Diabetes among Mexican Americans in Starr County, Texas

Transitioning From an In-Person Intervention to Augmented Text Messaging During COVID-19 in Mexican Americans With Prediabetes: The Starr County Diabetes Prevention Randomized Clinical Trial

PURPOSE

The purpose of the study was to explore the feasibility of using commonly available technology, such as text messaging, for diabetes prevention in rural Mexican American communities during COVID-19.

METHODS

Participants were selected from a diabetes prevention study funded by the National Institutes of Health that, prior to COVID-19, involved in-person group intervention sessions. Participants were predominantly female adults born in Mexico and Spanish-speaking. A subsample (n = 140) was divided into 3 cohorts: (1) 50 who completed the initial in-person intervention prior to the COVID-19 research pause, (2) 60 who needed additional support sessions to complete the intervention and thus received 10 text messages with links to relevant online diabetes prevention videos (TM+), and (3) 30 who received enhanced usual care involving health guidance offered during data collection (control). Repeated measures analysis of covariance was used to evaluate cohort differences at 24 months post baseline.

RESULTS

No significant cohort differences were found for depression, eating self-efficacy, alcohol intake, fat avoidance, or sedentary behaviors. Differences in A1C showed both in-person and TM+ cohorts having lower mean A1C levels (5.5%) than the control cohort (5.7%). The TM+ cohort had lower body mass index than other cohorts and a lower diabetes conversion rate (22.2%) compared to the control cohort (28%). Participants indicated preferences for in-person/TM+ combination interventions. The strongest positive feedback was for the TM+ intervention cooking demonstration videos.

CONCLUSIONS

Augmented text messaging combined with in-person sessions had similar outcomes to the all in-person strategy and thus has the potential for expanding the reach of diabetes prevention to many Mexican American communities.

Arsenic metabolism, diabetes prevalence, and insulin resistance among Mexican Americans: A mendelian randomization approach

Background

Differences in arsenic metabolism capacity may influence risk for type 2 diabetes, but the mechanistic drivers are unclear. We evaluated the associations between arsenic metabolism with overall diabetes prevalence and with static and dynamic measures of insulin resistance among Mexican Americans living in Starr County, Texas.

Methods

We utilized data from cross-sectional studies conducted in Starr County, Texas, from 2010-2014. A Mendelian randomization approach was utilized to evaluate the associations between arsenic metabolism and type 2 diabetes prevalence using the intronic variant in the arsenic methylating gene, rs9527, as the instrumental variable for arsenic metabolism. To further assess mechanisms for diabetes pathogenesis, proportions of the urinary arsenic metabolites were employed to assess the association between arsenic metabolism and insulin resistance among participants without diabetes. Urinary biomarkers of arsenic metabolites were modeled as individual proportions of the total. Arsenic metabolism was evaluated both with a static outcome of insulin resistance, homeostatic measure of assessment (HOMA-IR), and a dynamic measure of insulin sensitivity, Matsuda Index.

Results

Among 475 Mexican American participants from Starr County, higher metabolism capacity for arsenic is associated with higher diabetes prevalence driven by worse insulin resistance. Presence of the minor T allele of rs9527 is independently associated with an increase in the proportion of monomethylated arsenic (MMA%) and is associated with an odds ratio of 0.50 (95% CI: 0.24, 0.90) for type 2 diabetes. This association was conserved after potential covariate adjustment. Furthermore, among participants without type 2 diabetes, the highest quartile of MMA% was associated with 22% (95% CI: -33.5%, -9.07%) lower HOMA-IR and 56% (95% CI: 28.3%, 91.3%) higher Matsuda Index for insulin sensitivity.

Conclusions

Arsenic metabolism capacity, indicated by a lower proportion of monomethylated arsenic, is associated with increased diabetes prevalence driven by an insulin resistant phenotype among Mexican Americans living in Starr County, Texas.

The effects of gender and country of origin on acculturation, psychological factors, lifestyle factors, and diabetes-related physiological outcomes among Mexican Americans: The Starr County diabetes prevention initiative

OBJECTIVES

Examine acculturation and psychological, lifestyle, and physiological factors based on gender and country of origin (U.S. vs. Mexico).

METHODS

Baseline data from the Starr County diabetes prevention study (N = 300) were analyzed - acculturation (language), psychological factors (depression), lifestyle factors (sedentary behaviors), and diabetes-related physiological outcomes (insulin resistance). MANOVA and linear regression were used to examine variable relationships based on gender and country of origin and identify predictors of depression and insulin resistance.

RESULTS

Participants were: predominantly female (73%); 51 years of age, on average; born in Mexico (71%); and Spanish-speaking. Individuals spent 11 of their waking hours (range = 0-18 h) in sedentary activities. Compared to females, more males spoke English and reported fewer hours in sedentary activities. Compared to participants born in Mexico, those born in the U.S. were more likely to: speak English; report depressive symptoms; and exhibit elevated BMI and insulin resistance rates. Two distinct models significantly predicted depression (R² = 14.5%) and insulin resistance (R² = 26.8%), with acculturation-language entering into both models.

DISCUSSION

Significant gender and country-of-origin differences were found. Future research on diabetes prevention should examine other Hispanic subgroups and strategies for addressing individual differences, while employing cost-effective group interventions that incorporate these differences and reach more at-risk individuals.

Acculturation, Dietary Behaviors, and Macronutrient Intake Among Mexican Americans With Prediabetes: The Starr County Diabetes Prevention Initiative

PURPOSE

The purpose of the study was to examine the influences of sex and acculturation on dietary behaviors, macronutrient intake, and dietary quality in participants enrolled in a diabetes prevention initiative in Starr County, Texas.

METHODS

Baseline data from the Starr County diabetes prevention study (N = 300) were analyzed-acculturation (country of origin, years in Starr County, language and food preferences), depressive symptoms (Patient Health Questionnaire-9), healthy eating self-efficacy (Weight Efficacy Lifestyle Questionnaire-Short Form), diet quality (USDA Healthy Eating Index), fat avoidance (Fat Avoidance Scale, Spanish version), and macronutrients. Descriptive statistics and univariate analysis of covariance were used to examine differences based on acculturation, controlling for sex.

RESULTS

Participants were predominantly female (73%) and, on average, 51 years of age. Language and food preferences favored Spanish language and Hispanic foods, respectively. The majority (71%) was born in Mexico but had resided in Starr County for 33 years, on average. Depressive symptoms were moderate, and eating self-efficacy scores suggested low confidence in making healthy food choices, particularly for saturated fats. Spanish language preference was associated with worse dietary habits. The mean dietary quality score was lower than the national average (54 vs 59 nationally); females had slightly higher dietary quality than males and a higher mean fat avoidance score, although differences were not clinically significant. Intakes of carbohydrate, saturated fats, and cholesterol were higher than recommended daily allowances.

CONCLUSIONS

The overall preference for speaking Spanish and the influence of language on dietary intake should inform future dietary interventions. Accommodating cultural norms and food preferences remain major challenges to improving dietary quality among the diverse Hispanic ethnic groups.

Relationships Between Urinary Metals and Diabetes Traits Among Mexican Americans in Starr County, Texas, USA

Hispanics/Latinos have higher rates of type 2 diabetes (T2D), and the origins of these disparities are poorly understood. Environmental endocrine-disrupting chemicals (EDCs), including some metals and metalloids, are implicated as diabetes risk factors. Data indicate that Hispanics/Latinos may be disproportionately exposed to EDCs, yet they remain understudied with respect to environmental exposures and diabetes. The objective of this study is to determine how metal exposures contribute to T2D progression by evaluating the associations between 8 urinary metals and measures of glycemic status in 414 normoglycemic or prediabetic adults living in Starr County, Texas, a Hispanic/Latino community with high rates of diabetes and diabetes-associated mortality. We used multivariable linear regression to quantify the differences in homeostatic model assessments for pancreatic β-cell function, insulin resistance, and insulin sensitivity (HOMA-β, HOMA-IR, HOMA-S, respectively), plasma insulin, plasma glucose, and hemoglobin A1c (HbA1c) associated with increasing urinary metal concentrations. Quantile-based g-computation was utilized to assess mixture effects. After multivariable adjustment, urinary arsenic and molybdenum were associated with lower HOMA-β, HOMA-IR, and plasma insulin levels and higher HOMA-S. Additionally, higher urinary copper levels were associated with a reduced HOMA-β. Lastly, a higher concentration of the 8 metal mixtures was associated with lower HOMA-β, HOMA-IR, and plasma insulin levels as well as higher HOMA-S. Our data indicate that arsenic, molybdenum, copper, and this metal mixture are associated with alterations in measures of glucose homeostasis among non-diabetics in Starr County. This study is one of the first to comprehensively evaluate associations of urinary metals with glycemic measures in a high-risk Mexican American population.

