['Visfatin has shown to be increased in obesity and in type 2 diabetes. The aim of this study was to determine the change in plasma visfatin in severely obese (SO) persons after weight loss following bariatric surgery in relation to glucose concentration.', 'Visfatin and leptin were studied in 53 SO persons (BMI, 54.4 +/- 6.8 kg/m(2)) before and 7 months after bariatric surgery and in 28 healthy persons (BMI, 26.8 +/- 3.8 kg/m(2)). All of the patients underwent bariatric surgery with biliopancreatic diversion or gastric bypass.', 'The pre-surgery levels of visfatin in the SO group were greater than in the control group (55.9 +/- 39.9 vs. 42.9 +/- 16.6 ng/mL, p = 0.024). This increase was significant in the SO group with impaired fasting glucose (63.4 +/- 36.6 ng/mL) and diabetes (60.0 +/- 46.0 ng/mL). SO patients with normal fasting glucose had similar levels of visfatin to the controls. Seven months after surgery, visfatin levels were significantly increased (84.8 +/- 32.8 ng/mL, p < 0.001). This increase was independent of the pre-surgical glucose levels. The type of bariatric surgery had no influence on visfatin levels. Post-surgical visfatin was significantly correlated with the post-surgery plasma concentrations of leptin (r = 0.39, p = 0.014).'] Are plasma visfatin concentrations in severely obese subjects increased after intestinal bypass?