Inclusion Criteria:  Adult female or male (18 years of age or older) Diagnosed with type 1 or type 2 diabetes mellitus Decision to initiate venous blood glucose testing and CGM as per investigator's routine treatment practice; Signed informed consent  Exclusion Criteria:  Patients with moderate or more serious anemia defined as hemoglobin < 90g/L Patients with moderate or more serious subcutaneous edema: grading can be referred to: mild edema (a visible mild depression of eyelid, soft tissues below the orbit, subcutaneous tissue of the anterior tibia or subcutaneous tissue of the ankle after finger pressure); moderate (all the sparse tissues of the whole body have visible edema with obvious or deeper tissue depressions after finger pressure and slow subsidence); severe (severe edema of tissues all over the body, the skin of the low hanging part of the body is tense and shiny, and there may even be fluid exudation, sometimes accompanied by fluid accumulation in the thoracic cavity, abdominal cavity and sphincter cavity) Pregnant women