Leveraging pleiotropy to discover and interpret GWAS results for sleep-associated traits

Genetic association studies of many heritable traits resulting from physiological testing often have modest sample sizes due to the cost and burden of the required phenotyping. This reduces statistical power and limits discovery of multiple genetic associations. We present a strategy to leverage pleiotropy between traits to both discover new loci and to provide mechanistic hypotheses of the underlying pathophysiology. Specifically, we combine a colocalization test with a locus-level test of pleiotropy. In simulations, we show that this approach is highly selective for identifying true pleiotropy driven by the same causative variant, thereby improves the chance to replicate the associations in underpowered validation cohorts and leads to higher interpretability. Here, as an exemplar, we use Obstructive Sleep Apnea (OSA), a common disorder diagnosed using overnight multi-channel physiological testing. We leverage pleiotropy with relevant cellular and cardio-metabolic phenotypes and gene expression traits to map new risk loci in an underpowered OSA GWAS. We identify several pleiotropic loci harboring suggestive associations to OSA and genome-wide significant associations to other traits, and show that their OSA association replicates in independent cohorts of diverse ancestries. By investigating pleiotropic loci, our strategy allows proposing new hypotheses about OSA pathobiology across many physiological layers. For example, we identify and replicate the pleiotropy across the plateletcrit, OSA and an eQTL of DNA primase subunit 1 (PRIM1) in immune cells. We find suggestive links between OSA, a measure of lung function (FEV1/FVC), and an eQTL of matrix metallopeptidase 15 (MMP15) in lung tissue. We also link a previously known genome-wide significant peak for OSA in the hexokinase 1 (HK1) locus to hematocrit and other red blood cell related traits. Thus, the analysis of pleiotropic associations has the potential to assemble diverse phenotypes into a chain of mechanistic hypotheses that provide insight into the pathogenesis of complex human diseases.

Biobanking in Latinos: current status, principles for conduct, and contribution of a new biobank, El Banco por Salud, designed to improve the health of Latino patients of Mexican ancestry with type 2 diabetes

Underserved Latino communities experience a greater burden of type 2 diabetes mellitus (T2DM) than the general population. Predictors of glycemic control are likely to include both biological/genetic and social determinants of health (SDOH). A variety of approaches have been used with cohorts of Latino patients to study aspects of this health disparity, and those are reviewed briefly here. Such projects range from cohorts that are studies for a primary purpose, for example, to discover genetic variation associated with T2DM or to examine a particular aspect of SDOH that might be involved. Other studies have been conducted more as infrastructure that is broadly based in order to provide a resource that can be used by many investigators to address a variety of questions. From our experience and those of others, we propose a set of principles to ensure that needs of the community are identified and taken into account during the conduct of these studies. As an example of the implementation of these principles, we also describe a new biobank El Banco por Salud (El Banco), which was designed to improve access to studies designed to improve glycemic control and health in Latinos in partnership with Federally Qualified Health Centers in Arizona.

Whole-genome association analyses of sleep-disordered breathing phenotypes in the NHLBI TOPMed program

BACKGROUND

Sleep-disordered breathing is a common disorder associated with significant morbidity. The genetic architecture of sleep-disordered breathing remains poorly understood. Through the NHLBI Trans-Omics for Precision Medicine (TOPMed) program, we performed the first whole-genome sequence analysis of sleep-disordered breathing.

METHODS

The study sample was comprised of 7988 individuals of diverse ancestry. Common-variant and pathway analyses included an additional 13,257 individuals. We examined five complementary traits describing different aspects of sleep-disordered breathing: the apnea-hypopnea index, average oxyhemoglobin desaturation per event, average and minimum oxyhemoglobin saturation across the sleep episode, and the percentage of sleep with oxyhemoglobin saturation < 90%. We adjusted for age, sex, BMI, study, and family structure using MMSKAT and EMMAX mixed linear model approaches. Additional bioinformatics analyses were performed with MetaXcan, GIGSEA, and ReMap.

RESULTS

We identified a multi-ethnic set-based rare-variant association (p = 3.48 × 10-8) on chromosome X with ARMCX3. Additional rare-variant associations include ARMCX3-AS1, MRPS33, and C16orf90. Novel common-variant loci were identified in the NRG1 and SLC45A2 regions, and previously associated loci in the IL18RAP and ATP2B4 regions were associated with novel phenotypes. Transcription factor binding site enrichment identified associations with genes implicated with respiratory and craniofacial traits. Additional analyses identified significantly associated pathways.

CONCLUSIONS

We have identified the first gene-based rare-variant associations with objectively measured sleep-disordered breathing traits. Our results increase the understanding of the genetic architecture of sleep-disordered breathing and highlight associations in genes that modulate lung development, inflammation, respiratory rhythmogenesis, and HIF1A-mediated hypoxic response.

Whole exome sequencing identifies the novel putative gene variants related with type 2 diabetes in Mizo population, northeast India

The contribution of genes towards T2D development varies among different population groups across the world. It has been reported that a number of loci involved in T2D susceptibility are common across certain population groups, but ethnicity specific variants are also observed. The population of Mizoram has an independent ethnic identity and there are no scientific records about the history of the Mizo people; which makes this ethnic group unique and interesting to study. The aim of the study focuses on the identification of the gene variants which may contribute to T2D susceptibility in Mizo-Mongloid ethnic tribe of North east India through whole exome sequencing. The variants like 328G > C (KRT18), 997G > T (CYP4A11), 2368 T > C (SLC4A3), 508G > A (SLC26A5), 1659C > T (KCNS1), 650C > A (ABCD1) 821A > T (YTHDC2), 931G > T (PINX1), 3280C > A (TNRC6A), 48C > A(TACO1), 6035A > T(LAMA1), 805C > A(ACP7) and 806A > G(ACP7) variants were not reported for any disease in the database and were found to be pathogenic in different insilico analysis softwares. The changes in protein stability upon mutation has been predicted where 35.71% increases the stability of the protein, while 64.28% of the variants decrease the stability of the protein. These findings present the population specific variants which might involve in the susceptibility to T2D in Mizo population. Further, in this study some gene variants have contribution as a possible diagnostic or prognostic marker for other diseases as well, which suggests the need for performing association analysis for different disease manifestations in Mizo population in the near future.

Associations of variants In the hexokinase 1 and interleukin 18 receptor regions with oxyhemoglobin saturation during sleep

Sleep disordered breathing (SDB)-related overnight hypoxemia is associated with cardiometabolic disease and other comorbidities. Understanding the genetic bases for variations in nocturnal hypoxemia may help understand mechanisms influencing oxygenation and SDB-related mortality. We conducted genome-wide association tests across 10 cohorts and 4 populations to identify genetic variants associated with three correlated measures of overnight oxyhemoglobin saturation: average and minimum oxyhemoglobin saturation during sleep and the percent of sleep with oxyhemoglobin saturation under 90%. The discovery sample consisted of 8,326 individuals. Variants with p < 1 × 10(-6) were analyzed in a replication group of 14,410 individuals. We identified 3 significantly associated regions, including 2 regions in multi-ethnic analyses (2q12, 10q22). SNPs in the 2q12 region associated with minimum SpO2 (rs78136548 p = 2.70 × 10(-10)). SNPs at 10q22 were associated with all three traits including average SpO2 (rs72805692 p = 4.58 × 10(-8)). SNPs in both regions were associated in over 20,000 individuals and are supported by prior associations or functional evidence. Four additional significant regions were detected in secondary sex-stratified and combined discovery and replication analyses, including a region overlapping Reelin, a known marker of respiratory complex neurons.These are the first genome-wide significant findings reported for oxyhemoglobin saturation during sleep, a phenotype of high clinical interest. Our replicated associations with HK1 and IL18R1 suggest that variants in inflammatory pathways, such as the biologically-plausible NLRP3 inflammasome, may contribute to nocturnal hypoxemia.

From Sea to Shining Sea and the Great Plains to Patagonia: A Review on Current Knowledge of Diabetes Mellitus in Hispanics/Latinos in the US and Latin America

The past two decades have witnessed many advances in the prevention, treatment, and control of diabetes mellitus (DM) and its complications. Increased screening has led to a greater recognition of type 2 diabetes mellitus (type 2 DM) and prediabetes; however, Hispanics/Latinos, the largest minority group in the US, have not fully benefited from these advances. The Hispanic/Latino population is highly diverse in ancestries, birth places, cultures, languages, and socioeconomic backgrounds, and it populates most of the Western Hemisphere. In the US, the prevalence of DM varies among Hispanic/Latino heritage groups, being higher among Mexicans, Puerto Ricans, and Dominicans, and lower among South Americans. The risk and prevalence of diabetes among Hispanics/Latinos are significantly higher than in non-Hispanic Whites, and nearly 40% of Hispanics/Latinos with diabetes have not been formally diagnosed. Despite these striking facts, the representation of Hispanics/Latinos in pharmacological and non-pharmacological clinical trials has been suboptimal, while the prevalence of diabetes in these populations continues to rise. This review will focus on the epidemiology, etiology and prevention of type 2 DM in populations of Latin American origin. We will set the stage by defining the terms Hispanic, Latino, and Latin American, explaining the challenges identifying Hispanics/Latinos in the scientific literature and databases, describing the epidemiology of diabetes-including type 2 DM and gestational diabetes mellitus (GDM)-and cardiovascular risk factors in Hispanics/Latinos in the US and Latin America, and discussing trends, and commonalities and differences across studies and populations, including methodology to ascertain diabetes. We will discuss studies on mechanisms of disease, and research on prevention of type 2 DM in Hispanics/Latinos, including women with GDM, youth and adults; and finalize with a discussion on lessons learned and opportunities to enhance research, and, consequently, clinical care oriented toward preventing type 2 DM in Hispanics/Latinos in the US and Latin America.

