Biomedical subjects

B D Mitchell

Publications and source records attributed to B D Mitchell.

At least 73 records · Page 4Linked to original sources

PubMed1995

Relationships between physical activity, insulin levels and lipids in non-diabetic low income residents of Mexico City: the Mexico City Diabetes Study.

The epidemiologic data supporting an association between physical activity and lipoprotein profile is controversial. We hypothesized that physical activity is positively associated with triglyceride levels and negatively associated with high density lipoprotein (HDL) cholesterol levels, and that these associations are mediated by insulin activity. We tested these hypotheses in 819 male and 1159 female healthy non-diabetic Mexicans, aged 35-64 years, residing in Mexico City. Physical activity was assessed using a modified Stanford 7-day Physical Activity Recall. Serum glucose and insulin were evaluated in the fasting state and 2 h following a glucose challenge. Crude analysis indicated that physical activity was not associated with HDL cholesterol in males, but was associated with HDL cholesterol in females (r = 0.06; p = 0.025). Physical activity was not associated with triglyceride concentration in males or females. Multivariate results showed that the positive association between HDL cholesterol and physical activity in women remained after controlling for age, estrogen status, body mass index, and smoking. Furthermore, there was a significant interaction between physical activity, HDL cholesterol and an index of insulin sensitivity. Women with higher levels of insulin sensitivity had higher levels of HDL cholesterol. However, among women at lower levels of insulin sensitivity, those with greater physical activity were significantly more likely to have higher HDL cholesterol values.

Adult↗

PubMed1994

Proinsulin and specific insulin concentration in high- and low-risk populations for NIDDM.

Hyperinsulinemia and insulin resistance have been implicated as risk factors for the development of non-insulin-dependent diabetes mellitus (NIDDM). Recent data suggest that proinsulin may comprise a large proportion of immunoreactive insulin in subjects with NIDDM and possibly in those with impaired glucose tolerance (IGT) as well. Increased proinsulin concentrations are thought to be an early indicator of a failing pancreas. We examined proinsulin, insulin (using an assay that does not display appreciable cross-reactivity with proinsulin), and the fasting proinsulin:insulin ratio in 206 nondiabetic Mexican-American (a high-risk population for NIDDM) and 123 nondiabetic non-Hispanic white (a low-risk population for NIDDM) participants in the San Antonio Heart Study, a population-based study of diabetes and cardiovascular disease. Mexican-Americans had significantly higher fasting and 2-h proinsulin and insulin levels but similar fasting proinsulin:insulin ratios compared with non-Hispanic whites. After statistical adjustment for age, body mass index, waist-to-hip ratio, and glucose tolerance status, Mexican-Americans continued to have higher fasting and 2-h insulin and fasting and 2-h proinsulin concentrations but similar proinsulin:insulin ratios compared with non-Hispanic whites. The fasting proinsulin:insulin ratio was higher in 85 subjects with NIDDM compared with subjects with IGT or normal glucose tolerance (0.31, 0.09, and 0.07, respectively). Thus, nondiabetic subjects from a high-risk population for NIDDM are hyperinsulinemic (using an assay that does not cross-react with proinsulin) and, further, do not secrete more proinsulin relative to insulin itself than do nondiabetic subjects from a low-risk population.

Diabetes Mellitus, Type 2↗

PubMed1994

Clinical characteristics of type II diabetic subjects consuming high versus low carbohydrate diets in Mexico City and San Antonio, Texas.

