Type 2 Diabetes Outpatient Protocol

The study enrolled 340 outpatients with type 2 diabetes managed at any of the 51 participating clinics in Japan. The full list of study investigators is provided in Additional file 1. Enrollment began in July 2017 and ended in June 2018. The inclusion criteria were as follows: (1) patients with type 2 diabetes who had not used any glucose-lowering agents within 8 weeks before consenting, or those who had used only metformin; (2) those with HbA1c (NGSP values) levels of ≥ 7.1% (54 mmol/mol) but not > 10.0% (86 mmol/mol); (3) those aged between 20 and 80 years; (4) those with body mass index (BMI) of ≥ 23 kg/m²; (5) those who could be monitored closely for medication compliance; and (6) those who provided written consent to participate in the study. The following exclusion criteria were used: (1) patients with type 1 diabetes or secondary diabetes; (2) those with a medical history of diabetic ketoacidosis; (3) those with a medical history of myocardial infarction, cerebral infarction, or stroke within 12 weeks before consenting to the study; (4) those with severe liver disease having more than fivefold higher than normal levels of AST and ALT; (5) those with renal disease [serum creatinine ≥ 1.3 mg/dL, or estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73 m²]; (6) those with unstable hypertension or dyslipidemia within 12 weeks before consent to the study; (7) those who were pregnant or breastfeeding or were planning to become pregnant during the study; and (8) dehydrated patients [test results showed abnormalities in hematocrit or blood urea nitrogen (BUN) or patient complaints of dehydration].