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AIM: To examine the hypothesis that there would be ethnic differences in the relationship between ectopic fat and tissue-specific insulin resistance (IR) across a spectrum of glucose tolerance in Black African (BA) and White European (WE) men. MATERIALS AND METHODS: Fifty-three WE men (23/10/20 normal glucose tolerance [NGT]/impaired glucose tolerance [IGT]/type 2 diabetes [T2D]) and 48 BA men (20/10/18, respectively) underwent a two-step hyperinsulinaemic-euglycaemic clamp with infusion of D-[6,6-2H2]-glucose and [2H5]-glycerol to assess hepatic, peripheral and adipose tissue IR. Magnetic resonance imaging was used to measure subcutaneous adipose tissue, visceral adipose tissue (VAT) and intrahepatic lipid (IHL). Associations between ectopic fat and IR were assessed using linear regression models. RESULTS: There were no differences in tissue-specific IR between ethnic groups at any stage of glucose tolerance. VAT level was consistently lower in the BA population; NGT (p = 0.013), IGT (p = 0.006) and T2D (p = 0.015). IHL was also lower in the BA compared with the WE men (p = 0.013). VAT and IHL levels were significantly associated with hepatic IR in the BA population (p = 0.001) and with peripheral IR in the WE population (p = 0.027). CONCLUSIONS: The present study suggests that BA and WE men exhibit the same degree of IR across a glucose tolerance continuum, but with lower VAT and IHL levels in the BA population, suggesting that IR may be driven by a mechanism other than increased ectopic fat accumulation in BA men.
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Black African-Caribbean (BAC) populations are at greater risk of cardiometabolic disease than White Europeans (WE), despite lower fasting triacylglycerol (TAG) concentrations. However, limited data exist regarding postprandial fatty acid metabolism in BAC populations. This study determined the ethnic differences in postprandial fatty acid metabolism between overweight and obese WE and BAC men. WE (n=10) and BAC (n=9) men consumed two consecutive moderate-to-high fat meals; the first labelled with U-13C palmitate. The plasma concentration and appearance of meal-derived fatty acids in very-low density lipoprotein (VLDL)-TAG, chylomicron-TAG, and NEFA were determined over 8-hours. Indirect calorimetry with 13CO2 enrichment determined total and meal-derived fatty acid oxidation rates, and plasma b-hydroxybutyrate (3-OHB) concentration was measured to assess ketogenesis. BAC exhibited lower postprandial TAG (P=0.006) and VLDL-TAG (P=0.002) concentrations than WE. The appearance of meal-derived fatty acids in VLDL-TAG was lower in BAC than WE (P=0.004). Following the second meal, BAC showed a trend for lower chylomicron-TAG concentration (P=0.057). There were no ethnic differences in the appearance of meal-derived fatty acids in chylomicron-TAG. Cumulative fatty acid oxidation and the NEFA:3-OHB ratio were similar in WE and BAC. In conclusion, BAC exhibit lower postprandial TAG concentrations compared with WE men, driven by lower VLDL-TAG concentrations and possibly lower chylomicron-TAG in the late postprandial period. In BAC, the lower VLDL-TAG concentration was partially driven by a lower appearance of meal-derived fatty acids in VLDL-TAG. These findings suggest that postprandial fatty acid trafficking may be a less important determinant of cardiometabolic risk in BAC than WE men.
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Diabetes Gestacional , Feminino , Humanos , Gravidez , Diabetes Gestacional/genética , Percepção GustatóriaRESUMO
Chronotype studies investigating dietary intake, eating occasions (EO) and eating windows (EW) are sparse in people with type 2 Diabetes mellitus (T2DM). This analysis reports data from the CODEC study. The Morningness-Eveningness questionnaire (MEQ) assessed chronotype preference. Diet diaries assessed dietary intake and temporal distribution. Regression analysis assessed whether dietary intake, EW, or EO differed by chronotype. 411 participants were included in this analysis. There were no differences in energy, macronutrient intake or EW between chronotypes. Compared to evening chronotypes, morning and intermediate chronotypes consumed 36.8 (95% CI: 11.1, 62.5) and 20.9 (95% CI: -2.1, 44.1) fewer milligrams of caffeine per day, respectively. Evening chronotypes woke up over an hour and a half later than morning (01:36 95% CI: 01:09, 02:03) and over half an hour later than intermediate chronotypes (00:45 95% CI: 00:21; 01:09. Evening chronotypes went to sleep over an hour and a half later than morning (01:48 95% CI: 01:23; 02:13) and an hour later than intermediate chronotypes (01:07 95% CI: 00:45; 01:30). Evening chronotypes' EOs and last caffeine intake occurred later but relative to their sleep timings. Future research should investigate the impact of chronotype and dietary temporal distribution on glucose control to optimise T2DM interventions.
