Prevention of Loss of Renal Function Over Time in Patients with Diabetic Nephropathy

Management of hypertension is the mainstay of prevention and treatment of diabetic renal disease; evidence suggests that tight blood pressure control slows renal disease progression in established diabetic nephropathy. Inhibition of the renin-angiotensin-aldosterone system (RAAS) has renoprotective effects over and above those achieved by lowering systemic blood pressure. To date, however, no long-term study using hard end points has directly compared current mechanisms for RAAS inhibition, angiotensin II receptor blockade (ARB) and angiotensin-converting enzyme (ACE) inhibition. This issue was addressed in the recently published Diabetics Exposed to Telmisartan and Enalapril (DETAIL) study, a head-to-head comparison of telmisartan and enalapril in 250 patients with hypertension and type 2 diabetes mellitus and early-stage nephropathy. After 5 years’ treatment, change in glomerular filtration rate (GFR), the primary efficacy end point, was equivalent in the 2 treatment groups, as were all secondary end points. The expected steep decline in GFR in the first year was followed by a lesser decrease in the second year and then almost complete stabilization of renal function at ≥3 years. Over 5 years, no patient went into end-stage renal disease or required dialysis. There were also no increases in albumin excretion rate, nor was there an increase in creatinine beyond 200 μmol/L. Incidence of cardiovascular morbidity and mortality was extremely low in both treatment groups, a remarkable outcome given that almost 50% of patients had evidence of cardiovascular disease at randomization. Inhibition of the RAAS should play a major part in management of patients with type 2 diabetes with nephropathy, for which both telmisartan and enalapril provide long-term renoprotection.