Does diabetes affect weight loss after gastric bypass?

Background: Weight loss in diabetics improves glycemic control. We investigated whether diabetes mellitus (DM) adversely affects postgastric bypass weight loss.

Methods: Our database was queried for the demographics and outcomes of patients with and without DM who had undergone gastric bypass surgery. DM was subdivided by severity: diet-controlled, oral hypoglycemic agents, and insulin.

Results: Of the 3193 patients, 655 (20%) had DM. The DM group was older (45.8 +/- 10.4 yr versus 39.1 +/- 9.9 yr, P <.0001), with more co-morbidities: hypertension (70.5% versus 44.2%, P <.0001), sleep apnea (36.7% versus 26.1%, P <.0001), and venous stasis (5.6% versus 2.6%, P <.0001). More men had DM (25.6% versus 19.3%, P = .0006). The age-adjusted, preoperative weight, and body mass index were equal. A direct relationship was found between DM severity and age, weight, and co-morbidities. At 1 year, the DM group had a lower percentage of excess weight loss (60.8% +/- 16.6% versus 67.6% +/- 16.7%, P <.0001) and greater body mass index (34.2 +/- 7.1 kg/m(2) versus 32.3 +/- 7.2 kg/m(2), P <.0001). The percentage of excess weight loss was 67.6% for those without DM, 63.5% for those with diet-controlled DM, 60.5% for those with DM controlled by oral hypoglycemic agents, and 57.5% for those requiring insulin. DM resolved in 89.8% of those with diet-controlled DM, 82.7% of those taking oral hypoglycemic medication, and 53.3% of those requiring insulin. Hypertension resolution was greatest in patients without DM (74.4% versus 63.5%, P <.0001).

Conclusion: The results of our study have shown that those with DM typically have more co-morbidities, despite having no difference in preoperative weight compared with those without DM. Despite the lower weight loss, those with DM had significant resolution of their DM and hypertension and should not be deterred from undergoing gastric bypass surgery.