OBJECTIVE: To compare the clinical status of type II diabetic subjects identified in two population-based surveys, one performed in Mexico City, Mexico and the other in San Antonio, Texas. RESEARCH DESIGN AND METHODS: In a low income area of Mexico City, 3,517 age-eligible (35-64 years of age) individuals were randomly selected of whom 3,319 were interviewed at home and 2,198 were examined in a clinic (response rates 62.5%). In San Antonio, 2,357 similarly aged low-income Mexican Americans were randomly selected of whom 2,076 were interviewed at home and 1,511 were examined (response rate 64.1%). Oral glucose tolerance tests were performed at both sites and diabetes was diagnosed according to the World Health Organization (WHO) criteria. In Mexico City, 288 type II diabetic individuals were identified, and 255 were identified in San Antonio. The following variables were measured: height, weight, subscapular and triceps skinfolds, waist-to-hip circumference ratios (WHR), systolic and diastolic blood pressure (random 0 sphygmomanometer), fasting and 2-h postglucose load glucose and insulin concentrations, and fasting total-cholesterol, HDL-cholesterol, and triglyceride (TG) levels. A food frequency questionnaire was used to estimate total calories and the percentage of calories derived from protein, fat, and carbohydrate. Only type II diabetic patients were included in the analyses. Age-adjustment was performed by analysis of covariance for continuous variables and by the Mantel-Haenszel procedure for discrete variables. RESULTS: The mean age, the percentage newly diagnosed cases, and the percentage of males were similar in both sites. The percentage of diabetic patients treated with oral agents was significantly higher in Mexico City (56.9 vs. 72.7% in San Antonio and Mexico City, respectively, P < 0.001), whereas the percentage treated with insulin was significantly higher in San Antonio (18.8 vs. 2.1% for San Antonio and Mexico City, respectively, P < 0.001). A significant difference was observed in the percentage of calories derived from carbohydrate (61.7-63.2 vs. 47.1-47.5% for Mexico City and San Antonio, respectively, P < 0.001) and fat (18.4-20.0 and 30.1-33.0% for Mexico City and San Antonio, respectively, P < 0.001). Body mass index (BMI) was higher in San Antonio (27.6-30.4 vs. 30.2-32.9% for Mexico City and San Antonio, respectively, P < 0.05). Total serum cholesterol was similar at both sites. HDL cholesterol, however, was lower in Mexico City, both in newly and in previously diagnosed patients (30.5-35.8 vs. 39.6-43.3 mg/dl in Mexico City and San Antonio, respectively, P < 0.001). TG levels were higher in Mexico City patients (187-249 vs. 167-179 mg/dl in Mexico City and San Antonio, respectively, P < 0.001). The association between diabetes and the anthropometric and metabolic variables was similar in Mexico City and San Antonio with the following exceptions: Diabetes in Mexico City was associated with less of an elevation in BMI, WHR, and fasting insulin concentration and less of a reduction in the 2-h postoral glucose load insulin concentration compared with diabetes in San Antonio. In addition, although diabetes was associated with a lower HDL in San Antonio subjects, no association appeared between diabetes and HDL in Mexico City subjects. CONCLUSIONS: Diabetic subjects in Mexico City were more likely to be treated with oral agents and less likely to be treated with insulin compared with San Antonio patients. Previously diagnosed diabetic subjects in San Antonio had higher BMIs than diabetic subjects in Mexico City. Diabetic subjects in Mexico City ate less fat but more carbohydrate than those in San Antonio. TG levels were higher and HDL-cholesterol levels were lower in Mexico City diabetic subjects compared with those in San Antonio. San Antonio diabetic subjects had lower HDL levels than nondiabetic subjects but, in Mexico City, HDL levels were similar in diabetic subjects and nondiabetic subjects...

Adult↗

PubMed1994

NIDDM in Mexican-American families. Heterogeneity by age of onset.

