Purpose Diabetic macular oedema (DMO), a complication of diabetes, causes vision loss and blindness. Corticosteroids are usually used as a second‐line treatment. The aim of this study was to analyse the cost‐effectiveness of dexamethasone implants compared to cheaper and more frequently applied triamcinolone injections. Methods Markov‐modelling, which incorporated both eyes, was used for economic evaluation. The model consisted of five health states based on visual acuity, illustrating the progression of DMO. A cycle length of five months was chosen for dexamethasone and four months for triamcinolone. Time horizons of two and five years were applied. Transition probabilities and health state utilities were sourced from previous studies. The perspective used in this analysis was the hospital perspective. The health care costs were acquired from Kuopio University Hospital in Finland. Results In this cost‐effectiveness analysis, the incremental cost‐effectiveness ratio ICER with 3% discount rate was €56 591/QALY for a two‐year follow‐up and −€1 110 942/QALY for a five‐year follow‐up. In order to consider dexamethasone as cost‐effective over a 2‐year time horizon, the WTP needs to be around €55 000/QALY. Over the five‐year follow‐up, triamcinolone is clearly a dominant treatment. Sensitivity analyses support the cost‐effectiveness of dexamethasone over a 2‐year time horizon. Conclusions Since the sensitivity analyses support the results, dexamethasone would be a cost‐effective treatment during the first two years with WTP threshold around €55 000/QALY, and triamcinolone would be a convenient treatment after that. This recommendation is in line with the guidelines of EURETINA.