Evaluation of the efficacy of LX9211 compared to placebo in reducing DPNP. Please see study website: https://diabeticpainstudy.com/

Inclusion Criteria:

1. Participant has given written informed consent to participate in the study in accordance with local regulations
2. Adult male and female participants ≥18 years of age at the Screening Visit
3. Body mass index ≥18.0 to ≤40.0 kilogram per meter square (kg/m^2) at Screening
4. Diagnosis of type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM) with chronic DPNP, at Screening
5. Pain from DPNP present for at least 6 months prior to Screening
6. At the Screening Visit, glycosylated hemoglobin (A1C) must be ≤11%.
7. Stable regimen for the treatment of T1DM or T2DM for ≥3 months prior to Screening
8. Willing to adhere to the prohibitions and restrictions specified in the protocol.

Exclusion Criteria:

1. Presence of other painful conditions that may confound assessment or self-evaluation of DPNP
2. History of neurolytic or neurosurgical therapy for DPNP
3. Use of opioid medications for management of DPNP within the 2 months prior to the Screening Visit.
4. Use of prescription topical analgesics (eg, capsaicin) indicated for neuropathic pain within 3 months prior to Screening
5. Use of nonsteroidal anti-inflammatory drugs (NSAIDs) less than 2 weeks prior to Screening