Association of C-reactive protein with surrogate measures of insulin resistance among nondiabetic US from National Health and Nutrition Examination Survey 1999-2002

Markers of insulin resistance in Polycystic ovary syndrome women: An update

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders, affecting 5%-10% of women of reproductive age. The importance of this syndrome lies in the magnitude of associated comorbidities: infertility, metabolic dysfunction, cardiovascular disease (CVD), plus psychological and oncological complications. Insulin resistance (IR) is a prominent feature of PCOS with a prevalence of 35%-80%. Without adequate management, IR with compensatory hyperinsulinemia contributes directly to reproductive dysfunction in women with PCOS. Furthermore, epidemiological data shows compelling evidence that PCOS is associated with an increased risk of impaired glucose tolerance, gestational diabetes mellitus and type 2 diabetes. In addition, metabolic dysfunction leads to a risk for CVD that increases with aging in women with PCOS. Indeed, the severity of IR in women with PCOS is associated with the amount of abdominal obesity, even in lean women with PCOS. Given these drastic implications, it is important to diagnose and treat insulin resistance as early as possible. Many markers have been proposed. However, quantitative assessment of IR in clinical practice remains a major challenge. The gold standard method for assessing insulin sensitivity is the hyperinsulinemic euglycemic glucose clamp. However, it is not used routinely because of the complexity of its procedure. Consequently, there has been an urgent need for surrogate markers of IR that are more applicable in large population-based epidemiological investigations. Despite this, many of them are either difficult to apply in routine clinical practice or useless for women with PCOS. Considering this difficulty, there is still a need for an accurate marker for easy, early detection and assessment of IR in women with PCOS. This review highlights markers of IR already used in women with PCOS, including new markers recently reported in literature, and it establishes a new classification for these markers.

C-reactive protein in adult Samoans: Population variation and physiological correlates

OBJECTIVES

C-reactive protein (CRP) has been associated with adiposity and cardiometabolic disease risk in many populations but remains remarkably understudied in Pacific Islander populations. Here, we provide the first examination of correlates of CRP in adult Samoans (n = 108, ages 35-55 years) to test the hypotheses that CRP exhibits sex-dependent associations with measures of BMI, adiposity, and cardiometabolic disease risks.

METHODS

We analyzed associations between measures of adiposity (total fat mass, visceral fat mass, percent total body fat), body mass index (BMI), cardiometabolic risks, behaviors, demographics, and CRP. Unadjusted analyses of CRP were undertaken using Pearson's pairwise, and Spearman's rank correlations; one-way analysis of variance and Kruskal-Wallis tests assessed variables by CRP quartiles. Adjusted analyses of CRP correlates were examined using generalized linear regression.

RESULTS

Serum CRP ranged from 0.08 to 13.3 mg/L (median 1.4 mg/L) and varied significantly by sex t (108) = -2.47, p = .015. CRP was weakly to moderately associated with measures of adiposity and BMI (r and ρ ranged between 0.25 and 0.50, p < .05) and some cardiometabolic markers (including HbA1c, fasting insulin, and insulin resistance). CRP was significantly associated with percent body fat in women and men, adjusting for other variables.

CONCLUSIONS

These data are among the first to demonstrate CRP correlates in a sample of adult Samoans. CRP differed by sex and was associated with BMI, adiposity, and some cardiometabolic risk markers. These data align with findings in other populations.

Association between fasting insulin and C-reactive protein among adults without diabetes using a two-part model: NHANES 2005-2010

INTRODUCTION

Chronic inflammation is associated with the development, progression and long-term complications of type 2 diabetes. Hyperglycemia is associated with chronic low-grade inflammation, and thus has become the focus of many screening and treatment recommendations. We hypothesize that insulin may also be associated with inflammation and may be an additional factor to consider in screening and treatment.

METHODS

This study used National Health and Nutrition Examination Survey data from 2005 to 2010 to analyze the association between fasting insulin and C-reactive protein (CRP). A two-part model was used due to the high number of values reported as 0.1 mg/L. Two models were analyzed, both with and without the addition of waist circumference to other covariates in the model.

RESULTS

The final sample included 4527 adults with a mean age of 43.31 years. In the first model, higher fasting insulin was associated with increased odds of CRP > 0.1 mg/L (OR = 1.02, p < .001) and with higher CRP (β = 0.03, p < .001). In the adjusted model, including waist circumference as a covariate, higher fasting insulin was not associated with CRP > 0.1 mg/L (OR = 1.00, p = .307) but the association between higher fasting insulin and higher continuous CRP remained significant (β = 0.01, p = .012).

CONCLUSION

This study found that higher fasting insulin is associated with higher CRP. These results suggest that treatment approaches that simultaneously decrease insulin levels as well as glucose levels may provide additive anti-inflammatory effects, and therefore may improve long-term outcomes for adults with type 2 diabetes.

