Background: Insulin is a high-risk medicine, associated with hospital medication errors. Pharmacists play an important role in the monitoring of patients on insulin. Objective: To analyse interventions made by hospital pharmacists that were associated with insulin prescribing for inpatients with diabetes.Method: Retrospective audit of pharmacist interventions for adult inpatients for an 8-month period, 1 June 2019 to 31 January 2020. Pharmacist interventions recorded in the electronic medication management system by inpatient unit and dedicated high-risk medicine pharmacists were extracted, screened, and analysed.Results: Of 3,975 pharmacist interventions 3,356 (84.43%) were recorded by high-risk medicine pharmacists and 619 (15.57%) by inpatient unit pharmacists. July and August 2019 had the highest numbers of interventions with 628 and 643 (15.80% and 16.18%) respectively. Most of the interventions, namely 3,410 (85.79%) were classified as medicine optimisation interventions and 565 (14.21%) as prescribing errors. In the medicine optimisation intervention category, 2,985 (75.09%) were due to insulin not charted for ongoing administration.Conclusion: This study provides insights into pharmacist interventions for inpatients on insulin, showing that high-risk medicine pharmacists recorded most interventions. The classification of the insulin interventions into medicine optimisation and prescribing errors provides useful information for the training of prescribers in insulin management.