Glargine is commonly used in insulin supplemental therapy in patients with type 2 diabetes(T2D) at present. This study aims to investigate the current status of blood glucose control in patients with T2D treated with glargine. Glycated hemoglobin(HbA1c) will be tested in these patients to assess the blood glucose control and Continuous Glucose Monitoring System (CGMS) will be used to investigate the glucose variability. Islet function, duration of diabetes, complications, exercise, insulin dose, oral medication regimen and insulin antibodies will be recorded in detail. This study will analysis the association between these clinical characteristics and blood glucose control.

Inclusion Criteria:

1. Patients with T2DM, which was defined bypublished Criteria of World Health Organization in 1999;
2. Patients were using glargine with or without oral hypoglycemic drugs and having a stable dose of glargine for more than 2 month would be recruited into this study;
3. Patients had relatively constant diet and exercise in 2 month before the study;
4. Fasting blood glucose was between 6.1 and 16mmolL, and postprandial (or random) blood glucose <22.2mmol/L.

Exclusion Criteria:

1. Patients with severe cardiovascular diseases, such as stroke, transient ischemic attack, myocardial infarction, unstable angina, coronary artery bypass grafting, percutaneous coronary intervention, and heart failure;
2. Patients with severe infectious diseases;
3. Patients with acute complications of diabetes on admission, such as diabetic ketoacidosis, diabetic hyperosmolar nonketotic coma, and lactic acidosis;
4. Patients with history of psychiatric disorders and were unsuitable to use CGMS;
5. Any other situations that made patients unsuitable to participate in the study, such as alcoholism and drug abuse.

Chinese outpatients with type 2 diabetes in Nanjing First Hospital who meet the the eligibility criteria.