Variants in angiopoietin-2 (ANGPT2) contribute to variation in nocturnal oxyhaemoglobin saturation level

Genetic determinants of sleep-disordered breathing (SDB), a common set of disorders that contribute to significant cardiovascular and neuropsychiatric morbidity, are not clear. Overnight nocturnal oxygen saturation (SaO2) is a clinically relevant and easily measured indicator of SDB severity but its genetic contribution has never been studied. Our recent study suggests nocturnal SaO2 is heritable. We performed linkage analysis, association analysis and haplotype analysis of average nocturnal oxyhaemoglobin saturation in participants in the Cleveland Family Study (CFS), followed by gene-based association and additional tests in four independent samples. Linkage analysis identified a peak (LOD = 4.29) on chromosome 8p23. Follow-up association analysis identified two haplotypes in angiopoietin-2 (ANGPT2) that significantly contributed to the variation of SaO2 (P = 8 × 10-5) and accounted for a portion of the linkage evidence. Gene-based association analysis replicated the association of ANGPT2 and nocturnal SaO2. A rare missense SNP rs200291021 in ANGPT2 was associated with serum angiopoietin-2 level (P = 1.29 × 10-4), which was associated with SaO2 (P = 0.002). Our study provides the first evidence for the association of ANGPT2, a gene previously implicated in acute lung injury syndromes, with nocturnal SaO2, suggesting that this gene has a broad range of effects on gas exchange, including influencing oxygenation during sleep.

Using next-generation DNA sequence data for genetic association tests based on allele counts with and without consideration of zero inflation

The relationship between genetic variability and individual phenotypes is usually investigated by testing for association relying on called genotypes. Allele counts obtained from next-generation sequence data could be used for this purpose too. Genetic association can be examined by treating alternative allele counts (AACs) as the response variable in negative binomial regression. AACs from sequence data often contain an excess of zeros, thus motivating the use of Hurdle and zero-inflated models. Here we examine rough type I error rates and the ability to pick out variants with small probability values for 7 different testing approaches that incorporate AACs as an explanatory or as a response variable. Model comparisons relied on chromosome 3 DNA sequence data from 407 Hispanic participants in the Type 2 Diabetes Genetic Exploration by Next-generation sequencing in Ethnic Samples (T2D-GENES) project 1 with complete information on diastolic blood pressure and related medication. Our results suggest that in the investigation of the relationship between AAC as response variable and individual phenotypes as explanatory variable, Hurdle-negative binomial regression has some advantages. This model showed a good ability to discriminate strongly associated variants and controlled overall type I error rates. However, probability values from Hurdle-negative binomial regression were not obtained for approximately 25 % of the investigated variants because of convergence problems, and the mass of the probability value distribution was concentrated around 1.

Omics-squared: human genomic, transcriptomic and phenotypic data for genetic analysis workshop 19

Background

The Genetic Analysis Workshops (GAW) are a forum for development, testing, and comparison of statistical genetic methods and software. Each contribution to the workshop includes an application to a specified data set. Here we describe the data distributed for GAW19, which focused on analysis of human genomic and transcriptomic data.

Methods

GAW19 data were donated by the T2D-GENES Consortium and the San Antonio Family Heart Study and included whole genome and exome sequences for odd-numbered autosomes, measures of gene expression, systolic and diastolic blood pressures, and related covariates in two Mexican American samples. These two samples were a collection of 20 large families with whole genome sequence and transcriptomic data and a set of 1943 unrelated individuals with exome sequence. For each sample, simulated phenotypes were constructed based on the real sequence data. ‘Functional’ genes and variants for the simulations were chosen based on observed correlations between gene expression and blood pressure. The simulations focused primarily on additive genetic models but also included a genotype-by-medication interaction. A total of 245 genes were designated as ‘functional’ in the simulations with a few genes of large effect and most genes explaining < 1 % of the trait variation. An additional phenotype, Q1, was simulated to be correlated among related individuals, based on theoretical or empirical kinship matrices, but was not associated with any sequence variants. Two hundred replicates of the phenotypes were simulated. The GAW19 data are an expansion of the data used at GAW18, which included the family-based whole genome sequence, blood pressure, and simulated phenotypes, but not the gene expression data or the set of 1943 unrelated individuals with exome sequence.

Association of polymorphisms in the aldosterone-regulated sodium reabsorption pathway with blood pressure among Hispanics

BACKGROUND

Whereas genome-wide association study (GWAS) has proven to be an important tool for discovery of variants influencing many human diseases and traits, unfortunately its performance has not been much of all-around success for some complex conditions, for example, hypertension. Because some of the existing effective pharmacotherapeutic agents act by targeting known biological pathways, pathway-based analytical approaches could lead to more success in discovery of disease-associated variants. The objective of the present study was to identify functional variants associated with blood pressure in the aldosterone-regulated sodium reabsorption pathway using the simulated and real blood pressure phenotypes provided for Genetic Analysis Workshop 19.

METHODS

The present analysis included 1942 samples with exome sequencing data and for whom blood pressure phenotypes were available. Because only odd-numbered autosomes were available, we restricted analysis to 127 quality-controlled single-nucleotide polymorphisms from the aldosterone-regulated sodium reabsorption pathway. We performed pathway-based association analysis using appropriate regression models for single variant, haplotype and epistasis association analyses. To account for multiple comparisons, statistical significance was empirically derived by permutation procedure and Bonferroni correction.

RESULTS

The topmost pathway-based association signals were observed in PRKCA gene for diastolic blood pressure (DBP), systolic blood pressure (SBP), and mean arterial pressure (MAP) in both real and simulated data. The associations remained significant (P <0.05) after multiple testing corrections for the number of genes. Similarly, the pathway-based 2-locus epistasis analysis indicated significant interactions between INSR and PRKCG for SBP and MAP; INS and PIK3R2 for DBP; PIK3CD and ATP1B2 for hypertension in the real data set. We also observed significant within-gene interactions in INSR for SBP, DBP, and hypertension in the simulated data set.

CONCLUSION

The findings from this study show that pathway-based analytical approach targeting known biological pathways can be useful in identification of disease-associated variants that are otherwise undetectable by GWAS. The approach takes advantage of the assumption of nonindependence of variants within and across pathway genes which leads to reduced penalty of multiple testing and thus less-stringent statistical significance threshold.

Genetic Associations with Obstructive Sleep Apnea Traits in Hispanic/Latino Americans

RATIONALE

Obstructive sleep apnea is a common disorder associated with increased risk for cardiovascular disease, diabetes, and premature mortality. Although there is strong clinical and epidemiologic evidence supporting the importance of genetic factors in influencing obstructive sleep apnea, its genetic basis is still largely unknown. Prior genetic studies focused on traits defined using the apnea-hypopnea index, which contains limited information on potentially important genetically determined physiologic factors, such as propensity for hypoxemia and respiratory arousability.

OBJECTIVES

To define novel obstructive sleep apnea genetic risk loci for obstructive sleep apnea, we conducted genome-wide association studies of quantitative traits in Hispanic/Latino Americans from three cohorts.

METHODS

Genome-wide data from as many as 12,558 participants in the Hispanic Community Health Study/Study of Latinos, Multi-Ethnic Study of Atherosclerosis, and Starr County Health Studies population-based cohorts were metaanalyzed for association with the apnea-hypopnea index, average oxygen saturation during sleep, and average respiratory event duration.

MEASUREMENTS AND MAIN RESULTS

Two novel loci were identified at genome-level significance (rs11691765, GPR83, P = 1.90 × 10-8 for the apnea-hypopnea index, and rs35424364; C6ORF183/CCDC162P, P = 4.88 × 10-8 for respiratory event duration) and seven additional loci were identified with suggestive significance (P < 5 × 10-7). Secondary sex-stratified analyses also identified one significant and several suggestive associations. Multiple loci overlapped genes with biologic plausibility.

CONCLUSIONS

These are the first genome-level significant findings reported for obstructive sleep apnea-related physiologic traits in any population. These findings identify novel associations in inflammatory, hypoxia signaling, and sleep pathways.

Prevalence of Low Cardiovascular Risk Profile Among Diverse Hispanic/Latino Adults in the United States by Age, Sex, and Level of Acculturation: The Hispanic Community Health Study/Study of Latinos

BACKGROUND

Favorable levels of all readily measurable major cardiovascular disease risk factors (ie, low risk [LR]) are associated with lower risks of cardiovascular disease morbidity and mortality. Data are not available on LR prevalence among Hispanic/Latino adults of diverse ethnic backgrounds. This study aimed to describe the prevalence of a low cardiovascular disease risk profile among Hispanic/Latino adults in the United States and to examine cross-sectional associations of LR with measures of acculturation.

