Most of the patients are admitted acute coronary syndrome (ACS) have either DM or prediabetes. Newly detected hyperglycemia with ACS is detected even after the discharge from the hospital and outcome is also poor. Larger infarct size, lower left ventricular ejection fraction, increased risk of congestive cardiac failure and higher risk of “no-reflow” phenomenon after reperfusion are associated with hyperglycemia. Interaction between hyperglycemia and adverse outcome after ACS has an effect on myocardial energy balance, vascular function and inflammation and thrombosis. Oral hypoglycemic agents, glucose-insulin-potassium infusion in ACS, non-GIK insulin therapy in ACS and insulin administration are used to manage hyperglycemia. Hypoglycemia can be managed by acronym SAM–Stop insulin infusion; Assess the patients consciousness and cooperation and Manage the patient. The short-term goal is to keep blood glucose between 140 and 180 mg/dL which is achieved by continuous intravenous insulin infusion. Multidisciplinary and multifactorial therapeutic strategy is required to reduce the complications like heart failure and arrhythmias.