Study participants

Patients were recruited at the obesity centre at the Catholic University Hospital of the Sacred Heart, Rome, Italy. The patients underwent either RYGB or BPD for treatment of obesity. No randomization to the different surgical treatments was undertaken. Inclusion criteria for participating in the study were a BMI greater than 40 kg/m², no previous diagnosis of type 2 diabetes, with glycated haemoglobin (HbA1c) 7 per cent or less, and willingness to be included in the study. Exclusion criteria were major endocrine diseases, malignancies and liver cirrhosis.

At inclusion and follow‐up, blood samples were obtained from patients after overnight fasting and anthropometric data were collected. Blood chemistry analysis was undertaken at the central laboratory of the Catholic University Hospital of the Sacred Heart, Rome.