METHODS AND RESULTS

The multicenter, prospective, population-based Hispanic Community Health Study/Study of Latinos examined 16 415 men and women aged 18 to 74 years at baseline (2008-2011) with diverse Hispanic/Latino backgrounds. Analyses involved 14 757 adults (mean age 41.3 years; 60.6% women). LR was defined using national guidelines for favorable levels of serum cholesterol, blood pressure, and body mass index and by not having diabetes mellitus and not currently smoking. Age-adjusted LR prevalence was low (8.4% overall; 5.1% for men, 11.2% for women) and varied by background (4.2% in men of Mexican heritage versus 15.0% in women of Cuban heritage). Lower acculturation (assessed using proxy measures) was significantly associated with higher odds of a LR profile among women only: Age-adjusted odds ratios of having LR were 1.64 (95% CI 1.24-2.17) for foreign-born versus US-born women and 1.96 (95% CI 1.49-2.58) for women residing in the United States <10 versus ≥10 years.

CONCLUSIONS

Among diverse US Hispanic/Latino adults, the prevalence of a LR profile is low. Lower acculturation is associated with higher odds of a LR profile among women but not men. Comprehensive public health strategies are needed to improve the cardiovascular health of US Hispanic/Latino adults.

Diabetes Education in a Mexican-American Population: Pilot Testing of a Research-Based Videotape

A diabetes education videotape was designed and pilot tested in a sample of 30 Spanish-speaking Hispanic diabetic adults in a rural Texas-Mexico border community. The videotape provided an overview of diabetes, with emphasis on the concept of blood glucose; relationships between food, medications, exercise, and blood glucose levels; and blood glucose monitoring. Outcomes of videotape effectiveness were based on a 20-item knowledge test and interview data to assess acceptability of videotapes as a learning tool. Comparison of the knowledge test scores of the experimental group (those who viewed the tape before taking the knowledge test) with the control group (those who took the test before viewing the tape) produced a positive, moderate effect size of 0.61. Interviews with subjects indicated enthusiastic acceptance of the videotape as a means of transmitting diabetes information.

Sociocultural construction of food ways in low-income Mexican-American women with diabetes: a qualitative study

AIMS AND OBJECTIVES

The aim of the study was to explore how low-income Hispanic women, with at least 10 years of having type 2 diabetes, successfully manage the disease within a sociocultural context, especially in relation to foodways.

BACKGROUND

Managing type 2 diabetes is challenging, particularly for underserved populations such as low-income Hispanic women. This population segment has higher rates of type 2 diabetes, diabetes-related complications, obesity, and sedentary lifestyles than the general U.S.

POPULATION

Dietary management is a critical aspect of diabetes care, but it is perhaps the most difficult health behaviour to modify.

DESIGN

A qualitative and ethnographically based study was used.

METHODS

Participant observation and individual interviews explored the interrelationships of culture, food habits and type 2 diabetes among 12 low-income Hispanic women residing in an impoverished rural community located on the Texas-Mexico border.

RESULTS

Hispanic women used unique strategies to adjust their diet, particularly portion control; for example, they emphasised the 'use of the fork', based on the notion that Hispanic finger foods are less healthy. Women categorised foods as bad or acceptable, depending on the context, such as important family or social gatherings. Those with years of diabetes experience confidently took charge of the disease based on knowledge of their bodies and a desire to avoid complications, while acknowledging brief infractions of dietary 'rules' and balancing various social roles and expectations.

CONCLUSIONS

Hispanic women manage their type 2 diabetes within a sociocultural environment. Those with expertise make changes in how they eat to care for their diabetes, but also continue to maintain traditional foodways.

RELEVANCE TO CLINICAL PRACTICE

Foodways are critical to most cultural groups and modifying dietary behaviours can be challenging. Clinicians must develop self-management guidance within the sociocultural context of the patient if diabetes outcomes are to improve and be sustained.

Beyond type 2 diabetes, obesity and hypertension: an axis including sleep apnea, left ventricular hypertrophy, endothelial dysfunction, and aortic stiffness among Mexican Americans in Starr County, Texas

BACKGROUND

There is an increasing appreciation for a series of less traditional risk factors that should not be ignored when considering type 2 diabetes, obesity, hypertension, and cardiovascular disease. These include aortic stiffness, cardiac structure, impaired endothelial function and obstructive sleep apnea. They are associated to varying degrees with each disease categorization and with each other. It is not clear whether they represent additional complications, concomitants or antecedents of disease. Starr County, Texas, with its predominantly Mexican American population has been shown previously to bear a disproportionate burden of the major disease categories, but little is known about the distribution of these less traditional factors.

METHODS

Type 2 diabetes, obesity and hypertension frequencies were determined through a systematic survey of Starr County conducted from 2002 to 2006. Individuals from this examination and an enriched set with type 2 diabetes were re-examined from 2010 to 2014 including assessment of cardiac structure, sleep apnea, endothelial function and aortic stiffness. Individual and combined frequencies of these inter-related (i.e., axis) conditions were estimated and associations evaluated.

RESULTS

Household screening of 5230 individuals aged 20 years and above followed by direct physical assessment of 1610 identified 23.7 % of men and 26.7 % of women with type 2 diabetes, 46.2 and 49.5 % of men and women, respectively with obesity and 32.1 and 32.4 % with hypertension. Evaluation of pulse wave velocity, left ventricular mass, endothelial function and sleep apnea identified 22.3, 12.7, 48.6 and 45.2 % of men as having "at risk" values for each condition, respectively. Corresponding numbers in women were 16.0, 17.9, 23.6 and 28.8 %. Cumulatively, 88 % of the population has one or more of these while 50 % have three or more.

CONCLUSIONS

The full axis of conditions is high among Mexican Americans in Starr County, Texas. Individual and joint patterns suggest a genesis well before overt disease. Whether they are all mediated by common underlying factors or whether there exist multiple mechanisms remains to be seen.

Scaling Up Scientific Discovery in Sleep Medicine: The National Sleep Research Resource

ABSTRACT

Professional sleep societies have identified a need for strategic research in multiple areas that may benefit from access to and aggregation of large, multidimensional datasets. Technological advances provide opportunities to extract and analyze physiological signals and other biomedical information from datasets of unprecedented size, heterogeneity, and complexity. The National Institutes of Health has implemented a Big Data to Knowledge (BD2K) initiative that aims to develop and disseminate state of the art big data access tools and analytical methods. The National Sleep Research Resource (NSRR) is a new National Heart, Lung, and Blood Institute resource designed to provide big data resources to the sleep research community. The NSRR is a web-based data portal that aggregates, harmonizes, and organizes sleep and clinical data from thousands of individuals studied as part of cohort studies or clinical trials and provides the user a suite of tools to facilitate data exploration and data visualization. Each deidentified study record minimally includes the summary results of an overnight sleep study; annotation files with scored events; the raw physiological signals from the sleep record; and available clinical and physiological data. NSRR is designed to be interoperable with other public data resources such as the Biologic Specimen and Data Repository Information Coordinating Center Demographics (BioLINCC) data and analyzed with methods provided by the Research Resource for Complex Physiological Signals (PhysioNet). This article reviews the key objectives, challenges and operational solutions to addressing big data opportunities for sleep research in the context of the national sleep research agenda. It provides information to facilitate further interactions of the user community with NSRR, a community resource.

Diabetes in the Hispanic population

As the Hispanic population in the United States increases, more primary care physicians are being challenged to address the high incidence of diabetes and related metabolic disorders in Hispanic American patients. A variety of genetic, environmental, and socioeconomic factors contribute to this group's high susceptibility to diabetes. In this article, Drs Idrogo and Mazze discuss diagnosis of diabetes in Hispanic patients, as well as culturally sensitive screening and treatment strategies.

Association of a low-frequency variant in HNF1A with type 2 diabetes in a Latino population

IMPORTANCE

Latino populations have one of the highest prevalences of type 2 diabetes worldwide.

OBJECTIVES

To investigate the association between rare protein-coding genetic variants and prevalence of type 2 diabetes in a large Latino population and to explore potential molecular and physiological mechanisms for the observed relationships.

DESIGN, SETTING, AND PARTICIPANTS

Whole-exome sequencing was performed on DNA samples from 3756 Mexican and US Latino individuals (1794 with type 2 diabetes and 1962 without diabetes) recruited from 1993 to 2013. One variant was further tested for allele frequency and association with type 2 diabetes in large multiethnic data sets of 14,276 participants and characterized in experimental assays.

MAIN OUTCOME AND MEASURES

Prevalence of type 2 diabetes. Secondary outcomes included age of onset, body mass index, and effect on protein function.

