Type II diabetes and its complications in Mexican Americans

Predictors of Diabetes-Specific Knowledge and Treatment Satisfaction Among Costa Ricans

PURPOSE

The purpose of this study was to identify predictors of disease-specific knowledge and patient satisfaction among adult Costa Ricans with type 2 diabetes. Knowledge differences between Costa Ricans and Spanish-speaking US Latinos also were tested. The psychometric viability of a Spanish-language diabetes knowledge and client satisfaction measure with Costa Ricans was reviewed.

METHODS

The Diabetes Knowledge Questionnaire (DKQ) and the Client Satisfaction Questionnaire (CSQ) were administered to 162 Costa Rican adults with type 2 diabetes who were receiving services in the greater San Jose area. Sociodemographic, medical history, and anecdotal information also was collected.

RESULTS

More years of education, younger age, longer diabetes duration, and home glucose monitoring predicted diabetes knowledge. Home glucose monitoring and treatment with only oral hypoglycemics predicted significantly lower patient satisfaction. Costa Ricans exhibited greater diabetes knowledge than respondents in an earlier study with Spanish-speaking Latinos. CSQ psychometric limitations with Costa Ricans were identified.

CONCLUSIONS

The greater diabetes knowledge among Costa Ricans than US Latinos is likely due to more consistent, stable, and accessible care. Older, less educated, and newly diagnosed Costa Rican diabetes patients require more focused attention.

The Quality of Diabetes Management Among Mexican Adults in California: Does Generational Status Matter?

BACKGROUND

Although there is increasing knowledge regarding the association between generational status on diabetes risk, less is known about the effects of generational status on diabetes management among Mexicans.

OBJECTIVES

We test whether generational status is associated with variations in diabetes processes of care among Mexican adults to optimize disease management.

RESEARCH DESIGN

Weighted multivariate logistic regression was used to test the association between generational status on the quality of diabetes care processes and health care utilization adjusting for socioeconomic/demographic factors. Four generational cohorts were constructed: first generation immigrant; second generation; generation 2.5; and third generation.

SUBJECTS

We conducted analyses of 3072 self-identified foreign and US-born Mexican adults with diabetes who participated in the 2005, 2007, 2009, and 2011/2012 California Health Interview Surveys.

MEASURES

Three diabetes process outcomes were measured, including receipt of at least 1 eye examination, 1 foot examination, or 1 hemoglobin A1C test (HbA1c) in the past year. One secondary prevention outcome was measured, receipt of an annual influenza vaccine. Finally, we measured whether an individual with diabetes received an annual doctor visit.

RESULTS

A gradient of progressively decreased odds of receiving an eye examination and HbA1c test were observed and significant for most of the higher generations. Higher generations also had significantly decreased odds of receiving an annual flu vaccine.

CONCLUSIONS

Data collection on generational granularity and a specific focus on mixed acculturation status can vitally inform health system improvements in diabetes care among Mexicans in the United States.

Improving treatment in Hispanic/Latino patients

The prevalence of type 2 diabetes mellitus is higher in Hispanic/Latino individuals living in the United States compared with their non-Hispanic white counterparts. Many factors contribute to the increased prevalence of type 2 diabetes, including biological characteristics, socioeconomic conditions, and cultural aspects. The contribution of genetics to the risk of type 2 diabetes in Hispanic/Latino patients is becoming increasingly clear, but this inherent risk factor cannot be modified. However, certain socioeconomic and cultural factors, such as reduced access to healthcare, language barriers, cultural beliefs, and lack of cultural competence by the healthcare provider, are modifiable and should be overcome in order to improve the management of type 2 diabetes in Hispanic/Latino patients. At the healthcare system level, policies should be put into place to reduce disparities between Hispanics/Latinos and non-Hispanic whites regarding health insurance coverage and access to healthcare. At the healthcare provider and patient level, cultural beliefs should be taken into consideration when selecting adequate treatment. Overall, type 2 diabetes management should be individualized by identifying the preferred language and level of acculturation for each patient. These considerations are necessary to further improve communication through culturally appropriate educational materials and programs. These strategies may help to overcome the barriers in the treatment of type 2 diabetes in Hispanic/Latino patients.

Understanding the Hispanic/Latino patient

The Hispanic/Latino population is the largest minority group in the United States, representing approximately 16% of the population in 2010. The US Census Bureau defines Hispanic/Latino origin as ethnicity, which tends to be associated with culture and is distinct from race. Based on the US Census Bureau classifications, Hispanics/Latinos have at least 3 main racial backgrounds (white, black, and Native Indian), with the combination and proportion differing among Hispanic/Latino subgroups. The reflection of these racial differences in genetic ancestry partly explains why biological characteristics differ among Hispanic/Latino subgroups. Partly as a result of variations in biological characteristics, the risk of type 2 diabetes mellitus varies among Hispanic/Latino subgroups. According to data from the 1982 to 1984 Hispanic Health and Nutrition Examination Survey (HHANES), the prevalence of diagnosed and undiagnosed type 2 diabetes among adults aged 45 to 74 years was higher in Mexican Americans (23.9%) and Puerto Ricans (26.1%) compared with Cubans (15.8%). In addition to genetics, there are multiple social and cultural factors that affect the prevalence and course of type 2 diabetes in Hispanic/Latino individuals. Although certain aspects of Hispanic/Latino culture may become barriers in the management of type 2 diabetes in this population, these cultural characteristics may also represent an opportunity for prevention and/or improvement of care. It is important for healthcare providers to have an understanding and appreciation of Hispanic/Latino culture in order to provide their Hispanic/Latino patients with healthcare that is culturally and socially appropriate. Only by considering genetic, social, and cultural factors can type 2 diabetes be successfully prevented, treated, and managed in Hispanic/Latino patients.

