Blood tests will be performed at each visit. At baseline, Blood tests will include full blood count, urea and electrolytes, liver function tests, thyroid function tests, glucose, HBA1c, amylase and saved serum. At follow up visits, urea and electrolytes, thyroid function, serum amylase will be checked and serum will be stored. These samples are to check both safety and to allow measurement of Exenatide levels to be performed after trial completion.