The studies discussed here show two distinct roles for glucagon in the treatment of diabetes. Glucagon may have a direct role in the pathogenesis of diabetes, with a relative hyperglucagonaemia in all formsof diabetes. It is not clear if this is a consequence or a cause of diabetes, nor whether harmful or a possible endogenous counter-regulation mechanism to compensate for some adverse metabolic change. Antagonising glucagon action may reduce the associated hyperglycaemia, but may not be beneficial in terms of life expectation of the person with diabetes. One of the main causes of type 2 diabetes is obesity. Glucagon can cause significant weight loss through reducing food intake and increasing energy expenditure; and if this reduces obesity, could itself treat diabetes. To mitigate any hyperglycaemic effects of the glucagon, it will, however, have to be administered withanother hormone such as GLP-1 which releases insulin and thereby inhibits the enhanced gluconeogenesis of glucagon