Artifactual hypoglycemia results from either improper collection of blood samples or interfering substances in the blood. Such artifacts should be easily detected and avoided. Factitious hypoglycemia, on the other hand, results from deliberate subterfuge by the patient and may thus elude proper diagnosis for some time. The most common cause of factitious hypoglycemia is surreptitious injection of insulin, and this is best diagnosed by the triad of hypoglycemia, inappropriately high insulin levels, and low C-peptide levels. Persons with diabetes may also intentionally misuse blood glucose strips to create the impression of hypoglycemia.