The Impact of Ramadan Fasting on Glycemic and Blood Pressure Control in a Large Saudi Arabian Cohort with Type 2 Diabetes and Hypertension: A Longitudinal Interrupted Time Series Analysis

Introduction: The yearly observance of Ramadan, which includes prolonged daily fasting, presents a challenging scenario for patients with chronic illnesses, with existing studies presenting inconsistent findings on its metabolic implications. Objective: This study aimed to objectively measure the immediate and sustained impacts of Ramadan fasting on monthly mean Hemoglobin A1c (HbA1c), Systolic Blood Pressure (SBP), and Diastolic Blood Pressure (DBP) in a large, real-world cohort of Saudi Arabian patients with concomitant T2DM and HTN. Methods: A retrospective longitudinal study was carried out using electronic health record (EHR) data from a Saudi multi-facility healthcare system from December 2023 to May 2024. The analysis used a segmented regression for Interrupted Time Series (ITS) to estimate changes in outcomes, with Ramadan (March 2024) serving as the intervention point. Results: The final cohort comprised 15 289 patients. The ITS analysis showed that Ramadan resulted in a substantial reduction in mean HbA1c by −0.25% ( P < .001) and mean SBP by −4.12 mmHg ( P < .001). However, the post-Ramadan trend for HbA1c demonstrated a significant monthly increase of 0.15% ( P = .002), indicating a rebound impact. The reduction in SBP was not sustained, as it returned to pre-Ramadan levels in the months that followed. Conclusions: In this large Saudi cohort, Ramadan fasting was linked to transitory improvements in glycemic and blood pressure control. The ensuing rebound implies that, while fasting can be metabolically advantageous, the effects do not last without ongoing intervention. These results highlight the important necessity for rigorous post-Ramadan clinical follow-up to consolidate any gains made during the fasting period. These findings position Ramadan as a novel window for metabolic reset and a potential preventive opportunity against cardiorenal metabolic syndrome progression in high-risk populations.