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Cafeína , Diabetes Mellitus Tipo 2 , Humanos , Adulto , Cronotipo , Ingestão de Alimentos , SonoRESUMO
We evaluated glycaemic status in 948 Black adults with HIV and report a high prevalence of dysglycaemia (37.2%). HbA1c testing identified 38 (4.0%) individuals not previously known to have diabetes mellitus (DM) and showed suboptimal or poor glycaemic control in more than half of those with a prior DM diagnosis despite high levels of HIV control.
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Diabetes Mellitus Tipo 2 , Diabetes Mellitus , Infecções por HIV , Adulto , Humanos , Hemoglobinas Glicadas , Londres/epidemiologia , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/epidemiologia , Infecções por HIV/diagnóstico , Infecções por HIV/epidemiologia , GlicemiaRESUMO
In the UK, populations of Black African and Caribbean (BAC) ethnicity suffer higher rates of cardiometabolic disease than White Europeans (WE). Obesity, leading to increased visceral adipose tissue (VAT) and intrahepatic lipid (IHL), has long been associated with cardiometabolic risk, driving insulin resistance and defective fatty acid/lipoprotein metabolism. These defects are compounded by a state of chronic low-grade inflammation, driven by dysfunctional adipose tissue. Emerging evidence has highlighted associations between central complement system components and adipose tissue, fatty acid metabolism and inflammation; it may therefore sit at the intersection of various cardiometabolic disease risk factors. However, increasing evidence suggests an ethnic divergence in pathophysiology, whereby current theories fail to explain the high rates of cardiometabolic disease in BAC populations. Lower fasting and postprandial TAG has been reported in BAC, alongside lower VAT and IHL deposition, which are paradoxical to the high rates of cardiometabolic disease exhibited by this ethnic group. Furthermore, BAC have been shown to exhibit a more anti-inflammatory profile, with lower TNF-α and greater IL-10. In contrast, recent evidence has revealed greater complement activation in BAC compared to WE, suggesting its dysregulation may play a greater role in the high rates of cardiometabolic disease experienced by this population. This review outlines the current theories of how obesity is proposed to drive cardiometabolic disease, before discussing evidence for ethnic differences in disease pathophysiology between BAC and WE populations.
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AIM: People of Black African ancestry, who are known to be at disproportionately high risk of type 2 diabetes (T2D), typically exhibit lower hepatic insulin clearance compared with White Europeans. However, the mechanisms underlying this metabolic characteristic are poorly understood. We explored whether low insulin clearance in Black African (BA) men could be explained by insulin resistance, subclinical inflammation or adiponectin concentrations. METHODS: BA and White European (WE) men, categorised as either normal glucose tolerant (NGT) or with T2D, were recruited to undergo the following: a mixed meal tolerance test with C-peptide modelling to determine endogenous insulin clearance; fasting serum adiponectin and cytokine profiles; a hyperinsulinaemic-euglycaemic clamp to measure whole-body insulin sensitivity; and magnetic resonance imaging to quantify visceral adipose tissue. RESULTS: Forty BA (20 NGT and 20 T2D) and 41 WE (23 NGT and 18 T2D) men were studied. BA men had significantly lower insulin clearance (P = 0.011) and lower plasma adiponectin (P = 0.031) compared with WE men. In multiple regression analysis, ethnicity, insulin sensitivity and plasma adiponectin were independent predictors of insulin clearance, while age, visceral adiposity and tumour necrosis factor alpha (TNF-α) did not significantly contribute to the variation. CONCLUSION: These data suggest that adiponectin may play a direct role in the upregulation of insulin clearance beyond its insulin-sensitising properties.
