Anti-insulin receptor antibody hypoglycaemia may be the presenting feature of a wide variety of autoimmune diseases, as well of lymphomas. In this condition, antibodies that are directed against insulin receptors may mimic insulin action and cause hypoglycaemia, or block it and cause intractable hyperglycaemia. Plasma insulin and C-peptide levels may be high to very high when blood glucose levels are elevated due to excessive stimulation of the B cells, but are generally appropriately low during hypoglycaemia. The stimulatory antibodies may themselves be first-generation antibodies (Ab1) against the insulin receptor (Fig. 20.27) or antibodies against insulin antibodies (that is, anti-idiotypes: Ab2).
