Glucagon during OGTT: levels in lean individuals started to decrease between 5 and 10 minutes with suppression close to the observed maximum suppression after 30 minutes. In adolescents with obesity and NGT or IGT, glucagon levels tended to increase during the first 5 minutes of the OGTT. There was no lowering below fasting levels until 30 minutes. In individuals with obesity and T2D, glucagon levels increased during the initial 15 minutes, with no reduction below baseline until 60 minutes. This evidence concerns the gene GCG and obesity due to melanocortin 4 receptor deficiency.