Unexplained hypoglycemia: a focused approach to finding the cause.

Most episodes of recurrent hypoglycemia occur in patients with diabetes mellitus and can be prevented by changes in medication, diet, or activity. However, persistent, unexplained hypoglycemia can indicate a potentially grave, often treatable, underlying disorder, such as adrenal or pituitary insufficiency. Medication errors are another common cause of unexplained hypoglycemia. A focused laboratory workup is essential; obtain a plasma or serum glucose level and serum insulin and C-peptide levels. Insulin levels should be suppressed (less than 6 microIU/ml) when the glucose level is below 60 mg/dL. 'Normal' or high insulin and C-peptide levels suggest excessive endogenous insulin production. Another useful value is the serum beta-hydroxybutyrate level. Patients with insulin-mediated hypoglycemia typically have beta-hydroxybutyrate concentrations below 2.7 mg/dL. [ABSTRACT FROM AUTHOR]