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Diabetes Mellitus Tipo 2 , Resistência à Insulina , População Negra , Diabetes Mellitus Tipo 2/metabolismo , Etnicidade , Humanos , Insulina/metabolismo , Resistência à Insulina/fisiologia , MasculinoRESUMO
AIMS: In populations of black African ancestry (BA), a paradox exists whereby lower visceral adipose tissue is found despite their high risk for type 2 diabetes (T2D). This systematic review investigates ethnic differences in other ectopic fat depots (intrahepatic lipid: IHL; intramyocellular lipid: IMCL and intrapancreatic lipid; IPL) to help contextualise their potential contribution to T2D risk. METHODS: A systematic literature search was performed in December 2020 to identify studies reporting at least one ectopic fat comparison between BA and one/more other ethnicity. For IHL, a meta-analysis was carried out with studies considered comparable based on the method of measurement. RESULTS: Twenty-eight studies were included (IHL: n = 20; IMCL: n = 8; IPL: n = 4). Meta-analysis of 11 studies investigating IHL revealed that it was lower in BA populations vs pooled ethnic comparators (MD -1.35%, 95% CI -1.55 to -1.16, I2 = 85%, P < 0.00001), white European ancestry (MD -0.94%, 95% CI -1.17 to -0.70, I2 = 79%, P < 0.00001), Hispanic ancestry (MD -2.06%, 95% CI -2.49 to -1.63, I2 = 81%, P < 0.00001) and South Asian ancestry comparators (MD -1.92%, 95% CI -3.26 to -0.57, I2 = 78%, P = 0.005). However, heterogeneity was high in all analyses. Most studies found no significant differences in IMCL between BA and WE. Few studies investigated IPL, however, indicated that IPL is lower in BA compared to WE and HIS. CONCLUSION: The discordance between ectopic fat and greater risk for T2D in BA populations raises questions around its contribution to T2D pathophysiology in BA.
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Diabetes Mellitus Tipo 2 , Hipercolesterolemia , População Negra/genética , Diabetes Mellitus Tipo 2/genética , Etnicidade , Humanos , Gordura Intra-AbdominalRESUMO
OBJECTIVE: To evaluate the cultural tailoring methods used in type 2 diabetes (T2D), prevention and management interventions for populations of Black African ancestry and to examine their effectiveness on measures of glycaemia. DESIGN: Three databases were searched in October 2020; eligible studies used a randomised controlled trial (RCT) design to evaluate the effectiveness of culturally tailored lifestyle interventions compared with usual care for the prevention or management of T2D in adults of Black African ancestry. Cultural tailoring methods were evaluated using the Facilitator-Location-Language-Messaging (FiLLM) framework, whereby facilitator refers to delivery by individuals from the target community, language focuses on using native language or language appropriate to literacy levels, location refers to delivery in meaningful settings, and messaging is tailoring with relevant content and modes of delivery. RESULTS: Sixteen RCT were identified, all from USA. The mean age of participants was 55 years, majority female. Six of fifteen RCT reported significant improvements in glycated haemoglobin (HbA1c) at 6 and 8 months; one, in prediabetes, reported significantly improved fasting plasma glucose. Diabetes knowledge improvement (5/7 studies) was associated with HbA1c improvement. The majority tailored to location (12/16), facilitators (11/16), messaging (9/16) and language (6/16) domains of FiLLM. Those with ethnically matched facilitators and those which tailored to more than one domain showed the greatest HbA1C benefits. CONCLUSION: This evidence supports the effectiveness of culturally tailored lifestyle interventions for T2D management in populations of Black African ancestry, with further RCT needed to evaluate interventions for T2D prevention and for communities outside of the USA.
