Objective To identify determinants associated with insulin resistance and to assess the association between insulin resistance and cardiovascular events, vascular interventions and mortality in people with type 1 diabetes at high risk of cardiovascular disease. Design Prospective cohort study. Methods One hundred and ninety-five people with type 1 diabetes from the Secondary Manifestations of ARTerial disease (SMART) cohort were included. Insulin resistance was quantified by the estimated glucose disposal rate (eGDR) with higher eGDR levels indicating higher insulin sensitivity (i.e. lower eGDR levels indicating higher insulin resistance). Linear regression models were used to evaluate determinants associated with eGDR. The effect of eGDR on cardiovascular events, cardiovascular events or vascular interventions (combined endpoint) and on all-cause mortality was analysed using Cox proportional hazards models adjusted for confounders. Results In 195 individuals (median follow-up 12.9 years, IQR 6.7–17.0), a total of 25 cardiovascular events, 26 vascular interventions and 27 deaths were observed. High eGDR as a marker for preserved insulin sensitivity was independently associated with a lower risk of cardiovascular events (HR: 0.75; 95% CI: 0.61–0.91), a lower risk of cardiovascular events and vascular interventions (HR: 0.74; 95% CI: 0.63–0.87) and a lower risk of all-cause mortality (HR: 0.81; 95% CI: 0.67–0.98). Conclusions Insulin resistance as measured by eGDR is an additional risk factor for cardiovascular disease in individuals with type 1 diabetes. Modification of insulin resistance by lifestyle interventions or pharmacological treatment could be a viable therapeutic target to lower the risk of cardiovascular disease.