The diabetes mellitus is one of the most common diseases of the world. It is characterized by a large number of complications, including ketoacidosis and its severe form known as ketoacidosis diabetic coma. The aim was to estimate the causes of the development of diabetic ketoacidosis and the duration of treatment of an acute state in different age groups. Materials and methods. The random sampling of patients included 55 individuals with diabetes mellitus admitted to intensive care unit of the Vinnytsia Regional Highly Specialized Endocrinological Center aged from 9 up to 70 years in an emergency condition of diabetic ketoacidosis during 2009-2014. Average age of patients was 31,58 ± 17,18 years. Patients were divided into 3 clinical groups depending on their age. Diagnosis of diabetic ketoacidosis was made on the basis of the order of the Ministry of Public Health of Ukraine No. 254, 27.04.06. The results obtained were statistically processed by the Russian-language "Statistica 6.1" StatSoft, 1995. Results. In the most of the cases (27,2%) the acute condition was caused by improper diet. Insulin therapy disturbance ranked the 2nd place and made up 21,8% of all cases. 20 % of ketoacidosis cases were a disease debut in first diagnosed diabetes mellitus. An average duration of hospital staying ranged from 2,33 to 3,09 days and depended on clinical form of diabetic ketoacidosis. Conclusions. The commonest causes resulting in the emergency of diabetic ketoacidosis were improper diet, non-compliance with insulin therapy, and first diagnosed diabetes mellitus. The duration of the hospital treatment did not depend on age of patients, however considerably differed according to clinical form of diabetic ketoacidosis.