Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are the two most performed techniques in bariatric surgery. The aim of this study is to compare two surgical procedures in terms of weight loss and the development of comorbidities such as type II diabetes mellitus T2D, arterial hypertension, sleep apnea (OSAS), and gastroesophageal reflux disease (GERD).

Data from the German Bariatric Surgery Registry (GBSR) from 2005 to 2021 were used. 1,392 RYGB and 1,132 SG primary surgery patients were included. Minimum age 18 years; five-year follow-up data available. Tests were performed with a 5% significance level.

Loss of follow-up 95.41% within five years. Five years after surgery, the RYGB showed significant advantages in terms of excess weight loss (%EWL 64.2% vs. 56.9%) and remission rates of the studied comorbidities: hypertension (54.4% vs. 47.8%), OSAS (64.5% vs. 50.1%), and GERD (86.1% vs. 66.9%). Compared to the pre-test, individuals diagnosed with insulin-dependent T2D showed significant improvements with RYGB over a five-year period (remission rate: 75% vs. 63%). In contrast, non-insulin-dependent T2D showed no significant difference between the two approaches (p = 0.125).

Both surgical procedures resulted in significant weight loss and improved comorbidities. However, the improvement in comorbidities was significantly greater in patients who underwent RYGB than in those who underwent SG, suggesting that the RYGB technique is preferable.

Nevertheless, RYGB requires a high degree of surgical skill. Therefore, acquiring expertise in the technical facets of the surgery is essential to achieving favorable outcomes.