The aim of the present study was to determine the long-term outcomes of bifurcation lesions following a rotational atherectomy (ROTA) In this retrospective study, patients that had undergone a ROTA of the bifurcation coronary lesions in Juntendo University Hospital (Tokyo, Japan) were enrolled between January 2007 and December 2009, and received follow-up for a median duration of 48 months (range, 12-84 months). A total of 337 patients were enrolled. Each patient was treated with an average of 1.2 +/- 0.4 ROTA burrs (mean size, 2.9 +/- 0.3 mm). Baseline lesion length, reference diameter, minimal lumen diameter (MLD) and percentage of diameter stenosis (%DS) prior to the procedure were comparable between the DM and non-DM patients. Furthermore, MLD, %DS and acute gain following the procedure were similar between the two groups. At follow-up, DM patients exhibited a significantly decreased MLD (1.97 +/- 0.92 vs. 2.26 +/- 0.73 mm; P=0.0038), increased %DS (27.9 +/- 21.3 vs. 20.2 +/- 13.3%; P=0.022) and late loss (0.70 +/- 0.45 vs. 0.42 +/- 0.36 mm; P=0.0047) compared with the non-DM patients. Follow-up examinations (mean duration, 52.2 +/- 19.4 months) revealed that the DM patients experienced significantly higher rates of target lesion revascularization (TLR) [28 (15.7%) vs. 8 (5.0%); P=0.0011], target lesion (TL) restenosis [46 (25.8%) vs. 20 (12.6%); P=0.0019] and major adverse cardiac events (MACE) [36 (20.2%) vs. 19 (12.0%), P=0.039] compared with the non-DM patients. Although the usage of ROTA and drug-eluting stent evidently improved long-term outcomes in patients with bifurcation lesions, DM remained an independent risk factor for TLR, TL restenosis and MACE. Therefore, the management of DM in bifurcation lesions treated with ROTA requires increased investigation in future clinical practice.