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Diabetes Mellitus Tipo 2 , População Negra , Diabetes Mellitus Tipo 2/prevenção & controle , Feminino , Hemoglobinas Glicadas , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
INTRODUCTION: Black-British communities are disproportionately affected by type 2 diabetes (T2D). Structured education programs are a core component of T2D healthcare but they are less successful in people from minority ethnic groups. Culturally tailored T2D education has demonstrated greater benefits than usual care. The aim of our study was to evaluate acceptability, fidelity and trial feasibility of the Healthy Eating and Active Lifestyles for Diabetes ('HEAL-D') culturally tailored T2D self-management education and support (DSMES) program. RESEARCH DESIGN AND METHODS: A mixed-methods randomized controlled feasibility trial in black-British adults with T2D was conducted. Participants were assigned to control (usual care) or intervention (HEAL-D; 7 sessions, 14 hours of group-based culturally tailored diet and lifestyle education, behavior change support and supervised physical activity), in a ratio of 1:1. Primary outcomes were recruitment and retention rates, intervention attendance and completion. Fidelity was assessed through observations and qualitative evaluation was undertaken with participants and educators. RESULTS: 102 patients responded to invitation letters (n=1335); 63 were randomized but 8 were subsequently deemed ineligible due to high baseline glycosylated hemoglogin (HbA1c) requiring intensive medical management or missing baseline HbA1c measurement. Of the remaining 55 participants (27 intervention, 28 control), 69% were female, 47% were of African and 51% were of Caribbean ethnicity. 93% completed the trial, providing end point data. Intervention attendance was high; 85% completed the program (attendance at ≥5 sessions), and 74% attended ≥6 sessions. The intervention was delivered with acceptable fidelity, although the qualitative evaluations identified some areas of structure and format in need of refinement. CONCLUSIONS: We have shown it is feasible to recruit and randomize black-British adults with T2D to a trial of a culturally tailored DSMES program. We have shown the intervention is highly acceptable for both patients and healthcare providers. A future trial should assess clinical and cost-effectiveness of HEAL-D. TRIAL REGISTRATION NUMBER: NCT03531177.
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Diabetes Mellitus Tipo 2 , Autogestão , Adulto , Diabetes Mellitus Tipo 2/terapia , Dieta Saudável , Estudos de Viabilidade , Feminino , Humanos , Estilo de Vida , MasculinoRESUMO
AIMS: To develop an evidence-based, culturally tailored, diabetes self-management education and support programme for Black-British adults, called Healthy Eating and Active Lifestyles for Diabetes (HEAL-D), using participatory methods to engage key stakeholders in the intervention design process. METHODS: Black-British adults living with type 2 diabetes, healthcare professionals and community leaders were engaged in an intervention development study. The intervention structure, format, content and delivery were developed through three phases of participatory research: Phase 1, formative research, involved focus groups and interviews; interactive co-development workshops were conducted in Phase 2; and Phase 3 focused on materials development. RESULTS: In Phase 1, focus groups and interviews identified the importance of nurturing collectivism, a reliance on informal sources of information/advice, barriers to attending appointments associated with competing priorities of work, travel and carer commitments, and a preference for directness and simple, clear advice/messages. A priority for healthcare professionals was the intervention embedding within current primary care structures and aligning with incentivised targets/metrics. Phase 2 (workshops) highlighted key requirements: avoidance of medical settings, appropriately trained and culturally knowledgeable educators, flexible appointments, preference for verbal and visual information and avoidance of technical/medical terminology. In Phase 3 (materials development), culturally sensitive videos, short films and information booklets were developed to convey educational messages, and food photography was used to provide culturally relevant dietary advice. CONCLUSIONS: Participatory methods provide a means to understand the needs of specific communities. This approach enables the development of healthcare interventions that are sensitive to the needs of service users and providers.
