the relationship between decreasing categories of systolic and diastolic BP and the 16-year incidence of proteinuria (n=232 of 604) and estimated glomerular filtration rate of <60 mL/min/1.73 m 2 (n=158 of 547). Decreasing BP categories had lower relative risk (RR) of developing incident proteinuria (RR comparing decreasing quartiles of systolic BP: 1.00, 0.76, 0.58, 0.73; P for trend=0.03; RR comparing decreasing quartiles of diastolic BP: 1.00, 0.81, 0.66, 0.42; P for trend <0.0001) and incident estimated glomerular filtration rate <60 mL/min/1.73 m 2 (RR comparing decreasing quartiles of systolic BP: 1.00, 0.83, 0.61, 0.65; P for trend=0.03; RR comparing decreasing quartiles of diastolic BP: 1.00, 0.84, 0.82, 0.43; P for trend=0.001). These associations were independent of glycemic control and several putative confounding factors. Subjects with either systolic BP <120 mm Hg or diastolic BP <70 mm Hg had significantly lower RR (95% confidence interval) of incident proteinuria (0.63 [0.48 to 0.82]) and incident estimated glomerular filtration rate <60 mL/min/1.73 m 2 (0.60 [0.43 to 0.82]); corresponding population-attributable risks for these outcomes were 26.7% and 29.5%, respectively. Our study suggests that lower BP levels, even below the accepted normal range, are protective against kidney disease in adults with type 1 diabetes. Interventional trials are desirable to clarify the clinical significance of this association.

Angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists for preventing the progression of diabetic kidney disease

BACKGROUND

Angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor antagonists (AIIRA) are considered to be equally effective for patients with diabetic kidney disease (DKD), but renal and not mortality outcomes have usually been considered.

OBJECTIVES

To evaluate the benefits and harms ACEi and AIIRA in patients with DKD.

SEARCH STRATEGY

We searched MEDLINE (1966 to December 2005), EMBASE (1980 to December 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library issue 4 2005) and contacted known investigators.

SELECTION CRITERIA

Studies comparing ACEi or AIIRA with placebo or each other in patients with DKD were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) with 95% confidence intervals (CI). Heterogeneity among studies was explored using the Cochran Q statistic and the I(2) test, subgroup analyses and random effects metaregression.

MAIN RESULTS

Fifty studies (13,215 patients) were identified. Thirty eight compared ACEi with placebo, five compared AIIRA with placebo and seven compared ACEi and AIIRA directly. There was no significant difference in the risk of all-cause mortality for ACEi versus placebo (RR 0.91, 95% CI 0.71 to 1.17) and AIIRA versus placebo (RR 0.99, 95% CI 0.85 to 1.17). A subgroup analysis of studies using full-dose ACEi versus studies using half or less than half the maximum tolerable dose of ACEi showed a significant reduction in the risk of all-cause mortality with the use of full-dose ACEi (RR 0.78, 95% CI 0.61 to 0.98). Baseline mortality rates were similar in the ACEi and AIIRA studies. The effects of ACEi and AIIRA on renal outcomes (ESKD, doubling of creatinine, prevention of progression of micro- to macroalbuminuria, remission of micro- to normoalbuminuria) were similarly beneficial. Reliable estimates of effect of ACEi versus AIIRA could not be obtained from the three studies in which they were compared directly because of their small sample size.

AUTHORS' CONCLUSIONS

Although the survival benefits of ACEi are known for patients with DKD, the relative effects on survival of ACEi with AIIRA are unknown due to the lack of adequate direct comparison studies. In placebo controlled studies, only ACEi (at the maximum tolerable dose, but not lower so-called renal doses) were found to significantly reduce the risk of all-cause mortality. Renal and toxicity profiles of these two classes of agents were not significantly different.

Renin inhibition

PURPOSE OF REVIEW

Initial attempts to inhibit renin in humans have faced numerous difficulties. Molecular modeling and X-ray crystallography of the active site of renin have led to the development of new orally active renin inhibitors, such as aliskiren. Recent preclinical and clinical data suggest that this drug may be of value for treating patients with cardiovascular and renal disorders.

