Diabetic patients undergoing heart bypass have more complications.

On the operating table

This systematic review looked at how diabetes affects the outcomes of coronary artery bypass.  A higher risk of complications should influence clinical thinking about perioperative and postoperative management.

Clinical question:

In patients undergoing coronary artery bypass surgery, is diabetes associated with a higher risk of complications?

The review also looked for evidence on resource use, but insufficient data was found to permit analysis.

The evidence:

The reviewers found 24 observational cohort studies reporting outcomes of coronary artery bypass surgery.  The studies had a median follow-up of 4.3 years and a total of 100,217 participants, 28% of whom had diabetes.

When they combined all of the data, they found that patients with diabetes had a statistically significant higher risk of mortality, stroke, infection and renal failure.  However, they did not have a higher risk of atrial fibrillation or myocardial infarction.

The reviewers claimed that these patterns were consistent over time (the review included research that went back to 1981), when different definitions of diabetes and types of intervention were used.

Appraisal hints:

Users of this research are advised to consider:

  • Was there blind, independent assessment of the relevance and quality of each study?
  • Did the reviewers extract all of the patient data from each study?
  • Were the studies comparable in terms of clinical status, intervention and outcomes?
  • What was the methodological quality of the individual studies?
  • Did they perform sensitivity analysis to explore potential sources of bias or other confounders.


Zhang X, Wu Z, Peng X, Wu A, Yue Y, Martin J, Cheng D. Prognosis of diabetic patients undergoing coronary artery bypass surgery compared with nondiabetics: a systematic review and meta-analysis. J Cardiothorac Vasc Anesth. 2011 Apr;25(2):288-98. Epub 2010 Dec 13.

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I am an information scientist with an interest in making knowledge from systematic research more accessible to people who need it. This means you. I've been attempting this in the area of Evidence-Based Health Care since 1995. So far the results have been mixed. For some reason we expected busy clinicians to search databases and appraise papers instead of seeing patients. We also expected publishers to make the research freely available to the people who paid for it.. Ha! Hence The National Elf service.

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