Aims/IntroductionThe aim of the present study was to evaluate the efficacy and safety of ipragliflozin in treating Japanese type 2 diabetes patients with inadequate glycemic control by investigating diurnal variations of blood glucose and body composition.Materials and MethodsThis was an investigator‐initiated, multicenter, prospective study with a 6‐month treatment period. The primary outcome investigated was change in hemoglobin A1c levels from baseline. Secondary outcomes included changes in fasting plasma glucose, insulin resistance, variations in 24‐h glucose levels detected by continuous glucose monitoring, bodyweight, body composition, waist circumference and serum lipids. Adverse events were evaluated throughout the study.ResultsA total of 98 patients completed the study. Over the 6‐month period, ipragliflozin‐treated patients showed reduction in hemoglobin A1c levels by 0.3%, fasting plasma glucose levels by 13.0 mg/dL, bodyweight by 2.1 kg, body fat mass by 1.5 kg and extracellular water by 0.3 kg, as well as a decrease in systolic/diastolic blood pressures. Significant reductions from baseline in mean amplitude of glucose excursions and standard deviation, and the reduced frequency of hyperglycemia were confirmed. High‐density lipoprotein cholesterol was also significantly improved. Notably, the subgroup analysis of hemoglobin A1c levels, bodyweight, waist circumference, and body composition based on age, sex and body mass index showed similar reductions within each subgroup. The incidences of adverse events and adverse drug reactions were 20.0% and 1.0%, respectively, over the 6‐month period.ConclusionsIpragliflozin is a useful oral antidiabetic medication for patients with a wide range of background characteristics.