RESULTS

A single rare missense variant (c.1522G>A [p.E508K]) was associated with type 2 diabetes prevalence (odds ratio [OR], 5.48; 95% CI, 2.83-10.61; P = 4.4 × 10(-7)) in hepatocyte nuclear factor 1-α (HNF1A), the gene responsible for maturity onset diabetes of the young type 3 (MODY3). This variant was observed in 0.36% of participants without type 2 diabetes and 2.1% of participants with it. In multiethnic replication data sets, the p.E508K variant was seen only in Latino patients (n = 1443 with type 2 diabetes and 1673 without it) and was associated with type 2 diabetes (OR, 4.16; 95% CI, 1.75-9.92; P = .0013). In experimental assays, HNF-1A protein encoding the p.E508K mutant demonstrated reduced transactivation activity of its target promoter compared with a wild-type protein. In our data, carriers and noncarriers of the p.E508K mutation with type 2 diabetes had no significant differences in compared clinical characteristics, including age at onset. The mean (SD) age for carriers was 45.3 years (11.2) vs 47.5 years (11.5) for noncarriers (P = .49) and the mean (SD) BMI for carriers was 28.2 (5.5) vs 29.3 (5.3) for noncarriers (P = .19).

CONCLUSIONS AND RELEVANCE

Using whole-exome sequencing, we identified a single low-frequency variant in the MODY3-causing gene HNF1A that is associated with type 2 diabetes in Latino populations and may affect protein function. This finding may have implications for screening and therapeutic modification in this population, but additional studies are required.

Cardiovascular disease risk among the Mexican American population in the Texas-Mexico border region, by age and length of residence in United States

Introduction

Although the relationship between health behaviors and outcomes such as smoking and obesity with longer residence in the United States among Mexican American immigrants is established, the relationship between length of residency in the United States and risk for cardiovascular disease (CVD) is not fully understood. The objective of this study was to determine the relationship between immigrant status, length of residence in the United States, age, and CVD markers in a sample of Mexican American adults living in Brownsville, Texas.

Methods

We categorized participants in the Cameron County Hispanic Cohort study as immigrants in the United States for 10 years or less, immigrants in the United States for more than 10 years, or born in the United States. We conducted logistic and ordinary least squares regression for self-reported chronic conditions and CVD biomarkers.

Results

We found bivariate differences in the prevalence of self-reported conditions and 1 CVD biomarker (low-density lipoprotein cholesterol) by length of residence in the middle (41–64 y) and younger (18–40 y) age groups. After adjusting for covariates, the following varied significantly by immigrant status: stroke and high cholesterol (self-reported conditions) and diastolic blood pressure, systolic blood pressure, total cholesterol, and low-density lipoprotein cholesterol (CVD biomarkers).

Conclusion

The association between immigrant status, length of residence in the United States, and CVD markers varied. The effect of length of residence in the United States or immigrant status may depend on age and may be most influential in middle or older age.

Diabetes self-management and leptin in Mexican Americans with type 2 diabetes: the Starr County border health initiative

PURPOSE

The purpose of the study was to (1) characterize leptin in Mexican Americans with poorly controlled type 2 diabetes, (2) examine relationships among leptin and indicators of diabetes status (body mass index and A1C), and (3) explore the effects of a culturally tailored diabetes self-management education intervention on leptin.

METHODS

In Starr County, an impoverished Texas-Mexico border community, 252 Mexican Americans with type 2 diabetes were recruited to test a diabetes self-management education intervention culturally tailored in terms of language, dietary recommendations, social emphasis, family participation, and incorporation of cultural health beliefs. Groups of 8 participants were randomized to experimental or wait-listed control conditions. Outcomes were measured at 3, 6, and 12 months; by 12 months, 109 had complete leptin data.

RESULTS

Most participants were women and, on average, 55 years of age, diagnosed with diabetes for 8 years, obese, and in poor glycemic control. Three variables-body mass index, sex, A1C-explained 36% of the variance in baseline leptin; there were no intervention effects on leptin. Sex, time, and gender × time interaction effects on leptin were statistically significant; greater increases in leptin over time occurred in women compared to men. In women, fasting blood glucose changes from baseline to 12 months significantly predicted leptin changes from baseline to 12 months; in men, body mass index changes predicted leptin change.

CONCLUSIONS

With increasing obesity rates, further research is warranted to determine if leptin is a useful intervention target in type 2 diabetes.

The Diabetes Symptom Self-Care Inventory: development and psychometric testing with Mexican Americans

CONTEXT

Type 2 diabetes is prevalent throughout the world. In previous studies of Mexican Americans with type 2 diabetes, 95%-97% of those sampled reported having symptoms they believe were caused by diabetes and most self-treated their symptoms. To more accurately capture Mexican Americans' symptom prevalence and their self-treatments, the Diabetes Symptom Self-Care Inventory (DSSCI) was adapted from the Diabetes Self-Care Instrument.

OBJECTIVES

This article describes the modification process used to perfect the DSSCI for use in improving self-care among people with type 2 diabetes.

METHODS

This instrumentation study used qualitative and quantitative methods. The study was completed in four phases that used focus groups, cognitive interviews, and survey administration. Four convenience samples were drawn from community-dwelling Mexican American adults, aged 25-75 years, with type 2 diabetes in an urban area and a rural location in Texas.

RESULTS

Phase I: Seven focus groups (n=45) generated data for revising items. Phase II: Cognitive interviews with 16 participants were used to evaluate four revisions of the questionnaire. Phase III: Surveys were administered to 81 participants. Total number of symptoms on the DSSCI correlated with scores on the Centers for Epidemiological Studies-Depression scale (r=0.65, P<0.001), Illness Perception Questionnaire-Revised Diabetes Symptom subscale (r=0.57, P<0.001), and Audit of Diabetes-Dependent Quality of Life scale (r=-0.42, P<0.001). Minor revisions followed. Phase IV: Test-retest stability was demonstrated (n=44).

CONCLUSION

The DSSCI is a culturally relevant, sound measure of Mexican Americans' diabetes symptoms and the actions they take to address them.

The role of fat mass index in determining obesity

OBJECTIVES

The objective of this study is to compare body mass index (BMI), percent body fat (PBF), and fat mass index (FMI) and to investigate the accuracy of FMI as a convenient tool for assessing obesity.

DESIGN

Anthropometric measurements and bioelectrical impedance analyses were performed on 538 Mexican Americans (373 women and 165 men). Correlations between BMI and PBF and between FMI and PBF were investigated. The percentage of persons misclassified as obese using different classifications was calculated. Multiple linear regression analysis was performed to generate predictive models of FMI for males and females separately.

RESULTS

BMI and PBF were correlated in men (rho = 0.877; P < 0.0001) and women (rho = 0.966; P < 0.0001); however, 20 and 67.2% of the men and 9.2 and 84.2% of women, classified as normal weight and overweight by BMI, respectively, were diagnosed as obese by PBF. FMI and PBF were also correlated in men (rho = 0.975; P < 0.0001) and women (rho = 0.992; P < 0.0001). Four percent of the men classified as normal weight and 65.5% classified as overweight by BMI were obese by FMI, while 71.3% of women classified as overweight by BMI were obese by FMI. Misclassification of obesity between FMI and PBF categories was observed in 5.4% of men and 7.8% of women.

CONCLUSIONS

The discrepancy observed between BMI and PBF reflects a limitation of BMI. Conversely, FMI accurately assessed obesity in our study of Mexican Americans, but further studies are necessary to confirm our findings in different ethnic groups.

Influence of Hispanic ethnicity in prevalence of diabetes mellitus in sleep apnea and relationship to sleep phase

INTRODUCTION

Recent studies have shown a strong association between insulin resistance, diabetes mellitus, and obstructive sleep apnea (OSA). This association has not been previously reported in the Hispanic population. The objective of this study was to study the prevalence of diabetes in a cohort of Hispanic patients with OSA in comparison with a white cohort.

METHOD

We performed a retrospective chart review of 103 Hispanic patients and 69 white patients with OSA. All patients had undergone full-night baseline polysomnography. We excluded charts of patients who underwent split-night studies and those who did not have rapid eye movement (REM) sleep.

RESULTS

Both groups were well matched in terms of age, gender distribution, and body mass index. The prevalence of self-reported diabetes in Hispanic patients with OSA was 42.71% compared with 24.28% of whites (P = 0.005). A REM apnea hypopnea index (AHI) of > 20 was significantly associated with an increased prevalence of diabetes in the Hispanic population; this association was not seen in the white population.

CONCLUSION

There was a very high prevalence of diabetes in an unselected cohort of Hispanic patients with OSA compared with white patients.

Strong association of socioeconomic status with genetic ancestry in Latinos: implications for admixture studies of type 2 diabetes

AIMS/HYPOTHESIS

Type 2 diabetes is more prevalent in US American minority populations of African or Native American descent than it is in European Americans. However, the proportion of this epidemiological difference that can be ascribed to genetic or environmental factors is unknown. To determine whether genetic ancestry is correlated with diabetes risk in Latinos, we estimated the proportion of European ancestry in case-control samples from Mexico and Colombia in whom socioeconomic status had been carefully ascertained.

METHODS

We genotyped 67 ancestry-informative markers in 499 participants with type 2 diabetes and 197 controls from Medellín (Colombia), as well as in 163 participants with type 2 diabetes and 72 controls from central Mexico. Each participant was assigned a socioeconomic status scale via various measures.

RESULTS

Although European ancestry was associated with lower diabetes risk in Mexicans (OR [95% CI] 0.06 [0.02-0.21], p = 2.0 x 10(-5)) and Colombians (OR 0.26 [0.08-0.78], p = 0.02), adjustment for socioeconomic status eliminated the association in the Colombian sample (OR 0.64 [0.19-2.12], p = 0.46) and significantly attenuated it in the Mexican sample (OR 0.17 [0.04-0.71], p = 0.02). Adjustment for BMI did not change the results.

