In a case of insulin overdose, what investigation is the choice to confirm the diagnosis?

In cases of suspected insulin overdose, measuring insulin and C peptide levels is crucial for confirming the diagnosis. When an individual has an overdose of insulin, high levels of exogenous insulin will be present, but the C peptide level would help differentiate between endogenous and exogenous sources of insulin. C peptide is released in equal amounts to insulin from the pancreas and is not present when insulin is administered externally. Therefore, a high insulin level combined with low or undetectable C peptide levels indicates an overdose of exogenous insulin, confirming the diagnosis.

Blood glucose levels, while relevant for assessing the impact of insulin on glucose metabolism, do not confirm the diagnosis of an insulin overdose. Serum electrolytes and liver function tests, though important in the overall clinical assessment, do not provide specific information about the presence of insulin or its endogenous production, making them less direct in confirming an insulin overdose.