Cumulative inflammatory burden and obesity as determinants of insulin resistance in patients with established rheumatoid arthritis: cross-sectional study

OBJECTIVES

To describe the prevalence of insulin resistance (IR) in patients with established rheumatoid arthritis (RA) and to analyse the contribution of cumulative inflammatory burden and other factors to its development.

DESIGN

Observational cross-sectional study.

PARTICIPANTS

Patients with RA and controls matched for age, sex and Body Mass Index. We excluded patients with diabetes.

SETTINGS

Patients from an RA inception cohort at Hospital Regional Universitario de Málaga, Spain, were recruited between September 2016 and May 2018.

PRIMARY AND SECONDARY OUTCOME MEASURES

IR was evaluated using the homeostasis model assessment for IR and beta-cell function and the quantitative insulin sensitivity check index. Other variables included the cumulative 28-Joint Disease Activity Score (DAS28) with C reactive protein (CRP) body composition and cytokines. Two logistic regression models were constructed to identify factors associated with IR in patients with RA.

RESULTS

Eighty-nine patients with RA and 80 controls were included. The prevalence of IR was similar in both cases and controls. Inflammatory activity was controlled appropriately in patients during follow-up (mean DAS28 3.1 (0.8)). The presence of IR in patients with RA was associated with obesity (OR 6.01, 95% CI 1.9 to 8.7), higher cumulative DAS28-CRP values during follow-up (OR 2.8, 95% CI 1.3 to 6.0), and higher interleukin-1β levels (OR 1.6, 95% CI 1.1 to 2.4). The second model showed that the risk of IR increased by 10% for each kilogram of excess body fat.

CONCLUSION

In patients with well-controlled, established RA, IR is associated mainly with poorer control of inflammation from diagnosis and with obesity, specifically total fat mass.

Synergistic association of high-sensitivity C-reactive protein and body mass index with insulin resistance in non-diabetic adults

Epidemiological evidence has indicated that inflammatory markers and obesity are strongly correlated with insulin resistance (IR). However, there is a paucity of studies assessing the complex interaction between elevated hs-CRP and body mass index (BMI), particularly among Asians. This study investigated the additive interaction between hs-CRP and BMI on IR, using cross-sectional data from the 7th Korea National Health and Nutrition Examination Survey (2016–2018). A total of 5706 men and 6707 women aged 20 years or older were evaluated, and a multiple logistic regression analysis was used to assess the association of serum hs-CRP and BMI with IR, as measured by the triglyceride-glucose index (TyG index). Sex-specific median values were used to dichotomise the continuous TyG index variable into insulin-sensitive and IR categories. Biological interaction was evaluated using the Relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (SI). The joint effects of high hs-CRP and overweight/obesity on IR were greater than would be expected from the effects of the individual exposures alone. Relative to those with low hs-CRP and BMI < 23, having both exposures was related to increased IR with an adjusted OR of 2.97 (95% CI 2.50–3.52) in men and 3.08 (95% CI 2.67–3.56) in women with significant additive interactions. These findings demonstrate that IR prevention strategies that reduce both systematic inflammation and BMI may exceed the expected benefits based on targeting these risk factors separately.

The trajectory of high sensitivity C-reactive protein is associated with incident diabetes in Chinese adults

Background

We performed a cohort study to evaluate the association between the CRP trajectory and incident diabetes in Chinese adults.

Methods

Included were 6439 adults (4111 men and 2249 women; aged 46.6 ± 11.9 years). The concentration of high sensitivity CRP (hs-CRP) was measured in 2013 (baseline), 2014, and 2015. The hs-CRP trajectory was identified based the above three measurements by latent mixture modeling. Incident diabetes cases were diagnosed by fasting blood glucose (≥126 mg/dl) or Hb A1c (≥6.5%) during subsequent 3 years (2016–2018).

Results

Hs-CRP concentration during 2013–2015 was classified into 3 levels: low (< 1.0 mg/L), moderate (1.0–3.0 mg/L), and high (≥3.0 mg/L) based on a statement by American Heart Association. We named four hs-CRP trajectories as following: “low-stable” (low in 2013 and maintained at low concentration in 2014 and 2015), “moderate-fluctuated” (moderate in 2013, then increased to high concentration in 2014, and decreased to low concentration in 2015), “high-decreased” (high in 2013 but decreased to moderate concentration in 2014 and 2015), and “moderate-increased (moderate in 2013 and increased to high concentration in 2014 and 2015)”. We identified 235 incident diabetes during subsequent 3 years. The adjusted HR for incident diabetes was 1.71 (95% CI: 1.02, 2.87) comparing the moderate-increased and the low-stable group, after adjusting for potential confounders. In the secondary analyses, two single-measured hs-CRP concentration (in 2013 or in 2015) and the average of hs-CRP were associated with high risk of diabetes (P-trend< 0.01 for all).

Conclusions

The hs-CRP trajectory pattern was associated with altered incident diabetes in Chinese adults.