Unmet needs in Hispanic/Latino patients with type 2 diabetes mellitus

In the United States, the prevalence of adults who are overweight or obese is higher in Hispanics/Latinos compared with non-Hispanic whites. In addition, data from the National Health and Nutrition Examination Survey (NHANES) indicate that the prevalence of type 2 diabetes mellitus is consistently greater in racial/ethnic minority groups, such as Hispanics/Latinos, compared with non-Hispanic whites. In fact, data from the Centers for Disease Control and Prevention (CDC) from 2007 to 2009 suggest that the prevalence of type 2 diabetes is almost twice as high in Hispanics/Latinos compared with non-Hispanic whites (11.8% vs. 7.1%, respectively). Although genetics plays a role in the increased prevalence of type 2 diabetes in Hispanics/Latinos, cultural and environmental factors also contribute. In addition to the increased prevalence of type 2 diabetes in Hispanics/Latinos, evidence suggests that the patients in this population are often undertreated and, therefore, less likely to achieve control of their glucose, blood pressure, and lipid levels. Because individuals with type 2 diabetes have a 2- to 4-fold increased risk of cardiovascular disease compared with individuals with normal glucose levels, there is consensus that targeting environmental factors, particularly the development of obesity at an early age, is the most cost-effective approach to prevent the development of type 2 diabetes and its broad spectrum of complications, including cardiovascular disease. Cultural and socioeconomic barriers, such as language, cost, and access to goods and services, must be overcome to improve management of type 2 diabetes in this high-risk population. By increasing healthcare provider awareness and the availability of programs tailored to Hispanic/Latino individuals, the current treatment gap among ethnic minorities in the United States will progressively narrow, and eventually, disappear.

Type 2 diabetes among rural Hispanics in Washington State: perspectives from community stakeholders

During February-March 2006, elicitation interviews were conducted with 23 community stakeholders in the Yakima Valley, Washington State, to examine concerns about diabetes and to obtain recommendations for how to address concerns among Hispanics in this rural community. Using a snowball approach, stakeholders were identified from organizations providing care and outreach for Hispanics with diabetes. Interviews were guided by a social ecology approach and were conducted as part of a larger parent study using principles of community-based participatory research. Audiotaped interviews were transcribed and then coded by three staff members who identified common themes independently before meeting to reach consensus. Stakeholders represented health care delivery or social service organizations, churches, or local radio stations. Diabetes was perceived as an important problem among community members, who often underwent delayed diagnosis of the disease. Lack of disease knowledge, access to appropriate information or services, health insurance, and personal responsibility were perceived as barriers. Stakeholders recommended using exiting organizations and businesses as intervention channels, promoting cultural sensitivity of health professionals and volunteers, creating and distributing appropriate information, and organizing activities to promote awareness and disease management. Recommendations have informed the design of community interventions to lessen the impact of diabetes in the Yakima Valley.

O-GlcNAc cycling: emerging roles in development and epigenetics

The nutrient-sensing hexosamine signaling pathway modulates the levels of O-linked N-acetylglucosamine (O-GlcNAc) on key targets impacting cellular signaling, protein turnover and gene expression. O-GlcNAc cycling may be deregulated in neurodegenerative disease, cancer, and diabetes. Studies in model organisms demonstrate that the O-GlcNAc transferase (OGT/Sxc) is essential for Polycomb group (PcG) repression of the homeotic genes, clusters of genes responsible for the adult body plan. Surprisingly, from flies to man, the O-GlcNAcase (OGA, MGEA5) gene is embedded within the NK cluster, the most evolutionarily ancient of three homeobox gene clusters regulated by PcG repression. PcG repression also plays a key role in maintaining stem cell identity, recruiting the DNA methyltransferase machinery for imprinting, and in X-chromosome inactivation. Intriguingly, the Ogt gene resides near the Xist locus in vertebrates and is subject to regulation by PcG-dependent X-inactivation. OGT is also an enzymatic component of the human dosage compensation complex. These 'evo-devo' relationships linking O-GlcNAc cycling to higher order chromatin structure provide insights into how nutrient availability may influence the epigenetic regulation of gene expression. O-GlcNAc cycling at promoters and PcG repression represent concrete mechanisms by which nutritional information may be transmitted across generations in the intra-uterine environment. Thus, the nutrient-sensing hexosamine signaling pathway may be a key contributor to the metabolic deregulation resulting from prenatal exposure to famine, or the 'vicious cycle' observed in children of mothers with type-2 diabetes and metabolic disease.

Illness Beliefs Regarding the Causes of Diabetes among Latino College Students

This study examined the validity of the Klonoff and Landrine (1994) illness-belief scale when applied to Latino college students (n=156; 34% male, 66% female) at high-risk for future diabetes onset. Principal factor analysis yielded four significant factors - emotional, folk-beliefs, punitive, gene/hereditary - which accounted for 64.5% of variance and provided a culturally-relevant Latino perspective of the causes of diabetes. Additional analyses by age, gender, immigrant status and psychological acculturation revealed significant differences by age on the emotional and folk illness factors and a negative correlation between assimilation and endorsement of the emotional factor. The implication of these four illness factors for predicting health-related behaviors and health-outcomes among young Latinos was discussed as were recommendations for future research.