RECENT FINDINGS

The once-daily administration of aliskiren to hypertensive patients lowers blood pressure as strongly as, or more strongly than, standard doses of established angiotensin II type 1 receptor blockers. It further decreases blood pressure in combination with hydrochlorothiazide. The biochemical consequences of renin inhibition differ from those of angiotensin I-converting enzyme inhibition and angiotensin II antagonism, particularly in terms of angiotensin profiles and interactions with the bradykinin-nitric oxide-cGMP pathway and possibly the (pro)renin receptor.

SUMMARY

Blockade of the renin-angiotensin system with angiotensin I-converting enzyme inhibitors, angiotensin II type 1 receptor blockers or a combination of these drugs has become one of the most successful therapeutic approaches in medicine. It remains unclear, however, as to how to optimize the renin-angiotensin system blockade to maximize cardiovascular and renal benefits. In this context, renin inhibition to render the renin-angiotensin system fully quiescent is a new possibility requiring further study.

Beneficial Effect of TGFβ Antagonism in Treating Diabetic Nephropathy Depends on When Treatment Is Started

BACKGROUND

In diabetic rats with maximal activation of RAS induced by uninephrectomy, late treatment with anti-TGFbeta antibody limited renal injury only when combined with ACE inhibitor. We investigated whether in a two-kidney diabetic model the time at which treatment started predicted the response to TGFbeta antagonist.

METHODS

27 weeks after streptozotocin injection, animals had mild proteinuria and were randomized to receive irrelevant antibody, anti-TGFbeta antibody (1D11) or enalapril till 52 weeks (early treatment). The effect of agents alone or combined was also evaluated at the time of overt proteinuria (late treatment, 52-61 weeks).

RESULTS

When given early, 1D11 displayed marked antihypertensive and antiproteinuric effects. Glomerulosclerosis was reduced to the extent that a remarkable percentage of glomeruli without sclerosis appeared after treatment. Podocyte number was normalized. Renoprotection of 1D11 was comparable to enalapril. Despite control of blood pressure, in late treatment single agents did not reduce proteinuria significantly. Glomerulosclerosis and podocyte loss were partially limited by 1D11 or enalapril, but full protection was achieved by combination.

CONCLUSIONS

Renoprotective effect of TGFbeta antagonism crucially depends on the time at which treatment started. Effectiveness of early treatment with 1D11 would indicate that TGFbeta is a major mediator of damage in early diabetes. To tackle the renal damage in the phase of advanced disease, a combined treatment with ACE inhibitor is needed.

ACE-inhibitor use and the long-term risk of renal failure in diabetes

The incidence of end-stage renal disease (ESRD) owing to diabetes has continued to increase despite the extensive use of angiotensin-converting enzyme (ACE) inhibitors to prevent diabetic nephropathy, primarily from evidence of short-term effectiveness. We assessed the long-term effect of ACE inhibitors on the risk of ESRD. We formed a population-based cohort of all diabetic patients treated with antihypertensive drugs in the Province of Saskatchewan, Canada, between 1982 and 1986. The patients were followed up to the end of 1997 to identify cases of end-stage renal failure. A nested case-control analysis was used with the controls matched to each case on age, diabetes type, and duration of follow-up. The cohort comprised 6102 subjects, of which the 102 cases who developed end-stage renal failure were matched to 4129 controls. Relative to thiazide diuretic use, the adjusted rate ratio of end-stage renal failure associated with the use of ACE inhibitors was 2.5 (95% confidence interval 1.3-4.7), whereas it was 0.8 (95% confidence interval 0.5-1.4) for beta-blockers and 0.7 (95% confidence interval 0.4-1.3) for calcium antagonists. The rate ratio of end-stage renal failure with the use of ACE inhibitors was 0.8 (95% confidence interval 0.3-2.5) during the first 3 years of follow-up, but increased to 4.2 (95% confidence interval 2.0-9.0) after 3 years. ACE-inhibitor use does not appear to decrease the long-term risk of end-stage renal failure in diabetes. Our data suggest instead that ACE inhibitors might actually increase this risk, which may possibly contribute to the continued increasing incidence of ESRD owing to diabetes.

