Glycosylated Hemoglobin (HbA1c) is considered as one of the best markers to assess the glycaemia treatment over a period of 3 to 4 months, and is considered as predictive marker for perioperative mortality and morbidity. The impact of the elevated HbA1c on the risk of perioperative major cardiovascular events in patients undergoing coronary bypass revascularization (by retrospective analysis of perioperative cardiovascular events and preoperative HbA1c) is evaluated.

Inclusion Criteria:

• patients with Diabetes mellitus undergoing coronary bypass revascularization since 2012

Exclusion Criteria:

• disapproval of use of data for research purposes

all patients with diabetes mellitus

• undergoing coronary bypass revascularization at the Klinik für Herzchirurgie, Universitätsspital Basel, Spitalstrasse 21, CH 4031-Basel since 2012
• who did not disapprove of use of data for research purposes
• statistic stratification in serum level of glycosylated hemoglobin (HbA1c) > 6.5% and \