BACKGROUND: The occurrence of the late complications of diabetes is correlated with genetic factors. It has been reported that angiotensin I converting enzyme(AGE) gene is considered as the risk factor of the occurrence of the diabetic cardiovascular complications.OBJECTIVE: To investigate the correlation between the polymorphism of ACE gene and the cardiovascular complications of type 2 diabetes.DESIGN: A case-controlled study based on type 2 diabetic patients.SETTING: A laboratory of general biology,faculty of biology in a medical college.PARTICIPANTS: The study was conducted in the Molecular Biological Laboratory of North China Coal Medical College between February 2001 and June 2002. Type 2 diabetic patients selected from outpatient and inpatient departments of the affiliated hospital of our college were divided into two groups based on the complication of myocardial infarction. Myocardial infarction group(infarction group, n = 68) included 29 males and 39 females aged of(65±3) years old; non-myocardial infarction group(non-infarction group, n = 190) included 161 males and 29 females aged of(60±1) years old. Inclusion criteria: All patients were in accordance with WHO diagnostic criteria for type 2 diabetes set in 1985,and myocardial infarction was diagnosed by MRI; Exclusion criteria: Patients who had incomplete data or who were uncooperative.METHODS: Genome DNA was extracted by routine phenol/chloroform method. Amplified products were analyzed by 20 mL/L of agarose gel electrophoresis. The results were observed after ethidium bromide staining. The frequency of alleles and genotype was compared between two groups.MAIN OUTCOME MEASURES: The comparison of the distribution of ACE alleles and genotype in both groups of patients.RESULTS: DD homozygote frequency of type 2 diabetic patients complicated with myocardial infarction (64.7%) significantly increased to 41.2%(χ2 = 0. 833,P<0. 05) compared with 33.2% of patients without myocardial infarction (55.0%),while D allele frequency also significantly increased in patients with myocardial infarction as well (χ2 = 3. 849 1,P<0.05).CONCLUSION: D allele and DD genotype are risk factors of the occurrence of myocardial infarction in type 2 diabetes,and surveillance of these indicators provides theoretical references for the secondary rehabilitative prevention and the improvement of long term quality of life in diabetic patients complicated with myocardial infarction.