Modulation of the renal response to ACE inhibition by ACE insertion/deletion polymorphism during hyperglycemia in normotensive, normoalbuminuric type 1 diabetic patients

ACE inhibition protects kidney function, but ACE insertion/deletion (I/D) polymorphism affects renal prognosis in type 1 diabetic patients. ACE genotype may influence the renal benefits of ACE inhibition. We studied the impact of ACE I/D polymorphism on the renal hemodynamic changes induced by ACE inhibition in type 1 diabetes. We studied renal hemodynamics (glomerular filtration rate [GFR], effective renal plasma flow [ERPF], filtration fraction [GFR/ERPF], mean arterial pressure [MAP], and total renal resistances [MAP/ERPF]) repeatedly during normoglycemia and then hyperglycemia in 12 normotensive, normoalbuminuric type 1 diabetes and the II genotype (associated with nephroprotection) versus 22 age- and sex-matched subjects with the ACE D allele after three randomly allocated 2- to 6-week periods on placebo, 1.25 mg/day ramipril, and 5 mg/day ramipril in a double-blind, cross-over study. During normoglycemia, the hemodynamic changes induced by ramipril were similar in both genotypes. During hyperglycemia, the changes induced by ramipril were accentuated in the II genotype group and attenuated dose dependently in the D allele group (treatment-genotype interaction P values for ERPF, 0.018; MAP, 0.018; and total renal resistances, 0.055). These results provide a basis to different renal responses to ACE inhibition according to ACE genotype in type 1 diabetes.

Effect of irbesartan on the antioxidant defence system and nitric oxide release in diabetic rat kidney

BACKGROUND/AIMS

Increased oxidative stress is involved in the aetiology of diabetic nephropathy, and angiotensin II is reported to play a considerable role in the development of renal damage in diabetic kidney. Angiotensin antagonism can slow the progression of renal impairment in diabetes. The present study was thus designed to examine the effect of an angiotensin II type 1 (AT1) receptor antagonist, irbesartan on renal function, oxidative stress and nitric oxide (NO) release in streptozotocin (STZ)-induced diabetic rats.

METHODS

Diabetes was induced by a single intraperitoneal injection of streptozotocin (65 mg/kg) in rats. After 4 weeks of STZ injection, rats were divided into four groups: the control rats, diabetic rats and diabetic rats treated with irbesartan (25 and 50 mg/kg, orally) respectively till 8 weeks starting from 4 weeks after STZ injection. Renal function was assessed by creatinine, blood urea nitrogen, creatinine clearance and urea clearance. Oxidative stress was measured by renal malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase. We also measured renal nitrite levels.

RESULTS

At the end of the 8th week, diabetic rats exhibited renal dysfunction as evidenced by reduced creatinine and urea clearance along with enhanced albumin excretion rate as compared with control rats. Biochemical analysis of kidneys revealed a marked increase in oxidative stress demonstrated by increased lipid peroxidation and decreased activities of key antioxidant enzymes, GSH, SOD and catalase in diabetic rats. NO release was also significantly higher in diabetic rats than controls. Chronic treatment with irbesartan in diabetic rats significantly attenuated both renal dysfunction and oxidative stress along with increased NO levels as compared with untreated diabetic rats. The kidneys of diabetic rats showed morphological changes such as hyaline casts, glomerular thickening and moderate interstitial fibrosis and arteriolopathy, whereas irbesartan administration markedly prevented diabetic-induced renal morphological alterations.

CONCLUSIONS

The present study suggests that oxidative stress/nitrosative stress is increased in the diabetic kidney and AT1 receptor blockade can prevent these changes. The results also suggest that in STZ-induced diabetic rats, the protective action of irbesartan might be mediated, at least in part, by its effect on tissue oxidant/antioxidant status.

Equivalence of indapamide SR and enalapril on microalbuminuria reduction in hypertensive patients with type 2 diabetes

OBJECTIVES

To test whether microalbuminuria in patients with type 2 diabetes and hypertension is primarily dependent on the severity of hypertension, and to compare the effectiveness of two antihypertensive drugs with opposite effects on the renin-angiotensin system [the diuretic, indapamide sustained release (SR), and an angiotensin-converting enzyme inhibitor, enalapril] in reducing microalbuminuria.

DESIGN

A multinational, multicentre, controlled, double-blind, double-dummy, randomized, two-parallel-groups study over 1 year.

