Background: Painful diabetic peripheral neuropathy (PDPN) is a severe, disabling complication of type 2 diabetes mellitus (T2DM), closely associated with insulin resistance, chronic neuroinflammation, and oxidative stress. Plant-based dietary supplements, particularly Ceylon cinnamon (Cinnamomum verum), contain bioactive compounds with potential anti-diabetic, antioxidant, and neuroprotective properties.

Aim: To evaluate the effects of Ceylon Cinnamon (Cinnamomum verum) supplementation on blood glucose, lipid profile levels, body mass index (BMI), and pain intensity among adult individuals with painful diabetic peripheral neuropathy (PDPN).

Methods: A prospective, double-blind, randomized controlled trial (Double-Blind RCT) was conducted (Feb-July 2026) across endocrinology outpatient clinics in Jordan. Participants were randomly allocated in a 1:1 ratio to either the Intervention Group (n = 62; 500 mg Ceylon cinnamon twice daily for 6 months alongside standard care) or the Placebo Control Group (n = 62; 500 mg placebo capsules twice daily for 6 months alongside standard care). Clinical, biochemical, and pain assessments (using the Numeric Rating Scale [NRS]) were evaluated at baseline, 3 months, and 6 months post-intervention.