Temporal relationship between inflammation and insulin resistance and their joint effect on hyperglycemia: the Bogalusa Heart Study

BACKGROUND

Inflammation and insulin resistance play crucial roles in the development of type 2 diabetes mellitus (T2DM). We aim to examine the temporal relationship between high-sensitivity C-reactive protein (hsCRP) and insulin resistance in non-diabetic adults and their joint effect on the development of hyperglycemia.

METHODS

The longitudinal cohort from the Bogalusa Heart Study consisted of 509 non-diabetic adults (360 whites and 149 blacks, mean age = 42.8 years at follow-up) who had hsCRP, fasting glucose and insulin measured twice at baseline and follow-up over 6.8 years. Cross-lagged panel model was used to examine the temporal relationship between hsCRP and homeostasis model assessment for insulin resistance (HOMA-IR). Information on incident T2DM was collected in a survey in 6.1 years after the follow-up survey.

RESULTS

After adjusting for race, sex, age, body mass index, smoking, alcohol drinking and follow-up years, the path coefficient from baseline hsCRP to follow-up HOMA-IR (β2 = 0.105, p = 0.009) was significant and greater than the path from baseline HOMA-IR to follow-up hsCRP (β1 = 0.005, p = 0.903), with p = 0.011 for the difference between β1 and β2. This one-directional path from baseline hsCRP to follow-up HOMA-IR was significant in the hyperglycemia group but not in the normoglycemia group. In addition, participants with high levels of baseline hsCRP and follow-up HOMA-IR had greater risks of T2DM (odds ratio, OR = 2.38, p = 0.035), pre-T2DM (OR = 2.27, p = 0.006) and hyperglycemia (OR = 2.18, p = 0.003) than those with low-low levels.

CONCLUSIONS

These findings suggest that elevated hsCRP is associated with future insulin resistance in non-diabetic adults, and their joint effect is predictive of the development of T2DM.

Zuo Gui Wan Alters Expression of Energy Metabolism Genes and Prevents Cell Death in High-Glucose Loaded Mouse Embryos

Background

Zuo Gui Wan (ZGW) is a classic formula in traditional chinese medicine (TCM). Previous studies have shown that it is beneficial for impaired glucose tolerance (IGT) of adults and the offspring as well. This study aimed to understand the molecular mechanisms of the efficacy of ZGW on IGT.

Methods

We used high-glucose loaded 2-cell stage mouse embryos as a model and took advantage of single-cell RNA sequencing technology to analyze the transcriptome of the model with or without ZGW. Differential gene expression analysis was performed with DESeq2.

Results

High glucose can downregulate genes in the ribosome pathway, while ZGW can reverse this inhibition and as a result prevent embryo cell death caused by high glucose. Furthermore, high glucose can affect sugar metabolism and influence mitochondrial function, but ZGW can promote sugar metabolism via the tricarboxylic acid cycle mainly through upregulating the genes in the respiratory chain and oxidative phosphorylation.

Conclusions

ZGW had a protective effect on embryonic cell death caused by glucose loading. The reversion of inhibition of ribosome pathway and regulation of mitochondrial energy metabolism are main effects of ZGW on high-glucose loaded embryos. This research not only revealed the global gene regulation changes of high glucose affecting 2-cell stage embryos but also provided insight into the potential molecular mechanisms of ZGW on the IGT model.

Does one size fit all? The role of body mass index and waist circumference in systemic inflammation in midlife by race and gender

OBJECTIVE

This study investigates the associations of body mass index (BMI) and waist circumference (WC) with markers of systemic inflammation in midlife by race and gender.

DESIGN

Data were obtained from the Survey of Midlife in the United States, a cross-sectional, observational study of Americans 35 years old or older (White men: N = 410; White women: N = 490; Black men: N = 58; Black women: N = 117). Inflammation was measured by concentrations of fibrinogen and C-reactive protein (CRP) in fasting plasma and concentrations of E-selectin and interleukin-6 (IL-6) in fasting serum. Anthropometric data were used to obtain BMI and WC. Socio-demographic and health-related factors were assessed with a survey. Multivariate models by race and gender were estimated to test the roles of BMI and WC for each inflammation marker.

RESULTS

Compared to White men, Black women have higher BMI and higher levels of all four inflammation markers; White women have lower BMI, lower WC, and lower E-selectin and fibrinogen but higher CRP; and Black men have higher fibrinogen. After adjusting for socio-demographic and health-related covariates as well as perceived discrimination, WC is associated with all four markers of inflammation among White men and women; with three markers (fibrinogen, CRP, and IL-6) of inflammation among Black women; and with CRP (and marginally with fibrinogen and E-selectin) among Black men. BMI is associated with higher CRP and fibrinogen among Black men (marginally so for White men) but not for women of either race.

CONCLUSIONS

WC shows more consistent associations with inflammation markers than BMI, although the relationships vary by inflammation marker and population group. Our findings suggest that WC is a risk factor for systemic inflammation among White and Black men and women, and BMI is an additional risk factor for Black men.

