Association between type 2 diabetes mellitus and breast cancer risk: results from a population-based cohort study in Chinese women
- 1State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127 China
- 2Department of Epidemiology, Shanghai Cancer Institute, Shanghai, 200032 China
- 3State Key Laboratory of Systems Medicine for Cancer & Department of Epidemiology, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, No. 25, Lane 2200, Xie Tu Road, Shanghai, 200032 P. R. China
Abstract
Background: Although numerous epidemiological studies have reported significant associations between type 2 diabetes mellitus (T2DM) and breast cancer incidence, considerable heterogeneity exists across studies. Moreover, the breast cancer risk in relation to T2DM duration remains unclear. This study aimed to investigate the associations between T2DM, T2DM duration, and breast cancer risk in Chinese women.
Methods: A total of 72,295 women aged 40–70 years from the Shanghai Women’s Health Study were included. T2DM was defined as diagnosis after age 30, and categorized as prevalent at enrollment or incident during follow-up. Incident T2DM was treated as a time-dependent exposure in Cox proportional hazards regression models. The risk trajectory of breast cancer following T2DM diagnosis was characterized using categorical modelling analysis.
Results: Over a median follow-up of 19.08 years, 1,759 incident cases of breast cancer were identified. Compared to individuals without diabetes, overall T2DM was associated with an increased risk of breast cancer (HR = 1.22, 95%CI: 1.05–1.43). This association was significant in women diagnosed with incident T2DM during follow-up (HR = 1.28, 95% CI: 1.05–1.55) but not in those with prevalent T2DM at enrollment (HR = 1.15, 95% CI: 0.90–1.46). A clear trajectory of trend was observed, with the highest risk occurring within the first 5 years after T2DM diagnosis (HR = 4.22, 95% CI: 3.27–5.44).
Conclusions: T2DM was associated with an elevated breast cancer risk in Chinese women, which peaked at approximately 5 years post-diagnosis. Future studies should collect detailed information on treatment and lifestyle changes in study populations, to enable more in-depth analysis.
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s12889-026-28845-5.
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BibTeX
@article{tang2026association,
title = {{Association between type 2 diabetes mellitus and breast cancer risk: results from a population-based cohort study in Chinese women}},
author = {Dan-Dan Tang and Qiu-Ming Shen and Zhuo-Ying Li and Da-Ke Liu and Yu-Ting Tan and Hong-Lan Li and Yong-Bing Xiang},
journal = {BMC Public Health},
year = {2026},
month = jul,
doi = {10.1186/s12889-026-28845-5},
url = {https://doi.org/10.1186/s12889-026-28845-5},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Association between type 2 diabetes mellitus and breast cancer risk: results from a population-based cohort study in Chinese women
AU - Dan-Dan Tang
AU - Qiu-Ming Shen
AU - Zhuo-Ying Li
AU - Da-Ke Liu
AU - Yu-Ting Tan
AU - Hong-Lan Li
AU - Yong-Bing Xiang
PY - 2026
DA - 2026/07/31
JO - BMC Public Health
DO - 10.1186/s12889-026-28845-5
UR - https://doi.org/10.1186/s12889-026-28845-5
AB - Background: Although numerous epidemiological studies have reported significant associations between type 2 diabetes mellitus (T2DM) and breast cancer incidence, considerable heterogeneity exists across studies. Moreover, the breast cancer risk in relation to T2DM duration remains unclear. This study aimed to investigate the associations between T2DM, T2DM duration, and breast cancer risk in Chinese women. Methods: A total of 72,295 women aged 40–70 years from the Shanghai Women’s Health Study were included. T2DM was defined as diagnosis after age 30, and categorized as prevalent at enrollment or incident during follow-up. Incident T2DM was treated as a time-dependent exposure in Cox proportional hazards regression models. The risk trajectory of breast cancer following T2DM diagnosis was characterized using categorical modelling analysis. Results: Over a median follow-up of 19.08 years, 1,759 incident cases of breast cancer were identified. Compared to individuals without diabetes, overall T2DM was associated with an increased risk of breast cancer (HR = 1.22, 95%CI: 1.05–1.43). This association was significant in women diagnosed with incident T2DM during follow-up (HR = 1.28, 95% CI: 1.05–1.55) but not in those with prevalent T2DM at enrollment (HR = 1.15, 95% CI: 0.90–1.46). A clear trajectory of trend was observed, with the highest risk occurring within the first 5 years after T2DM diagnosis (HR = 4.22, 95% CI: 3.27–5.44). Conclusions: T2DM was associated with an elevated breast cancer risk in Chinese women, which peaked at approximately 5 years post-diagnosis. Future studies should collect detailed information on treatment and lifestyle changes in study populations, to enable more in-depth analysis. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s12889-026-28845-5.
SN - 1471-2458
ER -