Devices, methods, and systems for treating Type-2 Diabetes and/or obesity by facilitating the delivery of under-digested nutrients within the gastro-intestinal tract without substantial tissue removal are disclosed. In one aspect, the gastro-intestinal tract of a patient is modified by a gastro-intestinal treatment device comprising an elongate element configured to extend within the gastro-intestinal tract, a first attachment element and a second attachment element disposed on the elongate element, wherein the first attachment element and the second attachment element are configured to attach to the gastro-intestinal tract such that a portion of the gastro-intestinal tract is compressed between the first and the second attachment elements. The length of the gastro-intestinal tract modified by the device is effectively shortened, and its surface area is reduced.