The aim of the prospective observational GDC-Study in patients with newly diagnosed diabetes mellitus aged 18-69 years at inclusion into the study is to characterize in detail the clinical, metabolical and immunological phenotype and monitor the progression of the disease and to compare the phenotype to glucose tolerant humans of similar age, body mass and sex distribution.

In detail, the following questions will be answered:

1. Are there different phenotypes with respect to insulin secretion, insulin sensitivity, micro- and macrovascular status and diabetic neuropathy at time of diagnosis?
2. Which factors modify the progression of the disease (Nutrition, subclinical inflammation, energy metabolism and physical activity)?
3. Can we identify subgroups at baseline with different progression of the disease? Patients are thoroughly examined at baseline and after 2, 5, and 10 years with annual telephone contacts in between.

Inclusion Criteria:

• Clinical diagnosis of diabetes mellitus according to ADA criteria
• Age 18-69
• Diabetes duration since diagnosis < 12 months
• Control cohort: proven normal glucose tolerance according to ADA criteria

Exclusion Criteria:

• Diabetes mellitus category 3 B-H (ADA criteria)
• Pregnancy
• Severe renal, liver or heart disease
• malignant cancer
• severe psychiatric illness or addiction
• participation in an intervention trial

Patients are recruited from the general populations by screening