Renoprotective effects of blockade of angiotensin II AT1 receptors in an animal model of type 2 diabetes.

To evaluate the efficacy of angiotensin II receptor blockers (ARBs) for use in the treatment of diabetic nephropathy, we examined the effects of olmesartan medoxomil (olmesartan), an angiotensin II type 1 (AT1) specific ARB, on the progression of nephropathy in Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes. We used 2 doses of olmesartan, a sub-antihypertensive dose and an antihypertensive dose, to specifically examine whether the drug exerts beneficial effects on the kidney without lowering blood pressure. Olmesartan mixed in the diet at a concentration of 0.001% (approximately 0.6 mg/kg/day) or 0.01% (approximately 6 mg/kg/day) was administered for 19 weeks starting from 12 weeks of age, when the animals developed microalbuminuria. Lean non-diabetic rats served as controls. ZDF rats had hyperglycemia, hyperinsulinemia, and moderate hypertension as compared to lean control rats. Plasma glucose and insulin concentrations were not affected by olmesartan, and blood pressure was lowered only by the high dose of olmesartan. Progressive proteinuria in ZDF rats was greatly (about 70%) suppressed by the high dose of olmesartan and moderately (about 30%) suppressed by the low dose that did not significantly lower blood pressure. ZDF rats exhibited hyperlipidemia and hypoalbuminemia, both of which were substantially corrected by treatment with olmesartan. The histological evidence of glomerular and tubular damage in the ZDF rats was also reduced by the drug. These results indicate that AT1 receptor blockade with olmesartan retards the progression of nephropathy associated with type 2 diabetes without affecting glucose metabolism, and that this renal protective effect is at least partly independent of the antihypertensive effect of the drug.     

Clinical impact of reducing microalbuminuria in patients with type 2 diabetes mellitus

Diabetic nephropathy in type 2 diabetes is a leading cause of end-stage renal disease worldwide. Its early clinical sign is microalbuminuria, which is not only a predictor for progression of nephropathy but also an independent risk factor for cardiovascular disease. A few decades ago, diabetic nephropathy was believed to be progressive and irreversible. Thus, the main therapeutic objective for type 2 diabetic patients with microalbuminuria was to prevent progression to overt proteinuria. However, there is now growing evidence regarding remission/regression of diabetic nephropathy. In recent clinical trials using the renin-angiotensin system blockade drugs, a reduction in microalbuminuria by the use of these drugs has been noted. We also reported that a reduction in microalbuminuria was more frequent than progression to overt proteinuria and that multifactorial control approach was important to the reduction of microalbuminuria. These results for type 2 diabetes are similar to those previously reported for type 1 diabetes. Furthermore, our recent study showed that the 8-year cumulative incidence rate of renal and cardiovascular events was significantly lower in patients with remission than in those without it. The annual decline rate of estimated glomerular filtration rate in patients with remission was also significantly slower. These studies provide clinical evidence implying that the reduction of microalbuminuria in type 2 diabetic patients occurs frequently and brings about renal and cardiovascular risk reduction. Reducing microalbuminuria is therefore considered to be an important therapeutic objective and may be a biomeasure of therapeutic success in type 2 diabetic patients.     

Angiotensin converting enzyme inhibitors or angiotensin receptor blockers in nephropathy from type 2 diabetes

Type 2 diabetes is the most common cause of end-stage renal disease in the United States, and type 2 diabetes has been shown to be a myocardial infarction equivalent in regard to risk of death from a cardiovascular event. Proteinuria is a surrogate marker for renal disease progression, and although data favor both the angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) in reducing proteinuria, data for renal outcomes, such as time to dialysis, only exist for the ARBs, which clearly increase the duration to dialysis. Conversely, ACE inhibitors have overwhelming data that show substantial risk reduction from cardiovascular events and death in people with type 2 diabetes. Similar data on cardiovascular risk reduction are not yet available with ARBs, although two trials of renal disease progression did have cardiovascular endpoints as secondary outcomes. There were no significant differences between the ARB and control group except for first hospitalization with heart failure, where losartan reduced the risk by 32%, but there was a trend, albeit not significant, toward reduction of myocardial infarction. The first information regarding ARB effects on cardiovascular events as primary outcomes will come from the Losartan Intervention for Endpoint (LIFE) Reduction in Hypertension study. Therefore, as of this writing, all patients with type 2 diabetes and no evidence of nephropathy, ie, proteinuria and an elevated creatinine > 1.5 mg/dL, should be placed on an ACE inhibitor for cardiovascular risk reduction. If nephropathy is present, the evidence would support an ARB for therapy in concert with a a-blocker for cardiovascular risk reduction and renoprotection.     