CONCLUSIONS/INTERPRETATION

The proportion of non-European ancestry is associated with both type 2 diabetes and lower socioeconomic status in admixed Latino populations from North and South America. We conclude that ancestry-directed search for genetic markers associated with type 2 diabetes in Latinos may benefit from information involving social factors, as these factors have a quantitatively important effect on type 2 diabetes risk relative to ancestry effects.

The Animadora Project: identifying factors related to the promotion of physical activity among Mexican Americans with diabetes

PURPOSE

There is a dearth of information about factors related to physical activity among Mexican-Americans with diabetes. Self-efficacy and social support are associated with physical activity; however, little is known about their roles within different cultural groups.

DESIGN

Focus groups were used to identify factors that motivated walking.

SETTING

Two Mexican-American communities located in Tucson, Arizona.

SUBJECTS

Individuals who attended diabetes education.

INTERVENTION

A community-based provider organized walking groups with people who previously attended diabetes classes. Walkers participated in focus groups exploring themes related to their experiences.

MEASURES

Self-efficacy, social support, and collective efficacy. Grounded theory was used to analyze focus group results using two rounds of analysis; the first identified references to self-efficacy and social support, and the second added collective efficacy as a theoretic basis for walking.

RESULTS

Among 43 eligible participants, 20 participated in focus groups. Social support was expressed as commitment and companionship. Walkers demonstrated a high level of self-efficacy for walking. Development of group identity/social cohesion was also a motivator to walk. Collective efficacy emerged as an applicable theoretic model encompassing these themes and their interrelationship.

CONCLUSION

Collective efficacy, or the belief that the group can improve their lives through collective effort, is a viable theoretic construct in the development of physical activity interventions targeting Mexican-Americans with diabetes.

Texas-Mexico Border Intervention by Promotores for Patients With Type 2 Diabetes

Purpose The purpose of this study is to evaluate the impact of a promotores-led diabetes self-management program by comparing the outcomes (knowledge, beliefs, and HbA1c level) of Mexican American patients with type 2 diabetes who received usual diabetic care in a wait-list control group to those who received self-management education and follow-up by promotores in consultation with clinic providers and staff.

Methods This randomized control study compared the results of 63 patients who attended a promotores-led culturally sensitive diabetes self-management course at a commu- nity clinic with 68 patients in a wait-list, usual-care control group. Participants were Mexican Americans with type 2 diabetes who were patients at the clinic and at least 18 years of age. At baseline, 3 months, and 6 months, the Diabetes Knowledge Questionnaire (DKQ), Health Beliefs Questionnaire (HBQ), and HbA1c levels (drawn by the clinic laboratory) were collected.

Results There was a significant improvement in the intervention group's DKQ scores over time and in treatment by time. The baseline HbA1c level was 7.49 and did not change over time in either group. The DKQ, HBQ, and HbA1c results were significantly affected by age; the DKQ and HbA1c were affected by years with diabetes.

Conclusions The promotores-led diabetes self-management course improved the knowledge of patients with diabetes. Participant baseline HbA1c level was close to therapeutic level (much lower than reported in previous studies), suggesting participants received good medical care within the community clinic.

Identification of type 2 diabetes genes in Mexican Americans through genome-wide association studies

OBJECTIVE

The objective of this study was to identify DNA polymorphisms associated with type 2 diabetes in a Mexican-American population.

RESEARCH DESIGN AND METHODS

We genotyped 116,204 single nucleotide polymorphisms (SNPs) in 281 Mexican Americans with type 2 diabetes and 280 random Mexican Americans from Starr County, Texas, using the Affymetrix GeneChip Human Mapping 100K set. Allelic association exact tests were calculated. Our most significant SNPs were compared with results from other type 2 diabetes genome-wide association studies (GWASs). Proportions of African, European, and Asian ancestry were estimated from the HapMap samples using structure for each individual to rule out spurious association due to population substructure.

RESULTS

We observed more significant allelic associations than expected genome wide, as empirically assessed by permutation (14 below a P of 1 x 10(-4) [8.7 expected]). No significant differences were observed between the proportion of ancestry estimates in the case and random control sets, suggesting that the association results were not likely confounded by substructure. A query of our top approximately 1% of SNPs (P < 0.01) revealed SNPs in or near four genes that showed evidence for association (P < 0.05) in multiple other GWAS interrogated: rs979752 and rs10500641 near UBQLNL and OR52H1 on chromosome 11, rs2773080 and rs3922812 in or near RALGPS2 on chromosome 1, and rs1509957 near EGR2 on chromosome 10.

CONCLUSIONS

We identified several SNPs with suggestive evidence for replicated association with type 2 diabetes that merit further investigation.

Teaching how, not what: the contributions of community health workers to diabetes self-management

PURPOSE

The purpose of this study is to describe ways in which community health workers (CHWs) are used in various clinic and community settings to support diabetes self-management.

METHODS

Descriptive quantitative data were collected from logs completed by CHWs. Logs described mode, place, type, duration, and focus of individual contact between the CHW and the patient. Qualitative data were collected from semistructured interviews with patients. Interviews were conducted on site from June to August 2006. Interviewees included a purposeful sample of 47 patients who perceived being helped by CHWs.

RESULTS

CHWs reported providing assistance and teaching or practicing skills as the focus of most of the 1859 individual contacts. The assistance CHWs reported providing was most often in the form of encouragement/motivation. During interviews, patients shared that CHWs were helpful in demonstrating how to incorporate diabetes self-management (DSM) into their daily lives. The information patients shared also provided insight into what they perceived as encouragement/motivation from the CHWs. Quotes from interviews provide specific examples of how support from CHWs was different from that received from family and health care team members.

CONCLUSIONS

Both CHWs and patients perceived assistance being provided in similar ways, with consistent emphasis on encouragement/motivation. Interviews with the patients revealed that a personal connection along with availability and provision of key resources and supports for self-management made the CHW-patient interaction successful for DSM. Examples provide insight into the valuable contributions of CHWs to DSM. This insight should encourage guidelines that make CHWs a routine, standard part of the diabetes care team.

Comprehensive linkage and linkage heterogeneity analysis of 4344 sibling pairs affected with hypertension from the Family Blood Pressure Program

Linkage analyses of complex, multifactorial traits and diseases, such as essential hypertension, have been difficult to interpret and reconcile. Many published studies provide evidence suggesting that different genes and genomic regions influence hypertension, but knowing which of these studies reflect true positive results is challenging. The reasons for this include the diversity of analytical methods used across these studies, the different samples and sample sizes in each study, and the complicated biological underpinnings of hypertension. We have undertaken a comprehensive linkage analysis of 371 autosomal microsatellite markers genotyped on 4,334 sibling pairs affected with hypertension from five ethnic groups sampled from 13 different field centers associated with the Family Blood Pressure Program (FBPP). We used a single analytical technique known to be robust to interpretive problems associated with a lack of completely informative markers to assess evidence for linkage to hypertension both within and across the ethnic groups and field centers. We find evidence for linkage to a number of genomic regions, with the most compelling evidence from analyses that combine data across field center and ethnic groups (e.g., chromosomes 2 and 9). We also pursued linkage analyses that accommodate locus heterogeneity, which is known to plague the identification of disease susceptibility loci in linkage studies of complex diseases. We find evidence for linkage heterogeneity on chromosomes 2 and 17. Ultimately our results suggest that evidence for linkage heterogeneity can only be detected with large sample sizes, such as the FBPP, which is consistent with theoretical sample size calculations.

The changing spectrum of diabetes in Mexican American youth

Type 2 diabetes (T2DM) is now a pediatric disease. As in adults, it disproportionately affects ethnic and racial minorities, including Hispanics. The preponderance of Hispanics in south Texas are of Mexican American (MA) heritage. Over the past 16 years, we have accumulated a large cohort of children with diabetes. We have noted distinct differences in numerous parameters between MA children with T2DM and those with type 1 diabetes (T1DM). In order to explore these observations, we have reviewed the records of all children diagnosed with diabetes (n = 669) during the 9 years between January, 1990 and December, 1998 and seen by our pediatric diabetes group. In this cohort were 329 MA, 287 non-Hispanic whites (EA) and 53 African Americans. Compared to EA children with T1DM, MA children were more likely to have a parent with diabetes, to be hospitalized at the time of diagnosis and to lack health insurance. The differences between MA children with T1DM and T2DM were significant: specifically, children with T2DM were more likely to be female and pubertal with a body mass index >25 kg/m(2) and have acanthosis nigricans. Slightly more than 2/3 of the MA children with T2DM had at least one parent already diagnosed with T2DM. Less than 1/3 of the children with T2DM required hospitalization at the time of diagnosis and only a 1/4 have private health insurance. Over this 9-year interval, the apparent incidence of diabetes almost tripled in south Texas with the great majority of that increase due to the increasing numbers of children with T2DM.

