Rationale, aims and objectives We aimed to determine the effect of Clinical Practice Guideline (CPG) implementation on length of hospital stay of children and adolescents with diabetic ketoacidosis (DKA).Methods This was a 6-year (2008)(2009)(2010)(2011)(2012)(2013)(2014) case-control retrospective study conducted at King Khalid University Hospital, Riyadh, that compared patients with DKA managed using CPG with those treated before CPG implementation.Results There were 63 episodes of DKA in 41 patients managed using CPG compared with 40 episodes in 33 patients treated before implementation of CPG. Baseline characteristics of the 2 groups were similar (age, sex, newly diagnosed patients, recurrent DKA, DKA severity, and mean glycosylated hemoglobin). The mean length of hospital stay (±SD) was 68.6 ± 53.1 hours after implementation of CPG compared with 107.4 ± 65.6 hours before implementation (P < .001).The reduction in length of hospital stay equals to 1700 bed days saved per year per 1000 patients.Conclusions Implementation of CPG for DKA decreased the length of hospital stay.