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População Negra , Pesquisa Participativa Baseada na Comunidade/métodos , Diabetes Mellitus Tipo 2/reabilitação , Dieta Saudável/métodos , Comportamentos Relacionados com a Saúde/fisiologia , Educação de Pacientes como Assunto , Autogestão/educação , Adolescente , Adulto , Idoso , Diabetes Mellitus Tipo 2/etnologia , Escolaridade , Feminino , Estilo de Vida Saudável , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Reino Unido/epidemiologia , Adulto JovemRESUMO
The role of ectopic fat, insulin secretion and clearance in the preservation ofß-cell function in black African women with obesity who typically present with hyperinsulinaemia is not clear. We aim to examine the associations between disposition index (DI, an estimate of ß-cell function), insulin secretion and clearance and ectopic fat deposition. This is a cross-sectional study of 43 black South African women (age 20-35 years) with obesity (BMI 30-40 kg/m2) and without type 2 diabetes that measured the following: DI, insulin sensitivity (SI), acute insulin response (AIRg), insulin secretion rate (ISR), hepatic insulin extraction and peripheral insulin clearance (frequently sampled i.v. glucose tolerance test); pancreatic and hepatic fat, visceral adipose tissue (VAT) and abdominal s.c. adipose tissue (aSAT) volume (MRI), intra-myocellular (IMCL) and extra-myocellular fat content (EMCL) (magnetic resonance spectroscopy). DI correlated positively with peripheral insulin clearance (ß 55.80, P = 0.002). Higher DI was associated with lower VAT, pancreatic fat and soleus fat, but VAT explained most of the variance in DI (32%). Additionally, higher first phase ISR (P = 0.033) and lower hepatic insulin extraction (P = 0.022) were associated with lower VAT, independent from SI, rather than with ectopic fat. In conclusion, peripheral insulin clearance emerged as an important correlate of DI. However, VAT was the main determinant of a lower DI above ectopic fat depots. Importantly, VAT, but not ectopic fat, is associated with both lower insulin secretion and higher hepatic insulin extraction. Prevention of VAT accumulation in young black African women should, therefore, be an important target for beta cell preservation.
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INTRODUCTION: It is increasingly recognized that type 2 diabetes (T2D) is a heterogenous disease with ethnic variations. Differences in insulin secretion, insulin resistance and ectopic fat are thought to contribute to these variations. Therefore, we aimed to compare postprandial insulin secretion and the relationships between insulin secretion, insulin sensitivity and pancreatic fat in men of black West African (BA) and white European (WE) ancestry. RESEARCH DESIGN AND METHODS: A cross-sectional, observational study in which 23 WE and 23 BA men with normal glucose tolerance, matched for body mass index, underwent a mixed meal tolerance test with C peptide modeling to measure beta cell insulin secretion, an MRI to quantify intrapancreatic lipid (IPL), and a hyperinsulinemic-euglycemic clamp to measure whole-body insulin sensitivity. RESULTS: Postprandial insulin secretion was lower in BA versus WE men following adjustment for insulin sensitivity (estimated marginal means, BA vs WE: 40.5 (95% CI 31.8 to 49.2) × 103 vs 56.4 (95% CI 48.9 to 63.8) × 103 pmol/m2 body surface area × 180 min, p=0.008). There was a significantly different relationship by ethnicity between IPL and insulin secretion, with a stronger relationship in WE than in BA (r=0.59 vs r=0.39, interaction p=0.036); however, IPL was not a predictor of insulin secretion in either ethnic group following adjustment for insulin sensitivity. CONCLUSIONS: Ethnicity is an independent determinant of beta cell function in black and white men. In response to a meal, healthy BA men exhibit lower insulin secretion compared with their WE counterparts for their given insulin sensitivity. Ethnic differences in beta cell function may contribute to the greater risk of T2D in populations of African ancestry.
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Diabetes Mellitus Tipo 2 , Resistência à Insulina , Negro ou Afro-Americano , Estudos Transversais , Humanos , Insulina , MasculinoRESUMO
AIMS: We aimed to assess ethnic differences in inflammatory markers and their relationships with insulin sensitivity and regional adiposity between white European and black African men. METHODS: A total of 53 white European and 53 black African men underwent assessment of inflammatory markers alongside Dixon-magnetic resonance imaging to quantify subcutaneous and visceral adipose tissue and intrahepatic lipid. A hyperinsulinaemic-euglycaemic clamp was used to measure whole-body and adipose tissue insulin sensitivity. To assess ethnic differences in relationships, the statistical significance of an interaction term between adipokines and ethnic group was tested in multivariable regression models. RESULTS: The black African men exhibited significantly lower adiponectin and tumour necrosis factor-α (TNF-α) and greater interleukin-10 (IL-10) compared to white European men (all p < 0.05). There were no statistically significant ethnic differences in leptin, resistin, IL-6, interferon-γ, IL-13, IL-1ß, IL-8 and vascular endothelial growth factor. Several relationships differed significantly by ethnicity such that they were stronger in white European than black African men including IL-6 with visceral adipose tissue; adiponectin with subcutaneous adipose tissue; leptin with intrahepatic lipid; adiponectin, IL-6 and TNF-α with whole-body insulin sensitivity and TNF-α with adipose tissue insulin sensitivity (all pinteraction <0.05). Leptin significantly predicted whole-body insulin sensitivity in white European (R2 = 0.51) and black African (R2 = 0.29) men; however, adiponectin was a statistically significant predictor in only white European men (R2 = 0.22). CONCLUSIONS: While adiponectin is lower in black African men, its insulin sensitising effects may be greater in white men suggesting that the role of adipokines in the development of type 2 diabetes may differ by ethnicity.