Diabetes self-management among low-income spanish-speaking patients: A pilot study

BACKGROUND

The prevalence of type 2 diabetes and diabetes-related morbidity and mortality is higher among low-income Hispanics when compared to that of Whites. However, little is known about how to effectively promote self-management in this population.

PURPOSE

The objectives were first to determine the feasibility of conducting a randomized clinical trial of an innovative self-management intervention to improve metabolic control in low-income Spanish-speaking individuals with type 2 diabetes and second to obtain preliminary data of possible intervention effects.

METHODS

Participants for this pilot study were recruited from a community health center, an elder program, and a community-wide database developed by the community health center, in collaboration with other agencies serving the community, by surveying households in the entire community. Participants were randomly assigned to an intervention (n = 15) or a control (n = 10) condition. Assessments were conducted at baseline and at 3 months and 6 months postrandomization. The intervention consisted of 10 group sessions that targeted diabetes knowledge, attitudes, and self-management skills through culturally specific and literacy-sensitive strategies. The intervention used a cognitive-behavioral theoretical framework.

RESULTS

Recruitment rates at the community health center, elder program, and community registry were 48%, 69%, and 8%, respectively. Completion rates for baseline, 3-month, and 6-month assessments were 100%, 92%, and 92%, respectively. Each intervention participant attended an average of 7.8 out of 10 sessions, and as a group the participants showed high adherence to intervention activities (93% turned in daily logs, and 80% self-monitored glucose levels at least daily). There was an overall Group x Time interaction (p = .02) indicating group differences in glycosylated hemoglobin over time. The estimated glycosylated hemoglobin decrease at 3 months for the intervention group was -0.8% (95% confidence intervals = -1.1%, -0.5%) compared with the change in the control group (p = .02). At 6 months, the decrease in the intervention group remained significant, -0.85% (95% confidence intervals = -1.2, -0.5), and the decrease was still significantly different from that of the controls (p = .005). There was a trend toward increased physical activity in the intervention group as compared to that of the control group (p = .11) and some evidence (nonsignificant) of an increase in blood glucose self-monitoring in the intervention participants but not the control participants. Adjusting for baseline depressive scores, we observed a significant difference in depressive symptoms between intervention participants and control participants at the 3-month assessment (p = .02).

CONCLUSIONS

Low-income Spanish-speaking Hispanics are receptive to participate in diabetes-related research. This study shows that the pilot-tested diabetes self-management program is promising and warrants the conduct of a randomized clinical trial.

Improving efficacy of diabetes management using treatment algorithms in a mainly Hispanic population

OBJECTIVE

To compare clinical outcomes obtained using treatment algorithms versus standard "usual care" to treat patients with type 2 diabetes in a community setting.

RESEARCH DESIGN AND METHODS

An observational group comparison was implemented in three community-based clinics in San Antonio, Texas: 1). a community clinic following treatment algorithms (CC-TA), 2). university clinic following treatment algorithms (UC-TA), and 3). a community clinic following standard "usual care" practices (CC-SC). Three hundred fifty-eight recently diagnosed type 2 diabetic patients (90% Mexican American, from low-income neighborhoods) who were consecutively identified at the three clinics were recruited. Following medical and laboratory evaluation, participants were started on treatment for hyperglycemia, hypertension, and dyslipidemia and followed for 12 months.

RESULTS

Decrements in HbA(1c) at 12 months in the CC-TA and UC-TA were 3.1 and 3.3%, respectively, compared to 1.3% in the CC-SC (P < 0.0001). Corresponding decrements in fasting plasma glucose at 12 months were 94 and 99 mg/dl, respectively, versus 38 mg/dl in CC-SC (P < 0.0001). Reductions in total cholesterol, LDL cholesterol, and triglycerides at 12 months were greater in both algorithm-managed clinics compared to standard care-managed clinics (P < 0.0001). In algorithm-managed clinics, there were 30% more documented eye exams and 24% more documented foot exams than in standard care-managed patients.

CONCLUSIONS

Adherence to the treatment algorithms improved metabolic outcomes in type 2 diabetic patients to a greater extent than standard care practices. These results have important clinical implications for the treatment of type 2 diabetic patients.

Ethical issues in conducting migrant farmworker studies

Migrant farmworkers should be considered a vulnerable population because they work in a hazardous industry, are often members of an ethnic minority, have known difficulty in accessing health care, and are often of lower socioeconomic status. For these reasons, too, it is extremely important to conduct health-related research with this often-underserved group. However, because migrant farmworkers are vulnerable, investigators must be especially vigilant in protecting them from the potential harms of research and in ensuring that the special ethical issues that arise in research with this population are identified and addressed for every project. In response to the National Cancer Institute's concerns about the feasibility of conducting epidemiologic studies among migrant farmworkers, researchers undertook four feasibility studies near the Texas-Mexico border. Each study raised different, complex ethical questions that challenged the investigators, but whose resolution turned out to be crucial to the success of the studies.

Weight loss in obese Mexican Americans treated for 1-year with orlistat and lifestyle modification

OBJECTIVE

To evaluate the effectiveness of a culturally appropriate lifestyle intervention combined with orlistat in producing weight loss with obese Mexican-American women.

SUBJECTS

Mexican-American women (N=108), aged 21-65 y, with a body mass index (BMI) > or =27 kg/m(2) were randomized to 1 y of treatment with orlistat and a culturally tailored lifestyle modification intervention (OLM; n=56) or a wait-list control group (WLC; n=52).

DESIGN

A randomized, controlled, open-label 12-month study. Orlistat was dosed at 120 mg, three times per day. The OLM intervention included behavior modification, a low-fat (< or =30% of total daily calories) diet, and moderate physical activity (> or =150 min/week).

MEASUREMENT

Primary outcomes included changes in body weight (kg), BMI, waist circumference, blood pressure, glucose, and lipids.

RESULTS

A total of 72 (37 OLM, 35 WLC) and 66 participants (32 OLM, 34 WLC) completed the 6- and 12-month follow-ups, respectively. Repeated-measures ANOVA demonstrated a significant time x treatment interaction (Wilks' lambda=12.61; P<0.001), indicating that OLM-treated patients achieved significant weight loss relative to the WLC group during the study (mean percentage weight loss+/-s.e.m.; -8.1%+/-1.2 vs -1.6%+/-0.7 at 6 months and -8.8%+/-1.5 vs -0.2%+/-1.0 at 12 months, respectively). OLM-treated patients also experienced significant reductions in waist circumference, low-density-lipoprotein, and total cholesterol.

CONCLUSIONS

This study demonstrates the effectiveness of an intervention combining orlistat and lifestyle modification with Mexican-American women, a population with substantial risk for obesity.

Inconsistent use of diabetes medications, diabetes complications, and mortality in older mexican americans over a 7-year period: data from the Hispanic established population for the epidemiologic study of the elderly

OBJECTIVE

The aim of this study was to examine the relationship between inconsistency in use of diabetes drugs and risk of renal, eye, and circulation problems and death over a 7-year period in community-dwelling older Mexican Americans.

RESEARCH DESIGN AND METHODS

Data are from the four waves of the Hispanic Established Population for the Epidemiologic Study of the Elderly. In-home interviewers assessed consistency in use of diabetes medications among 908 diabetic Mexican Americans, aged >or=65 years. Diabetes and complications were by self-report. Subjects with poor consistency in use of medication were those who, at any time during the 7-year follow-up, discontinued or inconsistently used their diabetes medications and those who had no diabetic medications at home despite self-report of taking medicine for diabetes.

RESULTS

Thirty-six percent of our sample were inconsistent with diabetes medication usage. Older age and lack of supplemental health insurance were significantly associated with inconsistency of use of medication. In a multivariate logistic regression model, subjects with poor consistency in use of medication were more likely to report kidney problems (odds ratio [OR] 1.59; 95% CI 1.13-2.23; P = 0.008) at follow-up compared with those with good consistency, after controlling for age, sex, medication type, duration of diabetes, education, income, marital status, language of interview, insurance status, cognitive function, presence of depressive symptoms, activities of daily living, and instrumental activities of daily living. In Cox regression models, poor consistency with diabetic medication was also associated with increased all-cause mortality (hazard ratio [HR] 1.43; 95% CI 1.13-1.82; P = 0.003) and diabetes-related deaths (1.66; 1.20-2.30; P = 0.002) over a 7-year period after adjusting for relevant confounders.

CONCLUSIONS

Inconsistent use of diabetic medication was associated with an increased risk of kidney problems and deaths over a 7-year period in older Mexican Americans.

Impact of diabetes on cognitive function among older Latinos: a population-based cohort study

BACKGROUND AND OBJECTIVES

Type 2 diabetes, which is highly prevalent in older Mexican Americans, may influence cognitive functioning. We examined the association of diabetes with decline in global cognitive function and memory function over a 2-year period.

METHODS

Study subjects were derived from an existing cohort of Latinos aged 60 and over in the SALSA project (n=1,789). Statistical analysis was conducted using logistic regression and a generalized estimating equation (GEE).

