Introduction: Although the association between necrotizing otitis externa (NOE) and diabetes mellitus (DM) is well known, there is little knowledge in regards to the effects of DM and glycemic control (preadmission and during hospitalization) on the outcome of NOE. The aim of the study was to determine the effects of DM duration and preadmission glycemic control, and in-hospital glycemic control on NOE severity. Methods: A retrospective case series analysis, including all patients between the years 1990-2018 hospitalized due to NOE were included in the study. Data collected included NOE disease characteristics, duration of DM, DM associated comorbidities, glycated hemoglobin (HbA1c), urine micro-albumin and in-hospital blood glucose measurements. Disease severity was defined based on duration of hospitalization (above or below 20 days) and need for surgery. Results: Eighty nine patients were included in the study. Eighty three patients (94.3%) had DM. Preadmission HbA1c was 8.13% (5.8%-12.6%). Forty nine patients (65.5%) had mean blood glucose of ≥140mg\dL and 26 patients (34.5%) had ≤ 140mg/dL. DM duration was 157.88 months among NOE patients who required surgery, and 127.6 months among patients who were treated conservatively (p-value 0.25). HbA1c in patients hospitalized < 20 days was 7.6%, and 8.7% among NOE hospitalized ≥ 20 days (p-value 0.027). Seven patients with mean blood glucose of ≤140mg\dL had Pseudomonas Aeruginosa (PA-NOE) (26.7%), in comparison to 25 patients (51.0%) with mean blood glucose measurement of ≥140mg\dL (p=0.045). Conclusions: HbA1c levels at admission are associated with longer hospitalization duration among NOE patients. High mean blood glucose during hospitalization was associated with a higher likelihood for a PA infection, however it had no effect on disease outcome.