Pharmacodynamic Study of BIIB095 and BIIB074 in Healthy Participants and Participants With Painful Diabetic Polyneuropathy

Key Inclusion Criteria: * Healthy participants must be in good health, as determined based on medical history and screening evaluations * Participants with DPN * Must have a documented diagnosis of type 2 diabetes mellitus (DM) * Must have stable glycemic control * Must have at least clinical evidence of painful DPN * Pain related to DPN must be present for at least 6 months prior to screening * Average daily pain intensity over 7 consecutive days recorded during screening must be ≥ 4 on an 11-point numerical rating scale ranging from 0 (no pain) to 10 (worst pain imaginable) Key Exclusion Criteria: * Any neurologic or painful condition that could confound the interpretation of study results * History of any clinically significant cardiac, hematologic, hepatic, immunologic, urologic, pulmonary, dermatologic, psychiatric, renal, or other major disease. This includes any clinically significant endocrinologic or neurologic disease other than DM or DPN. * Use of local anesthetics or capsaicin for topical or regional treatment within 3 months prior to Screening. * Systemic use of sodium channel inhibitors Note: Other protocol-specific inclusion/exclusion criteria may apply.