The aim of this study was to determine the impact of diabetes mellitus (DM) on short-term
mortality and morbidity in patients undergoing coronary artery bypass surgery (CABG).
Diabetes mellitus is present in approximately 20% to 30% of patients undergoing CABG,
and the impact of diabetes on short-term outcome is unclear.
We performed a retrospective cohort study in 434 hospitals from North America. The
study population included 146,786 patients undergoing CABG during 1997: 41,663 patients
with DM and 105,123 without DM. The primary outcome was 30-day mortality. Secondary
outcomes were in-hospital morbidity, infections and composite outcomes of mortality
or morbidity and mortality or infection.
The 30-day mortality was 3.7% in patients with DM and 2.7% in those without DM; the
unadjusted odds ratio was 1.40 (95% confidence interval [CI], 1.31 to 1.49). After
adjusting for other baseline risk factors, the overall adjusted odds ratio for diabetics
was 1.23 (95% CI, 1.15 to 1.32). Patients treated with oral hypoglycemic medications
had adjusted odds ratio 1.13; 95% CI, 1.04 to 1.23, whereas those on insulin had an
adjusted odds ratio 1.39; 95% CI, 1.27 to 1.52. Morbidity, infections and the composite
outcomes occurred more commonly in diabetic patients and were associated with an adjusted
risk about 35% higher in diabetics than nondiabetics, particularly among insulin-treated
diabetics (adjusted risk between 1.5 to 1.61).
Diabetes mellitus is an important risk factor for mortality and morbidity among those
undergoing CABG. Research is needed to determine if good control of glucose levels
during the perioperative time period improves outcome.