The present study sought to evaluate the cost-effectiveness of first-line (immediate) versus delayed use of combination dapagliflozin and metformin in patients with type 2 diabetes, from the perspective of the Australian healthcare system. We developed a Markov model to simulate the progress of subjects with type 2 diabetes. Decision analysis was applied to assess the cost-effectiveness of first-line combination dapagliflozin and metformin versus first-line metformin monotherapy followed by gradual addition of dapagliflozin over time. Transition probabilities, costs (in Australian dollars) and utility data were derived from published sources. All costs, years of life lived and quality adjusted life years (QALYs) lived were discounted at an annual rate of 5%. Over a 20-year model period, first-line use of combination dapagliflozin and metformin was predicted to reduce the onset of hospitalisation of heart failure, cardiovascular deaths and all cause deaths by 5.5%, 57.6% and 29.6%, respectively. An additional 2.5 years of life (discounted) and 1.9 QALYs (discounted) would be gained per patient, at a cost of AUD $23,367 (discounted) per person. These figures equated to AUD $9,535 per years of life saved (YoLS) and AUD $12,477 per QALYs saved. Sensitivity analyses indicated the results to be robust. Compared to first-line metformin monotherapy followed by gradual addition of dapagliflozin, first-line use of combination dapagliflozin and metformin is likely to be a cost-effective approach to the management of Australians with type 2 diabetes mellitus.