A Prospective Cohort Study on the Associations of Diabetes With Cancer Risk in Chinese Men and Women

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.