The present invention provides 4-isopropylphenyl glucitol compounds which have no tendency to accumulate in the body and which inhibit SGLT1 activity to suppress postprandial hyperglycemia (or impaired glucose tolerance) through suppression of glucose absorption in the small intestine, whereby the compounds, for example, can suppress the onset of diabetes and metabolic syndrome or can treat these diseases.A 4-isopropylphenyl glucitol compound represented by the following formula (I) or a pharmaceutically acceptable salt thereof: wherein R1 represents a hydrogen atom, etc., R2 represents a methyl group, etc., R3 represents a C1-4 alkyl group substituted with an amino group(s), etc., and R4 represents a hydrogen atom, etc.