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Adiponectina/sangue , Diabetes Mellitus Tipo 2/sangue , Resistência à Insulina/etnologia , População Branca , Adolescente , Adulto , Idoso , Biomarcadores/sangue , População Negra , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/etnologia , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Reino Unido/epidemiologia , Adulto JovemRESUMO
Background: Women of black African heritage living in high income countries (HIC) are at risk of obesity and weight-related complications in pregnancy. This review aimed to synthesize evidence concerning attitudes to weight management-related health behaviors in pregnancy and postpartum, in women of black African ancestry, living in high-income countries. Methods: A systematic review of the literature and thematic evidence synthesis using the Capability-Opportunity-Motivation Behavioral change theoretical model (COM-B). Databases searched included MEDLINE, EMBASE, Web of Science, and Scopus. The CASP tool was used to assess quality. Results: Twenty-four papers met the selection criteria, most of which were from the US. Motivational factors were most commonly described as influencers on behavior. Normative beliefs about "eating for two," weight gain being good for the baby, the baby itself driving food choice, as well as safety concerns about exercising in pregnancy, were evident and were perpetuated by significant others. These and other social norms, including a cultural acceptance of larger body shapes, and daily fast food, created a challenge for healthy behavior change. Women also had low confidence in their ability to lose weight in the postpartum period. Behavior change techniques, such as provision of social support, use of credible sources, and demonstration may be useful to support change. Conclusions: The women face a range of barriers to engagement in weight-related health behaviors at this life-stage. Using a theoretical behavior change framework can help identify contextual factors that may limit or support behavior change.
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Período Pós-Parto , Apoio Social , Região do Caribe , Países Desenvolvidos , Feminino , Humanos , Lactente , Modelos Teóricos , GravidezRESUMO
INTRODUCTION: Poor access to, and engagement with, diabetes healthcare is a significant issue for black British communities who are disproportionately burdened by type 2 diabetes (T2D). Tackling these inequalities is a healthcare priority. The purpose of this research was to explore the experiences of healthcare practitioners providing diabetes self-management education and support (DSMES) to African and Caribbean adults living with T2D to inform the development of a culturally tailored DSMES program. RESEARCH DESIGN AND METHODS: Semi-structured interviews were carried out with a range of healthcare practitioners including diabetes specialist nurses, dietitians and general practitioners based in primary care in inner London. Thematic content analysis was used to identify barriers and facilitators relating to the provision of effective DSMES. RESULTS: Ten interviews were conducted. There was a strong consensus among healthcare practitioners for the importance of DSMES in T2D healthcare. However, practitioners discussed this area of practice as overwhelmingly challenging and recognized a wide range of barriers that they face. Four themes were identified: (1) The tension between structural and responsive care needs, particularly with growing numbers of patients alongside incentivized targets driving a care agenda that does not meet the needs of diverse communities; (2) challenges posed by cultural beliefs and practices, particularly a distrust of conventional medicine, rejection of body mass index standards and a belief in 'God's will'; (3) building relationships through cultural understanding: insiders and outsiders, particularly the benefits of racial concordance and cultural knowledge/resources and (4) getting the messages across, particularly the need to address gaps in structured education. CONCLUSION: Provision of culturally sensitive DSMES is a challenging area of practice for practitioners, who recognize the need for more training and resources to support them in developing cultural competence. Nonetheless, practitioners recognize the importance of DSMES and are striving to provide culturally sensitive care to their patients.
