Impact of perioperative management of glycemia in severely obese diabetic patients undergoing gastric bypass surgery

BACKGROUND: Roux-en-Y gastric bypass (RYGB) surgery is associated with rapid postsurgical improvement in glycemic control in patients with type 2 diabetes mellitus (T2 DM). However, there is little outcome-based evidence to guide the glycemic management of this patient group preoperatively. OBJECTIVES: We conducted 2 pilot studies randomizing patients to assess the impact of intensive glucose management pre- and post-RYGB on clinical outcomes after surgery. SETTING: University hospital. METHODS: In the GLUCOSURG-pre randomized controlled trial (RCT), 34 obese T2 DM patients with glycated hemoglobin (HbA1 c) ≥8.5% (69 mmol/mol) undergoing RYGB were randomly assigned to receive either glucose optimization or no optimization 3 months preoperatively. In the GLUCOSURG-post RCT, 35 obese T2 DM patients on insulin were randomly assigned to either intensive or conservative glucose management up to 2 weeks post- RYGB. HbA1c at 1 year post-RYGB was the primary outcome. RESULTS: In GLUCOSURG-pre, the HbA1 c at 1 year postsurgery was -3.0% (51.9 mmol/mol) in the optimized and -4.0% (45.4 mmol/mol) in the nonoptimized groups (P = .06). In GLUCOSURG-post, there were no significant differences in HbA1 c at 1 year postsurgery between the intensive and conservative groups [-2.4% (44.3 mmol/mol)] versus [-2.3% (44.3 mmol/mol), P = .73)]. CONCLUSIONS: Our pilot studies suggested that neither intensive management of glycemia in the 3 months pre- RYGB, nor the first 2 weeks post-RYGB resulted in better glycemic control one year after surgery. RYGB has substantial effects on glucose control, and additional intensive glucose-lowering interventions do not confer clinical benefits compared to conservative approaches.