Macrovascular complications in Mexican Americans with type II diabetes

Mexican Americans have a threefold greater prevalence of non-insulin-dependent (type II) diabetes mellitus than non-Hispanic whites in the San Antonio Heart Study, a population-based study of diabetes. In addition, Mexican-American diabetic subjects (n = 365) have greater fasting glycemia than non-Hispanic white diabetic subjects (P < 0.001). Despite these findings, and despite a higher prevalence of microvascular complications among Mexican Americans, there does not appear to be a marked difference in prevalence of macrovascular complications between Mexican-American and non-Hispanic white diabetic subjects. Mexican-American diabetic subjects have only a moderate excess of peripheral vascular disease (as judged by ankle-arm blood pressure ratios) relative to non-Hispanic white diabetic subjects (sex-adjusted Mantel-Haenszel odds ratio 1.84, 95% confidence interval 0.75-4.49). Mexican-American diabetic subjects actually reported fewer myocardial infarctions than non-Hispanic white diabetic subjects (sex-adjusted Mantel-Haenszel odds ratio 0.73, 95% confidence interval 0.31-1.71). Duration was not associated with either peripheral vascular disease or myocardial infarction. Severity of glycemia was only mildly associated with presence of peripheral vascular disease and negatively associated with self-reported myocardial infarction. This latter finding may represent a survival bias in that more severe diabetic subjects have already died and are not ascertained in a prevalence study. The absence of an ethnic difference in the prevalence of macrovascular disease contrasts with our previous reports from the San Antonio Heart Study, in which the prevalence of both retinopathy and proteinuria was observed to be higher in Mexican-American diabetic subjects. The different pattern of macrovascular and microvascular complications in Mexican-American versus non-Hispanic white diabetic subjects may provide insight into the differences in the etiology of these two types of complications in diabetes.