A 30 year old nurse is evaluated for recurrent hypoglycaemia. She feels shaky, anxious, and sweaty; her plasma glucose is 50 mg/dl during the attack at work. She then drinks coffee & feels better. These episodes have not happened outside the work environment. She takes no medications and is otherwise healthy. Which is the most appropriate test in this patient?

Whipple triad of symptoms: (1) Symptoms of hypoglycaemia (2) Low plasma glucose (3) Relief of symptoms with raising the plasma glucose level. The insulin levels must be obtained during an episode. If it is elevated, it suggests either endogenous hyperproduction of insulin or exogenous administration causing factitious hypoglycemia. C-peptide- determine normal cleavage of insulin from its precursor Normal C-peptide level with hypoglycaemia- surreptitious insulin use Low C-peptide level with hyperglycemia- pancreatic failure. Red flags in this case that point to surreptitious insulin use include the patient being a healthcare worker and the presence of symptoms only at work. Failure of counterregulatory hormones is rare cause of hypoglycaemia