Which of the following tests is not used in the diagnosis of insulinoma

Answer is B (Xylose test) : Xylose test is used in the diagnosis of malabsorption due to intestinal mucosal disease. This test is not used for the diagnosis of Insulinomas Fasting blood glucose, C- peptide levels and Insulin Glucose Ratio are all used in the diagnosis of Insulinomas. Diagnosis of Insulinomas 6,uU/m1 when blood glucose in < 40 mg/dl " align="left" height="40" width="237">Serum insulin levels (fasting) Serum glucose levels (fasting) Serum C- peptide levels (Elevated) Serum proinsulin levels (Elevated) Insulin / Glucose Ratio (> 0.3) Plasma fl-Hydroxybulyrate (Decreased) The most reliable test is a fast upto 72 hours with serum glucose, C-peptide and insulin levels measurements every 4-8 hours