Permissive role of hypertension in the development of proteinuria and progression of renal disease in insulin-dependent diabetic patients

Thiazolidinediones-benefits on microvascular complications of type 2 diabetes

Type 2 diabetes is associated with serious microvascular complications, such as nephropathy, retinopathy, and neuropathy, which have a significant impact on patients' quality of life, morbidity, and mortality. Type 2 diabetes management strategies to reduce the risk of microvascular complications include treatment of hyperglycaemia, hypertension, and other vascular risk factors. The importance of glycaemic control in reducing the risk of microvascular complications of diabetes is well established. However, many antihyperglycaemic therapies fail to provide adequate glycaemic control and do not prevent complications in the long term. The thiazolidinediones (TZDs) are a class of agents that provide sustained glycaemic control, mediated primarily by reductions in insulin resistance. Evidence reviewed suggests that the TZDs may have the potential to reduce microvascular complications through benefits that go beyond glycaemic control. Insulin resistance underlies a range of metabolic abnormalities, collectively known as the metabolic syndrome (MS), which are cardiovascular (CV) risk factors. Components include visceral obesity, hyperglycaemia, hypertension, dyslipidaemia, low-grade inflammation and microalbuminuria (an early manifestation of target organ damage). Reducing insulin resistance, therefore, has the potential to reduce both microvascular and macrovascular complications.

Calcium channel blockade in combination with angiotensin-converting enzyme inhibition or angiotensin II (AT(1)-receptor) antagonism in hypertensive diabetics and patients with renal disease and hypertension

Effective reduction in blood pressure (BP) improves survival and morbidity in hypertensive patients. Combination therapy with multiple antihypertensive agents is frequently required in clinical practice and therapeutic trials to achieve target BP. Patients at elevated cardiovascular risk achieve the greatest benefit from equivalent reduction in BP and also require more stringent BP control. In patients with hypertension and diabetes mellitus or renal disease, BP control is of primary importance and blockade of the renin-angiotensin system (RAS) should be the initial therapeutic intervention. Choice of combination therapy has been insufficiently studied in major clinical cardiovascular endpoint trials. Diuretic therapy remains the logical addition to RAS blockade. Despite previous debate, the available evidence suggests long-acting calcium-channel blockers are also a safe and very effective addition to improve BP control further. The choice of antihypertensive combination therapy should not override the fundamental necessity of lowering BP to target levels.

Cardiovascular disease and the kidney: an epidemiologic overview

Essential hypertension and congestive heart failure (CHF) are examples of cardiovascular disorders that may cause renal failure, although sometimes a primary kidney defect may lead to hypertension. Renal damage in malignant and severe hypertension is dramatic, extensive, and rapidly progressive, although nephrosclerotic damage, which develops slowly and appears late in hypertension, is a rare cause of morbidity because mild to moderate hypertension is now the most common form. However, the incidence of end-stage renal failure associated with hypertension is markedly increasing, perhaps because of underdiagnosis of renal damage in hypertension, insufficient lowering of blood pressure in clinical practice, or inability of antihypertensive drugs to lower blood pressure sufficiently to preserve the kidney, a goal that may need specific drugs that act, for example, on the renin-angiotensin system (RAS). Renal vasoconstriction and reduction of renal blood flow are early companions of cardiac insufficiency and may be involved in the development of sodium and water retention. Profound reduction of cardiac output and arterial hypotension in severe CHF may lead to acute renal failure. Chronic renal insufficiency is associated with elevated cardiovascular morbidity and mortality. Renal impairment is often caused by a disease process, such as diabetes mellitus, that involves both the cardiovascular system and the kidney. When the primary disease is renal, possible reasons for an association include renal-dependent increase in blood pressure, activation of the RAS, overproduction of other vasoactive substances of renal origin, and electrolyte imbalances leading to fatal arrhythmias.

Nephroprotective effect of antihypertensive drugs in essential hypertension

BACKGROUND

Effective antihypertensive treatment has prevented target-organ involvement in hypertension, markedly reducing morbidity and mortality from strokes, coronary heart disease, cardiac failure, and hypertensive emergencies. However, the incidence of hypertension-related end-stage renal disease continues to increase, suggesting that therapeutic reduction in arterial pressure by itself is not sufficient to prevent the development of hypertensive renal failure.

OBJECTIVE

To examine experimental and clinical data concerning the protective effect of reduction of arterial pressure on the progression of hypertension-related renal disease, and the evidence indicating that some antihypertensive agents may afford more nephroprotection, over and above that attributable to reduction of arterial pressure.

RESULTS

Results of numerous studies clearly indicate that adequate control of arterial pressure, irrespective of the antihypertensive agent used, slowed the progression of renal disease. Results of some studies suggest that lowering arterial pressure below the level that is usually considered adequate has an additional beneficial effect by slowing the progression of renal injury.

CONCLUSION

Results of a number of studies evaluating nephroprotective effects of various drugs and regimens have indicated that certain agents, most notably angiotensin converting enzyme inhibitors and their combination with calcium antagonists, afford more protection than do others at similar levels of reduction of arterial pressure. Results of still other studies suggest that certain agents that exert greater nephroprotection are more efficient at controlling arterial pressure. Therefore, further data are needed before any final conclusion can be drawn. However, it is clear that, in order to establish nephroprotection in patients with essential hypertension, the problem should not be further complicated by additional comorbid diseases such as diabetes mellitus.