METHODS

After a 4-week placebo run-in period, 570 patients (ages 60.0 +/- 9.9 years, 64% men) with type 2 diabetes, essential hypertension [systolic blood pressure (SBP) 140-180 mmHg, and diastolic blood pressure (DBP) < 110 mmHg], and persistent microalbuminuria (20-200 microg/min) were allocated randomly to groups to receive indapamide SR 1.5 mg (n = 284) or enalapril 10 mg (n = 286) once a day. Amlodipine, atenolol, or both were added, if necessary, to achieve the target blood pressure of 140/85 mmHg.

RESULTS

There was a significant reduction in the urinary albumin : creatinine ratio. Mean reductions were 35% [95% confidence interval (CI) 24 to 43] and 39% (95% CI 30 to 47%) in the indapamide SR and enalapril groups, respectively. Equivalence was demonstrated between the two groups [1.08 (95% CI 0.89 to 1.31%); P = 0.01]. The reductions in mean arterial pressure (MAP) were 16.6 +/- 9.0 mmHg for the indapamide SR group and 15.0 +/- 9.1 mmHg for the enalapril group (NS); the reduction in SBP was significantly greater (P = 0.0245 ) with indapamide SR. More than 50% of patients in each group required additional antihypertensive therapy, with no differences between groups. Both treatments were well tolerated.

CONCLUSIONS

Indapamide-SR-based therapy is equivalent to enalapril-based therapy in reducing microalbuminuria with effective blood pressure reduction in patients with hypertension and type 2 diabetes.

Effects of low dose ramipril on cardiovascular and renal outcomes in patients with type 2 diabetes and raised excretion of urinary albumin: randomised, double blind, placebo controlled trial (the DIABHYCAR study)

OBJECTIVE

To investigate whether a low dose of the angiotensin converting enzyme (ACE) inhibitor ramipril lowers cardiovascular and renal events in patients with type 2 diabetes who have microalbuminuria or proteinuria.

DESIGN

Randomised, double blind, parallel group trial comparing ramipril (1.25 mg/day) with placebo (on top of usual treatment) for cardiovascular and renal outcomes for at least three years.

SETTING

Multicentre, primary care study conducted mostly by general practitioners in 16 European and north African countries.

PARTICIPANTS

4912 patients with type 2 diabetes aged >50 years who use oral antidiabetic drugs and have persistent microalbuminuria or proteinuria (urinary albumin excretion > or = 20 mg/l in two consecutive samples), and serum creatinine < or = 150 micromol/l.

MAIN OUTCOME MEASURES

The primary outcome measure was the combined incidence of cardiovascular death, non-fatal myocardial infarction, stroke, heart failure leading to hospital admission, and end stage renal failure.

RESULTS

Participants were followed for 3 to 6 (median 4) years. There were 362 primary events among the 2443 participants taking ramipril (37.8 per 1000 patient years) and 377 events among the 2469 participants taking placebo (38.8 per 1000 patient years; hazard ratio 1.03 (95% confidence interval 0.89 to 1.20, P = 0.65)). None of the components of the primary outcome was reduced. Ramipril lowered systolic and diastolic blood pressures (by 2.43 and 1.06 mm Hg respectively after two years) and favoured regression from microalbuminuria (20-200 mg/l) or proteinuria (> 200mg/l) to normal level (< 20 mg/l) or microalbuminuria (P < 0.07) in 1868 participants who completed the study.

CONCLUSIONS

Low dose (1.25 mg) ramipril once daily has no effect on cardiovascular and renal outcomes of patients with type 2 diabetes and albuminuria, despite a slight decrease in blood pressure and urinary albumin. The cardiovascular benefits of a daily higher dose (10 mg) ramipril observed elsewhere are not found with an eightfold lower daily dose.