OBJECTIVE: Heredity has long been known as a risk factor for non-insulin-dependent diabetes mellitus (NIDDM), but the mode of inheritance of NIDDM remains unclear. We examined the distribution of diabetes in 29 Mexican-American families ascertained on a diabetic proband. RESEARCH DESIGN AND METHODS: Probands represented a random sample of diabetic Mexican Americans residing in low-income neighborhoods from San Antonio, TX. A total of 375 family members of these diabetic probands were examined, and diabetes was diagnosed according to the World Health Organization plasma glucose criteria. RESULTS: The prevalence of diabetes decreased from 28.2% in first-degree relatives of the probands to 13.3% in second-degree relatives to 11.1% in third-degree relatives. When compared with Mexican Americans with no parental history of diabetes, this represents an excess of diabetes of 2.0-, 1.3-, and 1.1-fold in first-, second-, and third-degree relatives, respectively. Five of the 29 probands (17%) had an age of diabetes onset < 40 years. In the first-degree relatives of these early-onset probands, diabetes prevalence was 47.0% (16 of 34) compared with only 24.1% (34 of 141) in the first-degree relatives of the 24 late-onset probands. After adjustment for age, this excess represented a fivefold increase in the odds of diabetes among relatives of the early-onset probands compared with relatives of the late-onset probands (P < 0.001). Moreover, the 16 affected family members of the early-onset probands had a mean age of diabetes onset of 42.7 years compared with 49.9 years for the 34 affected members of the late-onset probands, although this difference was not statistically significant (P = 0.13). CONCLUSIONS: NIDDM may be genetically heterogeneous in this Mexican-American population, with family members of early-onset diabetes patients being at higher risk for NIDDM than family members of late-onset diabetes patients.

Adolescent↗

PubMed1994

Genetic and environmental correlations among skinfold measures.

A bivariate genetic analysis, utilizing variance decomposition techniques based on maximum likelihood methods, was undertaken to examine the genetic and environmental correlations among eight skinfolds in a large pedigreed sample of Mexican Americans from San Antonio, Texas. The resulting correlation coefficients reveal significant values for both the genetic and environmental components among the traits examined. The genetic correlation coefficients showed the highest values between skinfolds from the same region (i.e., triceps, biceps, and forearm), while the environmental correlation remained fairly constant between all traits. These findings are further supported by a principal component analysis of the phenotypic, genetic, and environmental correlation matrices. This represents the first study to partition the phenotypic correlation between these traits into their genetic and environmental components. An examination of the graphical representations of the eigenvectors of these correlation matrices reveals that the patterns of central versus peripheral fat distribution seen in the phenotypic correlation matrix are largely a function of the genetic correlation structure. All these findings are interpreted as evidence of a global pleiotropic effect in the genetic expression of these traits, with what might be secondary regional pleiotropic effects among specific subsets of the skinfolds. In addition it appears that these pleiotropic effects exist against a background of a relatively constant shared environmental effect. It is concluded that these traits are not independent with respect to either shared genetic or environmental influences.

Adolescent↗

PubMed1994

Predictors of weight change in a bi-ethnic population. The San Antonio Heart Study.

To study demographic, anthropometric and metabolic determinants of weight change, we divided a random sample of 1493 Mexican Americans and non-Hispanic whites into two groups: weight gainers and weight losers. This classification was based on the weight change during the eight-year follow-up of participants of the San Antonio Heart Study, a population-based longitudinal study of diabetes and cardiovascular disease. Men gained significantly less weight and lost more weight than women. The average gains for weight gainers were 6.1 kg and 6.8 kg for men and women respectively; and the average losses for weight losers were 4.4 and 3.4 kg for men and women respectively. There was no ethnic difference in either category of weight change. Weight gainers were significantly younger and leaner than weight losers. Fasting insulin was the only independent metabolic predictor of weight change and only among the most obese tertile of the population: the higher the baseline levels of fasting insulin, the less the likelihood of gaining and the greater the likelihood of losing weight. Our results support the hypothesis that insulin resistance is part of a negative feedback mechanism that attenuates further weight gain among the obese.

Adult↗

PubMed1993

Exploring the HDL likelihood surface.

Using random initial parameter estimates, three segregation analysis models of the inheritance of HDL2 in the Berkeley GAW8 data set were maximized 5000 times each. Initial parameter estimates were assumed to be uniformly distributed on intervals formed by parameter boundaries. The three models were unrestricted, environmental, and Mendelian regressive type A models. Likelihood ratio tests of the global maxima rejected the Mendelian model and accepted the environmental model. However, tests using local maxima accepted the Mendelian model and both rejected and accepted the environmental model. Patterns among the initial parameter estimates of convergent runs were examined to develop empirical rules to increase the frequency of convergence. These rules were tested using data on apoAI in the Berkeley GAW8 data set.

