RESUMO

Although a number of obesity-related variables are recognized risk factors for NIDDM, few studies have addressed which one is the best predictor. A cohort of 721 Mexican Americans aged 25-64 years who were free of NIDDM at baseline were followed for an average of 7.2 years; 105 new cases of NIDDM were diagnosed. Body weight, body mass index (BMI), waist and hip circumferences, waist/hip ratio (WHR), triceps and subscapular skinfolds were all positively predictive of NIDDM independent of age and sex. There were modest to strong correlations between these anthropometric variables, however, waist circumference was the strongest predictor of NIDDM. The predictive power of a single measurement of waist circumference was at least equal to that of WHR and BMI combined. The risk of NIDDM for those in the highest quartile of waist circumference was 11 times greater than for those in the lowest quartile (95% confidence interval: 4.2-28.8). The waist-NIDDM relation was stronger in subjects with BMI < or = 27 kg/m2 (OR: 6.0 for a 1 SD difference) than in subjects with BMI > 27 kg/m2 (OR: 1.7 for a 1 SD difference). In multivariate analysis, waist circumference was the only significant predictor of NIDDM in models that included other anthropometric variables either separately or simultaneously. WHR and BMI were independent predictors of NIDDM after adjustment for each other, however, their predictive abilities disappeared after adjustment for waist circumference. The data indicate that waist is the best obesity-related predictor of NIDDM. This finding suggests that the distribution of body fat, especially abdominal localization, is a more important determinant than the total amount of body fat of the development of NIDDM in Mexican Americans.

Assuntos

RESUMO

The relative importance of insulin resistance and abnormal insulin secretion as risk factors for the development of non-insulin-dependent diabetes mellitus (NIDDM) is still controversial. Few data are available on insulin secretion as a risk factor for the development of NIDDM, especially in subjects with normal glucose tolerance. We examined the relation of fasting insulin (as a marker of insulin resistance) and the ratio of change in insulin to change in glucose during the first 30 min after glucose ingestion (delta I30/delta G30) (as a marker of insulin secretion) as predictors of the 7-year development of NIDDM in 714 initially nondiabetic Mexican-Americans. NIDDM developed in 99 subjects. The relative risk of NIDDM increased with higher quartiles of fasting insulin (quartile 1 [low], 1.0; quartile 2, 1.5; quartile 3, 2.0; and quartile 4 [high], 3.7; P < 0.0001) and lower delta I30/delta G30 (quartile 1 [low], 6.9; quartile 2, 1.9; quartile 3, 1.1; quartile 4 [high], 1.0; P < 0.001). Subjects with both increased fasting insulin and decreased delta I30/delta G30 had independent increases in NIDDM incidence (P < 0.001). Further, when we stratified subjects by baseline glucose tolerance, both increased fasting insulin and decreased delta I30/delta G30 significantly predicted NIDDM in subjects with both impaired and normal glucose tolerance at baseline. We conclude that both decreased insulin secretion (as assessed by low delta I30/delta G30) and increased insulin resistance (as assessed by fasting insulin) predict the development of NIDDM in Mexican-Americans, a group previously characterized as having hyperinsulinemia and insulin resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Assuntos

RESUMO

We have estimated the prevalence of non-insulin-dependent diabetes mellitus (NIDDM) in Mexican Americans and Anglos in three San Antonio neighborhoods. The age-adjusted NIDDM rates (both sexes pooled) for Mexican Americans were 14.5%, 10%, and 5% for residents of a low-income barrio, a middle-income transitional neighborhood, and a high-income suburb, respectively. In Mexican American women, though not in men, obesity also declined from barrio to suburbs. We have previously shown, however, that, although obesity is an important cause of NIDDM in Mexican Americans, there is a two- to fourfold excess in the rate of NIDDM in this ethnic group over and above that which can be attributed to obesity. We therefore speculated that genetic factors might also contribute to excess NIDDM in this ethnic group. The percent native American admixture of Mexican Americans as estimated from skin color measurements was 46% in the barrio, 27% in the transitional neighborhood, and 18% in the suburbs. The NIDDM rates in Mexican Americans thus paralleled the proportion of native American genes. Furthermore, the San Antonio Mexican American rates were intermediate between the NIDDM rates of "full-blooded" Pima Indians (49.9%), who presumably have close to 100% native American genes, and the San Antonio Anglo population (3.0%) and the predominantly Anglo HANES II population (3.1%), both of which presumably have few if any native American genes. The association of genetic admixture with NIDDM rates suggests that much of the epidemic of NIDDM in Mexican Americans is confined to that part of the population with a substantial native American heritage.

