MON-537 Differences in Insulin U-500 Requirements Between Ambulatory and Inpatient Settings.

Abstract Disclosure: F. Varsha: None. A. Dharia: None. M.C. Grimes: None. F. Hasan: None. Background: Patients with diabetes mellitus and severe insulin resistance often require concentrated U-500 insulin when daily insulin needs exceed 200 units. A notable clinical observation is that hospitalized patients on U-500 insulin typically require significantly lower doses compared to their outpatient regimens. This study investigates the differences in daily insulin requirements for patients using U-500 insulin in outpatient, inpatient, and discharge settings. Methods: A retrospective analysis of electronic medical records was conducted for adult patients on U-500 insulin for ≥3 months prior to hospitalization at three tertiary hospitals in Western Pennsylvania from January 1, 2016, to October 31, 2023. Exclusion criteria included length of stay <3 days, NPO status, surgical admissions, supraphysiologic steroid use, end-organ failure, active malignancy, or ICU/trauma admissions. The primary outcome was the comparison of weight-adjusted daily insulin requirements (WDI) pre-admission, on hospital day 3, and at discharge. Secondary outcomes included comparisons of total daily insulin requirements (TDI), glycemic control (mean glucose, hypoglycemia, hyperglycemia) and 30-day readmission rates. Results: The study included 44 patients with 59 admissions (60% male, 84% white). The average inpatient WDI was 0.83 units/kg on hospital day 3 and 0.79 units/kg at discharge, significantly lower than the outpatient WDI of 1.47 units/kg (p < 0.0001), reflecting a 45.2% reduction by hospital day 3 and 39.2% at discharge. Mean TDI requirements were 185 units (outpatient), 85.5 units (hospital day 3), and 100.3 units (discharge). Glycemic control (mean glucose: 192.8 mg/dL on day 3, 187 mg/dL at discharge) showed no significant association of inpatient dose reduction with hyperglycemia or hypoglycemia. Subgroup analyses by pre-admission BMI (<40 vs. ≥40) and HbA1c (<8% vs. ≥8%) revealed no differences in dose reduction (p = 0.91 and p = 0.27, respectively). Thirty-day readmission rates were unaffected by inpatient dose reductions. Conclusion: Inpatient U-500 insulin doses were approximately 45% lower than outpatient regimens, with no adverse impact on glycemic control or 30-day readmissions, regardless of BMI or HbA1c. These findings support standardized inpatient dose reductions and highlight the need for further research to optimize management for patients with severe insulin resistance. Presentation: Monday, July 14, 2025