We study in jejunum the relation between insulin signalling and insulin resistance in morbidly obese subjects with low (MO-low-IR) or with high insulin resistance (MO-high-IR), and with type 2 diabetes treated with metformin (MO-metf-T2DM), and the effect of insulin/leptin on intestinal epithelial cells (IEC). This evidence concerns the gene LEP and type 2 diabetes mellitus.