Genetic Predisposition to Disease↗

PubMed1993

Is microalbuminuria part of the prediabetic state? The Mexico City Diabetes Study.

Microalbuminuria is associated with increased cardiovascular mortality in both diabetic and non-diabetic subjects. A number of studies have indicated that insulin resistance, increased blood pressure and dyslipidaemia precede the onset of clinical diabetes. We examined various correlates of microalbuminuria in 1,298 non-diabetic subjects who participated in the Mexico City Diabetes Study, a population-based study of diabetes and cardiovascular risk factors. Both parental history of diabetes and impaired glucose tolerance were significantly associated with microalbuminuria. These results were not explained by differences in age or blood pressure between subjects with or without a parental history of diabetes or impaired glucose tolerance. In addition, subjects with microalbuminuria had increased 2-h insulin and triglyceride concentrations, a higher prevalence of hypertension, and decreased high density lipoprotein cholesterol concentrations relative to subjects without microalbuminuria. These results that microalbuminuria may be a feature of the prediabetic state.

Albuminuria↗

PubMed1993

Is there an ethnic difference in the effect of risk factors for diabetic retinopathy?

Mexican Americans have an increased prevalence and incidence of non-insulin-dependent diabetes mellitus (NIDDM). In addition, Mexican American diabetic subjects have an increased prevalence of retinopathy relative to Caucasian diabetic subjects. In Mexican American diabetic subjects, established risk factors may have a stronger effect on diabetic retinopathy, compared to Caucasian diabetic subjects. In this report, we compare the effect of established risk factors (age at examination, gender, age at diagnosis of diabetes, duration of diabetes, glycemia, type of therapy, systolic and diastolic blood pressure, and hypertension prevalence) between Caucasian diabetic subjects (n = 478), a low-risk population for NIDDM (Wisconsin Epidemiologic Study of Diabetic Retinopathy), and Mexican American diabetic subjects (n = 231), a high-risk population for NIDDM (San Antonio Heart Study). Retinopathy was classified into two categories (any or none) as assessed by seven standard stereoscopic retinal photographs read at the University of Wisconsin Reading Center. Mexican American diabetic subjects in Texas had an increased prevalence of any retinopathy (odds ratio = 1.71, 95% confidence interval: 1.25, 2.34), compared to Caucasian diabetic subjects in Wisconsin. Longer duration of diabetes, more severe glycemia, earlier age at diagnosis, and insulin therapy were associated with diabetic retinopathy in both Mexican Americans and Caucasians. Socioeconomic status was not associated with prevalence of retinopathy. Moreover, the effect of risk factors for retinopathy was similar in both ethnic groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Performance of semiquantitative food frequency questionnaires in international comparisons. Mexico City versus San Antonio, Texas.

International dietary comparisons present a number of methodologic difficulties. We developed two semiquantitative food frequency questionnaires for use in Mexico City and San Antonio, Texas. The Mexico City questionnaire contained 85 food items and the San Antonio questionnaire contained 108. Thirty-six items were common to both questionnaires. The questionnaires were administered to 128 Mexican Americans, 35 to 64 years old, residing in a low-income barrio neighborhood of San Antonio and to 644 similarly aged Mexicans residing in a low-income "colonia" of Mexico City. Major differences in fat and carbohydrate intake as a percent of total kilocalories were observed between the two study groups, with Mexico City residents consuming approximately 18 to 21% of calories from fat and 68 to 72% from carbohydrate compared to 29 to 33% from fat and 48 to 52% from carbohydrate for Mexican Americans from San Antonio. Both of these differences were highly statistically significant (P < 0.001). A number of arguments support the validity of these findings. First, the distribution of high- and low-fat foods was similar on both questionnaires. Also, of the top-ten foods (as contributors to total kilocalorie intake) in San Antonio, seven were high in fat (> 30% of kilocalories), whereas this was true of only three of the top-ten foods in Mexico City.

