Diabetic ketoacidosis (DKA) represents a serious acute complication of diabetes mellitus that necessitates immediate identification and intervention. Nurses serve as primary responders in the management of diabetic ketoacidosis (DKA); however, significant knowledge gaps remain, especially in resource-constrained environments. The purpose of this study is to analyze the effect of a structured educational training program on staff nurses' knowledge regarding diabetic ketoacidosis (DKA) at a tertiary hospital located in Gurugram, Haryana. Approach: A pre-experimental one-group pre-test post-test design was implemented involving 60 purposively selected staff nurses at SGT Hospital. A validated structured knowledge questionnaire on diabetic ketoacidosis, comprising 20 multiple-choice questions, was administered prior to and seven days following a 60-minute interactive teaching session. Data were analysed through descriptive statistics and paired t-tests; associations with demographic variables were evaluated using Chi-square tests. Results: In the pre-test, 48.3% of participants exhibited inadequate knowledge, 51.7% demonstrated moderate knowledge, and none achieved adequate knowledge. Post-intervention, no participant exhibited inadequate knowledge; 65.0% demonstrated moderate knowledge, while 35.0% attained adequate knowledge. Mean knowledge scores increased significantly from 10.46 ± 1.55 to 14.73 ± 1.62 (mean difference = 4.27; t = 13.31; p < 0.05). No significant associations were identified between pre-test scores and demographic variables, including dietary pattern (p = 0.193) and source of information (p = 0.522). The structured educational training program markedly improved nurses' understanding of DKA. Integrating regular in-service training and DKA-focused modules into nursing curricula enhances preparedness and patient outcomes.