Development of the Jackson Heart Study Coordinating Center

The public health burden caused by cardiovascular disease (CVD) continues to adversely affect individuals in terms of cost, life expectancy, medical, pharmaceutical and hospital care. This burden has been excessive in the case of African Americans. The objective of this paper is to chronicle the procedures and processes that were implemented in the development of the Jackson Heart Study Coordinating Center. The Jackson Heart Study (JHS) is a population-based investigation of traditional and emerging risk factors that predict progression to CVD among African Americans. In response to the struggle against CVD, the Jackson Heart Study has convened a professional, technical, and administrative staff with specific competence in the operation of a coordinating center to handle the wide variety of areas related to CVD studies. The Jackson Heart Study Coordinating Center (JHSCC) was created to assure validity of the JHS findings and provide the resources necessary to meet comprehensive statistical needs (planning, implementing and monitoring data analysis); data management (designing, implementing and managing data collection and quality control), and administrative support. The JHSCC began with a commitment to support study functions in order to increase participant recruitment, retention and safety, meet regulatory requirements, prepare progress reports, and facilitate effective communication with the community and between all JHS centers. The JHSCC facilitates the efforts of the JHS scientists through the development and implementation of the study protocol. The efforts of the JHSCC have resulted in the successful preparation of scientific reports and manuscripts for publication and presentation of study findings and results. In summary, the JHSCC has emerged as an effective research mechanism that serves as the driving force behind the Jackson Heart Study activities.

Population-based case-control study of diabetes and breast cancer risk in Hispanic and non-Hispanic White women living in US southwestern states

Diabetes mellitus has been associated with breast cancer, although no studies appear to have adequately assessed the association in Hispanic women, a population with a high prevalence of diabetes. The authors investigated this association in a population-based case-control study of Hispanic and non-Hispanic White women living in the southwestern United States. Breast cancer cases diagnosed in 1999-2004 were identified through state cancer registries (1,526 non-Hispanic Whites, 798 Hispanics). Age- and ethnicity-matched controls (1,599 non-Hispanic Whites, 924 Hispanics) were selected from commercial mailing lists and driver's license and Social Security records. Diabetes history was assessed through interviewer-administered questionnaires. Odds ratios and 95% confidence intervals were calculated using logistic regression, adjusting for age, body mass index at age 15 years, and parity. Having any type of diabetes was not associated with breast cancer overall (odds ratio = 0.94, 95% confidence interval: 0.78, 1.12). Type 2 diabetes was observed among 19% of Hispanics and 9% of non-Hispanic Whites but was not associated with breast cancer in either group. Gestational diabetes was inversely associated with breast cancer in both ethnic groups, especially when first diagnosed at age < or =35 years (odds ratio = 0.54, 95% confidence interval: 0.37, 0.79). In this study, diabetes was not associated with breast cancer overall, although the inverse association with gestational diabetes warrants further investigation.

Lack of excess maternal transmission of type 2 diabetes in a Korean population

The purpose of this study was to assess the familial clustering of type 2 diabetes and to investigate the presence of excess maternal transmission of type 2 diabetes in Korea. The medical records of 56,492 subjects (31,680 men and 24,812 women), who attended the Health Promotion Center were examined. The subjects were questioned about their parents' diabetes status. All study subjects were classified into the three groups (normal fasting glucose (NFG), impaired fasting glucose (IFG), and diabetes). Offspring with paternal diabetes (odds ratio 2.54, 95% CI 2.22-2.91, P < 0.001) and those with maternal diabetes (odds ratio 3.10, 95% CI 2.76-3.49, P < 0.001) were at increased risk for diabetes when compared to subjects without parental diabetes and adjusted for other clinical and biochemical variables. Offspring with bilineal parental diabetes were at a greater risk for diabetes (odds ratio 6.09, 95% CI 4.55-8.16, P < 0.001) when compared to subjects without parental diabetes. In both genders, offspring with maternal diabetes showed no increased risk for diabetes (odds ratio 1.22, 95% CI 0.92-1.37, P + 0.266 in men; odds ratio 1.31, 95% CI 0.95-1.81, P = 0.104 in women) when compared with those with paternal diabetes. The data suggested that parental type 2 diabetes was an independent risk factor for offspring type 2 diabetes in this Korean population. Excess maternal transmission of type 2 diabetes was not observed.

Evidence of a novel quantitative-trait locus for obesity on chromosome 4p in Mexican Americans

Although several genomewide scans have identified quantitative-trait loci influencing several obesity-related traits in humans, genes influencing normal variation in obesity phenotypes have not yet been identified. We therefore performed a genome scan of body mass index (BMI) on Mexican Americans, a population prone to obesity and diabetes, using a variance-components linkage analysis to identify loci that influence BMI. We used phenotypic data from 430 individuals (26% diabetics, 59% females, mean age +/- SD = 43 +/- 17 years, mean BMI +/- SD = 30.0 +/- 6.7, mean leptin (ng/ml) +/- SD = 22.1 +/- 17.1) distributed across 27 low-income Mexican American pedigrees who participated in the San Antonio Family Diabetes Study (SAFDS) for whom a 10-15-cM map is available. In this genomewide search, after accounting for the covariate effects of age, sex, diabetes, and leptin, we identified a genetic region exhibiting the most highly significant evidence for linkage (LOD 4.5) with BMI on chromosome 4p (4p15.1) at 42 cM, near marker D4S2912. This linkage result has been confirmed in an independent linkage study of severe obesity in Utah pedigrees. Two strong positional candidates, the human peroxisome proliferator-activated receptor gamma coactivator 1 (PPARGC1) and cholecystokinin A receptor (CCKAR) with major roles in the development of obesity, are located in this region. In conclusion, we identified a major genetic locus influencing BMI on chromosome 4p in Mexican Americans.

