Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 54 9 2025 10 03 1894 1905 EN Zhuanping Zeng 1. Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China 2. Key Laboratory of Glucolipid Metabolic Disorder, Ministry of Education of China, Guangdong Pharmaceutical University, Guangzhou 510006, China 3. School of Public Health, Guangdong Pharmaceutical University, Guangzhou 510006, China Jiao Guo 1. Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China 2. Key Laboratory of Glucolipid Metabolic Disorder, Ministry of Education of China, Guangdong Pharmaceutical University, Guangzhou 510006, China 3. School of Public Health, Guangdong Pharmaceutical University, Guangzhou 510006, China 2025 01 27 2025 05 07 Background: Pre-diabetes mellitus (PDM) is considered a precursor stage of type 2 diabetes mellitus (T2DM) and serves as an early warning sign for the disease. However, most studies only analyze the risk factors of T2DM, ignore the exploration of PDM.  Methods: Here 28,208 patients with T2DM were selected from 5 cities in the Pearl River Delta, Guangdong Province, China in 2017. Then a 1:1 matched case-control study was conducted according to the matching conditions. Finally, 28208 patients with PDM and 28208 patients with normal glucose tolerance (NGT) were matched, and when multiple subjects were matched, the same subjects in the region were preferredOrdered multiple logistic regression was used to analyze the influencing factors of T2DM and PDM. When analyzing the relationship between overweight, obesity, smoking, and T2DM, factors such as age, education level,  exercise were adjusted. Results: Overweight, obesity (OR=1.427, 95%CI:1.388~1.468; OR=1.829,95%CI:1.753~1.908) and smoking (OR=1.161,95%CI:1.113~1.212) were risk factors for the onset of T2DM by ordered multiple logistic regression. There was an additive interaction between overweight obesity and smoking in the developing of T2DM. Moreover, there were 0.196(0.051~0.341) relative excess risk due to the additive interaction, 9.1% (2.0%-16.1%) of T2DM exposed to both risk factors was attributable to the additive interaction, and the risk of T2DM in overweight and obese smokers was 1.203(1.004-1.402) times as high as the sum of risks in the participants exposed to a single risk factor too. Conclusion: Overweight obesity and smoking are the risk factors for the onset of T2DM. https://ijph.tums.ac.ir/index.php/ijph/article/view/37981 https://ijph.tums.ac.ir/index.php/ijph/article/download/37981/8646