Deep analyses of the associations of a series of biomarkers with insulin resistance, metabolic syndrome, and diabetes risk in nondiabetic middle-aged and elderly individuals: results from a Chinese community-based study

OBJECTIVE

The current study was designed to perform deep analyses of the associations of biomarkers, including high-sensitivity C-reactive protein (hs-CRP), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and homocysteine (Hcy), with insulin resistance (IR), metabolic syndrome (MetS), and diabetes risk and evaluate the abilities of biomarkers to identify IR, MetS, and diabetes risk in Chinese community-dwelling middle-aged and elderly residents.

PARTICIPANTS AND METHODS

A total of 396 participants older than 45 years underwent physical examinations and laboratory analyses following standardized protocol.

RESULTS

Serum hs-CRP concentrations were able to identify MetS, Chinese diabetes risk score (CDRS) ≥4, high-density lipoprotein-cholesterol (HDL-c) <0.9/1.0 mmol/L, and HDL-c <1.0/1.3 mmol/L (P<0.05 for all). Serum NT-proBNP concentrations were able to identify homeostasis model assessment of IR >1.5, CDRS ≥4, overweight, and blood pressure (BP) ≥140/90 mmHg (P<0.05 for all). Serum Hcy concentrations were able to identify CDRS ≥4, general obesity, overweight, and BP ≥140/90 mmHg (P<0.05 for all). Serum hs-CRP concentrations were independently associated with MetS as well as HDL-c <1.0/1.3 mmol/L and HDL-c <0.9/1.0 mmol/L (P<0.05 for all). Serum NT-proBNP concentrations were independently associated with BP ≥140/90 mmHg (P<0.05). Serum Hcy concentrations were independently associated with CDRS ≥4 (P<0.05).

CONCLUSION

Serum HDL-c levels were the major determinant of the associations between serum hs-CRP levels and MetS and the key link between inflammation and MetS. There was no other association of these biomarkers with IR, MetS, and diabetes risk after full adjustment.

Comparison of HOMA-IR, HOMA-β% and disposition index between US white men and Japanese men in Japan: the ERA JUMP study

AIMS/HYPOTHESIS

At the same level of BMI, white people have less visceral adipose tissue (VAT) and are less susceptible to developing type 2 diabetes than Japanese people. No previous population-based studies have compared insulin resistance and insulin secretion between these two races in a standardised manner that accounts for VAT. We compared HOMA-IR, HOMA of beta cell function (HOMA-β%) and disposition index (DI) in US white men and Japanese men in Japan.

METHODS

We conducted a population-based, cross-sectional study, comprising 298 white men and 294 Japanese men aged 40-49 years without diabetes. Insulin, glucose, VAT and other measurements were performed at the University of Pittsburgh. We used ANCOVA to compare geometric means of HOMA-IR, HOMA-β% and DI, adjusting for VAT and other covariates.

RESULTS

White men had higher HOMA-IR, HOMA-β% and DI than Japanese men, and the difference remained significant (p < 0.01) after adjusting for VAT (geometric mean [95% CI]): 3.1 (2.9, 3.2) vs 2.5 (2.4, 2.6), 130.8 (124.6, 137.3) vs 86.7 (82.5, 91.0), and 42.4 (41.0, 44.0) vs 34.8 (33.6, 36.0), respectively. Moreover, HOMA-IR, HOMA-β% and DI were significantly higher in white men even after further adjustment for BMI, impaired fasting glucose and other risk factors.

CONCLUSIONS/INTERPRETATION

The higher VAT-adjusted DI in white men than Japanese men may partly explain lower susceptibility of white people than Japanese people to developing type 2 diabetes. The results, however, should be interpreted with caution because the assessment of insulin indices was made using fasting samples and adjustment was not made for baseline glucose tolerance. Further studies using formal methods to evaluate insulin indices are warranted.

Gender differences in the association of insulin resistance and high-sensitivity c-reactive protein in obese adolescents

Background

Low-grade vascular inflammation is believed to initiate early atherosclerotic process by inducing insulin resistance (IR), with significant gender differences in adults. We evaluated the relationship between surrogate measures of inflammation and IR in obese adolescents.

Methods

The association among markers of inflammation [high-sensitivity c-reactive protein (hs-CRP)] and IR, cardiometabolic risk factors and body composition was retrospectively examined in 199 obese adolescents [(111 F/88 M), aged 15.5 ± 1.2 years]. Insulin resistance was assessed using homeostatic model assessment for insulin resistance (HOMA-IR).