Behavioral, metabolic, and molecular correlates of lower insulin sensitivity in Mexican-Americans

We determined whether lower insulin sensitivity persists in young, nonobese, nondiabetic Mexican-American [MA; n = 13, 27.0 +/- 2.0 yr, body mass index (BMI) 23.0 +/- 0.7] compared with non-Hispanic white (NHW; n = 13, 24.8 +/- 1.5 yr, BMI 22.8 +/- 0.6) males and females after accounting for cardiorespiratory fitness (maximal O(2) uptake), abdominal fat distribution (computed tomography scans), dietary intake (4-day records), and skeletal muscle insulin-signaling protein abundance from muscle biopsies (Western blot analysis). MA were significantly less insulin sensitive compared with their NHW counterparts when estimated by homeostatic model assessment of insulin resistance (MA: 1.53 +/- 0.22 vs. NHW: 0.87 +/- 0.16, P < 0.05) and the revised quantitative insulin sensitivity check index (MA: 0.45 +/- 0.08 vs. NHW: 0.58 +/- 0.19, P = 0.05). However, skeletal muscle protein abundance of insulin receptor-beta (IRbeta), phosphatidylinositol 3-kinase p85 subunit, Akt1, Akt2, and GLUT4 were not significantly different. Differences in indexes of insulin sensitivity lost significance after percent dietary intake of palmitic acid, palmitoleic acid, and skeletal muscle protein abundance of IRbeta were accounted for. We conclude that differences in insulin sensitivity between nonobese, nondiabetic MA and NHW persist after effects of chronic and acute exercise and total and abdominal fat distribution are accounted for. These differences may be mediated, in part, by dietary fat intake.

Evaluation of the institutionalization of the coordinated approach to child health (CATCH) in a U.S./Mexico border community

El Paso Coordinated Approach to Child Health (El Paso CATCH) was evaluated in 24 schools for outcome measures of moderate to vigorous physical activity (MVPA) during physical education (PE), content of PE lessons, content of school meals, and numerous process measures. Chi-square analyses compared frequency data across time for activity during PE and percentage fat in school meals. Descriptive summaries were used for process questionnaire results. Data were also compared to CATCH program goals. For most intervention schools, El Paso CATCH significantly increased MVPA, decreased fat in school meals, and decreased sodium in school breakfasts. However, some schools were not meeting the fat content goals for school lunches, and no schools met the vigorous physical activity (VPA) goals for PE or the sodium goals for school lunches.

Effects of hyperinsulinemia and obesity on risk of neural tube defects among Mexican Americans

Although both maternal obesity and diabetes mellitus increase the risk for neural tube defects, it is unknown whether they are independent risk factors or manifestations of an underlying prediabetic state such as hyperinsulinemia. We investigated whether hyperinsulinemia was a risk factor for neural tube defects independent of obesity and hyperglycemia in Mexican-American women. We identified case and control women from residents delivering or terminating pregnancies in hospitals or birthing centers in any of the 14 Texas-Mexico border counties during 1995-2000. Case women had a pregnancy affected by anencephaly, spina bifida, or encephalocele; randomly selected control women had normal births, frequency matched by year and birth facility. Questionnaire and laboratory values obtained 5-6 weeks postpartum were available for 149 case and 178 control women. Both hyperinsulinemia and obesity were related to increased neural tube defect risk [odds ratio (OR) = 1.91, 95% confidence interval (CI) = 1.21-3.01 and OR = 1.73, 95% CI = 1.03-2.92, respectively]. Adjustment for obesity only slightly reduced the effect of hyperinsulinemia (OR = 1.75, 95% CI = 1.09-2.82). Alternatively, a modest effect remained for obesity after adjustment for hyperinsulinemia (OR = 1.45, 95% CI = 0.84-2.51). Hyperinsulinemia is a strong risk factor for neural tube defects and may be the driving force for the observed risk in obese women.

A major locus for fasting insulin concentrations and insulin resistance on chromosome 6q with strong pleiotropic effects on obesity-related phenotypes in nondiabetic Mexican Americans

