Background: Hyperglycemic emergency is the most serious acute complications of diabetes mellitus and its impact have been increased among adult diabetic patients. Despite the growing up of hyperglycemic emergency impact among adults with diabetes, its incidence and predictors have not been well studied particularly in Ethiopia. Objective: To assess the incidence and predictors of hyperglycemic emergency among diabetic patients in Bahir Dar City public hospitals, Northwest Ethiopia, 2021. Method: A retrospective follow up study design was conducted among adult diabetic patients who were registered from January 1, 2016 to December 31, 2020, in Bahir Dar City public hospitals, Northwest Ethiopia. A simple random sampling technique was used to select patients. The data were entered into EPI data version 4.6 and analyzed using STATA version 14.0. Cox proportional hazard regression model was fitted to identify the independent predictors of hyperglycemic emergency. Result: Out of the 453 adult diabetic patients included in the study 147(32.45%) developed Hyperglycemic emergency in the entire follow-up period. Hence, the overall incidence was 1.22 per 100-person-month of observation and the overall median hyperglycemic free survival time was 53.85 months. Without Community health insurance (AHR = 1.63, 95%CI(1.14,2.35), type 1 diabetes mellitus (AHR = 2.75, 95%CI (1.68,4.51), history of medication noncompliance (AHR = 1.85, 95%CI(1.24,2.76), diabetes duration (AHR = 0.33, 95%CI(0.21,0.50), recent six month poor glycemic control (AHR = 3.47, 95%CI(2.17,5.56), follow up frequency of 2 to 3 months (AHR = 1.79,95%CI(1.06,3.01), acute recent illness (AHR = 2.99, 95%CI(2.03,4.43) and presence of comorbidities (AHR = 2.36, 95%CI(1.53,3.63) were significant predictors. Conclusion: The incidence of hyperglycemic emergency was high especially during the early three years of diabetes mellitus diagnosis. Diabetic care should be focused on over controlling the identified predictors of hyperglycemic emergency to prevent its public health and economic impacts. Keywords: hyperglycemic emergency, incidence, adult diabetic patients, Ethiopia