The aim of this paper was to assess the compliance with the basic principles of insulin self-administration and the selfmonitoring of blood glucose levels. Materials and methods: The study was conducted using author’s anonymous questionnaire to be completed by patients receiving insulin therapy. The questionnaires were completed by 73 patients (72% with type 2 diabetes, 18% with type 1 diabetes) who visited their family physician during the period of 3 months in 2013. Results: A total of 22 patients did not comply with the recommended interval between the administration of premeal insulin and a meal, 24 patients never measured their blood glucose levels after a meal, and as many as 57 respondents did not practice periodic self-measurements of night-time blood glucose levels. Most patients (42 respondents) reported the hospital as a place of insulin therapy training, whereas regional outpatient clinics (physicians and nurses) came second. Only 6 respondents reported diabetes clinics as the place of training. Also, 6 respondents stored their currently used insulin in a refrigerator. Conclusions: Patients receiving insulin therapy require a continuous re-education as well as periodic verification of the basic principles for the use of insulin therapy and the self-monitoring of blood glucose levels.