Insulin resistance and hyperinsulinemia are strong correlates of obesity and type 2 diabetes, but little is known about their genetic determinants. Using data on nondiabetics from Mexican American families and a multipoint linkage approach, we scanned the genome and identified a major locus near marker D6S403 for fasting "true" insulin levels (LOD score 4.1, empirical P<.0001), which do not crossreact with insulin precursors. Insulin resistance, as assessed by the homeostasis model using fasting glucose and specific insulin (FSI) values, was also strongly linked (LOD score 3.5, empirical P<.0001) with this region. Two other regions across the genome were found to be suggestively linked to FSI: a location on chromosome 2q, near marker D2S141, and another location on chromosome 6q, near marker D6S264. Since several insulin-resistance syndrome (IRS)-related phenotypes were mapped independently to the regions on chromosome 6q, we conducted bivariate multipoint linkage analyses to map the correlated IRS phenotypes. These analyses implicated the same chromosomal region near marker D6S403 (6q22-q23) as harboring a major gene with strong pleiotropic effects on obesity and on lipid measures, including leptin concentrations (e.g., LOD(eq) for traits-specific insulin and leptin was 4.7). A positional candidate gene for insulin resistance in this chromosomal region is the plasma cell-membrane glycoprotein PC-1 (6q22-q23). The genetic location on chromosome 6q, near marker D6S264 (6q25.2-q26), was also identified by the bivariate analysis as exerting significant pleiotropic influences on IRS-related phenotypes (e.g., LOD(eq) for traits-specific insulin and leptin was 4.1). This chromosomal region harbors positional candidate genes, such as the insulin-like growth factor 2 receptor (IGF2R, 6q26) and acetyl-CoA acetyltransferase 2 (ACAT2, 6q25.3-q26). In sum, we found substantial evidence for susceptibility loci on chromosome 6q that influence insulin concentrations and other IRS-related phenotypes in Mexican Americans.

Genome partitioning and whole-genome analysis

Standard DNA marker-based approaches to mapping genes that influence complex traits typically consider a limited number of hypotheses. Most of these hypotheses concentrate on the effect of a single individual locus (or relatively few loci) on the trait of interest. Although of tremendous importance scientifically, such hypotheses do not accommodate the full range of genetic phenomena that may contribute to phenotypic expression. We present novel approaches to complex trait analysis that make as complete use of marker information as is possible. The proposed methodologies can be used to entertain a wide variety of hypotheses, including those that engage, for example, the contribution of a particular chromosome, genome-wide heterozygosity, and multiple genomic regions, to phenotypic expression. We consider a number of possible extensions of the proposed methods as well as their limitations. Although we discuss many methodological details in the context of quantitative trait locus mapping involving sampling units such as human pedigrees and hybrids resulting from crosses between inbred strains of model organisms, our procedures can be easily adapted to standard sibpair and other sampling unit-based designs. Ultimately, the proposed approaches not only have the potential to increase power to identify individual loci that harbor trait-influencing genes, but also present a framework for testing a number of hypotheses about the nature of the genetic determinants of phenotypes in general.

A major susceptibility locus influencing plasma triglyceride concentrations is located on chromosome 15q in Mexican Americans

Although several genetic forms of rare or syndromic hypertriglyceridemia have been reported, little is known about the specific chromosomal regions across the genome harboring susceptibility genes for common forms of hypertriglyceridemia. Therefore, we conducted a genomewide scan for susceptibility genes influencing plasma triglyceride (TG) levels in a Mexican American population. We used both phenotypic and genotypic data from 418 individuals distributed across 27 low-income, extended Mexican American families. For the analyses, TG values were log transformed (ln TG). We used a variance-components technique to conduct multipoint linkage analyses for localizing susceptibility genes that determine variation in TG levels. We used an approximately 10-15-cM map, which was made on the basis of information from 295 microsatellite markers. After accounting for the effects of sex and sex-specific age terms, we found significant evidence for linkage (LOD = 3.88) of ln TG levels to a genetic location between the markers GABRB3 and D15S165 on chromosome 15q. This putative locus explains 39.7+/-7% (P=.000012) of total phenotypic variation in ln TG levels. Suggestive evidence was found for linkage of ln TG levels to two different locations on chromosome 7, which are approximately 85 cM apart from each other. Also, there is some evidence for linkage of high-density lipoprotein cholesterol concentrations to a genetic location near one of the regions on chromosome 7. In conclusion, we found strong evidence for linkage of ln TG levels to a genetic location on chromosome 15q in a Mexican American population, which is prone to disease conditions such as type 2 diabetes and the insulin-resistance syndrome that are associated with hypertriglyceridemia. This putative locus appears to have a major influence on ln TG variation.

Linkage of type 2 diabetes mellitus and of age at onset to a genetic location on chromosome 10q in Mexican Americans

Since little is known about chromosomal locations harboring type 2 diabetes-susceptibility genes, we conducted a genomewide scan for such genes in a Mexican American population. We used data from 27 low-income extended Mexican American pedigrees consisting of 440 individuals for whom genotypic data are available for 379 markers. We used a variance-components technique to conduct multipoint linkage analyses for two phenotypes: type 2 diabetes (a discrete trait) and age at onset of diabetes (a truncated quantitative trait). For the multipoint analyses, a subset of 295 markers was selected on the basis of optimal spacing and informativeness. We found significant evidence that a susceptibility locus near the marker D10S587 on chromosome 10q influences age at onset of diabetes (LOD score 3.75) and is also linked with type 2 diabetes itself (LOD score 2.88). This susceptibility locus explains 63.8%+/-9.9% (P=. 000016) of the total phenotypic variation in age at onset of diabetes and 65.7%+/-10.9% (P=.000135) of the total variation in liability to type 2 diabetes. Weaker evidence was found for linkage of diabetes and of age at onset to regions on chromosomes 3p, 4q, and 9p. In conclusion, our strongest evidence for linkage to both age at onset of diabetes and type 2 diabetes itself in the Mexican American population was for a region on chromosome 10q.

