Marc J Weigensberg

University of Southern California, Los Angeles, California, United States

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Publications (90)409.39 Total impact

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    ABSTRACT: Type 2 diabetes risk and its relationship to free fatty acid (FFA) exposure and visceral fat by prediabetes status in minority adolescents have yet to be explored. Therefore, the objective of this study was to examine the association of circulating FFA under varying conditions with prediabetes in Latino adolescents and to determine the relative relationships of FFA and visceral adiposity to insulin sensitivity, secretion, and β-cell function. Overweight or obese, but otherwise healthy Latino adolescent males and females (n = 164, 14.2 ± 2.5 years), were recruited for assessment of prediabetes, abdominal fat, and FFA levels taken at a fasting state (FFAF), during an OGTT (FFAOGTT), and overnight (FFANOCTURNAL). Prediabetic adolescents had a higher FFAF than those with normal glucose tolerance when controlling for age, sex, pubertal status, total percent body fat, and visceral fat. FFAOGTT and FFANOCTURNAL did not differ between participants with prediabetes and those with normal glucose tolerance after adjusting for covariates. Visceral fat was independently related to insulin sensitivity and secretion in pubertal adolescents; however, in post-pubertal adolescents, FFAF and visceral fat were both independent and negatively related to β-cell function. These results support a plausible progression of the lipotoxicity theory of diabetes development during the pubertal transition.
    Acta diabetologica. 08/2014;
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    ABSTRACT: The purpose of this study was to investigate how an intergenerational legacy of type 2 diabetes affected the knowledge, attitudes, and treatment strategies of Hispanic young adults with diabetes.
    The Diabetes Educator 05/2014; · 1.94 Impact Factor
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    ABSTRACT: AimTo examine challenges contributing to disruptions in care during the transition from paediatric to adult care among young adults with Type 1 diabetes who are primarily in ethnic minority groups and have low socio-economic status.Methods Participants (n = 20) were newly enrolled patients in a transition clinic for young adults with Type 1 diabetes with a history of loss to medical follow-up. Participants completed qualitative semi-structured interviews detailing their transition experiences in addition to demographic, HbA1c and psychosocial measures. Descriptive statistics were completed for quantitative data, and narrative thematic analysis of interviews was used to identify common themes. A mixed-method analysis was used to identify the associations between stressors identified in interviews and clinical and psychosocial variables.ResultsThree categories of challenges contributing to loss to follow-up were identified: psychosocial challenges, health provider and health system challenges and developmental challenges. Participants experienced a high degree of stressful life circumstances which were associated with higher HbA1c (r = 0.60, P = 0.005), longer duration of loss to follow-up (r = 0.51, P = 0.02), greater emergency department utilization (r = 0.45, P = 0.05), and lower life satisfaction (r = -0.62, P = 0.003).ConclusionsA confluence of challenges, including stressful life circumstances, healthcare system barriers and the developmental trajectory of young adulthood, contributes to a high risk of loss to follow-up and poor health in this population of young adults with Type 1 diabetes. An integrated approach to transition addressing medical and psychosocial needs may facilitate improved follow-up and health outcomes in clinical settings.This article is protected by copyright. All rights reserved.
    Diabetic Medicine 05/2014; · 3.24 Impact Factor
  • Journal of alternative and complementary medicine (New York, N.Y.) 05/2014; 20(5):A69. · 1.69 Impact Factor
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    ABSTRACT: While most studies have focused on investigating the preventive effects of physical activity on metabolic risk, the longitudinal impacts of metabolic syndrome (MetS) on activity levels is poorly understood. This study aims to examine the influence of MetS on initial activity levels and the trajectory of activity levels in Latina and African American female children over 12 months (n=55, 9±1 years). Metabolic measures, including fat and lean tissue mass by BodPodTM, fasting glucose, lipids, blood pressure, and waist circumference, were collected at baseline. Moderate-to-vigorous physical activity and sedentary behavior by accelerometry were collected on a quarterly basis. There were no significant differences in either initial activity levels by MetS status (Moderate-to-vigorous physical activity: 33±12 mins/day for MetS, 48±28 mins/day for Non-MetS, p=0.12; sedentary behavior: 408±57 mins/day for MetS, 421±72 mins/day for Non-MetS, p=0.67). Longitudinal declines in moderate-to-vigorous physical activity (p=0.038) and increases in sedentary behavior (p=0.003) were found. Daily sedentary behavior increased by 82.64 more minutes in youth with MetS than in those without over one year (p=0.015). This study yields the first evidence of the adverse effect of MetS on sedentary behavior. Targeted intervention strategies to reduce progressive sedentariness evident in minority youth with MetS are warranted.
