Weekly and seasonal patterns of acute myocardial infarction in patients with and without diabetes mellitus: A population-based study

Background and aim: Acute myocardial infarction (AMI) displays circadian, weekly, and seasonal variability, with higher incidence on Mondays and during winter. Diabetes mellitus (DM) may modulate susceptibility to these temporal fluctuations through altered autonomic, metabolic, and inflammatory responses. This study examined weekly and seasonal variations in AMI incidence and in-hospital mortality among patients with and without DM in a large, population-based cohort. Methods and results: We analyzed administrative health data from Lombardy, Italy (2000-2019), identifying all AMI hospitalizations (n = 281,164; 25 % with DM). Acute myocardial infarction onset and in-hospital mortality were evaluated by day of week and season in patients with and without DM. Weekly patterns showed a clear Monday peak, with a 12 % higher AMI risk compared with other weekdays, particularly among individuals with DM. A pronounced seasonal pattern was also observed, with a 29 % higher AMI incidence in winter versus other seasons, again more evident in DM patients. In-hospital mortality increased for AMI occurring on weekends and during winter months, with a consistently greater magnitude of risk among patients with DM after adjustment for demographics and comorbidities. Conclusions: Acute myocardial infarction incidence peaks on Mondays and in winter, while mortality is higher during weekends and colder months. These temporal patterns are more pronounced among individuals with DM. Awareness of these time-dependent risks may support targeted prevention strategies, optimized care pathways, and resource planning for high-risk groups such as patients with DM.