Adult↗

PubMed1993

Incidence of NIDDM and impaired glucose tolerance in hypertensive subjects. The San Antonio Heart Study.

Hypertension often occurs in association with NIDDM and IGT. We examined the association of hypertension at baseline to the 8-yr incidence of NIDDM and IGT in 1471 subjects who participated in the San Antonio Heart Study. Subjects who were hypertensive at baseline had a higher incidence of NIDDM (8.9 vs. 4.9%, P = 0.041) and IGT (25.2 vs. 10.0%, P < 0.001) than subjects who were normotensive at baseline. After adjusting for age, sex, ethnicity, obesity, body fat distribution, fasting glucose, and insulin, this excess was eliminated for NIDDM, but not for IGT. Specifically, the adjusted OR for NIDDM in hypertensive versus normotensive patients was 0.73 (95% Cl 0.34-1.58), whereas the adjusted OR for IGT was 1.87 (95% Cl 1.08-3.22). The excess risk of NIDDM in hypertensive patients can be explained by their greater age, obesity, more unfavorable body fat distribution, and hyperinsulinemia, whereas the excess risk of IGT is independent of these factors.

Adult↗

PubMed1993

Predicting diabetes. Moving beyond impaired glucose tolerance.

We developed predictive models for type II diabetes using stepwise multiple logistic regression analyses of a cohort of 844 Mexican Americans and 641 non-Hispanic whites who were nondiabetic at baseline and who were then followed for 8 yr. Models were developed for the overall population and separately for each sex and ethnic group. For optimal models, the multiple logistic regression program selected potential risk factors from a panel of 5 categorical and 14 continuous demographic, anthropometric, metabolic, and hemodynamic variables. For reduced models, the list of candidate variables was restricted to those commonly used in ordinary clinical practice, i.e., skinfolds, and serum insulin and postural glucose load variables were excluded. For all models, the stepwise process selected a mixture of anthropometric, glucose, lipid, and hemodynamic variables. The top 15% of the risk continuum for each model was defined as high risk to compare the performance of the models with the performance of impaired glucose tolerance (15% prevalence) as a predictor of diabetes. The relative risk of being high risk ranged from 12.16 to 35.29, whereas the relative risk of having impaired glucose tolerance ranged from 7.11 to 10.0. The sensitivity of the multiple logistic regression models ranged from 67.7 to 83.3% compared with 56.5 to 62.1% for impaired glucose tolerance. The results indicate that multivariate predictive models perform at least as well, if not better than impaired glucose tolerance in predicting type II diabetes but need not require an oral glucose load. Moreover, the models highlight the complex metabolic and hemodynamic syndrome that precedes diabetes.

Adult↗

PubMed1993

Stability over time of modern diagnostic criteria for type II diabetes.

OBJECTIVE: To examine the long-term stability of the World Health Organization criteria for diabetes in the 8-yr follow-up of the San Antonio Heart Study. A problem with older criteria for diagnosing diabetes was that many individuals classified as having borderline or chemical diabetes reverted to nondiabetic status on follow-up. Few studies have addressed this issue among diabetic patients who meet the more stringent, modern National Diabetes Data Group or World Health Organization criteria. RESEARCH DESIGN AND METHODS: We studied 98 Mexican-American and 44 non-Hispanic white type II diabetic patients 8 yr after they were diagnosed according to World Health Organization criteria in a population-based epidemiological survey. Patients were classified as follows: whether they were on pharmacological treatment for diabetes at baseline, or, if not, whether they had a prior diagnosis of diabetes at the time of their baseline survey visit or were newly diagnosed. RESULTS: Of the 142 patients who met the study criteria for type II diabetes at baseline and whose status at follow-up was known, 20 (14.1%; 95% confidence interval 9.0-20.5%) no longer met criteria at follow-up 8 yr later. All but 2 of those who reverted to nondiabetic status were from the newly diagnosed group. Two of 20 had lost more than 5.0 kg over the 8 yr and an additional 5 had lost 2.5-5.0 kg. The 20 patients who reverted to nondiabetic status lacked many of the associated anthropometric, physiological, and metabolic findings of diabetes such as obesity, unfavorable body fat distribution, and dyslipidemia. Moreover, only one had proteinuria, and none had any grade of diabetic retinopathy at baseline. CONCLUSIONS: Epidemiological surveys that rely on a single oral glucose tolerance test to determine the prevalence of type II diabetes may overestimate prevalence by as much as 16% (95% confidence interval 10.5-23.6%) (142/122 = 1.16). The actual overestimate could well be less because some patients who truly have diabetes at baseline may be in remission at follow-up as a result of significant weight loss. Despite these difficulties, the modern National Diabetes Data Group and World Health Organization criteria are more stable than earlier criteria.