    Pediatric exercise science 04/2014; · 1.57 Impact Factor
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    ABSTRACT: Evidence of associations between the built environment and obesity risk has been steadily building, yet few studies have focused on the relationship between the built environment and aspects of metabolism related to obesity's most tightly linked comorbidity, type 2 diabetes. To examine the relationship between aspects of the neighborhood built environment and insulin resistance using accurate laboratory measures to account for fat distribution and adiposity. Data on 453 Hispanic youth (aged 8-18 years) from 2001 to 2011 were paired with neighborhood built environment and 2000 Census data. Analyses were conducted in 2011. Walking-distance buffers were built around participants' residential locations. Body composition and fat distribution were assessed using dual x-ray absorptiometry and waist circumference. Variables for park space, food access, walkability, and neighborhood sociocultural aspects were entered into a multivariate regression model predicting insulin resistance as determined by the homeostasis model assessment. Independent of obesity measures, greater fast-food restaurant density was associated with higher insulin resistance. Increased park space and neighborhood linguistic isolation were associated with lower insulin resistance among boys. Among girls, park space was associated with lower insulin resistance, but greater neighborhood linguistic isolation was associated with higher insulin resistance. A significant interaction between waist circumference and neighborhood linguistic isolation indicated that the negative association between neighborhood linguistic isolation and insulin resistance diminished with increased waist circumference. Reducing access to fast food and increasing public park space may be valuable to addressing insulin resistance and type 2 diabetes, but effects may vary by gender.
    American journal of preventive medicine 04/2014; 46(4):378-87. · 4.24 Impact Factor
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    ABSTRACT: There is an urgent need for innovative and developmentally appropriate lifestyle interventions to promote healthy lifestyle behaviors and to prevent the early onset of type 2 diabetes and cardiovascular disease risk in obese Latino adolescents. Guided imagery offers promise to reduce stress and promote lifestyle behavior change to reduce disease risk in obese adolescents. Our objectives were: 1) To pilot test a new 12-wk lifestyle intervention using a randomized trial design in obese Latino adolescents, in order to determine the effects of the mind-body modality of Interactive Guided ImagerySM (IGI), over and above those of a didactic lifestyle education, on insulin resistance, eating and physical activity behaviors, stress and stress biomarkers; and 2) To explore the role of intervention-related changes in stress and stress biomarkers on changes in metabolic outcomes, particularly insulin resistance. Obese (BMI > 95th percentile), Latino adolescents (n = 35, age 14-17) were randomized to receive either 12 weekly sessions of a lifestyle education plus guided imagery program (GI), or lifestyle education plus a digital storytelling computer program (DS). Between-group differences in behavioral, biological, and psychological outcomes were assessed using unpaired T-tests and ANCOVA in the 29 subjects who completed the intervention. The GI group demonstrated significant reductions in leisure sedentary behavior (p < .05) and increases in moderate physical activity (p < .05) compared to DS group, and a trend toward reduced caloric intake in GI vs DS (p = .09). Salivary cortisol was acutely reduced by stress-reduction guided imagery (p < .01). There were no group differences in adiposity, insulin resistance, perceived stress, or stress biomarkers across the 12-week intervention, though decrease in serum cortisol over the course of the intervention was associated with improved insulin sensitivity (p = .03) independent of intervention group and other relevant co-variates. The improvements in physical activity and stress biomarkers following this pilot intervention support the role of guided imagery in promoting healthy lifestyle behavior change and reducing metabolic disease risk in obese Latino adolescent populations. Future investigations will be needed to determine the full effects of the Imagine HEALTH intervention on insulin resistance, stress, and stress biomarkers.Trial registration: Registry #: NCT01895595.