Value of Angiotensin receptor blocker therapy in diabetes

There are more clinical trials investigating angiotensin receptor blockers (ARBs) in diabetes than any other drug class, ranging from early "prevention" trials to the treatment of individuals with advanced organ damage. In its earliest manifestations, visceral adiposity predisposes to hypertension and hyperglycemia (metabolic syndrome). In these individuals, ARB therapy delays the progression to chronic hypertension and may also delay the progression to overt diabetes. Based on the increased cardiovascular disease risk of the metabolic syndrome, which is similar to stage 1 hypertension, both lifestyle modification and ARB therapy are justifiable. ARB therapy has also been found to delay the onset of microalbuminuria and retinopathy. In established diabetic nephropathy, ARB therapy is recommended as a standard alternative to angiotensin-converting enzyme inhibition to reduce macroalbuminuria and delay the progression to end-stage disease. Finally, large trials in ischemic heart disease, heart failure, and stroke have demonstrated clear benefits of ARB therapy. Because ARBs have side effect rates equal to placebo and far lower than any other antihypertensive drug class, the benefit/risk ratio is highly favorable across the entire spectrum of diabetic disease. Thus, ARB therapy is a highly attractive alternative for individuals at any stage of diabetes and with any pattern of complications.     

Pathogenesis and Treatment of Microalbuminuria in Patients With Diabetes: The Road Ahead

The incidence of type 2 diabetes is increasing in the United States, which is expected to result in an increased prevalence of microalbuminuria and higher cardiovascular risk. Microalbuminuria is an indication that a low-level inflammatory process is ongoing. In patients with hypertension, with or without diabetes, increasing urinary albumin excretion (UAE) is associated with elevated levels of inflammatory markers, endothelial dysfunction, and platelet activation. Microalbuminuria is associated with an increased incidence of cardiovascular disease (CVD) morbidity and mortality in patients with hypertension and in those with diabetes with or without hypertension. Antihypertensive agents that modulate the renin-angiotensin-aldosterone system (RAAS) can delay the onset and reduce progression of microalbuminuria and decrease CVD morbidity and mortality in patients with diabetes. Clinical trials provide a spectrum of results regarding the protective effects of RAAS-blocking agents. Consideration of baseline blood pressure (BP), UAE and CVD risk, and the extent of BP lowering with treatment is necessary when interpreting clinical trial results in patients with microalbuminuria. It remains to be determined whether targeting the underlying inflammatory process can retard or prevent microalbuminuria progression or whether treatment of microalbuminuria can prevent end-stage renal disease or death.     

Preventing renal complications in diabetic patients: the Diabetics Exposed to Telmisartan And enalaprIL (DETAIL) study

Diabetic nephropathy is characterised by hypertension and persistent proteinuria. If ineffectively controlled, a progressive decline in renal function can result in end-stage renal disease. Patients with diabetic nephropathy are also at greatly increased risk of cardiovascular disease. Angiotensin-converting enzyme (ACE) inhibitors display additional renoprotective effects beyond systemic blood pressure lowering, perhaps due to reduction in intraglomerular pressure by inhibition of angiotensin II activity. In type 2 diabetics, ACE inhibitors have variable effects, with some studies showing a reduction in microalbuminuria, prevention of the progression to macroalbuminuria and maintenance of renal function. Randomised studies have demonstrated that angiotensin II receptor blockers (ARBs), as well as controlling systemic blood pressure, delay progression of proteinuria in patients with diabetic nephropathy. Telmisartan has a number of features that may make it particularly suitable for the treatment of diabetic nephropathy. In addition to its long duration of action and almost exclusive faecal excretion, its high lipophilicity should assist in tissue penetration. The Diabetics Exposed to Telmisartan And enalaprIL (DETAIL) study was designed to compare the long-term renal outcome of treatment with telmisartan 40.80 mg versus enalapril 10.20 mg (with titration to the higher dose after 4 weeks) in patients with type 2 diabetes, mild-to-moderate hypertension and albuminuria. The primary endpoint is the change in glomerular filtration rate after 5 years' randomised treatment. Secondary endpoints are annual changes in glomerular filtration rate, serum creatinine and urinary albumin excretion, as well as incidences of end-stage renal disease, cardiovascular events, all-cause mortality and adverse events. The groundbreaking DETAIL study revealed that telmisartan conferred comparable renoprotection to enalapril and was associated with a low incidence of mortality.     

