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Background Metastatic dissemination is the leading cause of cancer-related mortality and is increasingly recognized as being influenced by systemic metabolic and endocrine factors. Patients with cardiometabolic diseases, specially Type 2 Diabetes Mellitus (T2DM), exhibit a higher incidence of cancer metastasis and poorer survival outcomes, yet the molecular mechanisms linking hyperinsulinemia to metastatic progression remain poorly defined. Insulin, chronically elevated in insulin resistance, dyslipidaemia, cardiac disease and T2DM, is a potent growth and survival factor capable of activating PI3K/AKT, MAPK, and TGF-β signalling pathways—networks known to regulate epithelial-to-mesenchymal transition (EMT). We hypothesized that sustained insulin exposure directly promotes EMT and metastatic behaviour in cancer cells, providing a mechanistic link between metabolic disease and cancer progression.Methods Human SKOV3 ovarian adenocarcinoma cells were cultured for up to 28 days under physiological (2–8 µg/mL) and hyperinsulinemic (50 µg/mL) insulin conditions. EMT-associated transcriptional changes were quantified by RT-qPCR, focusing on TGF-β, SMAD3, and MMP-9. Functional metastatic behaviour was assessed using Transwell migration and Matrigel invasion assays. Proteomic and phenotypic EMT markers were evaluated by immunocytochemistry, including epithelial markers E-cadherin and ZO-1 and the mesenchymal marker vimentin. Statistical significance was assessed using unpaired t-tests and one-way ANOVA with appropriate post-hoc analyses.Results Sustained insulin exposure induced a pronounced, time- and dose-dependent activation of EMT-related pathways. At 21–28 days, physiological insulin concentrations (2–8 µg/mL) significantly increased TGF-β expression (up to 11.2-fold, P ≤ 0.0001), accompanied by elevated SMAD3 transcription (up to 3.2-fold, P ≤ 0.0001). Hyperinsulinemia conditions produced a distinct response characterized by transient TGF-β signalling followed by robust upregulation of MMP-9, consistent with enhanced extracellular matrix remodelling. Functionally, insulin-treated cells demonstrated significantly increased migratory and invasive capacity, with invasion rising over two-fold compared to controls (P ≤ 0.001). At the protein level, insulin exposure resulted in marked downregulation of epithelial junctional proteins E-cadherin and ZO-1 and a concomitant increase in vimentin expression (P ≤ 0.0001), confirming a phenotypic EMT shift.Conclusions Our findings identify insulin as a direct and potent driver of EMT and metastatic behaviour in ovarian cancer cells, independent of glycaemic status. Chronic insulin exposure remodels tumour cell phenotype through TGF-β/SMAD-dependent signalling and matrix-degrading programs, enhancing migration and invasion. These results provide mechanistic insight into the increased metastatic risk observed in patients with T2DM, cardiometabolic disease and obesity and highlight insulin as a previously underappreciated regulator of the tumour microenvironment. This work underscores the importance of metabolic–oncologic cross-talk and suggests that strategies aimed at controlling hyperinsulinemia may have therapeutic relevance in limiting cancer metastasis.