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Diabetes Mellitus Tipo 2 , Autogestão , Adulto , Negro ou Afro-Americano , Região do Caribe , Atenção à Saúde , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/terapia , Humanos , LondresRESUMO
In this study, we aimed to assess ethnic differences in visceral (VAT), deep subcutaneous (dSAT), and superficial subcutaneous (sSAT) adipose tissue and their relationships with inflammatory markers between white European (WE) and black West African (BWA) men with normal glucose tolerance (NGT) and type 2 diabetes (T2D). Forty-two WE (23 NGT/19 T2D) and 43 BWA (23 NGT/20 T2D) men underwent assessment of plasma inflammatory markers using immunoassays alongside Dixon magnetic resonance imaging to quantify L4-5 VAT, dSAT and sSAT. Despite no ethnic differences in sSAT and dSAT, BWA men exhibited lower VAT (p = 0.002) and dSAT:sSAT (p = 0.047) than WE men. Adiponectin was inversely associated with sSAT in WE (p = 0.041) but positively associated in BWA (p = 0.031) men with T2D. Interleukin-6 (IL-6) was associated with VAT in WE but not in BWA men with NGT (WE: p = 0.009, BWA: p = 0.137) and T2D (WE: p = 0.070, BWA: p = 0.175). IL-6 was associated with dSAT in only WE men with NGT (WE: p = 0.030, BWA: p = 0.833). The only significant ethnicity interaction present was for the relationship between adiponectin and sSAT (Pinteraction = 0.003). The favourable adipose tissue distribution and the weaker relationships between adiposity and inflammation in BWA men suggest that adipose tissue inflammation may play a lesser role in T2D in BWA than WE men.
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População Negra/estatística & dados numéricos , Diabetes Mellitus Tipo 2/etnologia , Mediadores da Inflamação/sangue , Obesidade/etnologia , População Branca/estatística & dados numéricos , Adiponectina/sangue , Tecido Adiposo/diagnóstico por imagem , Tecido Adiposo/fisiopatologia , Adolescente , Adulto , Idoso , Biomarcadores/análise , Distribuição da Gordura Corporal , Estudos Transversais , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Obesidade/sangue , Obesidade/complicações , Adulto JovemRESUMO
AIM: To investigate relationships between insulin clearance, insulin secretion, hepatic fat accumulation and insulin sensitivity in black African (BA) and white European (WE) men. METHODS: Twenty-three BA and twenty-three WE men with normal glucose tolerance, matched for age and body mass index, underwent a hyperglycaemic clamp to measure insulin secretion and clearance, hyperinsulinaemic-euglycaemic clamp with stable glucose isotope infusion to measure whole-body and hepatic-specific insulin sensitivity, and magnetic resonance imaging to quantify intrahepatic lipid (IHL). RESULTS: BA men had higher glucose-stimulated peripheral insulin levels (48.1 [35.5, 65.2] × 103 vs. 29.9 [23.3, 38.4] × 103 pmol L-1 × min, P = .017) and lower endogeneous insulin clearance (771.6 [227.8] vs. 1381 [534.3] mL m-2 body surface area min -1 , P < .001) compared with WE men. There were no ethnic differences in beta-cell insulin secretion or beta-cell responsivity to glucose, even after adjustment for prevailing insulin sensitivity. In WE men, endogenous insulin clearance was correlated with whole-body insulin sensitivity (r = 0.691, P = .001) and inversely correlated with IHL (r = -0.674, P = .001). These associations were not found in BA men. CONCLUSIONS: While normally glucose-tolerant BA men have similar insulin secretory responses to their WE counterparts, they have markedly lower insulin clearance, which does not appear to be explained by either insulin resistance or hepatic fat accumulation. Low insulin clearance may be the primary mechanism of hyperinsulinaemia in populations of African origin.
