Details of studies on type 2 diabetes for thyroid cancer risk.

NIH-AARP (National Institutes of Health-American Association of Retired Persons) study; USRT (United States Radiologic Technologists) study; PLCO (Prostate, lung, colorectal and Ovarian Cancer Screening Trial) study.
aStudy quality was judged based on the Newcastle-Ottawa Scale (range, 1–9 stars).
bStandardized incidence ratio (SIR) per 1,000,000 within reference population.
cProstate, lung, colorectal and Ovarian Cancer Screening Trial (PLCO) data.
dParticipants who were classified into the highest quintile (quintile 5) were regarded as diabetic patients (including level for impaired fasting glucose metabolism).
eParticipants with Impaired Fasting Glucose (IFG, 100≤FBS or OGTT<125) or Impaired Glucose Tolerance (IGT, 140≤OGTT≤199) by 2009 ADA criteria.
fControls were benign thyroid diseases.