    BMC Complementary and Alternative Medicine 01/2014; 14(1):28. · 2.08 Impact Factor
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    ABSTRACT: There are limited data on the influence of vegetable consumption on adiposity and metabolic health, specifically nonstarchy vegetables and vegetables that are dark green and deep orange/yellow (also known as nutrient-rich vegetables). Our study examines the relationship between vegetable intake and adiposity, liver fat, and insulin dynamics in overweight Latino youth. This cross-sectional study of 175 overweight (body mass index ≥85th percentile) Latino youth (aged 8 to 18 years), with data collected during 2006-2011, included the following: dietary intake via multiple 24-hour recalls, total body fat via dual-energy x-ray absorptiometry, adipose tissue distribution and liver fat via magnetic resonance imaging, and insulin dynamics via frequently sampled intravenous glucose tolerance test. Linear regression and analysis of covariance were used for analysis, with the following a priori covariates: age, sex, energy intake, and total body fat. Participants who consumed the most nonstarchy vegetables (mean intake=1.7±1.0 servings/day) compared with the least (mean intake=0.1±0.1 servings/day) had 44% less liver fat (10.0%±8.5% vs 5.6%±8.7%; P=0.01). Nutrient-rich vegetable intake was positively correlated with insulin sensitivity (r=0.19; P=0.03). Consumers of nutrient-rich vegetables (mean intake=0.3±0.4 servings/day [n=107]), compared with nonconsumers (n=68), had 31% increased insulin sensitivity (1.6±1.6 vs 2.1±1.3×10–4/min/μU/mL; P=0.03) and 17% less visceral adipose tissue (2.3±0.9 vs 1.9±0.7 L; P=0.01). Consumption of specific vegetable types by overweight Latino youth is associated with positive metabolic outcomes, including reduced visceral and liver fat and risk factors for type 2 diabetes, even when consumed in small quantities. These may be relevant targets for interventions.
    Journal of the American Academy of Nutrition and Dietetics 01/2014; · 3.80 Impact Factor
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    ABSTRACT: Objective: Cortisol has been associated with preferential visceral adipose tissue (VAT) deposition; however findings in humans are mixed, which may be clarified when diet is considered. Design and Methods: Participants included 165 African American and Latino, overweight adolescents (BMI% 97.2±3.2%, ages 13-18, 67% Latino, 66% female). Body composition was determined by DEXA, abdominal fat depots (VAT, subcutaneous (SAT)) by multiple-slice MRI, time-controlled serum sample to measure cortisol, and 2-day multi-pass 24-hour dietary recall. Linear regression analysis examined the cross-sectional relationship between cortisol, and the interaction of diet and cortisol on adiposity measures. Sex, race, age and total body fat were a priori covariates. Results: There was a significant interaction between cortisol and sugar (total and added) in the prediction of VAT (pinteraction <=0.05). Amongst participants with high total or added-sugar intake, cortisol was significantly associated with VAT (ß=0.031 p<0.001; ß=0.026 p<0.001), with no relationship in low consumers of total or added-sugar. Conclusion: Dietary sugar may play an important role in modifying the relationship between cortisol and VAT, such that cortisol is significantly associated with elevated VAT under conditions of high sugar intake.
    Obesity 08/2013; · 3.92 Impact Factor
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    ABSTRACT: Context:Although overweight and obese African-Americans (AA) have less visceral adipose tissue (VAT) and liver fat (LF) than Hispanics, they have a similar risk for type 2 diabetes (T2D).Objective:We examined ethnic differences in the association between VAT and LF with risk factors for T2D to help explain this paradox.Design:Cross-sectional study.Setting:Primary care.Subjects:Overweight and obese AA (n=131; 15.5±3.3 years) and Hispanic adolescents (n=227; 14.7±3.0 years).Main Outcome Measures:Insulin sensitivity (SI), acute insulin response (AIR), and disposition index (DI) by FSIVGTT and minimal modeling.Results:LF, not VAT, was inversely associated with SI and the effect of high LF compared to low was more pronounced in AA (Pinteraction<0.05). In Hispanics, high LF was associated with a 24% lower SI (P<0.01), a 31% increase in AIR (P<0.01), and was not associated with DI (P=0.35). In AA, high LF was associated with a 49% lower SI (P<0.001), was not associated with an increase in AIR (P=0.25), and was associated with a 42% lower DI (P<0.01) indicating failure of compensatory insulin secretion/clearance in response to insulin resistance. Prediabetes changed the relationship between high/low LF and DI in Hispanics (Pinteraction=0.002) but not AA such that prediabetic Hispanics with high LF had a 43% lower DI (P=0.03) with no difference in those without prediabetes (P=0.06).Conclusions:LF has a stronger effect on SI compared to VAT. Our results suggest that the impact of high LF on poor beta-cell compensation is more pronounced in AA. In Hispanics, the combination of high LF and prediabetes contributes to poor beta-cell compensation.