Results

Males had higher body mass index SD-score (BMI-SDS), fat mass (FM), glucose, insulin, HOMA-IR, HbA_1c, hs-CRP, triglycerides: HDL-C (TG:HDL-C) ratio than females (p < 0.05), whereas females had higher c-peptide: insulin ratio than males (p < 0.05). Also, 50.8% of subjects were identified with metabolic syndrome with similar gender distribution (M: 57.9% vs. F: 45.1%, p = 0.32). Hs-CRP was correlated with HOMA-IR in the cohort, even when controlling for FM (r = 0.26; p < 0.0001). However, hs-CRP and HOMA-IR displayed a significant correlation only in females (r = 0.37; p < 0.0001) when adjusting for FM and pubertal status. Also, c-peptide: insulin ratio was inversely correlated with hs-CRP (r = −0.32; p < 0.001) and HOMA-IR (r = −0.62; p < 0.0001) and partially mediated the relationship between these biomarkers only among females (β = 0.36, p < 0.001 to β = 0.18, p < 0.05; Sobel Test: p < 0.01).

Conclusions

A positive association between hs-CRP and HOMA-IR was observed only in adolescent girls which was influenced by altered hepatic insulin clearance. This implies that obese adolescent girls may be at greatest risk of developing early atherosclerosis and diabetes.

Markers of Systemic Inflammation and Apo-AI Containing HDL Subpopulations in Women with and without Diabetes

Background. Besides their role in reverse cholesterol transport, HDL particles may affect the atherosclerotic process through the modulation of subclinical inflammation. HDL particles differ in size, composition, and, probably, anti-inflammatory properties. This hypothesis has never been explored in diabetic women, frequently having dysfunctional HDL. The potential relationship between lipid profile, Apo-AI containing HDL subclasses distribution, and common inflammatory markers (hsCRP, IL-6) was examined in 160 coronary heart disease- (CHD-) free women with and without type 2 diabetes. Results. Compared to controls, diabetic women showed lower levels of the atheroprotective large α-1, α-2, and pre-α-1 and higher concentration of the small, lipid-poor α-3 HDL particles (P < 0.05 all); diabetic women also had higher hsCRP and IL-6 serum levels (age- and BMI-adjusted P < 0.001). Overall, HDL subclasses significantly correlated with inflammatory markers: hsCRP inversely correlated with α-1 (P = 0.01) and pre-α-1 (P = 0.003); IL-6 inversely correlated with α-1 (P = 0.003), α-2 (P = 0.004), and pre-α-1 (P = 0.002) and positively with α-3 HDL (P = 0.03). Similar correlations were confirmed at univariate regression analysis. Conclusions. More atheroprotective HDL subclasses are associated with lower levels of inflammatory markers, especially in diabetic women. These data suggest that different HDL subclasses may influence CHD risk also through the modulation of inflammation.

Impaired retinal vasodilator responses in prediabetes and type 2 diabetes

PURPOSE

In diabetes, endothelial dysfunction and subsequent structural damage to blood vessels can lead to heart attacks, retinopathy and strokes. However, it is unclear whether prediabetic subjects exhibit microvascular dysfunction indicating early stages of arteriosclerosis and vascular risk. The purpose of this study was to examine whether retinal reactivity may be impaired early in the hyperglycaemic continuum and may be associated with markers of inflammation.

METHODS

Individuals with prediabetes (n = 22), type 2 diabetes (n = 25) and healthy age and body composition matched controls (n = 19) were studied. We used the Dynamic Vessel Analyzer to assess retinal vasoreactivity (percentage change in vessel diameter) during a flickering light stimulation. Fasting highly sensitive c-reactive protein (hs-CRP), a marker of inflammation, was measured in blood plasma.

RESULTS

Prediabetic and diabetic individuals had attenuated peak vasodilator and relative amplitude changes in retinal vein diameters to the flickering light stimulus compared with healthy controls (peak dilation: prediabetic subjects 3.3 ± 1.8%, diabetic subjects 3.3 ± 2.1% and controls 5.6 ± 2.6%, p = 0.001; relative amplitude: prediabetic subjects 4.3 ± 2.2%, diabetic subjects 5.0 ± 2.6% and control subjects 7.2 ± 3.2%, p = 0.003). Similar findings were observed in retinal arteries. Levels of hs-CRP were not associated with either retinal vessel response parameters.

CONCLUSION

Retinal reactivity was impaired in prediabetic and type 2 diabetic individuals in parallel with reduced insulin sensitivity but not associated with levels of hs-CRP. Retinal vasoreactivity measurements may be a sensitive tool to assess early vascular risk.

Evaluation of lasting high levels of CRP among the patients with metabolic syndrome

"Low-grade" systemic inflammation is common findings in patients with metabolic syndrome (MetS). When we assessed 256 MetS patients, we found eight patients who presented high levels of C-reactive protein (CRP) which are between 40 and 15 mg/L for more than 3 years. They have not satisfied any criteria of inflammatory diseases such as rheumatoid arthritis and the area of visceral fat estimated by computed tomography was more than 200 cm(2). All the other MetS patients of visceral fat over 200 cm(2) presented low levels of CRP which are less than 10 mg/L. Insulin resistance and ultrasound study of carotid plaques showed no differences between high and low levels of CRP patients. There are a series of MetS patients who show high levels of CRP without clinical symptoms of inflammatory diseases. High levels of CRP merely cannot be explained by visceral fat area, insulin resistance, or carotid plaques.

