Objective: Type 1 diabetes mellitus (T1DM) is a lifelong, metabolic disorder, typically arising in childhood and adolescence. Despite recent advances in diabetes management techniques, glycemic control remains substandard for many individuals This study examined the role of parental and child self-regulation in predicting effective glycemic control in children and adolescents with Type 1 diabetes mellitus (T1DM). Method: Sixty-three families (with children aged 3–18 years) with T1DM participated. Child, maternal, and paternal measures of temperament, including surgency (behavioral self-regulation), negative affect (emotional selfregulation), and effortful control (cognitive self-regulation) were collected, along with demographic information and haemoglobin A1c (glycemic control). Results: Higher parental and child effortful control was associated with better glycemic control. Higher child negative emotionality was associated with poorer glycemic control. No significant interactions between child and parent measures were identified. Conclusions: Both parental and child self-regulation play an independent role in glycemic control, and serve as targets for intervention in improving diabetes management in children and adolescents.