Perineural Botulinum Toxin Injection Versus Oral Duloxetine in Relief of Foot Pain in Painful Peripheral Diabetic Neuropathy

Painful diabetic peripheral neuropathy (DPN) is a frequent and disabling complication of diabetes that commonly causes persistent foot pain, sleep impairment, and decreased quality of life. While oral medications such as duloxetine are established treatment options, many patients experience incomplete pain control or encounter dose-limiting side effects. Perineural botulinum toxin type A (BTX-A) injection has emerged as an interventional approach designed to inhibit peripheral pain signaling with targeted, prolonged local effect. The purpose of this study is to compare the efficacy and safety of a single session of ultrasound-guided perineural BTX-A injection versus standard daily oral duloxetine therapy in relieving foot pain in patients with painful diabetic peripheral neuropathy. Participants will be randomly assigned to one of two groups using a double-dummy design to preserve blinding: * Group B (Botulinum Toxin): Receives a single session of ultrasound-guided perineural botulinum toxin type A injection around the ankle nerves plus daily oral placebo tablets for 12 weeks. * Group D (Duloxetine): Receives a single session of sham subcutaneous injection plus oral duloxetine tablets daily for 12 weeks (30 mg once daily for week 1, increased to 60 mg once daily for weeks 2-12). Participants will be followed for 6 months to evaluate changes in foot pain intensity on the Visual Analogue Scale (VAS) at 1 week, 1 month, 3 months, and 6 months. The study will also assess objective peripheral nerve function through bilateral nerve conduction studies (NCS) at baseline and 6 months, alongside evaluations of neuropathic pain scores, sleep quality, quality of life, and adverse effects.