    The Journal of Clinical Endocrinology and Metabolism 07/2013; · 6.31 Impact Factor
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    ABSTRACT: OBJECTIVE Little attention has been paid to possible intrinsic biological mechanisms for the decline in physical activity that occurs during puberty. This longitudinal observational study examined the association between baseline insulin sensitivity (SI) and declines in physical activity and increases in sedentary behavior in peripubertal minority females over a year.RESEARCH DESIGN AND METHODS Participants were Hispanic and African American girls (n = 55; 76% Latina; mean age 9.4 years; 36% obese). SI and other insulin indices were measured at baseline using the frequently sampled intravenous glucose tolerance test. Physical activity was measured on a quarterly basis by accelerometry and self-report.RESULTSPhysical activity declined by 25% and time spent in sedentary behaviors increased by ∼13% over 1 year. Lower baseline SI predicted the decline in physical activity measured by accelerometry, whereas higher baseline acute insulin response to glucose predicted the decline in physical activity measured by self-report. Time spent in sedentary behavior increased by ~13% over 1 year, and this was predicted by lower baseline SI. All models controlled for adiposity, age, pubertal stage, and ethnicity.CONCLUSIONS When evaluated using a longitudinal design with strong outcome measures, this study suggests that lower baseline SI predicts a greater decline in physical activity in peripubertal minority females.
    Diabetes care 07/2013; · 7.74 Impact Factor
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    ABSTRACT: Objective: Genetic variation in six genes has been associated with elevated liver fat and nonalcoholic fatty liver disease in adults. We sought to determine the influence of these genes on liver fat and whether a genetic risk score (GRS) would improve upon the ability of common clinical risk factors to predict elevated liver fat content (ELF) in Hispanic children. Design and Methods: 223 obese Hispanic children were genotyped for six SNPs. MRI was used to measure liver fat. A GRS was tested for association with ELF using multivariate linear regression. Predictors were assessed via ROC curves and pair-wise analysis was used to determine significance alone and combined with clinical markers. Results: Only variants in PNPLA3 and APOC3 genes were associated with liver fat (p<0.001, p=0.01, respectively). Subjects with a GRS=4 had ˜3-fold higher liver fat content than subjects with GRS of 0 (15.1±12.7% vs. 5.1±3.7%, p=0.03). While the addition of the GRS to a model containing BMI and liver enzymes increased ROC AUC from 0.83 to 0.85 [95% CI, 0.79-0.89], (p=0.01), it does not improve detection of ELF from a clinical perspective. Conclusions: Only PNPLA3 and APOC3 were related to ELF and a GRS comprised of these susceptibility alleles did not add to the discriminatory power of traditional biomarkers for clinical assessment of liver fat.
    Obesity 06/2013; · 3.92 Impact Factor
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    ABSTRACT: Eating breakfast is believed to promote a healthy body weight. Yet, few studies have examined the contribution of energy balance-related behavioral factors to this relation in minority youth. We assessed the associations between breakfast consumption and dietary intake, physical activity (PA), and adiposity before and after accounting for energy intake and PA in minority girls. Cross-sectional data were obtained on body mass index (BMI), percentage body fat (measured by BodPod), dietary intake (measured with 3-d dietary records), and PA (measured with 7-d accelerometry) from 87 Latina and African American girls 8-17 y of age (75% Latina, 80% overweight). Dietary records were used to categorize girls as more frequent breakfast eaters (MF; 2 or 3 of 3 d; n = 57) or less frequent breakfast eaters (LF; 0 or 1 of 3 d; n = 30). Chi-square tests, ANCOVA, and multiple regression analyses were conducted. Mediation was assessed with a Sobel test. Compared with the MF group, the LF group spent 30% less time (12.6 min/d) in moderate-to-vigorous-intensity PA (MVPA; P = 0.004) and had a higher percentage body fat (P = 0.029). MVPA accounted for 25% (95% CI: -8.8%, 58.1%; P = 0.139) of the relation between breakfast consumption and percentage body fat. We were unable to show that energy intake or MVPA was a significant mediator of the relation between breakfast consumption and adiposity in this sample. Evidence suggests that among predominantly overweight minority girls, MVPA, but not energy intake, was associated with both breakfast consumption and adiposity; however, a lack of power reduced our ability to detect a significant mediation effect. Other unobserved variables likely contribute to this relation.
