The ADA recommends that all people with diabetes at risk of level 2 or 3 hypoglycemia be prescribed glucagon. Studies of conventional reconstituted injectable glucagon showed low rates of successful delivery of a full dose and low prescription filling rates. Since July 2019, ready-to-use glucagon options have become commercially available. IBM® MarketScan® Research Database was used to study prescription patterns among people with T1D or T2D on insulin who had filled a glucagon prescription 2 years prior to July 2019 (pre-period) and/or 2 years after through July 2021 (post-period) . Logistic regression models (for feature selection of independent variables followed by two-way interaction identification from Multivariate Adaptive Regression Splines) were utilized to determine glucagon fills post-period based on variables pre-period (demographics, diabetes type, insurance, comorbidities, history of hypoglycemia, diabetes medications) . Classification trees were used to illustrate the effects of significant variables (variables added >1% accuracy from cross validation) . Of all insulin-treated people (n=138,826) over the 4-year period, 13.5% (T1D 48.4%, T2D 3.5%) had glucagon prescriptions filled. Of those who filled glucagon post-period (n=14,234) , 54.3% filled a ready-to-use glucagon. The primary drivers and % of glucagon fills post-period: overall included age <22 (63.3%) , T1D (37.4%) , and glucagon filled pre-period (62.2%) (each p<.001) ; among people with T1D, age <17 (81.6%) and glucagon filled pre-period (66.7%) (each p<.001) ; among people with T2D, glucagon filled pre-period (34.0%) , basal-bolus insulin filled in the 4-year period (4.4%) , and age <16 (58.6%) (each p<.001) . The results suggest that, despite guideline recommendations, glucagon prescription fills are low, and mostly by young people. Though at increased risk of hypoglycemia, fill was low in the elderly and people with T2D on basal-bolus insulin. After becoming available, ready-to-use glucagon represented over 50% of glucagon fills. Disclosure B. Mitchell: Employee; Eli Lilly and Company, Stock/Shareholder; Eli Lilly and Company. D. R. Nelson: Employee; Eli Lilly and Company. A. Meeks: Employee; Eli Lilly and Company. Y. Yan: Employee; Eli Lilly and Company. Funding Eli Lilly and Company