GPT and diabetes mellitus: Inhibition of glucagon receptor signalling and liver-preferential insulin action have been shown individually to have beneficial effects in preclinical models and individuals with diabetes (i.e. improved glycaemic control), but also have effects that are potential safety risks (i.e. alpha cell hyperplasia in response to glucagon receptor antagonists and increased levels of liver triacylglycerols and plasma alanine aminotransferase activity in response to glucagon receptor antagonists and liver-preferential insulin).