Background and Aims. Several factors are associated with a heightened risk of subsequent events, morbidity and mortality in patients with type 2 diabetes mellitus (T2DM) after an acute coronary syndrome (ACS). Improving the management of these patients is a challenge that requires urgent attention. We aimed to study the long-term effect of the change in treatment strategy depending on the HbA1c level detected during the hospitalization for ACS. Material and methods. The primary endpoints of this study were the major adverse cardiac events (MACE) at 12 months. From the originally included 221 patients 15 were lost (no response to follow-up phone calls). The suboptimal glycaemic control group (HbA1c>7.0%, n=84) was divided in two subgroups: patients who completed a diabetological consult with further treatment changes (intervention group) and patients without this referral (control group). Results. No significant differences in baseline characteristics were found between the 2 subgroups. The second subgroup had a triple risk for a MACE in 1 year (HR=2.8704, 95% CI: 1.109-7.423, p=0.0296) compared to the intervention group. No significant differences were found in secondary endpoints. Conclusion. This study suggests that, after hospitalization for an ACS, diabetologist referral and treatment strategy changes are recommended for all T2DM patients whose HbA1c level is over 7% before discharge.