The therapeutic use of lipoic acid in diabetes: a current perspective

Lipoic acid and its reduced derivative, dihydrolipoic acid (DHLA) are highl y promising antioxidant agents, which are potent attenuators of reactive sp ecies-mediated damage in vitro and in animal studies. Lipoic acid is a univ ersal antioxidant, effective in lipophilic and aqueous environments. In con trast to an equivalent endogenous agent, such as oxidised glutathione (GSSG ), lipoic acid acts as an antioxidant in its oxidised form. Lipoic acid has been evaluated in diabetic polyneuropathy, a condition which is thought to result in part from oxidant damage caused by long-term hyperglycaemia. Dia betic patients are prone to incur enhanced cellular free radical formation and reduced antioxidant defence. Treatment with lipoic acid has improved ne rve conduction velocity during studies in diabetic animals. Trials in diabe tic patients have often observed some relief of neuropathic symptoms during treatment with lipoic acid, but consistent objective benefits have been di fficult to establish. Lipoic acid is now used in Germany for the treatment of diabetic neuropathy and definitive evidence of efficacy should arise fro m postmarketing surveillance studies. It is possible that lipoic acid may b e more effective as a long-term dietary supplement aimed at the prophylacti c protection of diabetics from complications. (C) 2001 Elsevier Science B.V . All rights reserved.