It is reported that PDE-5 inhibitors have a higher failure rate in diabetic patients than in non-diabetic people.[43] PDE5 inhibitors require minimal nitric oxide production, which is impossible for diabetic neuropathy patients with severe neurological impairment.[44] ALA has a good explanation for this situation and can play a complementary role with PDE-5 inhibitors. The gene discussed is PDE5A; the disease is diabetic neuropathy.