The incidence of type 1 diabetes in children is growing and optimal treatment is needed to prevent or delay complications. Insulin degludec is a new basal insulin with ultra‐long effect. However, there are few published studies in children and adolescents. The first aim was to compare HbA1c levels in children and adolescents who received degludec from onset, to age/gender matched controls with other basal insulins. The second aim was to investigate HbA1c and total basal insulin dose, in patients who switched to insulin degludec from another basal insulin. Patients (n=251, 0–21 years) with type 1 diabetes, at Helsingborg Hospital, were divided into groups depending on insulin treatment. Data regarding basal insulin and HbA1c values were collected from medical records retrospectively. No significant differences in HbA1c levels were found between patients receiving degludec compared to age/gender matched controls (n=22) up to 12 months from onset. In patients who switched to degludec with HbA1c ≥70mmol/mol (n=38), median HbA1c levels decreased from 75 (70–130) to 74 (39–99; p=0.0143) after three months and to 70.5 (55–108; p=0.0290) after six months. For patients who switched from detemir to degludec (n=54) median daily basal insulin dosage reduced from 23.5 units to 22 units after six months treatment with degludec (p=0.0001). The same significance was not found for glargine. In our study, degludec has shown to be as effective in lowering HbA1c levels as other basal insulins in children and adolescents with type 1 diabetes. Degludec might be especially useful for patients with a poor metabolic control. However, further long‐term studies are needed. Copyright © 2021 John Wiley & Sons.