A compound of Formula (I): wherein: A is phenyl or a 5- or 6-membered heteroaryl ring, optionally substituted; R.sup.1 and R.sup.2 are selected from hydrogen and methyl; with the proviso that at least one of R.sup.1 and R.sup.2 is methyl; or a salt, pro-drug or solvate thereof, are described. Their use as GLK activators, pharmaceutical compositions containing them, and processes for their preparation are also described.