The present invention is a sulfonamide substituted xanthine derivative of formula I: ##STR00001## or a pharmaceutically acceptable salt thereof, wherein R1 is lower alkyl, lower alkyl substituted by phenyl, or lower alkyl substituted by halogen substituted phenyl; R2 is lower alkyl or lower alkyl substituted by lower cycloalkyl; and R3 is: ##STR00002## Compounds of formula I and pharmaceutically acceptable salts or prodrugs thereof show activity as modulators of gluconeogenesis.