We, the investigators at National Taiwan University Hospital, want to compare patients' islet cell function, insulin sensitivity and risk of chronic complications with normal subjects. Moreover, we want to examine whether they are at a higher risk of having metabolic syndrome and to answer whether we should screen the phenotypes of metabolic syndrome in impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) patients. Then, we want to examine the association between insulin sensitivity and islet functions.

We, the investigators at National Taiwan University Hospital, want to compare patients' islet cell function, insulin sensitivity and risk of chronic complications with normal subjects. Moreover, we want to examine whether they are at a higher risk of having metabolic syndrome and to answer whether we should screen the phenotypes of metabolic syndrome in impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) patients. Then, we want to examine the association between insulin sensitivity and islet functions.

Inclusion Criteria:

• Fasting glucose 100-125 mg/dl OR oral glucose tolerance test (OGTT) 2 hour glucose 140-199 mg/dl
• Diabetes mellitus

Exclusion Criteria:

• Pregnancy
• Children < 18 years old