Efficacy of Topical Lidocaine Gel vs. Oral Duloxetine for Painful Diabetic Peripheral Neuropathy

Inclusion Criteria: * Adult patients aged 30 to 70 years * Confirmed type 2 diabetes mellitus (as per WHO 2019 criteria) for at least 1 year * HbA1c \< or = 10% (or documented stable glycemic control over the preceding 3 months) * Diagnosis of painful diabetic peripheral neuropathy (PDPN) with a DN4 score \> or = 4/10 * Baseline Numeric Rating Scale (NRS) pain score \>= 4/10 (moderate-to-severe pain) * Willing and able to provide written informed consent Exclusion Criteria: * Known hypersensitivity or contraindication to lidocaine or duloxetine * Current use of other neuropathic pain medications (gabapentinoids, tricyclic antidepressants, opioids, or topical capsaicin) within 4 weeks of enrollment * Significant hepatic impairment (ALT or AST \> 3 times the upper limit of normal) * Severe renal impairment (eGFR \< 30 mL/min/1.73 m²) * Active skin lesions, open wounds, or dermatological conditions at the intended application site on the feet * Pregnant or lactating females * Other causes of peripheral neuropathy (e.g., alcohol-related, hypothyroidism, vitamin B12 deficiency, or Charcot-Marie-Tooth disease)