Treatment of microalbuminuria in patients with type 2 diabetes mellitus

Abstract

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.