Efficacy and Safety of Gabapentin/B-complex Versus Pregabalin in Diabetic Peripheral Neuropathy Pain Management

This is a multicenter, randomized, open-label, parallel, Phase 4 clinical trial to compare efficacy and safety of gabapentin/B-complex versus pregabalin in diabetic peripheral neuropathy pain (DPNP) management.

Primary Objective:

To compare the efficacy of gabapentin/B-complex versus pregabalin administered for 12 weeks in the treatment of pain in mild to moderate diabetic peripheral neuropathy (DPN) of acute or chronic presentation.

Secondary Objectives:

To determine the safety and tolerability of gabapentin/B-complex versus pregabalin administered for 12 weeks in the treatment of pain in mild to moderate DPN of acute or chronic presentation.

Subjects will be randomized in a 1:1 ratio to receive gabapentin/B-complex or pregabalin.

The duration of treatment per subject will be 12 weeks.

Eligibility Criteria:
Inclusion Criteria:

* Females or males undististincally
* Age 18 to 70 years
* Signed informed consent (IC) by the subject
* Diabetes mellitus (DM) Type 1 or 2
* Pain due to sensorial or motor DPN of low to moderate intensity, greater than or equal to (\>=) 1 year of evolution and less than or equal to (=\<)5 years of being diagnosed
* Subjects who score \>=40 millimeter (mm) in the visual analogue scale (VAS) of the McGill pain questionnaire (MPQ) at selection and Baseline visit, and who complete on a daily basis the numeric pain intensity (NPI) (at least 4 days a week) during the week previous to randomization and whose daily mean score is of at least 4, during the 7 days previous to randomization (with a wash-out period)
* Normal chest radiography
* Stable hypoglycemic treatment, at least 6 weeks before randomization
* Glycosylated hemoglobin (HbA1c) =\<10 percent at selection visit
* Women must not be pregnant and must not have pregnancy plans during the period of the study duration
* Subjects not medicated or under analgesic stable medication during a minimum of 4 weeks, where no acceptable relief of pain is achieved; in the last case, with the corresponding wash-out period
* Women of childbearing age must submit a negative pregnancy test before treatment randomization and should use a contraceptive method medically accepted, during the study period

Exclusion Criteria:

* Suicide risk defined as a score of 2 or higher, in question 9 of the beck depression test
* Congestive heart failure Class III or IV of the New York Heart Association (NYHA)
* Subjects with serious or unstable coronary heart disease, hepatic, kidney, respiratory, hematological alterations, problems with peripheral vascular disease, or other medical or psychiatric conditions that can put in risk the participation of the subject in the study or that may lead to hospitalization during the study period
* Any condition that may lead to confusion of the diagnostic of painful DPN, in particular amputations -other than fingers/toes-, not diabetic neurological disorder and skin conditions that may affect sensation at the painful limbs
* Subjects with Baseline calculated creatinine clearance less than (\<) 60 milliliter per minute (mL/min), Baseline leukocyte count \< 2,500 per cubic millimeter (/mm\^3), Baseline neutrophils count \< 1,500/mm\^3 or platelets \< 100 \* 10\^3 /mm\^3
* Subjects who have participated previously in some other study of pregabalin or gabapentin or gabapentin/B-complex, during 30 days previous to selection
* Subjects with encephalopathy caused by ammonia with alterations in the cycle of urea
* Subjects with uncontrolled closed-angle glaucoma
* Subject with presence of a disorder or an anticonvulsant treatment
* Breastfeeding women or during the first 3 months postpartum
* Morbid obesity (body mass index \[BMI\] \>=40)
* Glycosylated hemoglobin (HbA1c) greater than (\>) 10 percent
* Major surgery 3 months previous to randomization
* Any surgery 2 weeks previous to randomization process, or programmed during the study period should have been authorized by the Sponsor or appointed representative
* Blood donors 60 days previous to randomization
* Abuse or dependency of alcohol, narcotics, opioids or any other addictive substances, or energizing drinks
* History of hypersensitivity to the drugs in the study or drugs with similar chemical structures
* History or suspicion of lack of trust, poor cooperation of lack of compliance of medical treatments
* Subjects with arthritis, sciatic, fibromyalgia, restless leg syndrome, non-neuropathic muscle-skeletal pain or back chronic pain