Abstract Aims/hypothesis: Diabetes is known to accelerate the progression of atherosclerosis and increase plaque instability. However, there has been a lack of suitable animal models to study the effect of diabetes on plaque instability. We hypothesized that the tandem stenosis (TS) mouse model, which reflects plaque instability and rupture as seen in patients, can be applied to study the effects of diabetes and its respective therapeutic approaches on plaque instability/rupture. Methods: ApoE -/- mice at 7 weeks of age were injected with streptozotocin (STZ) for 5 consecutive days. 5 weeks after STZ injection, mice were surgically subjected to TS in the right carotid artery and fed with a high-fat diet for an additional 7 weeks. To validate this newly developed animal model, administration of the interventional drug dapagliflozin was provided via drinking water (25 mg/kg) 3 days after TS surgery. Results: Diabetic mice showed an increase in the size of unstable atherosclerotic plaques in the TS model. Plaque instability markers such as MCP-1, CD68, and necrotic core (NC) size were significantly increased. Mice treated with the sodium glucose co-transporter 2i (SGLT2i) dapagliflozin demonstrated attenuated glucose levels. Importantly, these mice demonstrated plaque stabilization with enhanced collagen accumulation, increased fibrosis, increased cap-to-lesion ratios, and significant upregulation of plaque NADPH oxidase 4 (NOX4) expression. Conclusions/interpretation: The TS mouse model in combination with the application of STZ represents a highly suitable and unique mouse model for studying plaque destabilization under diabetic conditions. Furthermore, for the first time, we provide evidence of plaque-stabilizing effects of SGLT2i. Our data also suggest that this newly developed mouse model is an attractive preclinical tool for testing anti-diabetic drugs for their highly sought-after potential to stabilize atherosclerotic plaques.