There are a few studies in which authors evaluated the efficacy of duloxetine and pregabalin in patients with PDPN with regard to disease characteristics; e.g., Ziegler et al. analysed data from three randomised control trials and found no associations between the efficacy of duloxetine and the patient’s age, type or duration of diabetes, severity of diabetic neuropathy, HbA1c baseline levels, or baseline insulin levels. The gene discussed is INS; the disease is diabetes mellitus.