Bariatric surgeries are a growing field as a treatment choice for morbid obesity (BMI > 35 kg/m2). Clinical and research evidence shows that shortly after RYGB, T2DM resolves with improving glucose tolerance. Foregut hypothesis behind bariatric surgeries postulate, that bypassed portions of intestine contain a substance, that acts as an anti-incretin, ie. to counteract metabolically favourable incretins. In view of the recent studies, it may be that GIP is really the anti-incretin behind this hypothesis.