OBJECTIVE: To describe glucagon prescription patterns in patients with type 1 (T1DM) or type 2 diabetes (T2DM) who received an initial insulin prescription. METHODS: Retrospective analyses were conducted with data from Truven Health MarketScan databases to assess time to glucagon prescriptions: filled within 1.5 months after index date (early) or after 1.5 months postindex (nonearly). The index date was the date of first insulin prescription between January 1, 2009 and December 31, 2011; for T2DM, without an insulin prescription in the previous 6 months; for T1DM, diabetes diagnosis preindex or within 3 months postindex. RESULTS: Analysis included 8,814 patients with T1DM and 47,051 with T2DM (49.3% and 2.4%, respectively) who had glucagon prescriptions filled. The median times to first glucagon prescription were 196 days (T1DM) and 288 days (T2DM). The rates of filling glucagon were highest in the first 1.5 months. The times to first hypoglycemia-related emergency room (ER) visit for T1DM and T2DM cohorts were initially similar for those with early glucagon versus nonearly glucagon prescriptions. After 10.8 and 2.5 months postindex, respectively, the percentage of hypoglycemia-related ER visits was lower for those with early glucagon prescriptions. CONCLUSION: Glucagon prescriptions filled for patients with diabetes who are initiating insulin are low. Patients with T1DM who were younger and healthier filled glucagon prescriptions more often; patients with T2DM who were younger and sicker and had a higher percentage of hypoglycemia-related ER visit history filled glucagon prescriptions more often. Glucagon filled early was associated with a lower incidence of hypoglycemia-related ER visits.