Exposure to type 2 diabetes and risk of coronary heart disease in Chinese men and women: findings from a cross-sectional national survey

Abstract

BackgroundCoronary heart disease generally occurs more frequently in men than in women. Findings from small studies (n<5000) in white populations suggest that type 2 diabetes imparts a higher risk of coronary heart disease to women than to men. We aimed to investigate this association in Chinese women versus men. MethodsWe did a cross-sectional national survey in 223 612 Chinese patients (age ≥18 years; 120 252 men and 103 360 women) with type 2 diabetes in 630 hospitals from 106 cities in 30 provinces of China in 2012. Demographic information, medical history, and drug use were documented. Coronary heart disease was defined as ischaemic heart disease with abnormal electrocardiogram (ECG) or stress test, myocardial infarction with typical changes in ECG and plasma enzyme testing, coronary revascularisation, percutaneous transluminal coronary angioplasty, or coronary atherectomy. We used multivariable binary logistic regression analysis to obtain odds ratios (ORs) for coronary heart disease in women versus men, controlling for age, hospital level, BMI, glucose monitoring at home, diabetes medications, diabetic nephropathy, HbA1c, systolic blood pressure, diastolic blood pressure, LDL cholesterol, HDL cholesterol, and triglyceride. We used additive interaction to test whether sex and exposure time to diabetes had a synergistic effect on the risk of coronary heart disease. Ethics approval was granted by the Ethics Committee of the Chinese People's Libration Army General Hospital, and all participants provided written informed consent. FindingsCompared with men, women had lower HbA1c, lower systolic and diastolic blood pressure, and similar low-density lipoprotein cholesterol levels. However, 11 684 (11·3%) of 103 360 women who had type 2 diabetes had coronary heart disease, compared with 12 758 (10·6%) of 120 252 men (p<0·0001). Subgroup multivariable analyses by duration of diabetes showed that women had a slightly higher risk of coronary heart disease than men after 5–10 years of exposure, and the effect size became larger from 15 years onwards. The overall effect of women versus men for coronary heart disease was 1·04 (95% CI 1·01–1·08) in patients who had diabetes for less than 15 years, and the effect size increased to 1·17 (1·07–1·28) in those with at least 15 years of diabetes. Compared with men who had diabetes for less than 15 years, the risk of coronary heart disease in those with at least 15 years of diabetes was increased by 1·82 times (95% CI 1·70–1·95) in women and by 1·56 times (1·51–1·73) in men. All three additive interaction measures were significant: the attributable proportion due to interaction was 0·12 (95% CI 0·03–0·20), relative excess risk due to interaction was 0·21 (0·05–0·37), and the synergy index was 1·35 (1·07–1·71). InterpretationExposure to type 2 diabetes for 15 years or more imparts a larger risk of coronary heart disease to Chinese women than to Chinese men. The excessive risk in women could not be explained by conventional risk factors of coronary heart disease. FundingNovo Nordisk China.