Pathogenesis of non-insulin-dependent (type II) diabetes mellitus (NIDDM) - genetic predisposition and metabolic abnormalities

Non-insulin-dependent diabetes mellitus (NIDDM), also known as type II diabetes, is characterized by abnormal glucose homeostasis, resulting in hyperglycemia, and is associated with microvascular, macrovascular, and neuropathic complications. NIDDM is a complex disease with many causes. Both genetic and environmental factors play important roles in the pathogenesis of NIDDM. Cumulative evidence on the high prevalence of NIDDM in certain ethnic groups, the high concordance rate for the disease in monozygotic twins, familial aggregation, and familial transmission patterns suggests that the genetic component plays an important etiological role in the development of NIDDM. In genetically predisposed individuals, there is a slow progression from a normal state to hyperglycemia, largely due to a combination of insulin resistance and defects in insulin secretion. Although numerous candidate genes responsible for insulin resistance and for the defects in insulin secretion have been reported, no specific gene(s) accounting for the majority of cases of the common type of NIDDM has been identified. Considerable evidence indicates that environmental and other factors, including diet, stress, physical activity, obesity and aging, also play an important role in the development of the disease. In conclusion, the pathogenic process of NIDDM depends on a complex interaction between genetic and environmental factors.

Lower-extremity functioning in older Mexican Americans and its association with medical problems

OBJECTIVE

To describe lower-extremity functioning in community-dwelling older Mexican Americans and to examine its relationship with medical problems.

DESIGN

Cross-sectional analyses of survey and performance-based data obtained in a population-based study employing area probability sampling.

SETTING

Households within selected census tracts of five Southwestern states: Arizona, California, Colorado, New Mexico, and Texas.

PARTICIPANTS

A total of 2873 Mexican Americans aged 65 years and older.

MEASUREMENTS

A multidimensional questionnaire assessing demographic, sociocultural, and health variables. Standardized tests of lower-extremity physical functioning included measures of standing balance, repeated chair stands, walking, and an overall summary measure.

RESULTS

Regression analyses revealed that being more than age 75 and female, having arthritis diabetes, visual impairments, or being obese or underweight were all significantly associated with performance on both individual and summary tests of lower-extremity functioning. In separate regression analyses, the total number of medical conditions was also associated with performance.

CONCLUSIONS

The likelihood of predicting performance or inability to complete tests of lower-extremity functioning was greatest for those aged 80 and older, those with arthritis or diabetes, and those with three or more medical conditions. Because of the high prevalence of diabetes in Mexican Americans, documentation of the association of diabetes with performance-based tests of lower-extremity functioning may help guide early interventions targeted to prevent progression to more severe limitations or disability.

Summary measures of the insulin resistance syndrome are adverse among Mexican-American versus non-Hispanic white children: the Corpus Christi Child Heart Study

BACKGROUND

Mexican-American (MA) adults are known to have a greater burden of diabetes and insulin resistance than non-Hispanic white (NHW) people. In this report, we examined data obtained from MA and NHW third-grade children for evidence of a pattern consistent with the insulin resistance syndrome. In addition, we developed two summary measures characterizing insulin resistance syndrome to compare measures of this syndrome among our population.

METHODS AND RESULTS

Data regarding fasting insulin, triglycerides, HDL cholesterol, systolic blood pressure, and body mass index (BMI) were available for 403 third-grade children. Median levels of insulin and glucose were significantly higher in MA boys and girls than in NHW boys and girls. Risk factors characterizing insulin resistance, including levels of insulin, triglycerides, systolic blood pressure, HDL cholesterol, and BMI were categorized as above or below the total population median. MA children were more likely than NHW children to have three or more adverse risk factors (55% versus 37%). When risk factors were converted to Z scores, and the five Z scores were summed for each individual, MA boys and girls had higher mean scores than NHW boys and girls (means for boys, 0.65 versus -0.97, P<.0001; girls, 0.52 versus -0.30, P<.04). Principal components analysis was used to create a summary score or index representing the insulin resistance syndrome. This summary score was significantly higher among MA boys and girls than NHW boys and girls (means for boys, 0.34 versus -0.72, P<.0001; girls, 0.35 versus -0.04, P=.056).

CONCLUSIONS

Our results support the hypothesis that MA children exhibit a greater degree of the insulin resistance syndrome than NHW children, especially among boys. We conclude that some of the factors responsible for the increased risk of NIDDM seen among MA adults are demonstrable in childhood.

Cardiovascular risk factors in Mexican-American and non-Hispanic white children: The Corpus Christi Child Heart Study

BACKGROUND

Information concerning differences in cardiovascular disease risk factors between Mexican-American and non-Hispanic white children is limited. We conducted a study to determine if there were ethnic differences in cardiovascular disease risk factors in children and whether such differences were explained by differences in body mass index.

METHODS AND RESULTS

Fasting glucose, insulin, and blood lipid concentrations, blood pressure, weight, and height were measured in a cross-sectional survey among 403 third-grade children in Corpus Christi, Tex. We found significantly higher fasting insulin and glucose concentrations among Mexican-American than among non-Hispanic white children. Mexican-American boys had slightly lower levels of HDL cholesterol and higher systolic blood pressure than non-Hispanic white boys. Ethnic differences in insulin and glucose were not explained by body mass index.

CONCLUSIONS

These results provide preliminary evidence that ethnic differences in insulin, glucose, body mass index, and other risk factors occur as early as age 8 to 10 years. Additional research is warranted on differences in risk factors in Mexican-American and non-Hispanic white children and the potential importance of insulin in influencing the natural history of these characteristics.