Preserving cardiac function in the hypertensive patient: why renal parameters hold the key.

The relationship between cardiovascular and renal pathologies is well recognized in advanced nephropathy and heart failure, but in early disease it has received less attention. Consequently, microalbuminuria screening and interventions that treat early nephropathy remain under-utilized cardioprotective strategies in the hypertensive patient. Agents that delay the progression of renal disease are likely to be cardioprotective by lessening the systemic consequences of renal dysfunction and may have additional cardioprotective effects by exerting beneficial effects on endothelia elsewhere in the body and within the heart. A critical driving factor within both renal and wider cardiovascular pathologies is overactivation of the renin-angiotensin-aldosterone system (RAAS). Accordingly, RAAS-directed antihypertensive agents including both angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) have been demonstrated to have renoprotective effects. In major prospective trials, two ARBs, losartan and irbesartan, have been demonstrated to be renoprotective in patients with frank proteinuria, and one ARB, irbesartan, has been shown to have renoprotective properties in patients with microalbuminuria. For patients with incipient or frank renal dysfunction, an aggressive RAAS-based approach to hypertension management, combining potent blood pressure control with proven renoprotection, may therefore constitute a key component of therapy targeted towards long-term cardioprotection.     

Combating diabetic nephropathy with drug therapy

Diabetes mellitus is the leading cause of end-stage renal disease and also increases the risk of atherosclerotic vascular disease. Hypertension amplifies both problems. Detection of microalbuminuria, a common and early manifestation of diabetic nephropathy and a marker for cardiovascular risk, permits early treatment to reduce progression of nephropathy and vascular disease in diabetes. Although optimal glycemic control is essential to reduce the risk of nephropathy, aggressive blood pressure lowering to a level of 130/80 mg Hg or below in hypertensive diabetic patients is as important as glycemic control. Initial drug therapy for nephropathy should include an angiotensin-converting enzyme inhibitor (or if contraindicated, an angiotensin receptor blocker), as several large randomized double-blinded multicenter clinical trials have demonstrated an independent renoprotective effect with renin angiotensin system inhibition. The role of advanced glycation end products in the pathogenesis of renal and vascular disease in diabetes is becoming more clearly established. However, the use of therapeutic strategies directed at blocking their effect still awaits further investigation. A multifaceted intervention program that combines optimal glycemic control, lifestyle modification/cardiovascular prevention guidelines such as lipid control and smoking cessation, with appropriate antihypertensive therapy when indicated, will prevent or delay both the occurrence and progression of diabetic nephropathy.     

Antihypertensive treatment in type II diabetes and diabetic nephropathy

Hypertension is very prevalent in patients with type II diabetes. Beside increasing the cardiovascular risk, hypertension has several deleterious effects on the kidney: hypertension promotes the development of diabetic nephropathy, the progression from microalbuminuria to overt diabetic nephropathy and progression to end stage renal disease. In this review, we analyze systematically the benefit of antihypertensive therapy in patients with type II diabetes, with either normo-albuminuria, microalbuminuria or overt nephropathy. General considerations are developed about the general use of antihypertensive drugs in this population. An approach based on the prevention of the global or absolute cardiovascular risk is further recommended due to the very high cardiovascular burden in this diabetic patients.     

Rationale and design of a study to evaluate management of proteinuria in patients at high risk for vascular events: the IMPROVE trial

Declining kidney function predicts increasing cardiovascular risk in people with hypertension. Microalbuminuria is a marker for cardiovascular risk and declining kidney function. Agents that block the renin-angiotensin-aldosterone system (RAAS), notably angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), reduce proteinuria and microalbuminuria, lower blood pressure and slow the progression of proteinuric kidney disease. Evidence is accumulating that the combination of an ACE inhibitor and an ARB is the optimal means of RAAS blockade in this setting, slowing the progression of nephropathy independently of blood pressure lowering to a greater degree than can be achieved using maximum approved doses of either agent alone. However, the emerging therapeutic potential of ACE inhibitor/ARB combination therapy in hypertensive kidney disease requires further characterization. The Irbesartan in the Management of PROteinuric patients at high risk for Vascular Events trial aims to determine definitively whether the combination therapy of an ARB, irbesartan and an ACE inhibitor, ramipril, is more effective than ramipril alone in reducing the urinary albumin excretion rate in patients at high cardiovascular risk with hypertension and proteinuria or microalbuminuria.     

