The invention provides an incretin-associated medicine capable of restraining secretion of GIP completely and promoting secretion of GLP-1 and highly safe. The medicine capable of promoting the secretion of GLP-1 (glucagon-like peptide-1) and restraining the secretion of the GIP (glucose-dependent insulinotropic peptide) comprises non-antagonistic inhibitor of clastic enzyme of cane sugar, such as L-gum sugar, D-wood sugar and D-tagatose, as an active ingredient.