Peri-operative hyperglycaemia is associated with poor post-operative outcomes in people with and without diabetes. Dexamethasone is a commonly used drug which works well to control post-operative nausea and vomiting. However, it is well recognised to cause transient hyperglycaemia. A 2018 Cochrane analysis and a recent large randomised controlled trial suggested that dexamethasone use was not associated with an increased risk of surgical site infection in those with or without diabetes. I argue that the data used to generate the Cochrane data were weak and of very low quality. My hypothesis is that the recent large study on dexamethasone use and surgical site infections did the wrong analysis, meaning that the safety of dexamethasone has yet to be established.