 This is an open-label a medical research study in which participants and researchers are told which treatments the participants are receiving, unblinded, multi-center and randomized study drug is assigned by chance study to compare the effectiveness and safety of tramadol HCl 37.5 mgacetaminophen 325 mg with gabapentin in participants with diabetic neuropathy. The study will consist of 4 periods: Screening period up to Day -14, Randomization period Day 1, Dosage adjustment period Day 15 and Maintenance period Day 43. The participants will be randomly assigned to 1 of the 2 treatment groups: tramadol HCl 37.5 mgacetaminophen 325 mg or gabapentin. Tramadol Hclacetaminophen group will receive 1 tablet for 3 days, then 1 tablet twice daily for 4 days followed by 1 tablet thrice daily for next 7 days. If there is no pain relief, the dosage can be increased up to 8 tablets per day for Day 15 to 28, and then the increased dosage will be maintained for Day 29 to 42. Gabapentin group will receive 300 mg on Day 1, 300 mg twice daily on Day 2, and 300 mg thrice daily for Day 3 to 7. Then for Day 8 to 14, participants will receive 300 mg in the morning, 300 mg in the midday and 600 mg in the evening. If there is no pain relief, gabapentin can be increased up to 3600 mg per day for Day 15 to 28, and then the increased dosage will be maintained for Day 29 to 42. Primarily, efficacy will be evaluated by pain intensity using numeric rating scale NRS. Participants safety will be monitored throughout the study. 