A Paired Case-Control Study On The Associations Between Polymorphism Of Apolipoprotein E (ApoE) Gene And Other Factors And Coronary Heart Disease In Type 2 Diabetic Patients

Objectives: The aim of the study is to explore the associations between polymorphism of apolipoprotein E (ApoE) gene and other factors and coronary heart disease in type 2 diabetic patients.Methods: A hospital-based case-control study was conducted in Tianjin from November 2003 to October 2004. 100 pairs of subjects were recruited. The cases were considered to be type 2 diabetic patients (2DM) with coronary heart disease which occured after 2DM, and the controls were considered to be type 2 diabetic patients without coronary heart disease. Each case was matched with one control on sex and age. Information was collected through face-to-face interview, which included demographic data, disease history, disease family history, dietetic habit, behavior pattern, social psychologic character, clinical data and laboratory data. Polymorphism of ApoE gene was assessed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP), the PCR and RFLP products were subjected to electrophoresis on 2% agarose gel and 12% polypropylene gel stained with ethidium bromide respectively. The effects of the risk factors on the coronary heart disease development in type 2DM patients were analysed by using the conditional logistic regression model. Odds ratio (OR) and its 95% confidence interval were estimated.Results: Results from univariate conditional logistic regression analysis showed that theε₄ allele of ApoE gene was associated with development of coronary heart disease intype 2 diabetic patients, the ε₄ allele of ApoE gene was more frequent among the patientsof coronary heart disease in type 2 diabetic patients. Compared with type 2 diabeticpatients without the e 4 allele of ApoE gene, the OR with 95% CI of type 2 diabetic patients with the e 4 allele of ApoE gene was 2.800 (1.360-5.764). After adjusting for diabetic duration, the results still showed that the association between the e 4 allele of ApoE gene and coronary heart disease in type 2 diabetic patients was statistically significant. No associations were observed between the e 2 and e 3 alleles of ApoE gene and coronary heart disease in type 2 diabetic patients. Results from univariate conditional logistic regression analysis also showed that the development of coronary heart disease in type 2 diabetic patients was associated with age when diabetes diagnosed, diabetes duration, glycemia control, history of hypertension, intake of fish/meat before diabetes, body mass index at investigation, systolic and diastolic blood pressure at investigation and low serum density lipoprotein (LDL) cholesterol level at investigation. The corresponding OR with 95% CI were 0.574(0.355-0.929), 1.577(1.118-2.223), 3.615(1.956-6.682), 3.000(1.601-5.620), 0.561(0.374-0.842), 1.401(1.018-1.927), 1.599(1.089-2.348), 1.637(1.064-2.516), 1.9 36(1.196-3.134) respectively. However, after adjusting for possible confounding factors, the associations between the development of coronary heart disease in type 2 diabetic patients and age when diabetes diagnosed or systolic or diastolic blood pressure at investigation were not statistically significant, but the development of coronary heart disease in type 2 diabetic patients was still associated with diabetes duration, glycemia control, history of hypertension, intake of fish/meat before diabetes, body mass index at investigation and low serum LDL level at investigation. No associations were observed between the following factors and the development of coronary heart disease in type 2 diabetic patients, such as education level serum fasting blood glucose level when diabetes diagnosed, family history of diabetes, the previously highest glycemia level, hypertension duration, hypertension treatment, hypertension control, family history of kidney disease, family history of hypertention, family history of coronary heart disease, exercise, smoking, alcohol drinking, egg intake, milk intake, vegetable intake, sweetmeat intake, salt intake, character, serum total cholesterol, triglycerides, high density lipoprotein cholesterol levels, very low density lipoprotein cholesterol levels, serum...