Diabetes and Prognosis After CABG | Journal Scan

Study Questions:

Following coronary artery bypass grafting (CABG), what is the long-term survival in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM)?


This was a nationwide population-based cohort study in patients who underwent CABG in Sweden from 2003 through 2013. All patients who underwent primary isolated nonemergency CABG were included. Type of DM (1 or 2) was obtained from the Swedish National Diabetes Register. All-cause mortality was the primary outcome.


The analytic sample included 39,235 patients (mean age, 67 years). During a mean follow-up of 5.9 (± 3.2) years, 6,765 (17%) patients died. In adjusted analyses and compared to patients without diabetes, hazard ratios (HRs) for death in patients with T1DM and T2DM were 2.04 (95% confidence interval [CI], 1.72-2.42) and 1.11 (95% CI, 1.05-1.18), respectively. The association between T2DM and cardiovascular death was not significant (HR, 1.08; 95% CI, 0.95-1.19). There was no difference in relative risks for death or cardiovascular events between women and men, neither in those with T1DM or T2DM. In patients with T1DM, 94% had a duration of disease longer than 20 years, compared with 10% in patients with T2DM.


In Swedish patients who underwent first isolated CABG, those with T1DM had more than double the long-term risk of death, compared to patients without diabetes. The long-term risk of death in patients with T2DM, compared to those without diabetes, was statistically significant, but smaller.


This is an important study that provides contemporary data on how prognosis after CABG differs for patients with T1DM, compared to those with T2DM. In adjusted analyses, T1DM was associated with a doubling of mortality following CABG, compared to those without diabetes; those with T2DM had only a minimally increased risk of death. Certainly, the difference in prognosis could be related to the difference in mean duration of disease between patients with T1DM and T2DM. Patients with T1DM appear to be a particularly vulnerable population following CABG, and future research should identify ways to reduce risk in this group.

Clinical Topics: Cardiac Surgery, Diabetes and Cardiometabolic Disease, Invasive Cardiovascular Angiography and Intervention

Keywords: Cardiac Surgical Procedures, Coronary Artery Bypass, Diabetes Mellitus, Type 1, Diabetes Mellitus, Type 2, Cohort Studies, Follow-Up Studies, Incidence, Metabolic Syndrome X, Mortality, Prognosis, Risk, Vulnerable Populations

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