The effect of medical conditions on the functional limitations of Mexican-American elderly

We examined the relationship of self-reported functional status to common medical conditions using a probability sample of 3050 noninstitutionalized Mexican-American men and women aged 65 or older and residing in the Southwestern United States (Arizona, California, Colorado, New Mexico, and Texas). All subjects were interviewed in person (n = 2,873) or by proxy (n = 177) in their homes during late 1993 and early 1994. The questionnaire obtained information on self-reported functional status and prevalence of arthritis, cancer, diabetes, stroke, heart attack, and hip fracture. The prevalence of medical conditions ranged from 4.1% for hip fracture to 40.8% for arthritis. Prevalence of impairments in seven activities of daily living ranged from 5.4% for eating to 11.7% for bathing, while 25.1% could not walk up and down stairs, and 28.9% could not walk a half mile without help. In multiple logistic regression analyses, previous diagnoses of stroke and hip fracture were most predictive of functional limitations, though all conditions examined (arthritis, cancer, diabetes, stroke, heart attack, and hip fracture) were independently associated with increased odds of impairment in some activities of daily living. In general, the odds for functional impairment associated with specific medical conditions were higher than those previously published for non-Hispanic white populations. The fact that Mexican-American elderly who live in the community and who have medical conditions, especially stroke and hip fracture, are at high risk for functional impairment probably reflects the low rate of institutionalization in this population and has implications for the provision of community-based long-term care services for Mexican-American elderly.

Evidence for linkage of regions on chromosomes 6 and 11 to plasma glucose concentrations in Mexican Americans

The genetic factors involved in type II diabetes are still unknown. To address this problem, we are creating a 10 to 15 cM genetic map on 444 individuals from 32 Mexican American families ascertained on a type II diabetic proband. Using highly polymorphic microsatellite markers and a multipoint variance components method, we found evidence for linkage of plasma glucose concentration 2 hr after oral glucose administration to two regions on chromosome 11: beta-hemoglobin (HBB) and markers D11S899/D11S1324 near the sulfonylurea receptor (SUR) gene. Iod scores at these two loci were 2.77 and 3.37, respectively. The SUR gene region accounted for 44.7% of the phenotypic variance. Evidence for linkage to fasting glucose concentration was also observed for two loci on chromosome 6, one of which is identical to a proposed susceptibility locus for type I diabetes (D6S290). When diabetics were excluded from the analyses, all Iod scores became zero, suggesting that the observed linkages were with the trait diabetes rather than with normal variation in glucose levels. Results were similar whether all diabetics were included in the analyses or only those who were not under treatment with oral antidiabetic agents or insulin.

Differential impact of obesity in related populations

To search for genetic and environmental determinants of obesity, we compared the prevalences and the impact of obesity in three populations from two cities: Mexican Americans (n = 820) and non-Hispanic whites (n = 1112) from San Antonio, Texas, and Mexicans from Mexico City (n = 1878). In the age range examined, 35-64 years, only Mexican men and women showed a significant increase in the prevalence of obesity with age. On the other hand, genetic ancestry, especially in women, made significant differences in the rates of obesity. Mexican Americans showed relatively high, and non-Hispanic whites low, rates of obesity. To discriminate between genetic and environmental influences mediating the impact of obesity on a set of hemodynamic and metabolic variables, we compared this impact between Mexican Americans and both non-Hispanic whites (same macro-environment, different gene pools), and Mexicans (same gene pool, different environments). We found that obesity always worsens the hemodynamic and metabolic profiles of individuals, but the magnitude of the effects may be variable. We showed that the levels of insulin concentrations for a given level of obesity were similar in Mexicans and Mexican Americans, suggesting that genetic influences predominate in determining insulin levels; the levels of triglycerides and HDL for a given level of obesity were similar in Mexican Americans and non-Hispanic whites, suggesting predominant environmental influences on lipid levels. On the other hand, the levels of glucose and systolic blood pressure for a given level of obesity were usually different between Mexican Americans and either of the other two populations, suggesting that these levels may result from genotype-by-environment interactions.

Diabetes care needs of Hispanic patients treated at inner-city neighborhood clinics in New York City

The charts of 254 Hispanic patients were selected from a sample of 321 patients with diabetes in four urban clinics that received federal funding to provide medical care in underserved communities. A standardized chart-audit protocol was used to assess the process of healthcare delivery and the presence of diabetes-associated comorbidities and complications in patients. Inconsistent recognition of obesity (11% identified vs 59% present), hyperlipidemia (17% identified vs 69% present), and renal dysfunction (3.5% identified vs 16% present) was evident on chart review. We also found inadequate compliance with current recommendations for diabetes care with respect to routine health screenings for diabetes-related complications, recognition of comorbid diagnoses, and referral of patients for recommended specialty consultations. Issues specific to the varied Hispanic populations may need to be considered to improve the delivery of diabetes care for the growing Hispanic population with diabetes.

Racial admixture in a Mestizo population from Mexico City

Seven genetic systems were used to investigate the racial composition of a sample from a low-income Mexico City Mestizo group, finding estimates of 0.590, 0.348, and 0.062 of Indian, White, and Black ancestry, respectively. The results are similar to another Mexico City group studied previously and to several Mestizo populations from different parts of the country. The one thing in common in all these groups is low socioeconomic status. There is only one report suggesting that Mexico City Mestizos have around 70% White ancestry, and there is reason to believe the sample was taken from a high socioeconomic group. It is suggested that low socioeconomic Mexican Mestizo groups are characterized by a high Indian ancestry, above 50%. © 1995 Wiley-Liss, Inc.

