The Role of Proper Insulin Injection Technique in the Treatment of Diabetes Mellitus

Inclusion Criteria: 1. Type 1 or type 2 diabetes mellitus; 2. At least 1 year of experience with insulin self-administration; 3. Use of insulin pen for insulin injections. 4. HbA1c \> 7.5 % measured at study entry or maximally 30 days prior to screening. 5. BMI below 40 kg/m2 at study entry. 6. Daily self-control of blood glucose level; 7. Access to the internet for watching video lessons. 8. Only outpatients are eligible for the study. 9. Availability of signed informed consent of the patient for inclusion in the study. Exclusion Criteria: 1. Pregnant women or women planning to become pregnant during the time of study, breastfeeding women; 2. Subjects using an insulin pump; 3. Those using treatment with a Glucagon-Like Peptide (GLP)-1 receptor agonists alone; 4. Subjects not fluent in Russian (reading and writing). 5. Patients at high risk for ketoacidosis and/or hyperglycemia. 6. Psychic, physical or any other reasons hampering patient participation in the study (based on the reasonable opinion of the physician-investigator).