Glucagon: prehospital therapy for hypoglycemia. STUDY OBJECTIVE: This study evaluated the efficacy of glucagon for prehospital therapy of hypoglycemia in patients without IV access. DESIGN: Prospective clinical trial. SETTING: Prehospital in a busy, urban emergency medical services system. TYPE OF PARTICIPANTS: Fifty consecutive patients presenting with documented hypoglycemia (ChemStrip BG less than or equal to 80 mg/dL) and symptoms of decreased level of consciousness, syncope, or seizure were enrolled. MEASURES AND MAIN RESULTS: Data collected included pretreatment (ChemStrip BG) and post-treatment serum glucose (hospital assay) as well as assessment of level of consciousness by a quantitative measure, the Glasgow Coma Score, and by a qualitative scale (0 to 3). The mean pretreatment blood glucose of 33.2 +/- 23.3 mg/dL increased after treatment to 133.3 +/- 57.3 mg/dL. Qualitative level of consciousness increased from a mean of 1.26 +/- .96 to 2.42 +/- .94 and Glasgow Coma Score increased from a mean of 9.0 +/- 4.19 to 13.04 +/- 3.68. The mean time until response was 8.8 minutes in those who responded to both level of consciousness criteria 82% (41 of 50). Glucagon administered for hypoglycemia resulted in a glucose increase in 98% (49 of 50) with headache as the only side effect noted in 4% (two of 50) of patients (P less than .0001). CONCLUSION: Glucagon is safe and effective therapy for hypoglycemia in the prehospital setting. 