    American Journal of Clinical Nutrition 06/2013; · 6.50 Impact Factor
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    ABSTRACT: AIMS: To determine the disclosure rates of psychosocial issues affecting routine diabetes care. METHODS: A total of 20 young adults were interviewed regarding the impact of psychosocial stressors on their diabetes care. The interviewer, endocrinologist and case manager reported the prevalence rates of psychosocial stressors. Disclosure rates were compared to determine the prevalence of psychosocial issues and the different patterns of disclosure. RESULTS: Participants reported a high number of psychosocial stressors, which were associated with poorer glycaemic control (r = 0.60, P = 0.005). Approximately half of all disclosed stressors (50.9%) were identified in routine care; other stressors were identified only through intensive case management and/or in-depth interviews. CONCLUSIONS: Identifying psychosocial stressors in routine care, and providing referrals to psychological or social services, is a significant unmet need and may improve glycaemic control among certain populations with diabetes. Systematic mechanisms of capturing this information, such as by screening surveys, should be considered. This article is protected by copyright. All rights reserved.
    Diabetic Medicine 06/2013; · 3.24 Impact Factor
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    ABSTRACT: Objective: To investigate the impact of eating frequency on dietary intake, physical activity (PA), metabolic, and adiposity measures in minority youth. Design and Methods: This analysis included 185 overweight (≥85(th) BMI percentile) Hispanic and African American youth (8-18 years) with the following cross-sectional measures: height, weight, BMI, dietary intake, body composition, metabolic parameters, PA, visceral adipose tissue (VAT), and subcutaneous adipose tissue. Each eating occasion (EO) was defined as ≥50 calories and ≥15 minutes from any previous EO. Participants were dichotomized based on EOs per 24-h into meal skippers <3 EO (MS; n=27) or normal/frequent eaters ≥3 EO (NFE; n=158). ANCOVAs were used to assess dietary intakes, metabolic outcomes, adiposity, and PA between eating frequency groups. Results: MS compared to NFE consumed 24% fewer calories per 24-h (p≤0.01), 21% more calories per EO (p≤0.01), ate 40% less often (p≤0.01), had 18% higher triglycerides (p=0.03), and 26% more VAT (p=0.03), with no differences in PA. Conclusions: Although meal skipping was associated with decreased energy intake, it was linked to increased calories per EO and higher triglycerides and VAT, which are strong indicators of deleterious metabolic profiles. These findings elucidate that meal skipping may be associated with increased VAT and related metabolic diseases in high-risk minority youth.
    Obesity 04/2013; · 3.92 Impact Factor
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    ABSTRACT: BACKGROUND: Blunted diurnal cortisol variation has been associated with overt cardiovascular disease in adults. The relationship between the diurnal cortisol variation and subclinical atherosclerosis in youth has yet to be investigated. The objectives of this study were to (1) determine the relationship between overnight cortisol measures and CIMT in overweight and obese, African-American and Latino children; (2) assess ethnic differences in these relationships; and (3) explore whether overnight cortisol and CIMT relationships were independent of inflammatory markers, C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-∝ (TNF-∝). METHODS: One hundred fifty-six overweight and obese African-American and Latino children (ages 8-17, 86M/70F, 55 African-American/101 Latino) underwent measures of CIMT by B-mode ultrasound, nocturnal cortisol rise (NCR=salivary cortisol rise from 2200h to awakening at 0530h), cortisol awakening response (CAR=salivary cortisol from time of awakening to 30min later), fasting serum cortisol and overnight urinary free cortisol. RESULTS: Using linear regression, salivary cortisol(0530h) and NCR were negatively associated with CIMT (β(standardized)=-0.215 and -0.220, p<0.01) independent of age, height, percent body fat, ethnicity and systolic blood pressure. Nocturnal salivary cortisol(2200h), morning serum cortisol, and overnight urinary free cortisol were not associated with CIMT. Using ANCOVA, participants with LOW NCR (NCR<0.44μg/dL, n=52) had significantly greater CIMT than those with HIGH NCR (NCR≥0.91μg/dL, n=52; 0.632±0.008 vs. 0.603±0.008mm, p=0.01) after controlling for covariates. Ethnicity was independently associated with CIMT, whereby African-American children had greater CIMT than Latino children (-0.028±0.009, p=0.006). The relationships between cortisol measures and CIMT did not differ between the two ethnic groups (all p(interaction)=0.28-0.97). CRP, IL-6 and TNF-∝ were not associated with CIMT (p>0.05). IL-6 was inversely related to NCR (r=-0.186, p=0.03), but it did not explain the relationship between NCR and CIMT. CONCLUSIONS: Salivary cortisol(0530h) and NCR, but not CAR, nocturnal salivary cortisol (2200h), morning serum cortisol or overnight urinary free cortisol were associated with CIMT, independent of relevant covariates, including inflammatory factors. A low awakening salivary cortisol or a blunted NCR may be related to increased atherosclerosis risk in overweight and obese minority youth. These findings support adult studies suggesting flattened daytime diurnal cortisol variation impacts cardiovascular disease risk.
