Body fat distribution and their associations with cardiovascular risk, insulin resistance and β-cell function: are there differences between men and women?

The importance of waist circumference and body mass index in cross-sectional relationships with risk of cardiovascular disease in Vietnam

BACKGROUND

Waist circumference (WC) is an indicator of intra-abdominal adipose tissue, high levels of which confer an increased risk of cardiometabolic disease. Population data on WC should be more informative than data on body mass index (BMI), which is a general indicator of body size. This study aimed to evaluate the importance of WC relative to BMI in cross-sectional relationships with blood pressure (BP), glucose, and total cholesterol (TC) in the adult population of Vietnam.

METHODS

The data were collected in a population-based survey conducted during 2009-10 using the "WHO STEPwise approach to surveillance of risk factors for non-communicable disease" (STEPS) methodology. The survey participants (n = 14 706 aged 25 to 64 years) were selected by multi-stage stratified cluster sampling from eight provinces representative of the eight geographical regions of Vietnam. All measurements were performed in accordance with the STEPS protocols. All analyses were performed using complex survey methods.

RESULTS

The measurements of WC and BMI were highly correlated (men r = 0.80, women r = 0.77). For men, the strongest and predominant associations with BP, glucose, and TC were for WC or an index based on WC. For women, this was true for glucose but BMI was more important for BP and TC. WC or an index based on WC provided better discrimination than BMI of hypertension and elevated glucose, and of raised TC for men. Information on four new anthropometric indices did not improve model fit or subject discrimination.

CONCLUSION

For BP/hypertension, glucose/elevated glucose, and TC/raised TC, WC was more informative than BMI for Vietnamese men, but both WC and BMI were important for Vietnamese women. Both WC and BMI need to be assessed for estimation of CVD risk in Vietnam.

INDICADORES ANTROPOMÉTRICOS E FATORES DE RISCO CARDIOVASCULAR EM TRABALHADORES RURAIS

RESUMO Introdução: A obesidade tem provocado diversos agravos à saúde, impulsionada pela industrialização, avanços tecnológicos, urbanização e estilo de vida; esses aspectos estão relacionados com disfunções cardiovasculares. Diversos fatores estão associados aos problemas saúde da população, os quais podem ser previamente identificados com técnicas simples, como medidas antropométricas e escores de risco, usadas para determinar possíveis riscos. Objetivo: Relacionar variáveis antropométricas com o Escore de Risco de Framingham (ERF) em trabalhadores rurais. Métodos: Estudo transversal com 138 trabalhadores rurais, submetidos ao questionário de estilo de vida, avaliação antropométrica, bioquímica, cardiovascular e determinação do ERF. A antropometria foi estimada com os indicadores índice de massa corporal, circunferência da cintura (CC), relação cintura-quadril (RCQ), índice de conicidade (IC) e razão circunferência cintura-estatura (RCEst); o perfil bioquímico identificou colesterol total, colesterol HDL, colesterol LDL, triglicerídeos e glicemia; a função cardiovascular foi avaliada pela pressão arterial sistólica e pressão arterial diastólica em repouso. A partir das informações, os sujeitos foram classificados segundo o ERF em G1 (baixo risco), G2 (risco intermediário) e G3 (alto risco). As análises estatísticas constaram de frequência e percentual, comparação de médias pelo teste Kruskal-Wallis, e correlação de Pearson ou Spearman, considerando p < 0,05. Resultados: Com relação aos ERF, 81,4% sujeitos do sexo feminino e 51,9% do masculino apresentaram baixo risco cardiovascular, com mais da metade dos trabalhadores com respostas inadequadas nos parâmetros RCQ (58,7%), RCEst (67,4%), CT (58,0%) e LDL (52,9%). Na relação do total de pontos absolutos do ERF com as variáveis antropométricas, CC e RCEst demonstraram correlações fracas (0,293 e 0,175, respectivamente) e RCQ e IC, correlações moderadas (0,475 e 0,459, respectivamente). Conclusão: Alguns indicadores antropométricos (RCQ e IC) apresentaram relações mais fortes com o ERF, apontando que são mais efetivas em determinadas populações, além de indicar a maior probabilidade de eventos cardiovasculares nos trabalhadores rurais. Nível de Evidência III; Estudos diagnósticos - Investigação de um exame para diagnóstico.

MR-based assessment of body fat distribution and characteristics

The assessment of body fat distribution and characteristics using magnetic resonance (MR) methods has recently gained significant attention as it further extends our pathophysiological understanding of diseases including obesity, metabolic syndrome, or type 2 diabetes mellitus, and allows more detailed insights into treatment response and effects of lifestyle interventions. Therefore, the purpose of this study was to review the current literature on MR-based assessment of body fat distribution and characteristics. PubMed search was performed to identify relevant studies on the assessment of body fat distribution and characteristics using MR methods. T1-, T2-weighted MR Imaging (MRI), Magnetic Resonance Spectroscopy (MRS), and chemical shift-encoding based water-fat MRI have been successfully used for the assessment of body fat distribution and characteristics. The relationship of insulin resistance and serum lipids with abdominal adipose tissue (i.e. subcutaneous and visceral adipose tissue), liver, muscle, and bone marrow fat content have been extensively investigated and may help to understand the underlying pathophysiological mechanisms and the multifaceted obese phenotype. MR methods have also been used to monitor changes of body fat distribution and characteristics after interventions (e.g. diet or physical activity) and revealed distinct, adipose tissue-specific properties. Lastly, chemical shift-encoding based water-fat MRI can detect brown adipose tissue which is currently the focus of intense research as a potential treatment target for obesity. In conclusion, MR methods reliably allow the assessment of body fat distribution and characteristics. Irrespective of the promising findings based on these MR methods the clinical usefulness remains to be established.

