The Use of Curcumin to Target Oxidative Stress and Inflammation in Type 2 Diabetes Mellitus and Its Complications: Molecular Mechanisms and Therapeutic Perspectives

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance, pancreatic β-cell dysfunction, and dysregulated glucose and lipid metabolism. Sustained hyperglycemia and hyperlipidemia promote excessive reactive oxygen species (ROS) production, antioxidant defense depletion, and chronic low-grade inflammation, thereby aggravating insulin signaling impairment, β-cell injury, and diabetes-related complications. Although current glucose-lowering therapies have improved glycemic control, weight management, and cardiorenal outcomes, oxidative stress and inflammation remain incompletely addressed in many individuals with T2DM. Curcumin, a natural polyphenol derived from Curcuma longa L., exhibits antioxidant, anti-inflammatory, lipid-regulating, insulin-sensitizing, and tissue-protective activities. Evidence suggests that curcumin may alleviate T2DM-associated oxidative stress by suppressing ROS generation, reducing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, modulating the advanced glycation end-product/receptor for advanced glycation end-product (AGE/RAGE) axis, activating nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) signaling, preserving mitochondrial homeostasis, and protecting β-cells. It may also inhibit nuclear factor-κB (NF-κB) and mitogen-activated protein kinase/c-Jun N-terminal kinase (MAPK/JNK) signaling, decrease pro-inflammatory cytokines and C-reactive protein (CRP), improve metabolic tissue inflammation, and attenuate gut-derived inflammation by regulating gut microbiota and intestinal barrier function. However, current clinical evidence mainly supports modest improvements in metabolic, inflammatory, oxidative stress-related, and selected complication-related biomarkers rather than definitive disease-modifying outcomes. Moreover, formulation heterogeneity, low bioavailability, limited pharmacokinetic reporting, and insufficient long-term endpoint data remain major translational barriers. This review summarizes the molecular mechanisms, clinical evidence, formulation-dependent interpretation, safety considerations, and translational limitations of curcumin as a candidate adjunctive intervention for T2DM, rather than as a replacement for evidence-based antidiabetic therapy.