Aim/Hypothesis: Children and adolescents with type 1 diabetes mellitus are often motivated to fast during Ramadan despite the challenges and multiple risks. This study aimed to demonstrate the impact of fasting during Ramadan on metabolic control in children and adolescents with type 1 diabetes mellitus in Tabuk city. Methods: This prospective cross-sectional study enrolled children and adolescents aged 11–18 years with type 1 diabetes mellitus who chose to fast during Ramadan 1442/2021 (Hijri/Georgian year, 30 days). The study consisted of three stages: assessment and planning before Ramadan, daily advice and communication during Ramadan, and assessment one month after Ramadan. Details about weight, insulin dose, HbA1c, home glucose records, and type of glucose monitoring (GM) were recorded. Results: Among 26 patients, 65% were female (35% male); 69% completed Ramadan fasting (fasting group) and 31% did not (broke-fasting group). In the fasting group, 88.9% used flash GM, whereas in the broke-fasting group, 11.1% used self-GM. The home glucose records before Iftar (sunset) were significantly different between the fasting and broke-fasting groups (p < 0.01). Conclusion: Fasting during Ramadan in children and adolescents with type 1 diabetes mellitus is possible. Pre-Ramadan management of type 1 diabetes mellitus has a significant impact on glucose control; however, large-scale population-based studies across the country are required to further validate these results.