This is a study of the efficacy of sitagliptin and glibenclamide in a short-term treatment on the glucose variability using continuous glucose monitoring (CGM) in Japanese participants with type 2 diabetes mellitus (T2DM). The primary hypothesis is that treatment with sitagliptin will be superior to treatment with glibenclamide in the change from baseline in mean amplitude of glycemic excursions (MAGE) through continuous glucose monitoring (CGM) after 13 days of treatment.