A441combination with insulin versus insulin alone for patients who are inadequately controlled despite high doses of insulin. Methods: The published and validated CARDIFF diabetes model was used to conduct the analysis. Clinical inputs were derived from a randomized clinical trial comparing dapagliflozin add-on to insulin with insulin regimens. Based on clinical inputs and the United Kingdom Prospective Diabetes Study (UKPDS) equations, the model predicts disease progression and the number of micro-and macro-vascular complications, along with diabetes-specific and all-cause mortality. The perspective of the National Health Service in England and Wales was adopted over a lifetime horizon. Local unit costs and utility data were assigned to the appropriate model parameters to calculate total Quality-Adjusted-Life-Years (QALYs) and total costs. Univariate and probabilistic sensitivity analyses (PSA) were conducted. Results: Compared to insulin, dapagliflozin added to insulin was associated with 0.342 incremental QALYs (95%CI: 0.288; 0.480) at an additional cost of £1,813 (95%CI: £1,165; £2,381), resulting in an incremental cost-effectiveness ratio (ICER) point estimate of £5,295 per QALY gained. The univariate analyses showed that no input parameter change inflated the ICER above £15,000 per QALY. At a willingness-topay threshold of £20,000 per QALY gained, the dapagliflozin treatment strategy was estimated to have a 100% probability of being cost-effective when compared to the insulin treatment strategy. These findings were shown to be robust with all sensitivity analyses. ConClusions: Dapagliflozin was shown to be a cost-effective treatment option in combination with insulin for patients who are inadequately controlled with insulin alone within established UK cost-effectiveness thresholds. PDB59Assessment of the Key Drivers of Cost-effeCtiveness in the eConomiC moDelling of CAnAgliflozin (CAnA) versus glimePiriDe (glim) in the treAtment of tyPe 2 DiABetes mellitus (t2Dm) in the uK setting