<prompt> Which of the following is not used in diagonosis of insulinoma72 hows fasting blood glucose levelsC peptide levelsInsulinglucose ratioD-xylose test  <response>: These blood tests are needed to diagnose insulinoma: glucose insulin C-peptide If available, a proinsulin level might be useful, as well. Other blood tests may help rule out other conditions which can cause hypoglycemia Ref Davidson edition23rd pg837 