Sima E, et al. - Long-term weight responders vs non-responders after Roux-en-Y gastric bypass (RYGBP) were analyzed for levels of leptin and gut hormones. In a subgroup analysis, they examined T2DM (type 2 diabetes mellitus) and normoglycemic participants for hormone levels. This study comprised 22 non-responders (BMI 40.6 ± 6.0 kg/m² after an excess BMI loss [EBMIL] of 26.0 ± 15.9%) and 18 responders (BMI 29.5 ± 3.5 kg/m² after an EBMIL of 74.9 ± 18.2%). A negative correlation of fat mass–adjusted fasting leptin with %EBMIL was observed. Higher levels of leptin were noted among non-responders during the oral glucose tolerance test. Non-responders displayed an early decrease in leptin and an early return of ghrelin to baseline levels. They noted an association of fasting leptin with weight result after RYGBP, and obesity might be promoted in long-term non-responders after RYGBP in relation to hormonal responses to a glucose oral load. Differences in peptide hormone levels were noted in independent correlation to poor long-term weight result and glycemic status after RYGBP.