Background: Type 2 diabetes mellitus (T2DM) is a progressive cardiometabolic disease in which many patients require treatment intensification despite lifestyle intervention and evidence-based pharmacotherapy. Oleanolic acid (OA), a pentacyclic triterpenoid found in olives and other plants, has shown insulin-sensitizing, antioxidant, anti-inflammatory, and hepatometabolic effects in experimental models. Aim: This narrative translational review evaluates OA as a potential investigational adjunct in T2DM, with emphasis on formulation-dependent bioavailability, translational limitations, clinical endpoints, safety, and patient relevance. Methods: We synthesized mechanistic, preclinical, pharmacokinetic, clinical, regulatory, and trial-registry evidence. As this was not a systematic review or meta-analysis, the evidence was interpreted narratively, with attention to study design, formulation, dose, model validity, comparator use, and potential sources of bias. Results: Preclinical studies suggest that OA may influence insulin signaling, hepatic glucose production, oxidative stress, inflammatory pathways, lipid metabolism, and β-cell stress. However, most mechanistic data derive from cell or animal models, often using high doses, short treatment durations, or models with limited human predictability. Human evidence remains limited. PREDIABOLE reported reduced progression from prediabetes to T2DM after long-term intake of OA-enriched olive oil, while BIO-OLTRAD demonstrated measurable systemic exposure after a 30 mg OA dose in functional olive oil. OLTRAD is testing this formulation as an adjunct to metformin-based therapy. Conclusion: OA is a plausible investigational adjunct, but clinical efficacy in established T2DM has not been established. Its future value depends on reproducible exposure, clinically meaningful outcomes, long-term safety, compatibility with contemporary therapies, and avoidance of disease-treatment claims unsupported by human trials. Relevance for Patients: OA-enriched functional foods may eventually complement, but should not replace, evidence-based diabetes treatment.