The impact of ambient temperature on HbA1c in Taiwanese type 2 diabetic patients: The most vulnerable subgroup

BACKGROUND/PURPOSE

The relationship between temperature variability and HbA1c has been reported in Caucasians, but not for Asians of Taiwanese origin. This study investigated the impact of temperature on HbA1c in various groups of Taiwanese with type 2 diabetes in Taiwan.

METHODS

For this longitudinal follow-up study which started in 2006, we recruited a total of 4399 patients with type 2 diabetes who had been regularly followed up at Chi Mei Medical Center and obtained local temperature data for 2006 to 2011 from Taiwan's Central Weather Bureau. We used a generalized estimated equation (GEE) to analyze the HbA1c level and its change over time with temperature and temperature changes, respectively.

RESULTS

We found a negative correlation between HbA1c and temperature (R = -0.475, p = 0.001). For every 1°C decrement in temperature, there was an increase in the risk of having a HbA1c level >7% [p < 0.001, adjusted odds ratio (OR): 1.01]. There was a significantly higher risk of HbA1c > 7% among those in the lowest quartile of temperatures than the highest quartile (p = 0.0038, adjusted OR: 1.13). Patients with diabetic patients were at higher risk of HbA1C > 7% in the winter and spring than those in the summer (adjusted OR: 1.13, p = 0.0027; adjusted OR: 1.14, p = 0.0022). After adjusting for various confounders, we found people who were younger than 65 years old, people who had diabetes for longer than 6 years, and people who had a body mass index (BMI) < 24 to be more susceptible to temperature changes (p = 0.0022, β: 0.0095; p < 0.0001, β: 0.0125; p < 0.0001, β: 0.016, respectively).

CONCLUSION

Our study suggests cold weather may adversely affect HbA1c levels in Taiwanese people with type 2 diabetes, especially in people under 65 years old, people with diabetes for longer than 6 years, and those with a BMI < 24.

Neck circumference: a useful screening tool of cardiovascular risk in children

OBJECTIVE

Early identification of cardiovascular risk factors consists an essential target for public health. The current study aims to examine the association between neck circumference and several cardiovascular risk factors and to compare it with well-established anthropometric indices.

METHODS

Demographic, anthropometric (body weight and height, waist, hip and neck circumference [WC, HC and NC, respectively]), biochemical (total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol, triglycerides [TG], fasting plasma glucose and serum insulin), clinical (pubertal stage, systolic and diastolic blood pressure [SBP and DBP, respectively]) and lifestyle (dietary intake, physical activity level) data were collected from 324 children (51.5% boys; 48.5% girls) aged 9-13 in Greece. Body mass index z-score (BMI z-score), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), homeostasis model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI) and fasting glucose to insulin ratio (FGIR) were calculated.

RESULTS

All indices (BMI z-score, NC, WC, HC, WHR and WHtR) were correlated with SBP, HDL and insulin-related indices (insulin, HOMA-IR, QUICKI and FGIR) and all indices except WHR with TG. LDL was correlated with BMI z-score, WC, WHR and WHtR, whereas DBP was correlated with BMI z-score, WC, HC and WHtR. In multivariate analysis, HDL, TG, SBP, insulin, HOMA-IR, QUICKI and FGIR were associated with all anthropometric indices; DBP with WC, HC, NC and WHtR; LDL with BMI z-score, WC, HC and WHtR.

CONCLUSIONS

NC is associated with most cardiovascular disease risk factors. These associations are comparable with those observed for BMI z-score, WC, HC, WHR and WHtR. NC could be a simple, alternative screening tool of cardiovascular risk in children.

Pleiotropic effects of incretins

Drugs that augment the incretin system [glucagon like peptide (GLP) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors] represent a novel class of anti-hyperglycemic agents that have shown to improve the health and survival of beta-cells (improvement in postprandial hyperglycemia) and suppress glucagon (improvement in fasting hyperglycemia). The incretins represent a large family of molecules referred to as the "glucagon superfamily of peptide hormones" of which more than 90% of the physiological effects of incretins are accomplished by GLP-1(7-37) and GLP1(7-36) amide and gastric insulinotropic peptide (GIP). GLP-1 mediates its effects via the GLP-1 receptor, which has a wide tissue distribution [pancreas, lung, heart, vascular smooth muscle cells, endothelial cells, macrophages and monocytes, kidney, gastrointestinal tract (stomach and intestine), central nervous system (neoortex, cerebellum, hypothalamus, hippocampus, brainstem nucleus tractus solitarius) and peripheral nervous system]. This would imply that the incretin system has effects outside the pancreas. Over time data has accumulated to suggest that therapies that augment the incretin system has beneficial pleiotrophic effects. The incretins have shown to possess a cardiac-friendly profile, preserve neuronal cells and safeguard from neuronal degeneration, improve hepatic inflammation and hepatosteatosis, improve insulin resistance, promote weight loss and induce satiety. There is growing evidence that they may also be renoprotective promoting wound healing and bone health.