Endocrine parts of pancreas called Islets of Langerhans. 2 populations of cells: A cells- secrete glucagon (RAISES blood glucose conc) - when all the 'gluc has gone'B cells- secrete insulin (LOWERS blood glucose conc)Type 1 diabetes:Autoimmune- where the body's immune system destroys B- cells which produce insulin Type 2 diabetesB cells STILL produce insulin BUT body cells become de-sensitised to insulinInsulin produced no longer has desired effect of lowering blood glucose conc