Cohen and colleagues make no mention of the evidence that treatment of type 2 diabetes with increasingly larger doses of sulfonylureas and insulin is not without serious risk from hypoglycaemia, weight gain, and possibly increased cardiovascular risk.1 A balanced account of this is needed in any review of incretins. There have been concerns that such treatments, or the hypoglycaemia and weight gain they produce, explain failure to reduce cardiovascular disease despite tightening glycaemic control. Large meta-analyses of sulfonylureas suggest that they may increase cardiovascular risk.2 3 By contrast, a large meta-analysis of dipeptidyl peptidase 4 inhibitors suggests significant cardiovascular benefit.4 …