Cost-effective strategies in the prevention of diabetic nephropathy

A significant subgroup of patients with diabetes mellitus are predisposed to developing diabetic nephropathy and it is in this subgroup that other diabetes- related complications, and in particular greatly increased cardiovascular disease risk, are concentrated. The high personal, social and financial costs of managing end-stage renal failure and the other complications associated with diabetic nephropathy make a powerful case for screening and effective intervention programmes to prevent the condition or retard its progression. As major breakthroughs in finding genetic susceptibility factors remain elusive, screening efforts continue to be based on microalbuminuria testing, despite increasing recognition of its limitations as a positive predictor of nephropathy. Interventions have been extensively studied, but results remain conflicting. Economic evaluations of such screening and intervention programmes are essential for health planners, yet models of the cost/benefit ratio of such interventions often rely on a rather slim evidence base. Where economic models are developed, they are frequently based on those papers that propound the greatest clinical benefits of a given intervention, leading to a possible over-estimation of the advantages of the chosen approach. Furthermore, the benefits of even such generally accepted interventions as ACE inhibitor treatment are less firmly established than generally appreciated. Lifestyle interventions are instinctively attractive, but are by no means a low-cost option (as is often assumed by both medical professionals and politicians). This review critically assesses the evidence for clinical efficacy and economic benefit of microalbuminuria screening and interventions such as intensive glycaemic control, antihypertensive treatment, ACE inhibition and angiotensin receptor blockade, dietary protein restriction and lipid-modifying therapy. The various costs associated with diabetic nephropathy are so great that even expensive interventions may have a favourable cost/benefit ratio, provided they are truly effective.

Effects of captopril and losartan on lipid peroxidation, protein oxidation and nitric oxide release in diabetic rat kidney

Increased oxidative stress has an important role in the pathogenesis of diabetic nephropathy. The aim of this study was to evaluate the effects of renin-anigiotensin system blockage, either by angiotensin-converting enzyme inhibition or angiotensin receptor blockage, on oxidative stress and nitric oxide release in diabetic rat kidneys. After induction of diabetes, six rats were given captopril, six rats were given losartan, and six rats served as diabetic controls. Six healthy rats were also included. At the end of an 8-week period nitric oxide release, lipid peroxidation and protein oxidation were measured in kidney cortices, and urinary albumin excretion (UAE) was determined in 24-h urine samples. Losartan- and captopril-treated diabetic rats had lower levels of UAE than diabetic controls. Diabetic rats had higher levels of lipid peroxidation and protein oxidation compared to healthy rats. NO release was significantly lower in diabetic groups than healthy controls. UAE levels showed a positive correlation with lipid peroxidation and a negative correlation with NO release. Inhibition of lipid peroxidation could be one of the protective mechanisms of renin-angiotensin axis inhibition in diabetic kidney tissues.

The cost of major comorbidity in people with diabetes mellitus

BACKGROUND

People with diabetes mellitus are more likely to have cardiovascular, renal and ophthalmic comorbidity than those without diabetes. Information on the economic impact of diabetes and its complications on the Canadian health care system is limited.

METHODS

To estimate health care expenditures for diabetes and its major complications, we identified people with diabetes in 1996 in Saskatchewan, using the administrative databases of Saskatchewan Health. We grouped utilization and expenditure data for prescription drugs, physician services, hospitalizations, day surgery procedures and dialysis services according to cardiovascular, renal and ophthalmic services, according to billing codes and the American Hospital Formulary Services classification for prescription drugs.

RESULTS

Of the 38 124 people identified (48.5% female and 9.7% registered Indians), 46.6% had cardiovascular-related records, 19.8% ophthalmic-related records and 6.6% renal-related records. Registered Indians had significantly fewer (p < 0.001) cardiovascular-related records than the rest of the diabetic population (35.1% v. 47.9%, respectively) but more renal- related records (11.7% v. 6.0%, respectively). The total 1996 Saskatchewan Health expenditure for the study group, within the observed categories, was estimated to be $134.3 million, of which $35.5 million (26.4%) was for cardiovascular-related services, $10 million (7.5%) for renal-related services and $3.3 million (2.5%) for ophthalmic-related services.

INTERPRETATION

In 1996, 36.4% of health care expenditures for people with diabetes was attributable to major comorbidity. Actions to prevent or control such comorbidity will yield significant cost savings.

Regression of albuminuria: latest evidence for a new approach

OBJECTIVE

To review the latest studies on antihypertensive strategies in the treatment of microalbuminuria, in order to highlight the association of microalbuminuria with hypertension and type 2 diabetes, the evidence for microalbuminuria as a risk factor for target-organ damage and mortality, and the prognostic significance of regression of microalbuminuria.

STUDY SELECTION

Randomized controlled trials in patients with hypertension, type 2 (non-insulin-dependent) diabetes mellitus and microalbuminuria, with changes in albumin excretion rate (AER) as a primary outcome measure.

RESULTS OF DATA ANALYSIS

Antihypertensive treatment is the most effective method for reducing microalbuminuria. Although microalbuminuria regression is related to reduction in blood pressure, antihypertensive drugs acting on the renin-angiotensin system have an antiproteinuric effect that is additional to that of blood pressure reduction. The combination of these agents with diuretics, even when used in low doses, may further reduce AER in these patients.

