Exenatide-test for Diagnosing Endogenous Hyperinsulinemic Hypoglycemia

Patients with suspicion for an insulinoma fulfilling all of the following inclusion criteria are eligible for the study: Inclusion Criteria: * Informed Consent as documented by signature * Biochemically proven endogenous hyperinsulinemic hypoglycemia: neuroglycopenic symptoms in the fasting state with low plasma glucose, inappropriately high serum insulin and C-peptide concentrations (standardized 72h fasting test).). Participants as control subjects fulfilling all of the following inclusion criteria are eligible for the study: Inclusion Criteria: * Informed Consent as documented by signature (Appendix Informed Consent Form) * Possession of the adequate match criteria (age, BMI and gender) to patients with suspicion for an insulinoma Exclusion Criteria: * Known hypersensitivity or allergy to Exenatide * Pregnant or breastfeeding female patients. A pregnancy test will be performed in all women of child bearing potential. * Calculated creatinine clearance below 40 ml/min * No signed informed consent * Intake of any glucagon-like peptide (GLP)-1 analogue (such as Byetta® or Bydureon®\[= Exenatide\]) * prediabetes or diabetes (HbA1c \> 5.7 %) * Previous abdominal surgery in the gastrointestinal tract * Any concomitant glucose-lowering drug (i. e. insulin, sulfonyl urea) * Any known intolerance to standardized meal (Maizena) * Any uncontrolled significant medical, psychiatric or surgical condition (active infection, unstable angina pectoris, cardiac arrhythmia, poorly contr…