By detecting the fasting and postprandial 120-minute glucose, insulin (Insulin, INS), C-peptide (C-peptide, Cp), glucagon (GCG) levels in newly diagnosed type 2 diabetes patients, or the 0-minute, 30-minute, 120-minute glucose, INS, Cp, GCG levels during the Oral Glucose Tolerance Test (OGTT), and examining the glucose, INS, Cp, GCG levels during hypoglycemia, the current status of islet alpha cell function in diabetic patients is observed. Type 2 diabetes patients willing to participate are treated with GLP-1RA for 3 months, and then retested for fasting and postprandial 120-minute glucose, INS, Cp, GCG, or the 0-minute, 30-minute, 120-minute glucose, INS, Cp, GCG during OGTT, as well as the counter-regulatory hormone levels during hypoglycemia, to assess the improvement of islet alpha cell function by GLP-1RA.