<prompt> A patient presents with symptoms of Hypoglycemia. Investigations reveal decreased blood glucose and increased Insulin levels. C-peptide assay is done which shows normal levels of C- peptide. The most likely diagnosis is:InsulinomaAccidental sulfonylurea ingestionAccidental exogenous Insulin administrationAccidental Metformin ingestion  <response>: Answer is C Accidental exogenous Insulin administration: Normal Reduced levels of C- peptide in the presence of increased insulin suggest a diagnosis of exogenous insulin administration as the cause of hypoglycemia. Approach to a patient with Hypoglycemia and Increased Insulin levels: Role of C- peptide Assay Normally Endogemous Insulin is secreted from 3-cells of pancreas in the form of Pro-insulin This proinsulin is then broken down to Insulin and C- peptide such that for each molecule of endogenous insulin, one molecule of C-peptide is produced. C-peptide levels are thus increased whenever endogenous insulin is increased e.g. Insulinomas, Sulfonylureas, Autoimmune processes and in cases of Insulin resistance type II DM. 