Intestine is able to produce endocrinologically active substances, which affect to body's intermediary metabolism. One of these substances in glucose-dependent insulinotrophic polypeptide (GIP, part of the incretin family), which potentiates the release of insulin postprandially. However, recent evidence suggests, that GIP may have more harmful than beneficial role in the pathogenesis: it has been shown that GIP participates in the development of insulin resistance, the key defect in the process of metabolic dysfunction. GIP may also regulate postprandial redistribution of splanchnic blood flow which might act in the body's nutrition handling [8].