Using a point-of-care (POC) platform, the investigators will investigate the effects of POC testing for glycated hemoglobin (HbA1c) and cystatin C at out-patient clinics on long-term diabetes outcomes.

Laboratory testing for HbA1c and cystatin C is time-consuming, and healthcare providers often do not have update results when they evaluate outpatients with diabetes. A POC testing platform may help address this issue, and the investigators aim to examine its effects on diabetes outcomes.

Inclusion Criteria:

-Adults aged 18 to 80 receiving treatment and follow-up for diabetes at outpatient clinics of Taichung Veterans General Hospital, Taichung, Taiwan.

Exclusion Criteria:

1. Past medical history of hemolytic anemia, hemoglobinopathies (sickle cell anemia HbS, fetal hemoglobin HbF), iron deficiency anemia, thalassemia, pernicious anemia, recent blood transfusions, acute bleeding requiring erythropoiesis-stimulating agents.
2. Chronic liver disease, cirrhosis, hyperbilirubinemia, asplenia (splenomegaly, splenectomy).
3. Hypertriglyceridemia (over 500 mg/dl), or alcoholism.
4. Thyroid dysfunction, active malignant tumors under treatment, HIV infection.
5. Long-term use (over three months) of steroids or cyclosporine.
6. Severe proteinuria (e.g., nephrotic syndrome), or a baseline eGFR <60 ml/min/1.73 m².

Data will be available from the principal investigator on reasonable request.