 An interventional study to investigate the efficacy and safety of diepalrestat BNV-222 in diabetic patients with diabetic peripheral neuropathy. Subjects will receive twice daily an oral dose of diepalrestat, an aldose reductase inhibitor, or placebo to investigate the effect on motor nerve conduction velocity MNCV and symptomatic clinical responses over 12 months of treatment. Subjects will be assessed at screening and baseline, with office visits every 12 weeks, for a total of 6 visits. The study will explore in a double-blind fashion, the effect of two doses of diepalrestat, 150 and 300 mg, to reduce the loss in nerve conduction velocity that is expected to be demonstrated in the group randomized to placebo treatment for up to 12 months. 