Treatment of Microalbuminuria in Patients with Type 2 Diabetes Mellitus

The incidence of type 2 diabetes mellitus is increasing world-wide, and is now one of the leading causes of end-stage renal disease in Western countries. Type 2 diabetes mellitus is also a major risk factor for cardiovascular events. Therefore, the early identification of patients at greatest risk, and the subsequent initiation of renal and cardiovascular protective treatments, are of the utmost importance. Microalbuminuria refers to a subclinical increase in urinary albumin excretion. By definition it corresponds to an albumin excretion rate of 20 to 200 microg/min (30 to 300 mg/day) or an albumin to creatinine ratio (mg/mmol) of 2.5 to 25 in males and 3.5 to 35 in females. Microalbuminuria is an important clinical finding because it is not only associated with an increased risk of progression to overt proteinuria (macroalbuminuria) and renal failure, but also cardiovascular events. In patients who progress to overt nephropathy, microalbuminuria usually precedes macroalbuminuria by an interval of 5 to 10 years. In patients with type 1 diabetes mellitus, blood pressure increases and renal function declines after the onset of macroalbuminuria. However, in patients with type 2 diabetes mellitus, hypertension and a decline in renal function may occur when albumin excretion is still in the microalbuminuric range. Large clinical trials have demonstrated that achieving tight glycemic (i.e. glycosylated hemoglobin < 7.0%) and blood pressure (i.e. < 130/85mm Hg) control retards the progression of renal disease. There is accumulating evidence to suggest that the use of antihypertensive agents which target the renin-angiotensin system (RAS) can slow the progression of renal disease and provide cardioprotection in patients with type 2 diabetes mellitus and microalbuminuria. Antihypertensive agents which target the RAS also appear to have advantages over and above reductions in systemic blood pressure. In summary, the annual screening of patients with type 2 diabetes mellitus for microalbuminuria, and the initiation of measures to retard the progression of renal and cardiovascular disease, are now considered part of routine clinical practice. In particular, the finding of microalbuminuria should provoke an intensified modification of the common risk factors for renal and cardiovascular disease, that is hyperglycemia, hypertension, dyslipidemia and smoking. Antihypertensive therapy in patients with microalbuminuria and type 2 diabetes mellitus should be initiated with angiotensin converting enzyme (ACE) inhibitors or angiotensin-II type 1 receptor antagonists.     

Type 2 diabetes: RENAAL and IDNT--the emergence of new treatment options

The Reduction in End Points in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study and the Irbesartan Diabetic Nephropathy Trial (IDNT) are two recently reported trials with hard end points, conducted in patients in advanced stages of diabetic nephropathy. Two other studies—the Irbesartan Microalbuminuria Study (IRMA)‐2 and the Microalbuminuria Reduction with Valsartan study (MARVAL)—were trials conducted in patients with type 2 diabetes with microalbuminuria, a cardiovascular risk factor associated with early‐stage diabetic nephropathy. These trials all had a common theme—that is, does an angiotensin receptor blocker (ARB) interfere with the natural history of diabetic nephropathy in a blood pressure‐independent fashion? Without question, the results of these trials legitimatize the use of the ARB class in forestalling the deterioration in renal function, which is almost inevitable in the patient with untreated diabetic nephropathy. These data can now be added to the vast array of evidence supporting angiotensin‐converting enzyme (ACE) inhibitor use in patients with nephropathy associated with type 1 diabetes. It now appears a safe conclusion that the patient with diabetic nephropathy should receive therapy with an agent that interrupts the renin‐angiotensin system. These studies have not resolved the question as to whether an ACE inhibitor or an ARB is the preferred agent in people with nephropathy from type 1 diabetes, though the optimal doses of these drugs remain to be determined. Head‐to‐head studies comparing ACE inhibitors to ARBs in diabetic nephropathy are not likely to occur, so it is unlikely that comparable information will be forthcoming with ACE inhibitors. An evidence‐based therapeutic approach derived from these trials would argue for ARBs to be the foundation of therapy in the patient with type 2 diabetes and nephropathy.     

