Introduction: Diabetes mellitus is increasing worldwide. Photobiomodulation is proposed as a therapeutic method in various medical concerns. This study aimed to compare the effects of photobiomodulation at the wavelength of 660, 808, or 660 + 808nm, on alveolar bone healing in diabetic rats. Materials and methods Bilateral maxillary first molars were extracted from diabetic Wistar rats (n = 36). Right-sided sockets were treated by an In-Ga-Al-P laser at 660nm (7.2 j/cm2, 24 s; DM660), Ga-Al-As laser at 808nm (7 j/cm2, 14 s; DM808), or a combination of these two sets (DM-dual) (n = 12). Left sides served as controls. On days 7 or 14, specimens were assigned for histomorphometric or RT-PCR analysis of RunX2, OCN, COL1 and VEGF expression. Results Irradiated sockets of groups DM-808 and DM-dual showed a significant increase in bone tissue and blood vessel establishment as compared to DM-660. Furthermore, group DM-dual exhibited the least amount of fibrosis tissue as compared to the other groups. Conclusion Within the limits of this study, our experimental model suggested photobiomodulation at 808nm, whether in form of single or combined irradiation, imposing a therapeutic influence on diabetic alveolar bone healing.