Effect of angiotensin-converting-enzyme (ACE) inhibitor trandolapril on human diabetic neuropathy: Randomised doubleblind controlled trial

Background Diabetes is a common cause of polyneuropathy. The development an d progression of nephropathy, retinopathy, and neuropathy are closely relat ed. Angiotensin-converting enzyme (ACE) inhibitors delay progression of bot h nephropathy and retinopathy. We investigated the effect of ACE inhibition on diabetic neuropathy. Methods We recruited 41 normotensive patients with type I or type II diabet es and mild neuropathy into a randomised double-blind placebo-controlled tr ial. Changes in the neuropathy symptom and deficit scores, vibration-percep tion threshold, peripheral-nerve electrophysiology, and cardiovascular auto nomic function, were assessed at 6 and 12 months. The primary endpoint was the change in peroneal nerve motor conduction velocity. Findings We found no significant difference at baseline for age, HbA(1c), b lood pressure, or severity of neuropathy between two groups. There was no c hange in HbA(1c) over the treatment period. Peroneal motor nerve conduction velocity (p=0.03) and M-wave amplitude (p=0.03) increased, and the F-wave latency (p=0.03) decreased and sural nerve action potential amplitude incre ased (p=0.04) significantly after 12 months of treatment with trandolapril compared with placebo. Vibration-perception threshold, autonomic function, and the neuropathy symptom and deficit score showed no improvement in eithe r group. Interpretation The ACE inhibitor trandolapril may improve peripheral neurop athy in normotensive patients with diabetes. Larger clinical trials are nee ded to confirm these data before changes to clinical practice can be advoca ted.