Effects of epalrestat, an aldose reductase inhibitor, on diabetic peripheral neuropathy in patients with type 2 diabetes, in relation to suppression of N(ɛ)-carboxymethyl lysine.

OBJECTIVE: We investigated the efficacy of epalrestat, an aldose reductase inhibitor, for diabetic peripheral neuropathy in Japanese patients with type 2 diabetes.
METHODS: A total of 38 type 2 diabetic patients (22 men and 16 women; mean ± S.E.M. age 63.3 ± 1.0 years; duration of diabetes 9.6 ± 0.8 years) with diabetic neuropathy were newly administered 150 mg/day epalrestat (EP group). Motor nerve conduction velocity (MCV), sensory nerve conduction velocity (SCV), and minimum F-wave latency were evaluated before administration of epalrestat and after 1 and 2 years. Serum N(ɛ)-carboxymethyl lysine (CML) as a parameter of advanced glycation end products (AGEs), lipid peroxide, and soluble vascular cell adhesion molecule (sVCAM)-1 as a parameter of angiopathy were measured before administration and after 1 year. We compared the results with those of 36 duration of diabetes-matched type 2 diabetic patients (mean ± S.E.M. duration of diabetes 8.2 ± 0.7 years) as control (C group).
RESULTS: The EP group showed significant suppression of deterioration of MCV (P<.01) and minimum F-wave latency (P<.01) in the tibial nerve and SCV (P<.05) in the sural nerve compared to those in the C group after 2 years. There was a significant difference in change in CML level between groups (-0.18 ± 0.13 mU/ml in the EP group vs. +0.22 ± 0.09 mU/ml in the C group, P<.05) after 1 year.
CONCLUSIONS: Epalrestat suppressed the deterioration of diabetic peripheral neuropathy, especially in the lower extremity. Its effects might be mediated by improvement of the polyol pathway and suppression of production of AGEs.