Introduction:
Diabetes mellitus (DM) is one of the most prevalent modifiable risk factors for acute coronary syndrome (ACS). Patients with DM constitute approximately 25%–30% of those admitted with ACS. However, data on the prevalence of unrecognized DM among patients with ACS in Iraq is generally limited.

Material and methods:
This cross-sectional study was conducted on patients admitted with ACS to Al Sadir Teaching Hospital, Basra Teaching Hospital, and Basra Specialized Cardiac Center in Basra. Patients with known diabetes or conditions affecting glucose or hemoglobin A1c (HbA1c) levels were excluded. This was a consecutive sampling of eligible patients. All patients admitted during the study period who met the inclusion criteria were approached and invited to participate. Those who consented were enrolled until the desired sample size was achieved. Data were collected through direct interviews and a structured questionnaire, with anthropometric measurements and laboratory investigations, including fasting blood sugar (FBS), random blood sugar (RBS), HbA1c, and lipid profile. Patients were classified as normal, prediabetes, or newly diagnosed diabetes.

Results:
A total of 275 ACS patients were included (mean age: 56.6 ± 12.5 years; 72% male). Screening revealed that 15.3% had unrecognized diabetes and 11.6% had prediabetes. Newly diagnosed diabetes was significantly associated with younger age (P = 0.007), smoking (P = 0.013), higher BMI (P = 0.01), dyslipidemia (P = 0.001), family history of diabetes (P < 0.001), and STEMI presentation (P = 0.047).

Conclusions:
Unrecognized DM causes a significant burden among ACS patients. Effective screening for DM would aid in early detection and proper management, particularly among younger ACS patients, those with a family history of DM, smokers, and obese patients.