The present invention provides a preventive or therapeutic medicine for
diabetes containing as an active ingredient a fused-heterocyclic compound
of the formula (I') or its salt: ##STR00001## [wherein G is CN,
NO.sub.2, CO.sub.2R.sup.4, CHO, SO.sub.2NR.sup.aR.sup.b or
CONR.sup.aR.sup.b; R.sup.1 is a halogen atom, a --O--R.sup.5 group or a
--S--R.sup.5 group; R.sup.2 is a halogen atom, a --O--R.sup.5 group
(wherein R.sup.5 is as defined above) or an amino group which may be
substituted; and each of R.sup.8 and R.sup.10 which are independent of
each other, is a hydrogen atom, a halogen atom or an alkyl group].
