Glycemic control in type 1 diabetic patients (DMT1) is the key to prevent acute complications, delay chronic conditions, and influences the overall quality of life. Nutritional education based on diabetic unit counting in necessary to achieve good glycemic control and represents integral part of the therapy. Main objectives of this research were to assess nutritional and lifestyle habits of DMT1 patients in the Republic of Croatia (RC), the degree of impact the disease has on the quality of life, education level and the application of dietary recommendations. An observational study was conducted on DMT1 patients in RC by on-line questionnaire created specifically for the purpose of the present research. Total of 101 DMT1 patients mean age 25 ± 8.9 years (6 to 50 years of age, 22.8 % male, 77.2 % women) completed the questionnaire. Recommended HbA1c is achived by 49.4 % of adult patients and 60.0 % of children and adolescents. Results indicate that with age, HbA1c worsens (r=-0.249) and at the same time, the quality of diet deteriorates (r=-0.338). Diabetic retinopathy is present in 10.9 % DMT1 patients, 7.9 % has neuropathy, and 2.0 % diabetic kidney disease. 30.3 % of DMT1 patients are not satisfied with education about diabetes and have problem achieveing good glycemic control. Consequently, patients that implemented the method of diabetic units counting have better HbA1c (p=0.023). DMT1 negatively affects patients' social life, mental and physical health and the overall quality of life. The results clearly indicate an urgent need for a professional and adequate education, with special emphasis on re-education of DMT1 patients.