RESULTS

Logistic regression analysis indicated that baseline diabetes was a significant predictor of major cognitive impairment in Modified Mini Mental State Exam (3MSE) (OR=1.68, 95% CI=1.21, 2.34) and word-list test (OR=1.31, 95% CI=0.99, 1.75). GEE analysis showed that there was no significant difference between diabetic and nondiabetic subjects in change of cognitive scores over 2 years (3MSE, mean=-0.58, 95% CI=-1.48, 0.32; word-list test, mean=-0.10, 95% CI=-0.32, 0.11).

CONCLUSIONS

More diabetic complications were associated with major cognitive decline among diabetic subjects. Research on long-term impact of treatment for type 2 diabetes is warranted.

Obesity and hunger among Mexican-Indian migrant children on the US-Mexico border

BACKGROUND

Although Mexican-Indian migrant workers live under precarious conditions in both Mexico and the USA, they have more access to food than they did in their original communities. The nutritional status and food security among the children of these workers have not been reported.

OBJECTIVE

The purpose of this study was to assess the prevalence of overweight, obesity, undernutrition and hunger among migrant children in a city on the US-Mexico border.

DESIGN

During 2001-2002, a total of 1767 children from six schools from the Tijuana Indian school system was measured to assess anthropometric status. Third and fifth grade children were also interviewed for their perception of hunger experience and dietary intake by 24-h recall method.

RESULTS

The overall prevalence of overweight and obesity was 38%. Abdominal obesity was found in 26% of subjects, while 43% had both obesity and abdominal obesity. The prevalence of undernutrition according to weight-for-age was 1.2%, and by height-for-age it was 4.8%. The prevalence of hunger was 2.5%, and at risk of hunger was 44%. Daily intake of food groups in servings was: 8.7 grains, 1.2 fruit, 1.0 vegetable, 2.1 milk and 2.6 meat. Only one child (0.07%) consumed The Apple of Health recommended portions.

CONCLUSIONS

This study confirmed the coexistence of obesity, hunger, undernutrition and limited food group consumption among Indian children living in a prosperous and the largest US-Mexico border city.

Impact of antidiabetic medications on physical and cognitive functioning of older Mexican Americans with diabetes mellitus: a population-based cohort study

PURPOSE

The current study was designed to evaluate the utility of antidiabetic medications in affecting changes in physical and cognitive functioning among older Mexican Americans with diabetes over a 2-year period.

METHODS

A longitudinal analysis with repeated measurements between 1999 and 2001 was performed in a cohort of Mexican Americans, 60 or older, in the SALSA Project. Statistical analysis was conducted using a generalized estimating equation.

RESULTS

For subjects with diagnosed diabetes </= 5 years (N = 381), there was less decline in physical and cognitive functioning over 2 years among subjects on treatment, compared to those without treatment. For subjects with diagnosed diabetes of 5+ years (N = 337), the effect of antidiabetic medications was more significant in preventing the decline in physical and cognitive functioning (ADL: mean in log scale = -0.10, 95% CI = -0.16, -0.04, 3MS: mean = 6.35, 95% CI = 3.23, 9.48). Combination therapy of antidiabetic agents appeared to be more effective than monotherapy in preventing the decline in physical and cognitive functioning for subjects.

CONCLUSIONS

Antidiabetic drugs appear to be useful in alleviating the decline in physical and cognitive functioning among older Mexican Americans with diabetes, especially for those with a longer duration of the disease.

Lower extremity amputations in diabetic Mexican American elders: incidence, prevalence and correlates

This study was designed to determine the incidence and prevalence of amputations in diabetic Mexican American elders and to identify correlates of lower extremity amputations. Data for this study came from baseline and two follow-up interviews of the Hispanic Established Population for the Epidemiological Study of the Elderly (EPESE) conducted in five southwestern states (Texas, California, New Mexico, Colorado and Arizona) in 1993-1994. Of the 3050 subjects aged 65 and older, 690 reported diabetes, and from these, 60 (8%) reported having at least one lower extremity amputation. Losing a leg was the most common type of amputation (53%). Twelve percent of respondents reported a new amputation and 40% of amputees reported a second amputation during follow-up. Mortality among amputees was 46% during a 5-year follow-up. Multiple logistic regression analysis showed that being male and having eye problems, hip fracture and diabetes for 10 or more years were significantly associated with lower extremity amputations at baseline, whereas obesity, stroke and 10 or more years with diabetes were significantly associated with new amputations at 5-year follow-up. Gender and disease history were associated with lower extremity amputations at baseline and follow-up. These variables may be useful in developing patient education and intervention programs.

Diabetes as a predictor of change in functional status among older Mexican Americans: a population-based cohort study

OBJECTIVE

Epidemiological studies have demonstrated that older Mexican Americans are at high risk for type 2 diabetes and its complications. Type 2 diabetes leads to a more rapid decline in functional status among older Mexican Americans with diabetes. This study was designed to examine the impact of diabetes on change in self-reported functional status over a 2-year period among older Mexican Americans with diabetes.

RESEARCH DESIGN AND METHODS

We performed a longitudinal analysis with repeated measurements of functional limitations in a cohort of Mexican Americans aged > or =60 years in the Sacramento Area Latino Study on Aging (SALSA). Diabetes was diagnosed on the basis of self-report of physician diagnosis, medication use, and fasting plasma glucose. Functional status was measured by assessment of activities of daily living (ADL) and instrumental activities of daily living (IADL) at baseline and 1 and 2 years.

RESULTS

Of 1,789 SALSA participants, 585 (33%) had diabetes at baseline. Diabetic subjects reported 74% more limitations than nondiabetic subjects in ADL (summary score for number of limitations, 0.99 vs. 0.57; P = 0.002) and 50% more limitations in IADL (summary score for number of limitations, 7.83 vs. 5.25; P < 0.0001). The annual rate of increase in limitations of ADL and IADL was 0.046 and 0.033 (log scale) on each scale among diabetic subjects compared with 0.013 and 0.003 (log scale) among nondiabetic subjects (P < 0.0005). Complications of diabetes were found to increase ADL and IADL limitations among diabetic subjects. Longer duration of diabetes was also associated with an increase in ADL and IADL limitations.

CONCLUSIONS

There was lower baseline functional status and a more rapid decline in functional status among older Mexican Americans with diabetes versus those without diabetes.

Dietary and plasma lipid, lipoprotein, and apolipoprotein profiles among elderly Hispanics and non-Hispanics and their association with diabetes

BACKGROUND

There are limited data about dietary intakes and plasma lipids of elderly US Hispanics.

OBJECTIVE

The disparity in prevalence of type 2 diabetes among population groups underscored our need to assess dietary and plasma risk factors for cardiovascular disease.

DESIGN

Plasma lipids and apolipoproteins and dietary intakes of macronutrients were measured in elderly subjects (60-98 y): 490 Hispanics of Caribbean origin (Puerto Ricans and Dominicans) and 163 non-Hispanic whites. Plasma values were related to ethnicity and to macronutrient intake. Differences in plasma lipids due to diabetes were assessed among the Hispanics.

RESULTS

Intakes of carbohydrate and polyunsaturated fatty acids were higher and intakes of cholesterol and saturated and monounsaturated fatty acids were lower in Hispanics than in non-Hispanic whites. Concentrations of total cholesterol, HDL cholesterol, and apolipoprotein A-I were significantly lower among Hispanic women than among non-Hispanic white women; a similar trend was seen in men. Dyslipidemia (high triacylglycerols and low HDL cholesterol) was more prevalent among Hispanics with than without diabetes.

CONCLUSIONS

Ethnic differences in serum lipids exist and appear to be associated with differences in dietary intakes. However, both Hispanics and non-Hispanic whites had lipid profiles indicating a high risk of cardiovascular disease. Hispanics with diabetes were at higher risk of dyslipidemia than were those without diabetes. Our data suggest that lifestyle changes, including diet modification and exercise, could be of significant benefit to both ethnic groups.

The impact of diabetes on adult employment and earnings of Mexican Americans: findings from a community based study

Epidemiological studies indicate that minority populations in the US - including African Americans, Native Americans and Mexican Americans - are particularly at risk for diabetes and that their complications are more frequent and severe. Using microdata from a 1994-1999 population based study of middle aged and older Mexican Americans in the Southwest, this study analyzes the impact of diabetes on the employment and earnings outcomes of adults 45 years of age and older. The empirical results from estimating maximum likelihood employment and earnings models suggest that diabetes leads to lower productivity and earnings for women but has no statistically significant impact on their employment probability. In the case of men, however, diabetes leads to a lower employment propensity but has no effect on earnings. Thus, the problems associated with this condition could lead to potential future financial difficulties particularly for high-risk populations in their later years.

Reaching underserved populations and cultural competence in diabetes education

Diabetes self-management education has gained in importance over the past decade as research has documented the benefits of such interventions in improving glucose control and reducing diabetes-related complications. Although minority populations bear a disproportionate burden of diabetes, past strategies have not addressed cultural characteristics of groups typically underrepresented in diabetes research. Recent research literature on the development of culturally competent diabetes self-management is summarized and an example of a culturally competent intervention designed for Spanish-speaking Mexican Americans is presented. Recent research is laying the foundation for future intervention development to meet the cultural needs of racial/ethnic groups.