Drug Treatment for Hypertensive Patients in Special Situations: Diabetes and Hypertension

Diabetes mellitus and hypertension is often associated, but with a different type of development in type 1 and type 2 diabetes. Type 1 diabetes, renal disease, starting with microalbuminuria, is associated with increasing blood pressure or hypertension, whereas the patient without renal disease is most often normotensive. Poor metabolic control is a predictor of microalbuminuria or incipient nephropathy, but with microalbuminuria hypertension is an important risk factor for progression along with poor glycemic control. The same is the case for overt renal disease, and metabolic control is important in all stages of renal disease in type 1 diabetes. It has also been shown that good metabolic control as well as antihypertensive treatment, especially with ACE-inhibitors, often combined with other agents is quite effective in preventing progression in renal disease in all its stages.

In type 2 diabetes, blood pressure elevation is often found as early as at the actual diagnosis, and blood pressure significantly increases according to the degree of albuminuria, normo-microalbuminuria and clinical proteinuria (macroalbuminuria). Elevated blood pressure is an important risk for renal disease but more importantly so also for cardiovascular disease. Several studies document that antihypertensive treatment in particular with ACE-inhibitors is important in preventing microalbuminuria, in treating microalbuminuria and thus preventing progression, also in overt renal disease. Near-normalization of blood pressure is vital. Regarding cardiovascular disease, a series of studies now document that antihypertensive treatment with various antihypertensive agents is able to significantly reduce a number of major cardiovascular complications in diabetes, such as cardiac disease, stroke, and also microvacular disease, including retinopathy. Several studies show that antihypertensive treatment should be started at a level higher than 140–150/90. The blood pressure to be achieved during treatment is probably around 140/85 mmHg or even 130180 mmHg as a pragmatic goal. However, there is no sign of a J-shaped curve in any of the studies, and therefore even lower blood pressure could be advantageous. Even mortality, at least fiom diabetes-related causes can be effected by antihypertensive treatment. With more advanced renal disease, normalization of blood pressure is increasingly difficult, especially systolic blood pressure, and therefore it is recommendable to screen patients much earlier on with focus on blood pressure recordings and measurements of albuminuria, including microalbuminuria, and to treat early.     

Effects of the angiotensin receptor blocker azilsartan medoxomil versus olmesartan and valsartan on ambulatory and clinic blood pressure in patients with stages 1 and 2 hypertension

Azilsartan medoxomil is an angiotensin receptor blocker (ARB) being developed for hypertension treatment. To compare this ARB with others in the class, we studied the effects of 2 doses of azilsartan medoxomil, with valsartan 320 mg and olmesartan medoxomil (olmesartan) 40 mg, in a randomized, double-blind, placebo-controlled trial using ambulatory blood pressure (BP) monitoring and clinic BP measurements. The primary efficacy end point was the change from baseline in 24-hour mean systolic BP. Hierarchical analysis testing for superiority over placebo was followed by noninferiority analysis and then superiority testing of azilsartan medoxomil (80 mg and then 40 mg) versus the comparator ARBs. For 1291 randomized patients, mean age was 56 years, 54% were men, and baseline 24-hour mean systolic BP was 145 mm Hg. Azilsartan medoxomil at 80 mg had superior efficacy to both valsartan at 320 mg and olmesartan at 40 mg: placebo-adjusted 24-hour systolic BP was lowered (-14.3 mm Hg) more than 320 mg of valsartan (-10.0 mm Hg; P<0.001) and 40 mg of olmesartan (-11.7 mm Hg; P=0.009). Azilsartan medoxomil at 40 mg was noninferior to 40 mg of olmesartan (difference: -1.4 mm Hg [95% CI: -3.3 to 0.5]). For clinic systolic BP, both doses of azilsartan medoxomil were superior to the comparator ARBs. Safety and tolerability were similar among the placebo and 4 active treatments. These data demonstrate that azilsartan medoxomil at its maximal dose has superior efficacy to both olmesartan and valsartan at their maximal, approved doses without increasing adverse events. Azilsartan medoxomil could provide higher rates of hypertension control within the ARB class.     