Adult↗

PubMed1993

Differences in the prevalence of diabetes and impaired glucose tolerance according to maternal or paternal history of diabetes.

OBJECTIVE: To determine whether diabetes risk is influenced by which parent (a parental history of diabetes is a well-documented risk factor for NIDDM) is reported to have diabetes. RESEARCH DESIGN AND METHODS: We compared the prevalence of NIDDM and IGT for 4914 subjects according to their parental history of diabetes (mother only, father only, both parents, neither parent). Subjects were drawn from the San Antonio Heart Study, a population-based survey of diabetes and cardiovascular risk factors conducted in Mexican American and non-Hispanic white individuals between 1979-1988. RESULTS: Men with a parental history of diabetes had a higher prevalence of both NIDDM and impaired glucose tolerance than men reporting no parental history of diabetes. Prevalence was equally high regardless of which parent, or whether both parents, had diabetes. In contrast, in women, only a maternal history of diabetes was associated with a higher prevalence of NIDDM and impaired glucose tolerance. Virtually no difference in NIDDM prevalence was found between women with a paternal-only history of diabetes and women with no parental history of diabetes. CONCLUSIONS: Results differed markedly between men and women. The reason for this sex difference is unclear. It may represent a measurement bias, a sex-specific environmental effect, or a genetic effect that is expressed or transmitted differently between the sexes.

Adult↗

PubMed1993

Clinical gallbladder disease in NIDDM subjects. Relationship to duration of diabetes and severity of glycemia.

OBJECTIVE: To examine the relationship between the prevalence of gallbladder disease and severity of glycemia among diabetic individuals and to provide insight into whether the diabetes-gallstone association is a causal one, because NIDDM patients have an increased prevalence of clinical gallbladder disease. RESEARCH DESIGN AND METHODS: We examined 462 diabetic individuals identified during the San Antonio Heart Study, a population-based survey of diabetes and cardiovascular disease in Mexican Americans and non-Hispanic whites. Diabetes was diagnosed according to National Diabetes Data Group criteria. RESULTS: The prevalence of self-reported gallbladder disease was 34.2% in diabetic women and 7.2% in diabetic men. Although duration of diabetes was positively related to the prevalence of gallbladder disease (P < 0.01), type of therapy was not associated, and fasting glucose concentration was inversely associated with gallbladder disease. CONCLUSIONS: Factors other than hyperglycemia may account for the increased prevalence of gallbladder disease in diabetic subjects.

Adult↗

PubMed1993

A comparison of three methods for assessing Amerindian admixture in Mexican Americans.

