Effect of acetyl-l-carnitine in the treatment of diabetic peripheral neuropathy: A systematic review and meta-analysis

Background/aim Deficiency of acetyl-L-carnitine (ALC) and L-carnitine (LC) appears to play a role in peripheral diabetic neuropathy, although the evidence in humans is still limited. We conducted a systematic review and meta-analysis investigating the effect of ALC on pain and electromyographic parameters in people with diabetic neuropathy. Methods A literature search in major databases, without language restriction, was undertaken. Eligible studies were randomized controlled trials (RCTs) or pre- and post-test studies. The effect of ALC supplementation on pain perception and electromyographic parameters in patients with diabetic neuropathy was compared vs. a control group (RCTs). The effect of ALC/LC on electromyographic parameters were also calculated vs. baseline values. Standardized mean differences (SMD) and 95% confidence intervals (CIs) were used for summarizing outcomes. Results Six articles, with a total of 711 diabetic participants, were included. Three RCTs (340 treated with ALC vs. 203 placebo and 115 with methylcobalamine) showed that ALC reduces pain perception (SMD = -0.45; 95% CI: -0.86 to -0.04; P = 0.03; I2 = 85%). Compared to controls, ALC supplementation improved nerve conduction velocity and amplitude response for ulnar nerve (both sensory and motor component). Compared to baseline values, ALC/LC supplementation improved nerve conduction velocity for all the sensory and motor nerves (except ulnar and peroneal) investigated and the amplitude of all nerves. The onset of adverse events was generally limited to minor side effects. Conclusion ALC appears to be effective in reducing pain due to diabetic neuropathy compared to active or placebo controls and improving electromyographic parameters in these patients.