Does antihypertensive treatment prevent progression of microalbuminuria to overt proteinuria in insulin-dependent diabetic patients?

Prospective studies in insulin-dependent diabetic patients have shown that microalbuminuria is a strong predictor of clinical nephropathy. Because this syndrome is associated with a dramatic excess in mortality, different types of intervention have been proposed for insulin-dependent diabetic patients with microalbuminuria to prevent or postpone clinical nephropathy. The effects of antihypertensive treatment are being extensively investigated. Beta-blockers, calcium antagonists, and angiotensin-converting enzyme inhibitors have proved effective in reducing albumin excretion and postponing overt proteinuria in hypertensive and normotensive insulin-dependent diabetic patients with microalbuminuria. However, many problems remain to be solved. A decrease in albumin excretion may not be an adequate endpoint for intervention trials, because it has been shown that patients with normal albumin excretion can develop diabetic nephropathy lesions, whereas patients with microalbuminuria alone may have little or no pathology. The patients included in these trials all had incipient diabetic nephropathy but exhibited different functional, and probably morphological, forms of the disease. For insulin-dependent diabetic patients with microalbuminuria, the real aim of antihypertensive treatment is not to reduce urinary albumin excretion or to prevent its progression but to preserve renal function and to reduce the incidence of premature cardiovascular deaths. To achieve this, we have to improve our knowledge of the natural history of the early pathology of diabetic nephropathy and of the mechanisms of action of antihypertensive treatment. New large-scale intervention trials will have to be designed in which the patients will have to be carefully characterized on the basis of functional and morphological data.(ABSTRACT TRUNCATED AT 250 WORDS)