Association study of candidate gene polymorphisms and obesity in a young Mexican-American population from South Texas

BACKGROUND AND AIMS

Obesity is increasingly a health problem and a risk factor for diabetes in young Mexican-American populations. Genetic association studies in older, mostly non-Hispanic populations have reported that polymorphisms in the candidate genes HSD11B1, CRP, ADIPOQ, PPARG, ANKK1, ABCC8 and SERPINF1 are associated with obesity or diabetes. We analyzed the polymorphisms rs846910, rs1205, rs1501299, rs1801282, rs1800497, rs757110 and rs1136287 in these candidate genes, for association with obesity and metabolic traits in a young Mexican-American population from south Texas.

METHODS

Genotyping of the seven common SNPs were performed by allelic discrimination assays in 448 unrelated Mexican Americans (median age = 16 years) from south Texas. χ(2) tests and regression analyses using additive models were used for genetic association analyses adjusting for covariates; p values were corrected for multiple testing by permutation analyses.

RESULTS

rs1800497 (ANKK1) shows association with waist circumference (p = 0.009) and retains the association (p = 0.03) after permutation testing. Analysis of metabolic quantitative traits shows that rs846910 (HSD11B1) was associated with HOMA-IR (p = 0.04) and triglycerides (p = 0.03), and rs1205 (CRP) with HOMA-IR (p = 0.03) and fasting glucose levels (p = 0.007). However, the quantitative traits associations are not maintained after permutation analysis. None of the other SNPs in this study showed associations with obesity or metabolic traits in this young Mexican-American population.

CONCLUSIONS

We report a potential association between rs1800497 (linked to changes in brain dopamine receptor levels) and central obesity in a young Mexican-American population.

Ethnicity, obesity and the metabolic syndrome: implications on assessing risk and targeting intervention

Pediatric obesity threatens the future health of a growing number of children worldwide. An added challenge in identifying the patients at greatest need for intervention due to their elevated risk for future disease is that pediatric obesity and the associated metabolic syndrome manifest differently among different ethnic groups. African-Americans and Hispanics are more likely to exhibit obesity and insulin resistance and are at a higher risk for developing Type 2 diabetes. Nevertheless, using current criteria, African-American adolescents are much less likely to be diagnosed with metabolic syndrome, largely owing to lower rates of dyslipidemia. Further development is needed in ethnicity-inclusive means of risk identification among adolescents to accurately target treatment toward children at highest risk for future disease and to motivate adolescent patients and their families towards lifestyle improvement. Effective targeting and intensive treatment efforts may help in avoiding future sequelae of obesity among all ethnicities.

A novel syndrome of mandibular hypoplasia, deafness, and progeroid features associated with lipodystrophy, undescended testes, and male hypogonadism

CONTEXT

Mandibuloacral dysplasia (MAD) is an autosomal recessive progeroid disorder associated with type A (partial) or B (generalized) lipodystrophy and is due to mutations in lamin A/C (LMNA) or zinc metalloproteinase (ZMPSTE24) genes.

OBJECTIVE

The objective of the study was to report a novel syndrome with some overlapping features with MAD.

RESULTS

We report seven patients with mandibular hypoplasia, deafness, progeroid features (MDP), and associated lipodystrophy. These patients have similar features to MAD patients such as hypoplastic mandible, beaked nose, stiff joints, and sclerodermatous skin. However, the patients did not harbor any disease causing variants in LMNA or ZMPSTE24 and showed distinct characteristics such as sensorineural hearing loss and absence of clavicular hypoplasia and acroosteolysis. All males with MDP had undescended testes and were hypogonadal. One adult female showed lack of breast development. Skinfold thickness, dual-energy X-ray absorptiometry and whole-body magnetic resonance imaging for body fat distribution revealed a lack of lipodystrophy in a prepubertal female but a progressive loss of sc fat presenting with partial lipodystrophy in young adults and generalized lipodystrophy in older patients.

CONCLUSIONS

Patients with MDP syndrome have a few overlapping but some distinct clinical features as compared with MAD, suggesting that it is a novel syndrome. The molecular basis of MDP syndrome remains to be elucidated.

Associations among 25-hydroxyvitamin D, diet quality, and metabolic disturbance differ by adiposity in adults in the United States

CONTEXT

Recent evidence indicates that a higher plasma level of 25-hydroxyvitamin D [25(OH)D] is associated with lower adiposity and a reduced number of metabolic disturbances (MetD).

OBJECTIVES

We examined associations among dietary quality, 25(OH)D, percent body fat (%BF), and MetD, and a pathway linking them, across central obesity.

