Patients' knowledge of their insulin pumps and glucose control during hospitalization has not been studied. The aim was to study the determinants of glycemic control in patients using continuous subcutaneous insulin infusion (CSII) in the hospital. Three groups of patients were identified: those who did not need any inpatient education and continued on CSII (gorup A), those who received education then continued on CSII (group B), and those for whom CSII was not appropriate and were treated with multiple daily insulin injections (gorup C). We compared the measures of glycemic control between the 3 groups and analyzed which variables impacted glucose control. There were 50 patients, with 51 hospital admissions, 57% males, mean age 48 ± 13 years, 86% had type 1 diabetes (T1DM). The mean DM duration was 26 ± 14 years, mean duration of CSII use was 8.7 ± 6 years, and mean HbA1c was 7.6 ± 1.4%. The mean duration of hospital stay was 5.6 ± 4.6 days. Mean blood glucose (BG) and frequency of hyperglycemia and hypoglycemic events among the 3 groups adjusted for their duration of hospital stay were not statistically different. None of the patients developed diabetic ketoacidosis while using their pump.Stepwise multivariate analysis revealed knowledge of hypoglycemia correction was the single most important predictor of mean BG (P < .001). Patients who received inpatient education performed similarly to patients who did not need inpatient education. Patients who receive inpatient education on CSII fare similar as patients who did not require inpatient education.