Assuntos

Assuntos

RESUMO

From a public health perspective, Mexican Americans are widely recognized as an understudied population. Available evidence suggests that Mexican Americans shared equally with non-Hispanic Caucasians (Anglo Americans or "Anglos") in the national decline in coronary heart disease (CHD) mortality during 1970-1976. This finding is somewhat unexpected in view of Mexican Americans' relatively lower socioeconomic status, and it suggests that studying this ethnic group may be strategic in understanding which factors have operated to produce the decline in general. Data obtained from a random sample of Mexican Americans and Anglos residing in three socioeconomically and culturally distinct neighborhoods in San Antonio, Texas, indicated that Anglos were significantly more informed than Mexican Americans about CHD prevention and generally reported engaging in more behaviors specifically aimed toward prevention than did Mexican Americans. Levels of knowledge were not particularly high in either ethnic group; moreover, reported behavior lagged considerably behind knowledge. While Mexican Americans were significantly less likely than Anglos to volunteer knowledge about major heart attack symptoms, there were negligible ethnic differences in awareness of the need for prompt utilization of medical treatment resources when a heart attack actually occurs. Awareness of the need for prompt action was notably high among both ethnic groups. Although limitations in the nature and scope of the data dictate that these findings should be interpreted with caution, the results tend to argue in the direction that prompt access to medical treatment when coronary emergencies occur may have made a relatively greater contribution to the CHD mortality decline in both Mexican Americans and Anglos than did changes in life-style. Much additional data are needed, however, before a definitive explanation of the decline will be possible.

Assuntos

RESUMO

Social class may act in different ways as a barrier to gene flow in urban populations, depending on ethnicity. We test the hypothesis that biological variation is affected by social class subdivision using skin reflectance data collected for 393 Anglo-American and 930 Mexican-American adults in the major urban population of San Antonio, Texas. Two socioeconomic groups were sampled for the Anglo-American population: a middle-income transitional group and a high-income suburban group. In addition, we sampled a third socioeconomic group for Mexican-Americans: a low income barrio. Sex and age effects on skin color are minimal. Social class has no effect on skin color variation for Anglo-Americans, whereas there is a highly significant effect on social class subdivision for Mexican-Americans. Admixture estimates were derived from skin reflectance data and show that the proportion of native American ancestry decreases as social class increases.

Assuntos

RESUMO

Obesity and Type 2 (non-insulin-dependent) diabetes mellitus are common in the Mexican American population. It is not clear whether this is merely a specific instance of the more general phenomenon of excess Type 2 diabetes and obesity among poor people, or whether Mexican Americans have a discrete genetic susceptibility to Type 2 diabetes. The latter consideration arises because Mexican Americans are of mixed native American and European ancestry and native Americans may have a genetic predisposition to Type 2 diabetes which Mexican Americans could share. We studied 936 Mexican Americans and 398 Anglo-Americans randomly selected from three socially and culturally distinct neighborhoods in San Antonio, Texas. Three categories of obesity--lean, average, and obese--were defined using the Anglo-American distribution of the sum of the triceps and subscapular skinfold. Mexican Americans were two to four times as likely to fall into the obese category as Anglo-Americans, but within categories, the two ethnic groups were closely matched in terms of sum of skinfolds. The prevalence of Type 2 diabetes, however, was significantly greater in Mexican Americans than in Anglo-Americans even when the comparisons were made within the three obesity categories. The summary prevalence ratio, controlling for obesity, was 2.54 for men (p = 0.004) and 1.70 for women (p = 0.036). Thus, lean Mexican Americans are still at greater risk of Type 2 diabetes than equally lean Anglo-Americans. Conversely, although Type 2 diabetes prevalence increases as expected with increasing obesity in both ethnic groups, obese Anglo-Americans are still relatively protected compared with equally obese Mexican Americans. Plasma glucose was significantly higher in Mexican Americans than in Anglo-Americans even after controlling for obesity. These results indicate that, although obesity contributes to Type 2 diabetes in Mexican Americans, it does not by itself explain the entire excess prevalence rate.

