Phase 1: Baseline investigation (nation-wide survey)

Aims: To investigate whether diabetes and prediabetes is a risk factor for cancers of all sites as well as for specific type of cancer, such as breast and colorectal cancer.

Subjects and Methods: A nation-wide survey will be carried out in 200,000-250,000 individuals selected from 20-25 communities stratified according to geographic regions (northeast, north, east, south central, northwest, and southwest China), degrees of urbanization (large cities [Beijing, Shanghai, and provincial capitals], midsize cities, county seats, and rural townships), and economic development status (as assessed on the basis of the gross domestic product [GDP] for each province). A comprehensive examination including questionnaire, anthropometric measurements, biochemical analysis will be performed in each study participant. Diabetes and prediabetes should be diagnosed by OGTT according to the WHO 1999 criteria, while the diagnosis of cancer is established on the self-report questionnaire and cross checking with the tumor registry or a proof of doctor's diagnosis.

Phase 2: Cohort follow-up

Aims : To examine factors that modify the risk of cancer in diabetes, prediabetes and normal glucose regulation (NGR).

Subjects and Methods: To recruit and follow all type 2 diabetes, prediabetes, and sex,age-matched NGR (1:1) in each community for at least 3 years. For diabetes, treatment target is HbA1c ≤ 7.0% with treatment paradigm recommended by local guideline.

Phase 1

Inclusion Criteria:

1. Age >= 40 years old
2. Gender: males and females
3. Provide written informed consent
4. Satisfactory compliance

Phase 2

Inclusion Criteria:

1. Age >= 40 and =< 75 years old
2. Gender: males and females
3. Provide written informed consent
4. Satisfactory compliance

Exclusion Criteria:

1. History of cancer;
2. History of LADA and other autoimmunity diseases;
3. Acute diabetic complication, acidosis, etc;
4. Moderate to severe liver, kidney dysfunction, i.e. ALT/AST > 2.5 times the upper limit of normal range or Ccr < 25ml/min;
5. Any other condition or major systemic diseases that the investigator feels would interfere with trial participation or evaluation of results.

In phase 1, 200,000-250,000 individuals selected from 20-25 communities stratified according to geographic regions, degrees of urbanization, and economic development status In Phase 2, 30,000-40,000 type 2 diabetes, 20,000-30,000 prediabetes, 30,000-40,000 normal glucose regulation, recruited from the baseline survey