DESIGN

This cross-sectional nationally representative study used extensive data from the National Health and Nutrition Examination Surveys of 2001-2004.

PARTICIPANTS

U.S. adults aged at least 20 yr were stratified by central obesity (CO) status. Sample sizes ranged from 1943 (all MetD combined) to 7796 (each component).

MAIN OUTCOME MEASURES

%BF was measured using dual-energy x-ray absorptiometry, and MetD was measured with individual continuous nonadiposity outcomes (e.g. fasting plasma glucose) and with a composite count index of binary MetD with prespecified cutoff points (Index I).

RESULTS

A higher 25(OH)D was associated with better dietary quality, lower %BF, and lower number of MetD. These inverse 25(OH)D-%BF and 25(OH)D-MetD associations (i.e. fasting blood glucose, homeostatic model assessment of insulin resistance, C-reactive protein, and Index I) were significantly stronger among the CO+ group. Finally, the pathway linking the dairy component of the Healthy Eating Index (HEIdairy) to Index I through 25(OH)D and %BF indicated complete mediation among the CO- group, but HEIdairy and 25(OH)D had direct inverse associations with Index I among the CO+ group.

CONCLUSIONS

Due to potential genetic differences between CO- and CO+ groups, empowering U.S. adults with central obesity to make related behavioral changes may be especially effective in improving their vitamin D status and metabolic profile.

Surrogate markers of insulin resistance: A review

Insulin resistance is a hallmark of obesity, diabetes, and cardiovascular diseases, and leads to many of the abnormalities associated with metabolic syndrome. Our understanding of insulin resistance has improved tremendously over the years, but certain aspects of its estimation still remain elusive to researchers and clinicians. The quantitative assessment of insulin sensitivity is not routinely used during biochemical investigations for diagnostic purposes, but the emerging importance of insulin resistance has led to its wider application research studies. Evaluation of a number of clinical states where insulin sensitivity is compromised calls for assessment of insulin resistance. Insulin resistance is increasingly being assessed in various disease conditions where it aids in examining their pathogenesis, etiology and consequences. The hyperinsulinemic euglycemic glucose clamp is the gold standard method for the determination of insulin sensitivity, but is impractical as it is labor- and time-intensive. A number of surrogate indices have therefore been employed to simplify and improve the determination of insulin resistance. The object of this review is to highlight various aspects and methodologies for current and upcoming measures of insulin sensitivity/resistance. In-depth knowledge of these markers will help in better understanding and exploitation of the condition.

Cardiovascular fitness and risk factors of healthy African Americans and Caucasians

BACKGROUND

African Americans have a higher prevalence of and mortality rates from cardiovascular disease than Caucasians. One important risk factor for cardiovascular disease is poor cardiovascular fitness. We quantified associations between fitness and related primary risk factors for cardiovascular disease in healthy African Americans and Caucasians.

METHODS AND RESULTS

Participants included African American (n = 91) and Caucasian (n = 51) men and women aged 18 to 45 years with a body mass index less than 38 kg/m2, fasting blood glucose less than 126 mg/dL, and blood pressure less than 140/90 mm Hg. Fitness, waist and hip circumference, percent body fat, fasting blood glucose, insulin, lipid profiles, and C-reactive protein (CRP) were measured. The majority of African Americans (57.1%) were low-fair fitness (Caucasians, 31.4%), and only 20.8% were good/high fitness (Caucasians, 39.2%). The number of cardiovascular disease risk factors increased with decreasing fitness, and CRP was negatively associated with fitness in both groups.

CONCLUSIONS

Low fitness may characterize apparently healthy African Americans as at risk for cardiovascular disease. Including fitness as a risk factor may improve early identification of at-risk African Americans. Importantly, prescribing exercise as medicine and promoting regular physical activity to improve fitness is essential among African Americans.

Association of inflammation with worsening HOMA-insulin resistance

AIMS/HYPOTHESIS

We examined the cross-sectional and longitudinal relationships between C-reactive protein (CRP), a marker of low-grade inflammation, and insulin resistance and whether the association was independent of obesity and oxidative stress.

METHODS

CRP and insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]) data were obtained in a population-based, prospective observational study, Coronary Artery Risk Development in Young Adults (CARDIA), during 1992-2006.

RESULTS

CRP showed a significant positive association with insulin resistance, both cross-sectionally and longitudinally (5 year follow-up). The estimated increment in HOMA-IR was 0.34 log(e)(pmol/l x [mmol/l]/156.25) (p value for trend <0.0001) in the highest vs lowest CRP quartiles in cross-sectional analysis, whereas the corresponding estimate was 0.12 (p trend <0.0001) in the highest vs lowest CRP quartiles longitudinally over 5 years. The gradient of HOMA-IR across CRP was attenuated but remained statistically significant after controlling for body fat measurements (0.06 in the highest vs lowest CRP in both cross-sectional [p value for trend = 0.001] and longitudinal analyses [p value for trend = 0.01]), and was little changed by further adjustment for oxidative stress markers (F(2)-isoprostanes and oxidised LDL). There were consistent increments in the levels of HOMA-IR with increasing concentrations of CRP over time. In contrast, higher HOMA-IR did not predict future increases in CRP. Findings were similar using fibrinogen as the predictor variable.

