Continuous Glucose Monitoring Trajectories in Patients with Acute Coronary Syndrome

Background Continuous glucose monitoring (CGM) captures dysglycaemia and glycaemic variability after acute coronary syndrome (ACS), but patient-level trajectories from early recovery to mid-term follow-up—particularly in people without diabetes—remain insufficiently characterised. Methods In this prospective multicentre observational study (ORACLE programme), consecutive high-risk ACS patients wore a FreeStyle Libre 3/3 Plus sensor for 14–15 days near discharge and again at ~ 4 months. We quantified CGM time-in-range metrics (70–180 mg/dL and tight range 70–140 mg/dL), time above/below range, and variability/risk indices, including within-day profiles. Clinically relevant changes were categorised using pre-specified thresholds, and predictors of worsening were explored using multivariable models. Results Among 274 enrolled patients, 213 had analyzable baseline CGM recordings meeting quality criteria. Early post-ACS mean time-in-range 70–180 was 85.7 ± 21.4%, time in tight range 70–140 was 69.6 ± 27.7%, time above range > 180 was 12.8 ± 21.5%, and time below range < 70 was 1.5 ± 3.3% (mean glucose 131.4 ± 35.6 mg/dL; glucose management indicator 6.4 ± 0.8%). CGM demonstrated marked inter-individual heterogeneity and a reproducible late-morning (10:00–12:00) vulnerability window with lower range time and higher hyperglycaemic exposure, consistent across diabetes status and similar on weekdays and weekends; adverse CGM profiles were more prominent in patients with diabetes, older individuals, and women. Although CGM parameters improved modestly over the initial monitoring period, overall control deteriorated from baseline to ~ 4 months, including in patients without diabetes. Tight-range time decreased by 3.8% (95% CI − 6.67 to − 0.99; p = 0.0077) and mean glucose increased by 3.85 mg/dL (p = 0.035), accompanied by worsening variability and risk indices. Across CGM endpoints, ~ 20–40% of patients showed a worsening trajectory (20.2% by broad time-in-range thresholds); higher comorbidity burden clustered with deterioration, with hypertension and COPD independently associated with tight-range worsening. Conclusions After ACS, CGM reveals substantial inter-individual heterogeneity and a reproducible late-morning vulnerability window. From discharge to mid-term follow-up, deterioration—also affecting patients without diabetes—may be preferentially detected by tight-range and variability/risk metrics that traditional monitoring of blood glucose and static measures such as HbA1c may overlook, supporting CGM-informed phenotyping to refine post-ACS metabolic surveillance.