Glycaemic control during Ramadan in adults with type 1 diabetes using continuous glucose monitoring: Saudi Arabia

Ramadan fasting poses clinical challenges for adults with type 1 diabetes mellitus (T1DM), particularly with respect to glycemic control. Real-world data describing changes in continuous glucose monitoring (CGM)–derived metrics across Ramadan remain limited. This study assessed changes in CGM-derived glycemic parameters during Ramadan fasting in adults with T1DM and explored whether these changes differed according to baseline glycemic control. This prospective observational real-world study included 81 adults with T1DM who intended to fast during Ramadan 2025 and were routinely followed at two diabetes centers. CGM-derived parameters, including average glucose concentration, time in range (TIR), time above range (TAR), time below range (TBR), and glycemic variability, were evaluated across three predefined periods: pre-Ramadan, the first two weeks of Ramadan, and the last two weeks of Ramadan. Changes over time were assessed using non-parametric paired comparisons. Subgroup analyses were performed according to baseline HbA1c level (≤ 7% vs. >7%) among participants with available data, and findings were interpreted descriptively. The median age of participants was 30 years, and 35.8% were men. Median HbA1c was 8.0% (IQR: 7–9%). TIR declined from the pre-Ramadan period (51.5%) to the first two weeks of Ramadan (45.0%) and remained lower during the last two weeks (47.0%). Average glucose concentrations increased during Ramadan, while TBR and glycemic variability showed no consistent changes. Participants with HbA1c > 7% experienced more pronounced deterioration in glycemic parameters, whereas those with HbA1c ≤ 7% demonstrated smaller and largely transient changes. In this real-world cohort of adults with T1DM, Ramadan fasting was associated with deterioration in CGM-derived glycemic control, particularly among individuals with suboptimal pre-Ramadan glycemic control. These findings highlight the importance of pre-Ramadan assessment, patient education, and CGM use to support safer fasting in routine clinical practice.