Vascular complications in non-insulin dependent diabetics in Thailand. Thai Multicenter Research Group on Diabetes Mellitus

Ten hospitals participated in a cross-sectional study to determine the prevalence of vascular complications in non-insulin dependent diabetes mellitus (NIDDM). The patients were 1433 females and 627 males, aged 24-88 years (mean +/- S.D. = 58.0 +/- 9.9). Duration of diabetes varied from newly diagnosed to 42 years (mean +/- S.D. = 8.2 +/- 6.5). Obesity was noted in 16.9% of males and 27.4% of females. The prevalence of hypertension, myocardial infarction (MI), hemiplegia, absent dorsalis pedis pulse, gangrene and amputation were 38.4, 2.8, 3.7, 5.8, 0.3 and 1.3%, respectively. Diabetic retinopathy (DR) was found in 32.1% of the patients. Proteinuria of > or = 2+ was observed in 18.7% of the patients. Stepwise multiple logistic regression analysis revealed that hypertension was significantly and independently correlated with MI, hemiplegia and DR but not with proteinuria or absent dorsalis pedis pulse. DR and proteinuria had a strong correlation with each other. Age of the patients weakly correlated with macrovascular diseases. Diabetic control and duration showed a weak correlation with microvascular complications. This study showed that DR was frequently found in Thai NIDDM. Hypertension was not only the commonest disorder but it also showed an independent association with other vascular complications. Early detection and intervention for both need to be emphasized and re-enforced in clinical practice.

Birthweight and adult health outcomes in a biethnic population in the USA

Recent data indicate that low-birthweight adults are at a higher risk than their high-birthweight peers of developing ischemic heart disease or a cluster of conditions known as the IRS, which includes dyslipidaemias, hypertension, unfavorable body fat distribution and NIDDM. Thus far these observations have been limited to Caucasians from the United Kingdom. we extended these observations to a broader segment of the general population by studying the association of birthweight and adult health outcomes in a biethnic population of the United States. We divided a group of 564 young adult Mexican-American and non-Hispanic white men and women participants of the San Antonio Heart Study into tertiles of birthweight and compared metabolic, anthropometric, haemodynamic, and demographic characteristics across these tertile categories. Additionally, we studied birthweight as a predictor of the clustering of diseases associated with the IRS, defined as any two or more of the following conditions: hypertension, NIDDM or impaired glucose tolerance, dyslipidaemia. Normotensive, non-diabetic individuals whose birthweight was in the lowest tertile had significantly higher levels of fasting serum insulin and a more truncal fat deposition pattern than individuals whose birthweight was in the highest tertile, independently of sex, ethnicity, and current socioeconomic status. Also, the odds of expressing the IRS increased 1.72 times (95% confidence interval: 1.16-2.55) for each tertile decrease in birthweight. These findings were independent of sex, ethnicity, and current levels of socioeconomic status or obesity. In conclusion, low birthweight could be a major independent risk factor for the development of adult chronic conditions commonly associated with insulin resistance in the general population.

The reproducibility of data from a Food Frequency Questionnaire among low-income Latina mothers and their children

We examined the 3-month and 1-year reproducibility of mothers' and children's dietary intakes of calories and 11 nutrients derived from oral administrations of a food frequency questionnaire to 166 Latina women. One-year correlations generally ranged from 0.40 to 0.55 for both mothers and children. For most nutrients, roughly half the children in the highest (lowest) quartile of intake at baseline were also in the highest (lowest) quartile 1 year later. The food frequency questionnaire has great potential for measuring typical nutrient intakes in these populations.

Diabesity: the deadly pentad disease

Insulin resistance and hyperinsulinemia are characteristic features not only of obesity and NIDDM, but are associated with the development of hypertension, hyperlipidemia, and atherosclerosis. DeFronzo et al has used the analogy that insulin resistance can be viewed as a large iceberg submerged just below the water. The physician recognizes only the tips of the iceberg--obesity, diabetes, hypertension, hypertriglyceridemia and low-HDL cholesterol, and atherosclerosis--which protrude above the surface, while the complete insulin-resistance syndrome may be missed. With the recognition that insulin resistance consists of a cluster of nutritional causes and biochemical abnormalities, it is important for the various subspecialties to work together closely to define the mechanism(s) responsible for the defects in insulin-mediated glucose metabolism and to discover effective strategies for prevention and treatment.

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.

Food sources, dietary behavior, and the saturated fat intake of Latino children

BACKGROUND

Recent recommendations for Americans aged 2 and older call for a reduction in the average saturated fat intake to less than 10% of calories.

METHODS

Using 24-hour dietary recalls collected from mothers of 4- to 7-year-old urban Latino children, we identified foods and dietary behavior patterns that distinguish children with higher and lower mean daily percentages of calories from saturated fat.

RESULTS

Compared with children in the lowest quintile of intake, children in the highest quintile consumed more than twice as much saturated fat per day from high-fat milk products (18.5 g vs 7.8 g), mostly from whole milk. They did not consume different kinds of milk or different amounts of milk per eating occasion, but on average they consumed milk more frequently (2.8 vs 1.6 eating occasions per day). Even children in the lowest quintile, on average, exceeded the 10% of calories from saturated fat currently recommended. If low-fat (1% fat) milk had been substituted without other dietary changes, all but the highest two quintiles would have been within the recommended level.

CONCLUSIONS

The substitution of low-fat for whole milk appears to be a key strategy for preschool children for achieving recommended levels of saturated fat intake.