A Study of LY3556050 in Adult Participants With Diabetic Peripheral Neuropathic Pain

Inclusion Criteria: * Have a history and current diagnosis of Type 1 Diabetes (T1D) or Type 2 Diabetes (T2D) diagnosed for at least 6 months prior to screening. * Have a stable glycemic control on stable diabetes treatment regimen for at least 90 days prior to day 1 with a hemoglobin A1c (HbA1c) ≤10 for T1D and HbA1c ≤11 for participants with T2D at time of screening. * Have a history of daily peripheral neuropathic pain for at least 12 weeks based on participant report or medical history. * Have a visual analog scale (VAS) pain value ≥40 and \<95 during screening. * Have presence of diabetic peripheral neuropathy of symmetrical nature and in lower extremities for ≥6 months and diagnosed by a score of Part B ≥3 on Michigan Neuropathy Screening Instrument * Are willing to maintain a consistent regimen of any ongoing nonpharmacologic pain-relieving therapies (for example, physical therapy) and will not start any new nonpharmacologic pain-relieving therapies during study participation. * Are willing to discontinue all medications taken for chronic pain conditions, except allowed concomitant pain medication permitted per protocol, for the duration of the study * Have a body mass index ≤45 kilogram/square meter (kg/m²) (inclusive). * Are men, or women able to abide by reproductive and contraceptive requirements. Exclusion Criteria: * History of other potentially causative and/or confounding sources of pain that may impair self-assessment of pain due to DPNP. * Have had a procedure within the past 6 months intended to produce permanent sensory loss in the target area of interest (for example, ablation techniques. * Have had cancer within 2 years of baseline, except for cutaneous basal cell or squamous cell carcinoma resolved by excision. * Are, in the judgment of the investigator, actively suicidal and therefore deemed to be at significant risk for suicide. * Have in the judgement of the investigator, an acute, serious, or unstable medical condition or a history or presence of any other medical illness that would preclude study participation. * Have a positive HIV test result at screening. * Have a surgery planned during the study for any reason. * Have a substance use disorder as defined by the Diagnostic and Statistical Manual of Mental Disorders (5th edition; DSM-5; American Psychiatric Association)