Effect of losartan on albuminuria, peripheral and autonomic neuropathy in normotensive microalbuminuric type 2 diabetics

Background: Angiotensin converting enzyme (ACE) inhibitors are emerging as effective agents for preventing microvascular complications of diabetes. Losartan (angiotensin II antagonist) has an antihypertensive efficacy equivalent to ACE inhibitors, however its role in microvascular complications is not yet known. Material and Methods: We studied the efficacy of losartan (50 mg once daily for 12 weeks) on albuminuria, peripheral and autonomic neuropathy in 25 normotensive microalbuminuric type 2 diabetics who were asymptomatic for neuropathy. Results: Mean age was 46.6 ± 4.34 years with the average duration of diabetes being 8.1 ± 1.54 years. Albuminuria improved significantly from 54 ± 9.35 mg/L to 32.8 ± 25 mg/L (Paired student's t-test, P=0.0005) after therapy. Autonomic neuropathy was observed in 64% while 76% had peripheral neuropathy; but there was no improvement with losartan. The duration of diabetes had a negative correlation with autonomic neuropathy. It also had a similar negative correlation with median and common peroneal nerve motor conduction velocities (Pearson's correlation coefficient, r = -0.53, P<0.01 and r = -0.56, P<0.01 respectively) implying that autonomic and peripheral neuropathy worsen as a diabetic ages. However, no correlation existed between albuminuria and autonomic or peripheral nerve function. Conclusion: Autonomic and peripheral neuropathy are highly prevalent in normotensive microalbuminuric diabetic patients. Losartan remarkably improves albuminuria but a similar benefit in autonomic or peripheral neuropathy is not seen over 12 weeks. The future may see a defining role for losartan in microvascular complications in normotensive diabetics.