CONCLUSIONS

Blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers is a most effective means of treating microalbuminuria and preventing its progression to overt nephropathy and, perhaps, the associated cardiovascular disease. The effect of this strategy may be improved further with the use, as first-line treatment, of a combination of angiotensin-converting enzyme inhibitor and diuretic.

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.

A comparison of outcomes with angiotensin-converting--enzyme inhibitors and diuretics for hypertension in the elderly

BACKGROUND

Treatment of hypertension with diuretics, beta-blockers, or both leads to improved outcomes. It has been postulated that agents that inhibit the renin-angiotensin system confer benefit beyond the reduction of blood pressure alone. We compared the outcomes in older subjects with hypertension who were treated with angiotensin-converting-enzyme (ACE) inhibitors with the outcomes in those treated with diuretic agents.

METHODS

We conducted a prospective, randomized, open-label study with blinded assessment of end points in 6083 subjects with hypertension who were 65 to 84 years of age and received health care at 1594 family practices. Subjects were followed for a median of 4.1 years, and the total numbers of cardiovascular events in the two treatment groups were compared with the use of multivariate proportional-hazards models.

RESULTS

At base line, the treatment groups were well matched in terms of age, sex, and blood pressure. By the end of the study, blood pressure had decreased to a similar extent in both groups (a decrease of 26/12 mm Hg). There were 695 cardiovascular events or deaths from any cause in the ACE-inhibitor group (56.1 per 1000 patient-years) and 736 cardiovascular events or deaths from any cause in the diuretic group (59.8 per 1000 patient-years; the hazard ratio for a cardiovascular event or death with ACE-inhibitor treatment was 0.89 [95 percent confidence interval, 0.79 to 1.00]; P=0.05). Among male subjects, the hazard ratio was 0.83 (95 percent confidence interval, 0.71 to 0.97; P=0.02); among female subjects, the hazard ratio was 1.00 (95 percent confidence interval, 0.83 to 1.21; P=0.98); the P value for the interaction between sex and treatment-group assignment was 0.15. The rates of nonfatal cardiovascular events and myocardial infarctions decreased with ACE-inhibitor treatment, whereas a similar number of strokes occurred in each group (although there were more fatal strokes in the ACE-inhibitor group).

CONCLUSIONS

Initiation of antihypertensive treatment involving ACE inhibitors in older subjects, particularly men, appears to lead to better outcomes than treatment with diuretic agents, despite similar reductions of blood pressure.

Blood pressure and cardiac autonomic function in relation to risk factors and treatment perspectives in Type 1 diabetes

The cumulative incidence of diabetic nephropathy in Type 1 diabetes mellitus is in the order of 25 30%. The recognition that elevated blood pressure (BP) is a major factor in the progression of these patients to end-stage renal failure has led to the widespread use of antihypertensive therapy in order to preserve glomerular filtration rate and ultimately to reduce mortality. The routine measurement of microalbuminuria allows early identification of the subgroup of patients at increased risk of developing clinical nephropathy. Microalbuminuric Type 1 diabetic patients show a number of characteristic pathological abnormalities. In addition to elevated BP and abnormal circadian rhythm, there are also associated abnormalities of vagal function, lipid profile and endothelial function, as well as an increased prevalence of retinopathy. The first section of this two-part review focusses on the early changes associated with renal involvement in Type 1 diabetes. It addresses the associations between urinary albumin excretion, glycaemic control, smoking, BP, circadian BP variation, QT interval abnormalities and autonomic function in three groups of patients; those with normoalbuminuria, those progressing towards microalbuminuria and those with established low-grade microalbuminuria.

