Study on Serum Transcriptomics and Metabolomics in Patients With Diabetic Peripheral Neuropathy

Inclusion Criteria: * Patients diagnosed with diabetes mellitus (type 1 or type 2) * For the diabetic peripheral neuropathy (DPN) group: meet diagnostic criteria for painful diabetic peripheral neuropathy (P-DPN), defined as persistent pain and/or paresthesia in both lower limbs, with at least one objective sign of neuropathy (reduced ankle reflex, reduced vibration perception, or abnormal nerve conduction velocity when available), and a DN4 score ≥ 4 * For the diabetic control (DC) group: patients with diabetes mellitus but no evidence of peripheral neuropathy * For the healthy control (HC) group: healthy volunteers without diabetes or neuropathy, matched for sex and age * Aged between 18 and 80 years (inclusive) * Able to perform activities of daily living independently and cooperate with study procedures * No severe cardiac, cerebral, hepatic, renal, or other systemic diseases, and no severe mental illness or cognitive impairment * Willing to participate and provide written informed consent Exclusion Criteria: * Peripheral neuropathy caused by factors other than diabetes, including but not limited to hypothyroidism, alcohol abuse, medications, genetic disorders, or other systemic diseases * Presence of limb ulcers, gangrene, or a history of skin ulceration or non-healing wounds * Acute diabetic complications such as diabetic ketoacidosis, hyperosmolar hyperglycemic state, lactic acidosis, or severe infections within the past 3 months * Severe hepatic or renal impairment, or severe cardiovascular or cerebrovascular diseases (e.g., unstable angina, myocardial infarction, multiple cerebral infarctions, cerebral hemorrhage) * Scars or hyperpigmentation at the testing site that may interfere with accurate measurements * Pregnancy, breastfeeding, or planned pregnancy during the study period * Participation in another interventional clinical trial within 3 months prior to screening * For the diabetic control (DC) group: presence of peripheral neuropathy * For the healthy control (HC) group: history of diabetes mellitus, peripheral neuropathy, or use of medications affecting neurological function