CONCLUSIONS/INTERPRETATION

Although a substantial portion of this association was explained by obesity, CRP was independently related to concurrent and future insulin resistance.

To assess, to control, to exclude: effects of biobehavioral factors on circulating inflammatory markers

Behavioral scientists have increasingly included inflammatory biology as mechanisms in their investigation of psychosocial dynamics on the pathobiology of disease. However, a lack of standardization of inclusion and exclusion criteria and assessment of relevant control variables impacts the interpretation of these studies. The present paper reviews and discusses human biobehavioral factors that can affect the measurement of circulating markers of inflammation. Keywords relevant to inflammatory biology and biobehavioral factors were searched through PubMed. Age, sex, and hormonal status, socioeconomic status, ethnicity and race, body mass index, exercise, diet, caffeine, smoking, alcohol, sleep disruption, antidepressants, aspirin, and medications for cardiovascular disease are all reviewed. A tiered set of recommendations as to whether each variable should be assessed, controlled for, or used as an exclusion criteria is provided. These recommendations provide a framework for observational and intervention studies investigating linkages between psychosocial and behavioral factors and inflammation.

Synergistic role of inflammation and insulin resistance as coronary artery disease risk factors in African Americans and Caucasians

The separate roles of inflammation and insulin resistance (IR) in the pathogenesis of cardiovascular disease (CVD) are well recognized. We investigated whether presence of inflammation would modify coronary artery disease (CAD) risk prediction in subjects with or without IR. Insulin, glucose, CRP and fibrinogen levels were determined in 317 Caucasians and 222 African Americans undergoing diagnostic coronary angiography. Extent of CAD was defined by a composite score (0-75). The overall prevalence of IR (HOMA-IR>or=3.0) in Caucasians and African Americans was 32.5% and 22.9%, respectively (P<0.05). The degree of CAD (composite score) was higher in subjects with IR (20.7 vs. 14.5, P=0.014 and 20.1 vs. 13.1, P=0.031 for Caucasians and African Americans, respectively), and in a multiple regression model IR was an independent predictor for CAD in both groups. In both ethnic groups, subjects with a combination of IR and high CRP (>or=3mg/l) had significantly higher composite score compared to those with no IR and low CRP (<3mg/l) (21.2 vs. 13.9, P<0.05 and 20.9 vs. 10.2, P<0.05 for Caucasians and African Americans, respectively). Similarly, the composite score was significantly higher in subjects with IR and high fibrinogen (>or=340 mg/dl) compared to those with no IR and low fibrinogen. In conclusion, elevated levels of inflammatory markers were positively associated with IR. Further, a combination of IR and inflammation resulted in a higher degree of CAD in both Caucasians and African Americans. The results suggest that inflammation may potentiate the cardiovascular risk factor role of IR.

C-reactive protein is elevated 30 years after eclamptic pregnancy

Women with a history of preeclampsia or eclampsia (seizure during preeclamptic pregnancy) are at increased risk for cardiovascular disease after pregnancy for reasons that remain unclear. Prospective studies during pregnancy suggest that inflammation, dyslipidemia, and insulin resistance are associated with increased risk of preeclampsia. Elevated serum C-reactive protein (CRP >3 mg/L) is an indicator of inflammation and cardiovascular risk. We hypothesized that Icelandic postmenopausal women with a history of eclampsia would manifest higher concentrations of serum CRP than Icelandic postmenopausal controls with a history of uncomplicated pregnancies. We also asked whether elevated CRP is associated with the dyslipidemia and insulin resistance previously identified in this cohort. CRP, measured by high-sensitivity enzyme-linked immunoassay, was higher in women with prior eclampsia (n=25) than controls (n=28) (median mg/L [interquartile range]: 9.0 [0.9 to 13.2] versus 2.0 [0.3 to 5.1]; P<0.03). This difference remained significant after adjustment for body mass index, smoking, hormone replacement, and current age. Women with prior eclampsia clustered into either high CRP (range 8.97 to 40.6 mg/L, n=13) or lower CRP (median 1.0, range 0.05 to 3.77, n=12) subsets. The prior eclampsia/high CRP subset displayed significantly elevated systolic blood pressures, lower high-density lipoprotein (HDL) cholesterol, higher apolipoprotein B, and higher fasting insulin and homeostasis model of insulin resistance (HOMA) values compared to controls, whereas the prior eclampsia/low CRP subset differed from controls only by marginally increased apolipoprotein B. The triad of inflammation, low HDL, and insulin resistance may elevate risk for both preeclampsia/eclampsia and cardiovascular disease in later life.