Abstract Introduction Approximately 1 in 4 patients admitted to the hospital carry a diagnosis of diabetes mellitus1 and 1 in 10 patients are admitted due to diabetes complications.2 Although Internal Medicine residents comprise the primary care team for the vast majority of patients admitted to major academic hospitals, there is a paucity of resources and standardized training for inpatient diabetes management, specifically designed for residents. Methods We developed a structured resident education program consisting of a mobile/web application ("EndoApp") as an accessible resource combined with a series of short lectures. The EndoApp is comprised of checklists, guidelines, and calculators based on the most recent American Diabetes Association (ADA) and American Association of Family Physicians (AAFP) recommendations. The application addresses five major areas of inpatient insulin management—i) insulin pharmacokinetics, ii) admission dosage calculation, iii) inpatient insulin regimen adjustment, iv) management of diabetic emergencies, and v) equipment and prescription management at discharge. The confidence level of residents for each of the five areas were surveyed at months 0, 1, and 3, after the start of the program on a scale of 1-5. Results Our 3-month interim analysis showed that the confidence of residents in all five areas of inpatient insulin management improved over the study period. Increased confidence was seen in post-graduate year (PGY) 1, 2, and 3 residents. The Admission Insulin Dosing Calculator was the most frequently used function (45% of residents), followed by DKA/HHS helper (23% of residents), and Inpatient Dosage Adjustment Guidelines (21% of residents). Residents who used the Admission Insulin Dosing Calculator had greater increase in provider confidence compared to those who did not use the function. Subjective feedback from residents included expanding functions to include hypoglycemia and non-emergent hyperglycemia management, as well as having recordings of supplementary lectures available on the application. Conclusion Structured resident education in inpatient insulin management utilizing a mobile/web application and lectures as supplementary material is a promising approach to improve resident education and confidence in inpatient diabetes management.