To study the effect of an ileocolonic formulation of ox bile extract on insulin sensitivity, postprandial glycemia and incretin levels, gastric emptying, body weight and fasting serum FGF-19 (fibroblast growth factor) levels in overweight or obese type 2 diabetic subjects on therapy with DPP4 (dipeptidyl peptidase-4) inhibitors (e.g. sitagliptin) alone or in combination with metformin.