    Psychoneuroendocrinology 02/2013; · 5.59 Impact Factor
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    ABSTRACT: Context:Optimizing effective prevention and treatment of type 2 diabetes in youth is limited by incomplete understanding of its pathophysiology and how this varies across ethnicities with high risk.Objective:The aim of this study was to examine the contribution of visceral adipose tissue (VAT), hepatic fat fraction (HFF), and pancreatic fat fraction (PFF) to prediabetes in overweight/obese African American (AA) and Latino youth.Design and Setting:We conducted a cross-sectional study in an academic pediatric care facility.Subjects:A total of 148 healthy, overweight/obese adolescents (56 AA, 92 Latino; 72 males, 76 females; age, 15.5 ± 1.2 y; BMI z-score, 2.1 ± 0.5) participated in the study. They were normal glucose tolerant (n = 106) and prediabetic (n = 42), based on fasting glucose of 100-125 mg/dL and/or 2-hour glucose of 140-199 mg/dL, and/or hemoglobin A1C 6.0-6.4%.Main Outcome Measures:We measured sc abdominal adipose tissue, VAT, HFF, and PFF by 3-Tesla magnetic resonance imaging and measured total body fat by dual-energy x-ray absorptiometry.Results:Adolescents with prediabetes had 30% higher HFF (P = .001) and 31% higher PFF (P = .042), compared to those with normal glucose tolerance after controlling for age, sex, pubertal stage, ethnicity, total percentage body fat, and VAT. Logistic regression showed that PFF predicted prediabetes in AAs and HFF predicted prediabetes in Latinos, with the odds of having prediabetes increased by 66% for every 1% increase in PFF in African Americans, and increased by 22% for every 1% increase in HFF in Latinos.Conclusion:These data demonstrate that ectopic fat phenotypes associated with prediabetes are established by adolescence. Ethnic differences in the deposition of ectopic fat in adolescents with prediabetes may differ, with pancreatic fat in AAs, vs hepatic fat in Latino adolescents, being associated with diabetes risk.
    The Journal of Clinical Endocrinology and Metabolism 02/2013; · 6.31 Impact Factor
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    ABSTRACT: OBJECTIVE In adults, 1-h glucose during an oral glucose tolerance test (OGTT) predicts the development of type 2 diabetes independent of fasting and 2-h glucose concentrations. The purpose of the current investigation was to examine the utility of elevated 1-h glucose levels to prospectively predict deterioration in β-cell function and the development of prediabetes in high-risk youth.RESEARCH DESIGN AND METHODS Obese Latino youth with a family history of type 2 diabetes (133 male and 100 female; age 11.1 ± 1.7 years) completed a baseline OGTT and were divided into two groups based upon a 1-h glucose threshold of 155 mg/dL (<155 mg/dL, n = 151, or ≥155 mg/dL, n = 82). Youth were followed annually for up to 8 years for assessment of glucose tolerance, body composition by dual-energy X-ray absorptiometry, and insulin sensitivity, insulin secretion, and the disposition index by the frequently sampled intravenous glucose tolerance test.RESULTSOver time, the ≥155 mg/dL group exhibited a significantly greater decline in β-cell function compared with youth with a 1-h glucose <155 mg/dL (β = -327.8 ± 126.2, P = 0.01). Moreover, this decline was independent of fasting or 2-h glucose and body composition. When the data were restricted to only participants with normal glucose tolerance at baseline, a 1-h glucose ≥155 mg/dL was independently associated with a 2.5 times greater likelihood of developing prediabetes during follow-up (95% CI 1.6-4.1, P = 0.0001).CONCLUSIONS These data suggest that a 1-h glucose ≥155 mg/dL during an OGTT is an independent predictor of β-cell deterioration and progression to prediabetes among obese Latino youth.
