The long-term results after biliopancreatic diversion (BPD) in patients with type 2 diabetes (T2D) and severe obesity is still being debated. Retrospective evaluation of the long-term metabolic and clinical conditions of patients with T2D following BPD. University hospital. A total of 173 patients with T2D and severe obesity were investigated prior to and at 3-5 and 10-20 years after BPD. Anthropometric, biochemical, and clinical findings preoperatively and throughout follow-up were considered. The long-term data were compared with those of a cohort of 173 T2D patients with obesity treated with conventional therapy. T2D resolved within the first postoperative phases in most patients, and in the long and very long term, the fasting blood glucose level remained above the normal range in only 8% of patients. Likewise, a stable improvement of blood lipid pattern was observed (follow-up rate 63%). In contrast, in nonsurgical patients in the long term, the glucose and lipid metabolic parameters remained in the pathologic range in all cases. In the BPD group, a very high number of severe BPD-related complications was recorded, and 27% of the BPD patients died, whereas in the control group, 87% of patients were still alive at the end of the follow-up period (P < .02). Despite the high T2D stable resolution rate and the normalization of most metabolic data at 10-20 years following surgery, these results indicate that BPD should be indicated with caution in the surgical treatment of T2D in patients with severe obesity.