CHIN-HSIAO TSENG2020-06-012020-06-0120140014-2972https://www.scopus.com/inward/record.uri?eid=2-s2.0-84908666270&doi=10.1111%2feci.12323&partnerID=40&md5=5732f9edc774354d2cc80418cf59c8a1https://scholars.lib.ntu.edu.tw/handle/123456789/496084Purpose: To evaluate whether diabetes is a risk factor for breast cancer considering confounders and potential detection examinations. Methods: National Health Insurance data on 501 747 women without breast cancer were retrieved. Three-year cumulative incidence (2003-2005) and risk ratios (RRs) between diabetic and nondiabetic women were calculated. Potential detection examinations were compared between diabetic and nondiabetic women by chi-square test. Odds ratios (ORs) were estimated by logistic regression for diabetes status/duration with and without adjustment for potential detection examinations and confounders. Results: The crude RR (95% confidence interval [CI]) for all ages, and age groups < 50, 50-64 and ? 65 years, was 2·62 (2·31-2·91), 2·69 (2·11-3·44), 1·39 (1·15-1·68) and 1·37 (1·03-1·84), respectively. Patients with diabetes more frequently received potential detection examinations than nondiabetes (17·5% vs. 7·4%, P-value < 0·001). The unadjusted OR (95% CI) for breast cancer for diabetes status (yes vs. no) was 2·63 (2·31-2·98) and was significant for any diabetes duration. The OR for diabetes status was 1·81 (95% CI: 1·59-2·06) after adjustment for potential detection examinations. In models adjusted for potential detection examinations, age, living region, occupation, comorbidities and used medications, OR for diabetes status attenuated to 1·13 (95% CI 0·96-1·32, P-value = 0·14) and none was significant for any diabetes duration. Potential detection examinations were associated with a fivefold to sevenfold higher risk in various models, indicating a strong impact of detection bias. Conclusions: An association between diabetes and breast cancer is observed, but this can be due to potential detection bias and confounders. ? 2014 Stichting European Society for Clinical Investigation Journal Foundation.[SDGs]SDG3adult; age distribution; aged; Breast Neoplasms; complication; Diabetes Mellitus, Type 2; female; human; middle aged; risk factor; selection bias; Taiwan; Adult; Age Distribution; Aged; Breast Neoplasms; Diabetes Mellitus, Type 2; Female; Humans; Middle Aged; Risk Factors; Selection Bias; Taiwanjournal article10.1111/eci.12323251043322-s2.0-84908666270