The kidney in diabetes: dynamic pathways of injury and repair. The Camillo Golgi Lecture 2007

Diabetic nephropathy is the most common cause of end-stage renal disease (ESRD). The natural history of diabetic nephropathy has changed over the last decades, as a consequence of better metabolic and blood pressure management. Thus, it may now be possible to delay or halt the progression towards ESRD in patients with overt diabetic nephropathy, and the decline of renal function is not always inexorable and unavoidable. Also, the rate of progression from microalbuminuria to overt nephropathy is much lower than originally estimated in the early 80s. Furthermore, there is now evidence that it is possible, in humans, to obtain reversal of the established lesions of diabetic nephropathy. This review focuses on the contribution of kidney biopsy studies to the understanding of the pathogenesis and natural history of diabetic nephropathy and the identification of patients at high risk of progression to ESRD. The classic lesions of diabetic nephropathy and the well-established structural-functional relationships in type 1 diabetes will be briefly summarised and the renal lesions leading to renal dysfunction in type 2 diabetes will be described. The relevance of these biopsy studies to diabetic nephropathy pathogenesis will be outlined. Finally, the evidence and the possible significance of reversibility of diabetic renal lesions will be discussed, as well as future directions for research in this field.     

Drug treatment for hypertensive patients in special situations: diabetes and hypertension.

Diabetes mellitus and hypertension is often associated, but with a different type of development in type 1 and type 2 diabetes. Type 1 diabetes, renal disease, starting with microalbuminuria, is associated with increasing blood pressure or hypertension, whereas the patient without renal disease is most often normotensive. Poor metabolic control is a predictor of microalbuminuria or incipient nephropathy, but with microalbuminuria hypertension is an important risk factor for progression along with poor glycemic control. The same is the case for overt renal disease, and metabolic control is important in all stages of renal disease in type 1 diabetes. It has also been shown that good metabolic control as well as antihypertensive treatment, especially with ACE-inhibitors, often combined with other agents is quite effective in preventing progression in renal disease in all its stages. In type 2 diabetes, blood pressure elevation is often found as early as at the actual diagnosis, and blood pressure significantly increases according to the degree of albuminuria, normo-microalbuminuria and clinical proteinuria (macroalbuminuria). Elevated blood pressure is an important risk for renal disease but more importantly so also for cardiovascular disease. Several studies document that antihypertensive treatment in particular with ACE-inhibitors is important in preventing microalbuminuria, in treating microalbuminuria and thus preventing progression, also in overt renal disease. Near-normalization of blood pressure is vital. Regarding cardiovascular disease, a series of studies now document that antihypertensive treatment with various antihypertensive agents is able to significantly reduce a number of major cardiovascular complications in diabetes, such as cardiac disease, stroke, and also microvacular disease, including retinopathy. Several studies show that antihypertensive treatment should be started at a level higher than 140-150/90. The blood pressure to be achieved during treatment is probably around 140/85 mmHg or even 130/80 mmHg as a pragmatic goal. However, there is no sign of a J-shaped curve in any of the studies, and therefore even lower blood pressure could be advantageous. Even mortality, at least from diabetes-related causes can be effected by antihypertensive treatment. With more advanced renal disease, normalization of blood pressure is increasingly difficult, especially systolic blood pressure, and therefore it is recommendable to screen patients much earlier on with focus on blood pressure recordings and measurements of albuminuria, including microalbuminuria, and to treat early.     

Outcomes of antiproteinuric RAAS blockade: High-dose compared with dual therapy

Proteinuria is both a marker and a mediator of progressive renal damage; higher levels are associated with greater cardiovascular and renal risk. At normal and low levels of proteinuria (in the microalbuminuria range), the rate of hard renal events (dialysis and doubling of creatinine) is much lower than the mortality rate. At higher levels of proteinuria, the renal event rate surpasses the mortality rate. In the overt nephropathy range (proteinuria > 0.5 g/L), patients who achieve lower proteinuria with therapy have improved hard renal outcomes, but this result has not been demonstrated in the microalbuminuria range. For patients with more severe overt nephropathy, there is a basic rationale for additional blockade of the renin-angiotensin-aldosterone system (RAAS). Dual blockade of this system and supramaximal dosing with an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin receptor blocker (ARB) have been demonstrated to reduce proteinuria in these patients more than therapy using the maximum recommended doses of these agents. However, evidence that dual blockade provides additional benefits for hard renal and cardiovascular outcomes is lacking, and only one study shows a benefit for supramaximal dosing. Both treatment strategies increase the risk for complications such as hyperkalemia. Therapy for patients with nephropathy should include treatment with the maximum recommended doses of an ACE inhibitor or ARB in addition to lowering blood pressure to target. For patients with overt nephropathy, more research is required on the role of dual therapy or supramaximal dosing to reduce hard renal and cardiovascular outcomes. Practitioners using either of these strategies to manage proteinuria should monitor their patients carefully.     