Microalbuminuria in type 1 and type 2 diabetes mellitus: evidence with angiotensin converting enzyme inhibitors and angiotensin II receptor blockers for treating early and preventing clinical nephropathy

A cumulative incidence of diabetic nephropathy of 25% to 40% has been documented after duration of diabetes of at least 25 years in both type 1 and type 2 diabetic patients. Diabetic nephropathy has become the leading cause (25%-44%) of end-stage renal failure in Europe, the United States, and Japan. Until the early 1980s, no renoprotective treatment was available for use in diabetic nephropathy. Death occurred on average 5 to 7 years after the onset of persistent proteinuria. The two main treatment strategies for prevention of diabetic nephropathy are improved glycemic control and blood pressure lowering, particularly using drugs blocking the renin-angiotensin system. Megatrials and meta-analyses have clearly demonstrated the beneficial effect of both the above-mentioned treatment modalities. Secondary prevention, that is, treatment modalities applied to diabetic patients at high risk for developing diabetic nephropathy (eg, those with microalbuminuria) has been documented, applying angiotensin converting enzyme inhibitors and angiotensin II receptor blockade. The renoprotective effects of these drugs are independent of their beneficial reduction in blood pressure.

New trends in the treatment of diabetic nephropathy in children

Nephropathy is the main cause of morbidity and mortality in patients with Type 1 diabetes and persistent microalbuminuria is the best marker of the consequent risk for its development in adults. In the paediatric population, puberty has long been recognised as a major risk period for the development of microangiopathic complications, although it is not necessarily associated with the progression to frank proteinuria. In fact, as many as 50% of subjects might revert to normoalbuminuria. Hypertension is a further risk factor and accelerates the progression of micro and macrovascular complications. There is evidence that angiotensin-converting enzyme inhibitors reduce renal damage by one or more mechanisms independent of their antihypertensive effects and they are the drug class of choice for the treatment of diabetic nephropathy. However, as angiotensin II receptor antagonists are more specific they might become the obvious treatment choice in the near future. There is no consensus on who should be treated with reno-protective drugs in the paediatric population, and when this should occur, due to the lack of a clear definition of the natural history of microalbuminuria in this age group. In this review controversial aspects of this issue are presented and discussed.

Clinical pharmacokinetics and selective pharmacodynamics of new angiotensin converting enzyme inhibitors: an update

The angiotensin converting enzyme (ACE) inhibitors are widely used in the management of essential hypertension, stable chronic heart failure, myocardial infarction (MI) and diabetic nephropathy. There is an increasing number of new agents to add to the nine ACE inhibitors (benazepril, cilazapril, delapril, fosinopril, lisinopril, pentopril, perindopril, quinapril and ramipril) reviewed in this journal in 1990. The pharmacokinetic properties of five newer ACE inhibitors (trandolapril, moexipril, spirapril, temocapril and imidapril) are reviewed in this update. All of these new agents are characterised by having a carboxyl functional groups and requiring hepatic activation to form pharmacologically active metabolites. They achieve peak plasma concentrations at similar times (t(max)) to those of established agents. Three of these agents (trandolapril, moexipril and imidapril) require dosage reductions in patients with renal impairment. Dosage reductions of moexipril and temocapril are recommended for elderly patients, and dosages of moexipril should be lower in patients who are hepatically impaired. Moexipril should be taken 1 hour before meals, whereas other ACE inhibitors can be taken without regard to meals. The pharmacokinetics of warfarin are not altered by concomitant administration with trandolapril or moexipril. Although imidapril and spirapril have no effect on digoxin pharmacokinetics, the area under the concentration-time curve of imidapril and the peak plasma concentration of the active metabolite imidaprilat are decreased when imidapril is given together with digoxin. Although six ACE inhibitors (captopril, enalapril, fosinopril, lisinopril, quinapril and ramipril) have been approved for use in heart failure by the US Food and Drug Administration, an overview of 32 clinical trials of ACE inhibitors in heart failure showed that no significant heterogeneity in mortality was found among enalapril, ramipril, quinapril, captopril, lisinopril, benazepril, perindopril and cilazapril. Initiation of therapy with captopril, ramipril, and trandolapril at least 3 days after an acute MI resulted in all-cause mortality risk reductions of 18 to 27%. Captopril has been shown to have similar morbidity and mortality benefits to those of diuretics and beta-blockers in hypertensive patients. Captopril has been shown to delay the progression of diabetic nephropathy, and enalapril and lisinopril prevent the development of nephropathy in normoalbuminuric patients with diabetes. ACE inhibitors are generally characterised by flat dose-response curves. Lisinopril is the only ACE inhibitor that exhibits a linear dose-response curve. Despite the fact that most ACE inhibitors are recommended for once-daily administration, only fosinopril, ramipril, and trandolapril have trough-to-peak effect ratios in excess of 50%.