    Diabetes care 01/2013; · 7.74 Impact Factor
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    Elizabeth A Pyatak, Daniella Florindez, Marc J Weigensberg
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    ABSTRACT: The purpose of this study was to explore motivations underlying nonadherent treatment decisions made by young adults with type 1 diabetes. Eight emerging adults each completed a series of semi-structured interviews concerning their approaches to diabetes care, relationships with clinicians, and everyday activities and routines. A narrative thematic analysis was used to develop initial themes and refine them through continued data collection and review of the research literature. FIVE THEMES WERE IDENTIFIED AS MOTIVATING NONADHERENCE: (1) efforts to mislead health care providers, (2) adherence to alternative standards, (3) treatment fatigue and burnout, (4) social support problems, and (5) emotional and self-efficacy problems. Instances of nonadherence generally involved a combination of the five identified themes. Participants reporting nonadherence also described difficulties communicating with care providers regarding their treatment. Nonjudgmental communication between providers and emerging adults may be particularly important in promoting positive health outcomes in this population.
    Patient Preference and Adherence 01/2013; 7:709-18. · 1.33 Impact Factor
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    ABSTRACT: What is already known about this subject Physical activity declines as children enter puberty. Leptin is cross-sectionally associated with physical activity, but there are conflicting findings on the magnitude and direction of this association. Leptin concentrations fluctuate during puberty, and may impact energy balance. What this study adds Leptin predicts the decline in physical activity during the start of puberty independent of central adiposity. Based on a median split of leptin, girls with low leptin levels have higher levels of physical activity than girls with high leptin levels at the start of puberty. Leptin levels at the start of puberty may provide a biological basis for the age-related physical activity decline in girls. BACKGROUND: Leptin may influence moderate to vigorous physical activity (MVPA) at the start of puberty. The direction and magnitude of this association are unclear. OBJECTIVES: To determine the effect of baseline leptin on MVPA over 1 year in minority girls at high risk for obesity. METHODS: Data came from TRANSITIONS, a longitudinal observational study on the age-related MVPA decline. Fifty peripubertal girls aged 8-11 years at baseline participated. Baseline leptin (ng mL(-1) ) was collected via a duplicated assay using a double antibody radio immune assay. MVPA (min d(-1) ) was measured using accelerometers for at least four 10-h days on a quarterly basis for up to 1 year. RESULTS: Continuous leptin was negatively related to MVPA (P = 0.001) independent of central adiposity at baseline and predicted the MVPA decline over 1 year (P = 0.002). For descriptive purposes, baseline leptin was dichotomized at the sample median into 'high leptin' and 'low leptin' categories to determine whether MVPA trajectories differed between these groups. Girls with 'low leptin' at baseline had significantly higher levels of MPVA at baseline, visit 1 and visit 2 compared to girls with 'high leptin'. CONCLUSIONS: High leptin levels predicted nearly a 12.6% decline in MVPA over 1 year. These findings provide support for the biological basis of declining MVPA as girls enter puberty.
    Pediatric Obesity 09/2012; · 2.28 Impact Factor

Publication Stats

2k Citations
409.39 Total Impact Points


  • 2003–2014
    • University of Southern California
      • • Department of Pediatrics
      • • Department of Preventive Medicine
      • • Department of Physiology and Biophysics
      Los Angeles, California, United States
  • 2013
    • University of Texas MD Anderson Cancer Center
      Houston, Texas, United States
  • 2011
    • Stanford University
      • Stanford Prevention Research Center
      Stanford, CA, United States
  • 2010
    • California Lutheran University
      • Exercise Science
      Thousand Oaks, California, United States
  • 2007–2010
    • Arizona State University
      • • School of Nutrition and Health Promotion
      • • College of Nursing and Health Innovation
      Mesa, AZ, United States
    • University of Texas at El Paso
      • Department of Health Promotion
      El Paso, TX, United States
  • 2009
    • Keck School of Medicine USC
      Los Angeles, California, United States
  • 2004–2007
    • University of California, Los Angeles
      • Department of Pediatrics
      Los Angeles, California, United States
    • Southern California University of Health Sciences
      Whittier, California, United States
  • 2006
    • University of Alberta
      • Department of Pediatrics
      Edmonton, Alberta, Canada