The objectives of this clinical study is to assess the effect of the amount of carbohydrate intake and meals differing in glycemic index (GI) in patients of type 2 diabetes mellitus treated with an SGLT2 inhibitor (Luseogliflozin), which inhibits glucose reabsorption from renal uriniferous tubule, on glucose variability by using continuous glucose monitoring (CGM), and to establish dietary therapy which reduces the risk of hypoglycemia in patients treated with SGLT2 inhibitors. In addition, blood and urine samples are collected for metabolome analysis that will be performed as an extension study of the clinical study.