Assuntos

RESUMO

An epidemiologic study was carried out on Mexican Americans and Anglos residing in two socioeconomically and culturally distinct target areas in San Antonio: a middle income, ethnically integrated area ("transitional") and an upper income, predominantly Anglo area ("suburbs"). Although suburbanite Mexican Americans were leaner than their lower income counterparts, they were still more overweight than suburbanite Anglos. Even after adjusting for these differences in relative weight, however, Mexican Americans were still more likely than Anglos to express the opinion that Americans are too concerned about losing weight. Expressed as a per cent of the maximum score, Mexican American women in the transitional neighborhood scored 77% on this attitude item compared with 60% for Angle women (p less than 0.0005). Comparable ethnic differences on this attitude item were found in men in the transitional neighborhood and in suburbanites of both sexes. In the transitional neighborhood Mexican American women scored lower than Anglo women on a "sugar avoidance" and a "dieting behavior" scale: 23% for Mexican Americans and 45% for Anglos (p less than 0.0005) on the "sugar avoidance" scale. Comparable ethnic differences on this scale were found for men in the transitional neighborhood and for both sexes on the "dieting behavior" scale. Although no ethnic differences on these behavioral scales were found in the more affluent suburbs, these results nevertheless have public health relevance because the majority of Mexican Americans in the United States are of low socioeconomic status.

Assuntos

RESUMO

An epidemiologic survey of cardiovascular risk factors was carried out on a random sample of Mexican Americans living in two low income census tracts in Laredo, Texas. The prevalence of overweight was found to be intermediate between US national estimates and the rates recorded for Pima Indians. Similarly, the prevalence of fasting hyperglycemia was intermediate between the rates observed in a sample or predominantly Caucasian individuals and those observed in Pima Indians. Excess hyperglycemia in the Laredo Mexican American population compared to predominantly Caucasian populations does not appear to be due to a lower level of medical control of diabetes in the former. Rather, it probably reflects a true excess in the prevalence of diabetes. Serum cholesterol and triglyceride concentrations were also higher in Laredo Mexican Americans than in a Caucasian comparison population. Mexican Americans are of mixed European and native American ancestry. Native Americans have high rates of diabetes which could be on a genetic basis. The intermediate rates of hyperglycemia in Mexican Americans could thus have a genetic explanation. On the other hand, sociocultural determinants could be important since these are known to influence obesity which is a major precursor of diabetes.

Assuntos

RESUMO

In recent years there has been a marked improvement in the level of hypertension control nationally in both blacks and whites. Information is still lacking, however, on the level of hypertension control in Mexican Americans. The authors carried out a cardiovascular risk factor survey on a random sample of Mexican Americans living in two low income census tracts in Laredo, Texas. The percentages of hypertensive women who had been previously diagnosed, were under treatment, and were "under control" compared favorably with national figures for blacks and whites. Corresponding percentages for men indicated that their level of diagnosis, treatment and "control" still lagged behind the national figures. The prevalence of hypertension in Laredo Project participants was intermediate between those observed in national studies for blacks and whites. This finding did not clearly emerge when comparisons were based on either blood pressure distributions or prevalence of elevated diastolic pressures. These results indicate that, because of the increasing number of "controlled" hypertensives in the population, comparisons between populations and across time can no longer be based exclusively on blood pressure measurements, but must include cases of "controlled" hypertension.

Assuntos