The Effects of Ceylon Cinnamon (Cinnamomum Verum) Supplementation on Blood Glucose, Lipid Profile Levels, Body Mass Index, and Pain Intensity Among Adult Individuals With Painful Diabetic Peripheral Neuropathy: A Double-Blind Randomized Controlled Trial

Type 2 diabetes mellitus (T2DM) represents a global public health crisis characterized by progressive metabolic dysfunction, chronic hyperglycemia, and systemic vascular and neural complications (World Health Organization [WHO], 2023). Painful diabetic peripheral neuropathy (PDPN) is one of the most disabling microvascular complications of T2DM, arising from complex pathophysiological processes including prolonged exposure to hyperglycemia, insulin resistance (IR), excessive oxidative stress, and chronic neuroinflammation (Atsaves & Ricketts, 2020; Jain & Sahu, 2023; WHO, 2023). Clinically, PDPN presents as persistent burning, shooting, or stabbing pain, severely impairing patient mobility, sleep quality, overall daily functionality, and quality of life (Abu-Shennar & Bayraktar, 2022).

While pharmacological strategies remain the primary modality for managing neuropathic pain in T2DM, many agents carry significant adverse effect profiles or provide incomplete symptomatic relief (Atsaves & Ricketts, 2020). Consequently, there is growing clinical interest in safe, natural nutraceutical adjuncts capable of targeting the underlying metabolic and inflammatory driving factors of nerve injury. Ceylon cinnamon (Cinnamomum verum) has gained considerable attention due to its rich content of bioactive compounds, such as cinnamaldehyde, polyphenols, and type-A procyanidin polymers, which exhibit insulin-mimetic, antioxidant, and anti-inflammatory activities (Akilen et al., 2010; Kermani et al., 2022; Khan et al., 2003; Rani & Sharma, 2021).

Mechanistically, Ceylon cinnamon (Cinnamomum verum) bioactive compounds enhance insulin receptor autophosphorylation, upregulate glucose transporter type 4 (GLUT4) translocation via the phosphatidylinositol 3-kinase (PI3K) pathway, and downregulate glycogen synthase kinase-3β (GSK3β) (Baker et al., 2008; Khan et al., 2003; Zare et al., 2021). Furthermore, Ceylon cinnamon polyphenols mitigate neuroinflammation and nociceptive signaling by dampening pro-inflammatory cytokine secretion (e.g., TNF-α, IL-6) and reducing advanced glycation end-product (AGE) accumulation within peripheral myelin sheaths and Schwann cells (Jain & Sahu, 2023; Rani & Sharma, 2021).

Despite the growing body of global and national literature examining the metabolic effects of cinnamon supplementation in T2DM, significant knowledge gaps remain. On a global scale, prior clinical trials have predominantly focused on short-term glycemic and lipid modulations, largely neglecting the direct therapeutic impact of nutraceuticals on peripheral neuropathic pain severity (Jain & Sahu, 2023; Rani & Sharma, 2021). Locally, while Jordanian clinical and nursing research has comprehensively addressed diabetes self-management, self-efficacy, and pain education among patients with diabetic neuropathy (Abu-Shennar & Bayraktar, 2022; Khattab et al., 2020; Khraisat et al., 2023), no randomized clinical trial has yet evaluated the adjunctive role of bio-standardized phytotherapy in this population.

To our knowledge, this study represents the first double-blind, randomized controlled trial (RCT) both globally and in Jordan to rigorously investigate the therapeutic potential of Ceylon cinnamon (Cinnamomum verum) specifically in patients with PDPN over a prolonged 6-month period, bridging the critical gap between metabolic optimization and neurosensory pain attenuation.