Objective: Diabetics represent an increasing proportion of patients undergoing coronary artery bypass graft (CABG). Glycosylated hemoglobin (HbA1C) is a key indicator for glycemic control. The degree of glycemic control is directly reflected in the outcome after CABG. Our study aims to analyze the early outcome concerning preoperative HbA1C levels. Methods: This prospective study evaluated the early outcome of 623 isolated elective CABG patients over 19 months. The patients were divided into group A (347 patients) with HbA1C < 7% and group B (276 patients) with HbA1C ≥ 7%. Postoperative renal failure, myocardial infarction, atrial fibrillation (AF), wound infection, cerebrovascular accidents, and 30-day mortality were recorded. Results: Baseline characteristics showed a non-significant difference between both groups. The mean age of patients in group A was 59.6 years, and in group B it was 59.5 years. The mean graft number was 3.35 and 3.32 for groups A and B, respectively. First-month death was 0.9% in group A and 1.4% in group B without a significant difference. The incidence of AF, superficial wound infection, and other site infections showed a statistically substantial difference between both groups. Conclusion: Increased levels of HbA1c, more than 7%, may be a potential risk factor for postoperative complications with a substantial rise in the risk of wound infections (superficial sternal and non-sternal surgical) and AF.