In recent years, a marked increase in the relative use of sleeve gastrectomy (SG) has occurred. However, long-term head-to-head comparison of the impact of this bariatric surgery (BS) procedure with the still considered "gold standard" Roux-en-Y gastric bypass (GBP) in subjects with type 2 diabetes mellitus (T2DM) is surprisingly low. The aim of this review manuscript is to appraise current evidence on the potential of GBP and SG as long-term therapeutic tool for subjects with T2DM. In our opinion, unfortunately, review of current literature does not allow to properly answer which of the two surgeries would be better as procedure of choice for subjects with T2DM. Arguably, the apparent superiority of GBP over SG could be overcome by the addition of a malabsortive component to SG in a staged approach restricted to those failing to achieve the desired metabolic outcomes. Nonetheless, whether this serves as basis for the election of SG as primary strategy for those with T2DM is questionable.