Introduction: There are a plenty of factors influencing glycemic control in children with type 1 diabetes mellitus (DM). The aim of this study was to determine the factors influencing metabolic control in children with type 1 DM. Materials and Method: The study was performed in 200 children with type 1 DM between the ages 6 months to 18 years. This study was conducted by interviewing individually with the children and their families and completing the questionnaires related to their demographic features and data associated with their illness. The laboratory findings and medical information of the patients from the charts were also retrospectively recorded. Results: There were a total of 200 patients including 104 (52%) girls and 96 (48%) boys. The mean age of the patients was 11.7 (±4.26) years. The mean duration of diabetes was 3.8 years (6 months to 14 years). Eighty-nine percent of all patients and all of the patients between 12 and 18 years of age were on intensive insulin therapy. Mean insulin dose was 0.84±0.19 units/kg/day. The mean HbA1c value was 8.8%. Body mass index (BMI) mean z-score was -0.06±1.19. There were no correlations between HbA1c and the duration of diabetes or age although a positive correlation was found with insulin dose (r=0.27 p<0.01). It was found that intensive therapy did not lower HbA1c values or the risk of severe hypoglycemia. Nevertheless, there was a decrease in HbA1c values of 72 (36%) patients whose therapy was converted from conventional therapy to intensive therapy (p<0.05). HbA1c values were found to be higher in patients who lived with more than 4 persons in the house, who were non-compliant to follow-up or diet, who had more than 3 symptomatic hypoglycemia in the last 6 months, who had episodes of diabetic ketoacidosis (DKA), who were adolescent at the time of diagnosis, and who were admitted with diabetic ketoacidosis at the time of diagnosis (p<0.05). Although there was a correlation between insulin doses and durations of diabetes (r=0.45 p<0.05), no correlation was determined with BMI z-score (r=0.075 p=0.29). The BMI z-score was significantly higher after therapy compared with the value before therapy (p<0.01). Conclusion: In type 1 DM, obtaining a good metabolic control depends on many factors. In this study, duration of diabetes longer than 5 years, crowded families, irregular follow-up visits, poor compliance to diet, presence of symptomatic hypoglycemia, presence of episodes of DKA, presence of DKA at diagnosis, and being an adolescent at the time of diagnosis were found to be the risk factors that associated with poor metabolic control. © The Journal of Current Pediatrics, published by Galenos Publishing.