Psychological factors and patients' health-related quality of life (HRQOL) affect the outcome of patients with type 1 diabetes mellitus (T1DM). In this study, we aimed to determine the HRQOL status in patients with T1DM and its association with glycemic control and medication adherence. In this cross-sectional study, 227 T1DM patients were selected from the diabetes clinic, Imam Ali Hospital, Alborz University of Medical Sciences, and the Gabric database registry from 2020 to 2022. Demographic and diabetes characteristic checklist, medication adherence questionnaire (8-item Morisky Medication Adherence Scale (MMAS)), and QOL questionnaires (Short-Form-12 and PedsQL) were filled. Independent sample T-test was used to assess mean of QOL subscales with glycemic control and medication adherence. A logistic regression model was used to evaluate the association between glycemic control and medication adherence with QOl. Overall QOL scores in adults and children were 33.4 ± 7.1 based on Short-Form-12 and 76.2 ± 17.8 based on PedsQL, respectively. It was demonstrated that adults with Moderate/High adherence had higher QOL (p-value = 0.007). Likewise, Children with good glycemic control had higher psychosocial health scores (0.048). Logistic regression analysis did not reveal a significant association between adherence and QOL or Glycemic control and QOL in both adjusted and crude models. Better glycemic control and medication adherence in children and adults, respectively, are related to the psychological aspects of QOL. We suggest that emotional intelligence, which is replaced by other predictors during adulthood, may contribute to glycemic control in children in the early years following diagnosis.