background: mediastinitis is a serious complication of median sternotomy and is associated to significant morbidity and mortality. diabetes is a feared risk factor for mediastinitis and viewed with caution by cardiovascular surgeons. objective: to identify risk factors for mediastinitis in diabetics undergoing cabg surgery with use of unilateral ita in the division of cardiovascular surgery of pronto socorro cardiológico de pernambuco - procape. methods: retrospective study of 157 diabetics operated between may 2007 and april 2010. nine preoperative variables, five intraoperative variables and seven postoperative variables possibly involved in the development of postoperative mediastinitis were evaluated. univariate and multivariate logistic regression analyses were applied. results: the incidence of mediastinitis was 7% (n=11), with a lethality rate of 36.1% (n=4). variables associated with increased risk of mediastinitis were: use of pedicled ita (or 8.25, 95% ci 2.03 to 66.10, p=0.016), postoperative renal complications (or 5.10, 95% ci 1.03 to 25.62, p=0.049) and re-operation (or 7.45, 95% ci 1.24 to 42.17, p=0.023). in multivariate analysis using backward logistic regression, only one variable remained as independent risk factor: use of pedicled ita (or 7.64, 95% ci 1.95 to 61.6, p=0.048), in comparison to skeletonized ita. conclusions: we suggest that diabetics should be considered for strategies to minimize risk of infection. in diabetics that undergo unilateral ita, the problem seems to be related to how ita is harvested. diabetics should always be considered for use of skeletonized ita.