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Diabetes Mellitus , Hiperinsulinismo , Resistência à Insulina , Negro ou Afro-Americano , População Negra , Técnica Clamp de Glucose , Humanos , Insulina , MasculinoRESUMO
OBJECTIVE: We investigated the effects of a 12-week exercise intervention on insulin sensitivity (SI) and hyperinsulinemia and associated changes in regional and ectopic fat. RESEARCH DESIGN AND METHODS: Healthy, black South African women with obesity (mean age 23 ± 3.5 years) and of isiXhosa ancestry were randomised into a 12-week aerobic and resistance exercise training group (n = 23) and a no exercise group (control, n = 22). Pre and post-intervention testing included assessment of SI, insulin response to glucose (AIRg), insulin secretion rate (ISR), hepatic insulin extraction (FEL) and disposition index (DI) (AIRg × SI) (frequently sampled i.v. glucose tolerance test); fat mass and regional adiposity (dual-energy X-ray absorptiometry); hepatic, pancreatic and skeletal muscle fat content and abdominal s.c. and visceral adipose tissue volumes (MRI). RESULTS: Exercise training increased VO2peak (mean ± s.d.: 24.9 ± 2.42 to 27.6 ± 3.39 mL/kg/min, P < 0.001), SI (2.0 (1.2-2.8) to 2.2 (1.5-3.7) (mU/l)-1 min-1, P = 0.005) and DI (median (interquartile range): 6.1 (3.6-7.1) to 6.5 (5.6-9.2) × 103 arbitrary units, P = 0.028), and decreased gynoid fat mass (18.5 ± 1.7 to 18.2 ± 1.6%, P < 0.001) and body weight (84.1 ± 8.7 to 83.3 ± .9.7 kg, P = 0.038). None of these changes were observed in the control group, but body weight increased (P = 0.030). AIRg, ISR and FEL, VAT, SAT and ectopic fat were unaltered after exercise training. The increase in SI and DI were not associated with changes in regional or ectopic fat. CONCLUSION: Exercise training increased SI independent from changes in hyperinsulinemia and ectopic fat, suggesting that ectopic fat might not be a principal determinant of insulin resistance in this cohort.
Assuntos
Tecido Adiposo/metabolismo , Terapia por Exercício/métodos , Hiperinsulinismo/metabolismo , Hiperinsulinismo/terapia , Resistência à Insulina , Obesidade/metabolismo , Obesidade/terapia , Adiposidade , Adulto , Glicemia , Feminino , Humanos , Hiperinsulinismo/complicações , Obesidade/complicações , África do Sul , Resultado do Tratamento , Adulto JovemRESUMO
We assessed differences in mitochondrial function in gluteal (gSAT) and abdominal subcutaneous adipose tissue (aSAT) at baseline and in response to 12-weeks of exercise training; and examined depot-specific associations with body fat distribution and insulin sensitivity (SI). Obese, black South African women (n = 45) were randomized into exercise (n = 23) or control (n = 22) groups. Exercise group completed 12-weeks of aerobic and resistance training (n = 20), while the control group (n = 15) continued usual behaviours. Mitochondrial function (high-resolution respirometry and fluorometry) in gSAT and aSAT, SI (frequently sampled intravenous glucose tolerance test), body composition (dual-energy X-ray absorptiometry), and ectopic fat (MRI) were assessed pre- and post-intervention. At baseline, gSAT had higher mitochondrial respiratory capacity and hydrogen peroxide (H2O2) production than aSAT (p < 0.05). Higher gSAT respiration was associated with higher gynoid fat (p < 0.05). Higher gSAT H2O2 production and lower aSAT mitochondrial respiration were independently associated with lower SI (p < 0.05). In response to training, SI improved and gynoid fat decreased (p < 0.05), while H2O2 production reduced in both depots, and mtDNA decreased in gSAT (p < 0.05). Mitochondrial respiration increased in aSAT and correlated with a decrease in body fat and an increase in soleus and hepatic fat content (p < 0.05). This study highlights the importance of understanding the differences in mitochondrial function in multiple SAT depots when investigating the pathophysiology of insulin resistance and associated risk factors such as body fat distribution and ectopic lipid deposition. Furthermore, we highlight the benefits of exercise training in stimulating positive adaptations in mitochondrial function in gluteal and abdominal SAT depots.