Epidemiologic studies have revealed that Mexican Americans experience an excess of non-insulin-dependent diabetes mellitus, gallbladder disease, and obesity relative to non-Hispanic whites. It has been hypothesized that the greater susceptibility of Mexican Americans to these disorders may be related to their greater degree of Amerindian genetic admixture. We evaluate the comparability of three different methods of assessing individual genetic admixture in Mexican Americans. Subjects were enrolled as part of the San Antonio Heart Study and were examined between 1979 and 1988 (n = 3301). Three different methods were used to assess Amerindian admixture: we queried subjects about their ancestors' ethnic origin, we measured subjects' skin color, and we estimated genetic admixture directly by analysis of polymorphic blood markers. These measures were generally poorly correlated with each other, with the highest correlations observed between skin color and proportion of Mexican-origin grandparents. In men, none of these three measures of genetic admixture was associated with the prevalence of diabetes, gallbladder disease, or obesity. In women, consistent positive associations were observed between admixture and all three diseases, regardless of the admixture measure used (ie, disease prevalence was higher among women with more Amerindian admixture). In both sexes, height was negatively correlated with all three measures of admixture, and admixture was also significantly correlated with body mass index and central adiposity in women. These data suggest that the three measures considered may assess different dimensions of admixture, but that for epidemiologic research, no one may be claimed to be superior to the others.

Adult↗

PubMed1992

Lipoprotein(a) concentrations in Mexican Americans and non-Hispanic whites: the San Antonio Heart Study.

There is considerable evidence that lipoprotein(a) (Lp(a)) is a strong independent risk factor for coronary heart disease. Based on their risk factor profile, Mexican Americans have an increased risk of coronary heart disease, yet Mexican Americans have coronary heart disease mortality similar to or lower than that of non-Hispanic whites. The authors therefore attempted to determine whether Mexican Americans had decreased Lp(a) concentrations relative to non-Hispanic whites in the San Antonio Heart Study, a population-based study of diabetes and cardiovascular disease. Lp(a) concentrations (mg/dl) were significantly lower in Mexican Americans (n = 316) than in non-Hispanic whites (n = 242) (men: 10.4 vs. 16.3; women: 11.5 vs. 16.4). In addition, the proportion of persons with Lp(a) concentrations of > or = 30 mg/dl (the threshold at which increased risk of coronary heart disease is believed to occur) was significantly higher in non-Hispanic whites than in Mexican Americans (18.6% vs. 7.6%; Mantel-Haenszel odds ratio (adjusted for sex) = 2.79). Age, obesity, body fat distribution, cigarette smoking, alcohol consumption, and glucose and insulin concentrations were not significantly related to Lp(a) levels. Decreased Lp(a) concentrations may account in part for Mexican Americans' relative protection from coronary heart disease mortality.

Adult↗

PubMed1992

The relation between serum insulin levels and 8-year changes in lipid, lipoprotein, and blood pressure levels.

Hyperinsulinemia is associated with an adverse pattern of cardiovascular risk factors, including obesity, elevated triglyceride levels, low levels of high-density lipoprotein (HDL) cholesterol, and elevated blood pressure. Whether hyperinsulinemia precedes (and perhaps causes) this deterioration in the risk factors or merely accompanies the deterioration is controversial. We therefore examined the 8-year changes in lipids, lipoproteins, and blood pressure as a function of baseline levels of fasting insulin in 1,383 nondiabetic Mexican-American and non-Hispanic white subjects enrolled between October 1979 and November 1982 in the San Antonio Heart Study, a population-based longitudinal study of cardiovascular risk factors and diabetes in San Antonio, Texas. After age and concomitant changes in body mass index were adjusted for, fasting insulin at baseline was found to be correlated positively with 8-year changes in triglyceride levels and negatively with 8-year changes in HDL cholesterol levels (p less than 0.05). Among the non-Hispanic whites, insulin was more strongly correlated with a decline in HDL cholesterol levels in women than in men (p less than 0.001). Fasting insulin was also positively correlated with changes in both systolic and diastolic blood pressure in non-Hispanic whites, but not in Mexican Americans, although these correlations were slightly diminished and no longer achieved statistical significance after subjects receiving antihypertensive medications were excluded. These results support the hypothesis that in nondiabetic subjects, insulin has a direct regulatory effect on triglyceride and HDL cholesterol levels. These data provide evidence for a possible role for insulin in blood pressure regulation, at least in non-Hispanic whites, although further analysis of this issue is warranted.

Adult↗