Got it - a meta analysis but not favourable overall in terms of the efficacy of ALA.
Mijnhout GS, Kollen BJ, Alkhalaf A, Kleefstra N, Bilo HJ; Kollen; Alkhalaf; Kleefstra; Bilo (2012). "Alpha lipoic Acid for symptomatic peripheral neuropathy in patients with diabetes: a meta-analysis of...