An amyio-1, 6-glucosidase inhibitor enhanced inhibition of hepatic glucose production in combination with glycogen phosphorylase inhibitor. The inhibitory activity of 1-deoxynojirimycin ( 1) toward human maltase was identical to that of voglibose ( 10) of an anti-diabetic agent. l-Isofagomine ( 8), a noncompetitive inhibitor of lysosomal β-glucosidase. also showed a chaperoning activity in N370S Gaucher fibroblasts.