Abstract Disclosure: J.E. Lee: None. O. Hamidi: None. S. Mirfakhraee: None. Continuous subcutaneous hydrocortisone infusion (CSHI) via insulin pump is an alternative therapy for treating patients with adrenal insufficiency (AI) and allows for adjustable hydrocortisone delivery to provide more physiologic glucocorticoid replacement. Retrospective case series of 9 patients on CSHI showed a reduction in total daily dose of glucocorticoid by 34% and a decrease in hospitalization admissions due to adrenal crisis by 50%. In a double-blind placebo-controlled study, CSHI in patients with primary AI did not demonstrate benefit in subjective health status metrics compared to oral hydrocortisone; however, patients had good baseline subjective health scores. Due to a scarcity of data, CSHI is likely underutilized in patients who may benefit from this individualized therapy. Our research objectives were to analyze the change in total daily glucocorticoid dose, number of adrenal crises events and hospitalization days, glucocorticoid-related comorbidities, and quality of life of patients transitioned to CSHI. We performed a single-center, retrospective longitudinal follow-up study in 23 consecutive patients (87% women, median age 40 years at time of CSHI initiation) treated with CSHI between 2015 and 2023. Types of adrenal insufficiency were 48% secondary AI, 35% glucocorticoid induced AI, and 17% primary AI. CSHI delivery settings were generated by a formula that we derived using each patient’s daily oral glucocorticoid dose and preferred waking time. Median time from AI diagnosis to CSHI implementation was 41 months, and median duration of CSHI was 25 months. Total daily dose of glucocorticoid (in hydrocortisone equivalent) before CSHI vs during CSHI decreased from 30.0mg (15.0mg to 80.0mg) to 26.6mg (14.4mg to 200.5mg) (p= 0.45). Median number of adrenal crisis events decreased from 1 (0 to 13) to 0 (0 to 38) (p=0.25), and hospitalization days due to adrenal crisis decreased from 2 (0 to 46) to 0 (0 to 58) (p=0.53). No significant differences were noted for change in weight, blood pressure, diabetes, cardiovascular and cerebrovascular events, total cholesterol, LDL, and triglyceride levels. Median HDL decreased from 59 to 51 (p=0.01). In terms of subjective health status, 10 patients completed SF-36 survey while on CSHI. Significant impairments were noted in physical health, vitality, and general health with median score less than 40. At the conclusion of the study, 20 patients (87%) preferred CSHI therapy. Only 3 patients stopped CSHI for reasons of inconvenience, skin irritation at pump site, and better symptom control on oral therapy. No significant CSHI-related safety concerns were noted. In conclusion, CSHI is a safe and effective way to deliver individualized therapy to patients with difficult to control AI. CSHI led to reduction in glucocorticoid exposure and fewer adrenal crisis events and hospitalization days due to adrenal crisis. Presentation: 6/1/2024