RECOGNITION AND DOCUMENTATION
Blood should be drawn, whenever possible, before giving glc to allow documentation of a low plasma [glc]. Convincing documentation of hypoglycemia requires fulfillment of Whipple’s triad. Thus, the ideal time to measure plasma glc level: during a symptomatic episode. A normal glucose level: excludes hypoglycemia as the cause of the symptoms.
A low glucose level confirms that hypoglycemia is the cause of the symptoms, provided the latter resolve after the glucose level is raised. When the cause of the hypoglycemic episode is obscure, additional measurements—made while the glucose level is low and before treatment—should include plasma insulin, C-peptide, proinsulin, and β-hydroxybutyrate levels; also critical are screening for circulating oral hypoglycemic agents and assessment of symptoms before and after the plasma glucose concentration is raised. When the history suggests prior hypoglycemia and no potential mechanism is apparent, the diagnostic strategy is to evaluate the patient as just described and assess for Whipple’s triad during and after an episode of hypoglycemia. On the other hand, while it cannot be ignored, a distinctly low plasma glucose concentration measured in a patient without corresponding symptoms raises the possibility of an artifact (pseudohypoglycemia)