BACKGROUND: Apart from diabetes itself, even minor glycometabolic dysregulation may be associated with an increased risk of cardiovascular disease. We analyzed the prevalence and predictive value of glycometabolic disturbances in patients with a suspected acute coronary syndrome (ACS). METHODS: In a prospective follow-up study, admission glucose and Hba1C levels in all consecutive patients with suspected ACS were measured. Dysglycemia was defined as a Hba1C of 5.6-6.1% with a non-fasting glucose above 7.8 mmol/L. Both predictors of glycometabolic disturbances and the predictive value of glycometabolic disturbances were studied. RESULTS: Of the 521 patients with a suspected ACS who were included in the study, 332 (64%) had an ACS and 189 (36%) had atypical chest pain. A total of 115 patients (22%) had diabetes and 65 (13%) had dysglycemia. Patients with diabetes or dysglycemia had an increased risk of a confirmed diagnosis of ACS (RR 2.3, 95% CI 1.5-3.4). Multivariate analyses did not change these findings. CONCLUSIONS: One in three patients with suspected ACS had a glucose metabolism disturbance. Glycometabolic disturbance was strongly associated with a confirmed diagnosis of ACS. Whether intensive treatment of patients with disturbed glucose metabolism may improve long-term prognosis needs to be assessed.