Inclusion Criteria:  Men or women aged 19 to 75 years old Patients with type 1 diabetes or insulin-dependent type 2 diabetes Patients on multiple daily insulin-injection or continuous subcutaneous insulin infusion therapy for more than 1 year Patients with HbA1c ≥ 7.0% at screening Patients willing to use a FSGM system Patients with informed consent  Exclusion Criteria:  Insulin-independent type 2 diabetes patients Gestational diabetes patients Patients within 1 year of diabetic diagnosis Patients taking drugs for severe cognitive impairment or psychiatric problems Patients who received oral or parenteral corticosteroid therapy for more than 7 consecutive days within 1 month before screening test Patients with severe infection, before and after surgery, and severe trauma Patients on dialysis at the end of renal failure Patients who have a history of substance abuse or alcoholism within 12 weeks through patient history taking, diagnosis records, and past treatment records Pregnant or lactating women Participating in other clinical trials under R&D other than this clinical trial, or if other clinical trial drugs are administered within 4 weeks before the trial Patients who are using a CGMS/FSGM or who have been using it within 12 weeks