A number of hypotheses have been put-forth to explain this counterregulatory defect in alpha-cell glucagon secretion in response to hypoglycaemia, which include: a loss of islet autonomic innervation; defects in neural glucose-sensing; alpha-cell insensitivity or irresponsiveness to paracrine signalling from beta-cells; an impairment in autocrine alpha-cell signalling or intrinsic defects from the alpha-cells themselves; as well as abnormally excessive somatostatin secretion from delta-cells [241]. Here, SST is linked to Hypoglycemia.