A practical approach to achieving recommended blood pressure goals in diabetic patients.

Approximately 11 million Americans have both hypertension and diabetes mellitus. This double diagnosis places such patients at high risk for renal damage, especially end-stage renal disease. The sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends a blood pressure goal of less than 130/85 mm Hg to reduce or slow the onset of renal disease and cardiovascular events in patients with hypertension and diabetes mellitus. Recent data, however, now suggest that an even lower diastolic blood pressure goal (ie, <80 mm Hg) may be necessary. Studies have shown that use of angiotensin-converting enzyme inhibitors can prevent the progression of microalbuminuria to overt proteinuria, reduce proteinuria in patients with overt diabetic nephropathy, slow the deterioration of the glomerular filtration rate, delay progression to end-stage renal disease, and lower blood pressure. Thus, all diabetic patients with blood pressure greater than 130/80 mm Hg should begin angiotensin-converting enzyme inhibitor treatment and be titrated to moderate or high doses until the blood pressure goal is achieved. However, monotherapy still may not control blood pressure to the recommended target. Studies have shown that use of multiple antihypertensive agents is necessary and successful in helping patients reach their target blood pressure, and this may offer more renoprotection than one agent used singly. A case study that applies these concepts in outpatient practice is included.     

Losartan and end-organ protection--lessons from the RENAAL study

BACKGROUND: The Reduction in ENdpoints with the Angiotensin Antagonist Losartan (RENAAL) study reported that losartan delayed the progression of renal disease in patients with type 2 diabetes and nephropathy. Diabetic or renally impaired patients are at high cardiovascular risk, a risk potentially increased in patients with both conditions. HYPOTHESIS: This post hoc analysis examined whether baseline proteinuria was predictive of cardiovascular outcomes, and whether losartan modifies the risk of cardiovascular outcomes in these patients given its renal-protective effects. METHODS: The RENAAL study compared losartan with placebo (in addition to conventional antihypertensive medications) in type 2 diabetic patients with proteinuria. Morbidity and mortality due to cardiovascular causes were ascertained, and the relationship between baseline proteinuria and cardiovascular outcome was determined. The effect of treatment with losartan was examined using three time-to-event analyses of composite cardiorenal outcomes as described below. RESULTS: Increasing baseline proteinuria was associated with significantly increased risk of myocardial infarction (MI) and all-cause or cardiovascular death, but not stroke. Losartan significantly reduced the risk for the combined endpoint of end-stage renal disease (ESRD), MI, stroke, or death by 21% (p < or = 0.005), irrespective of whether all-cause or cardiovascular death was included in the analysis. In addition, losartan reduced the risk for the composite of ESRD or cardiovascular death by 19.2% (p < 0.05). CONCLUSION: In patients with type 2 diabetes and nephropathy, there is an increased risk of MI and cardiovascular or all-cause mortality. Treatment with losartan is associated with a reduction in proteinuria, a delay in the onset of ESRD, and no increased risk of cardiovascular events in this pre-ESRD population.     

Combination therapy with angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists in the treatment of patients with type 2 diabetes mellitus

Aggressive therapy for patients with type 2 diabetes mellitus and renal disease is warranted given the natural history of this disease. Although antagonizing the renin-angiotensin system is clearly important, how this is accomplished is of considerable controversy. On the one hand, recent clinical trials of patients with type 2 diabetes mellitus with renal disease demonstrate unequivocally the renal protective effect of angiotensin receptor blockers (ARBs). Although the results of the recently published LIFE trial are encouraging, inconsistencies have been observed with ARBs in reducing cardiovascular end points. On the other hand, angiotensin-converting enzyme inhibitors have a dramatic effect in reducing cardiovascular events but have not been shown convincingly to reduce progression of renal disease in patients with type 2 diabetes mellitus. These studies leave us in a quandary as to the optimal initial treatment regimen for patients with type 2 diabetes mellitus and renal disease despite the recent recommendations from the American Diabetes Association (Alexandria, Va). Given the fact that many of these individuals will require administration of multiple antihypertensive agents, perhaps the initial treatment with a combination of an ARB and angiotensin-converting enzyme inhibitor affords optimal cardiovascular and renal protection for patients with type 2 diabetes mellitus and renal disease. Future clinical trials should be designed to address this issue.