hypoglycemia ddx

This patient has symptomatic hypoglycemia and fulfills Whipple's triad (blood glucose <55 mg/dL, hypoglycemic symptoms, relief of symptoms with glucose administration).  In addition, his contemporaneous insulin and C-peptide levels are at the upper limit of normal, suggesting that his hypoglycemia is due to excess release of endogenous insulin.

In light of this patient's access to his father's glyburide, a possible explanation for his hypoglycemia is surreptitious sulfonylurea use.  This should be confirmed with a hypoglycemic drug screen.  Glyburide has a relatively long duration of action, and patients with intentional or inadvertent overdose can develop recurrent hypoglycemia and warrant extended observation for frequent glucose monitoring; alternately, the patient may be surreptitiously taking glyburide while in the hospital.

Insulinomas can cause recurrent episodes of hypoglycemia with normal to high insulin and C-peptide levels.  However, these tumors are rare and typically present at an older age.  If the oral hypoglycemic drug screen is negative, further imaging (eg, abdominal CT scan) would be warranted.

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