Hyperglycaemic relapse may occur as a result of ageing, poor adherence to diabetes management, and insufficient intervention for underlying mechanisms of type 2 diabetes mellitus, such as impaired incretin action.23, 24 Notably, even mild hyperglycaemia can result in β cell impairment,25, 26 potentially exacerbating a vicious cycle. This evidence concerns the gene GCG and type 2 diabetes mellitus.