Voglibose is an alpha-glucosidase inhibitor used for lowering post-prandial blood glucose levels in patients with diabetes mellitus. Voglibose is known for its ability to increase glucagon-like peptide-1 (GLP-1) secretion in humans. Our recent study demonstrated new mechanisms by which voglibose increases plasma active GLP-1 levels in diabetic ob/ob mice. As expected, the stimulatory effects of voglibose on GLP-1 secretion resulted in increased active GLP-1 levels in plasma in the 1-day dosing study. Unexpectedly, chronic but not 1-day treatment with voglibose decreased plasma dipeptidyl peptidase-4 (DPP-4) activity by reducing its circulating protein levels. We have also revealed that chronic dosing of voglibose increased Neurod1 and Glucagon gene expression, and GLP-1 content in the lower gut. Active GLP-1 levels in plasma achieved by chronic treatment with voglibose were higher than those achieved by 1-day treatment. In the present overview, by using acarbose, another alpha-glucosidase inhibitor with different selectivity, as a comparator, we demonstrated that inhibition of alpha-glucosidase induces a decrease in plasma DPP-4 activity in ob/ob mice. Notably, compared to acarbose, voglibose has demonstrated more favorable effects on DPP-4 activity, GLP-1 secretion and gut GLP-1 content, when glucose levels were equally improved, leading to higher plasma active GLP-1 levels. These findings provide new insights into the mechanism underlying the increases in active GLP-1 circulation by voglibose.