Associations between surrogate measures of insulin resistance and waist circumference, cardiovascular risk and the metabolic syndrome across Hispanic and non-Hispanic white populations.

AIMS: We evaluated the relations between surrogate indices of insulin resistance and waist circumference, metabolic syndrome and coronary heart disease risk across Hispanic and non-Hispanic white populations. METHODS: The study was a cross-sectional analysis of participants without diabetes in the San Antonio Heart Study, Mexico City Diabetes Study and Spanish Insulin Resistance Study. We evaluated commonly used indices of insulin resistance, including homeostasis model assessment, McAuley's index, Gutt's insulin sensitivity index, Avignon's insulin sensitivity index and the Stumvoll index with and without demographics, the modified Matsuda index and the product of the triglycerides and glucose index. The metabolic syndrome was defined by American Heart Association/National Heart, Lung, and Blood Institute criteria and coronary heart disease risk by Framingham risk scores. RESULTS: The Stumvoll index with demographics and the Avignon's insulin sensitivity index had the strongest correlations with waist circumference across populations. The triglycerides and glucose and McAuley's indices had the most robust correlations with Framingham risk score. The triglycerides and glucose index had the greatest ability to detect individuals with the metabolic syndrome and ≥ 10% coronary heart disease risk. Some indices display significant variability in the strength of the relationship with adiposity and coronary heart disease risk across populations. CONCLUSIONS: There are significant differences between insulin resistance indices regarding the ability to detect the metabolic syndrome and coronary heart disease risk across populations. Studies may need to consider the index of insulin resistance that best suits the objectives.

Was the historic contribution of Spain to the Mexican gene pool partially responsible for the higher prevalence of type 2 diabetes in mexican-origin populations? The Spanish Insulin Resistance Study Group, the San Antonio Heart Study, and the Mexico City Diabetes Study.

OBJECTIVE: Mexican-American populations in San Antonio, Texas (SA-MA) and Mexico have a higher prevalence of type 2 diabetes than non-Hispanic whites in San Antonio (SA-NHW). However, the higher prevalence of type 2 diabetes in Mexican-origin populations might be related, in part, not to Native American genetic admixture but to Spanish genetic admixture. RESEARCH DESIGN AND METHODS: Four population-based epidemiological surveys conducted with Mexican-origin and European-origin samples provided data relevant to this question. In all four surveys, type 2 diabetes was defined as fasting plasma glucose > or =7.0 mmol/l or 2-h glucose > or =11.1 mmol/l or use of antidiabetic agents. RESULTS: A comparison of the two Mexican-origin populations showed that the age- and sex-adjusted prevalence of type 2 diabetes was lower in Mexico than in SA-MA (15.1 vs. 17.9%, P = 0.032). Between the two European-origin populations, the prevalence of type 2 diabetes was lower in SA-NHW than in Spain (6.2 vs. 9.1%, P < 0.0001), but differences were attenuated by adjustment for BMI or after stratification by education. In logistic regression analyses, type 2 diabetes was associated with Mexican ethnic origin after adjusting for age, education, BMI, and waist-to-hip ratio. CONCLUSIONS: The prevalence of type 2 diabetes in Spain was intermediate between that in Mexican-origin populations and SA-NHW. Although the higher degree of Native American admixture is a major contributor to the higher rates of type 2 diabetes, we cannot completely rule out a partial contribution of Spanish admixture to diabetes susceptibility among Mexican- origin populations.