Association of total and central adiposity measures with fasting insulin in a biracial population of young adults with normal glucose tolerance: the CARDIA study

Cardiovascular risk factors: Is the metabolic syndrome related to aging? Epidemiology in a Portuguese population

AIMS

The primary objective of our study is to determine the prevalence of the metabolic syndrome in the population. The secondary objective is to determine the prevalence of cardiovascular risk factors, anthropometric alterations and the prevalence of target organ damage and their relationship with aging.

MATERIAL AND METHODS

The sample for the study was obtained by means of a consecutive population-based demonstration in 803 adults over 18 years of age belonging to the labor force of the company Grupo Delta SA. The study was carried out according to the guidelines of the Declaration of Helsinki. The individuals included in the study voluntarily participated, once informed of the purpose of the study, giving their prior verbal consent, to the company's human resources department, in the case of Delta Group workers.

RESULTS

23.8% of the population has metabolic syndrome more prevalent in males, no smoking, no significant alcohol consumption, sedentary, with a high Body mass index (BMI). Its prevalence increases with age.

CONCLUSION

We found that the prevalence of metabolic syndrome increases with age and is present in people of working age, increasing the risk of cardiovascular diseases, work-related absences, and socio-economic costs.

Tracking weight change, insulin resistance, stress, and aerobic fitness over 4 years of college

OBJECTIVE

To determine if weight gain is accompanied by development of insulin resistance (IR) during 4 years in college.

PARTICIPANTS

Two cohorts of college students were enrolled in fall semesters 2009 and 2010 and tracked for 4 years.

METHODS

Following a 12-hour fast, subjects reported for measurement of body mass index (BMI), perceived stress (PSS), aerobic fitness, and blood glucose, insulin, and lipids.

RESULTS

In the first year, 33% of subjects were overweight or obese, and 20% were hyperinsulinemic. Year 4 had 29 remaining subjects with disproportionate attrition of overweight and obese individuals. Just over half the subjects gained weight (WI), whereas nearly 30% lost considerable amounts (WD). WD showed significant decline in fasting insulin, low-density lipoprotein (LDL) cholesterol, and PSS from year 1. WI was primarily highly fit men who did not demonstrate increased IR.

CONCLUSION

WI was not associated with IR over 4 years of college.

Rationale, design, and methods for Canadian alliance for healthy hearts and minds cohort study (CAHHM) - a Pan Canadian cohort study

Background

The Canadian Alliance for Healthy Hearts and Minds (CAHHM) is a pan-Canadian, prospective, multi-ethnic cohort study being conducted in Canada. The overarching objective of the CAHHM is to understand the association of socio-environmental and contextual factors (such as societal structure, activity, nutrition, social and tobacco environments, and access to health services) with cardiovascular risk factors, subclinical vascular disease, and cardiovascular and other chronic disease outcomes.

Methods/Design

Participants between 35 and 69 years of age are being recruited from existing cohorts and a new First Nations Cohort to undergo a detailed assessment of health behaviours (including diet and physical activity), cognitive function, assessment of their local home and workplace environments, and their health services access and utilization. Physical measures including weight, height, waist/hip circumference, body fat percentage, and blood pressure are collected. In addition, eligible participants undergo magnetic resonance imaging (MRI) of the brain, heart, carotid artery and abdomen to detect early subclinical vascular disease and ectopic fat deposition.

Discussion

CAHHM is a prospective cohort study designed to investigate the impact of community level factors, individual health behaviours, and access to health services, on cognitive function, subclinical vascular disease, fat distribution, and the development of chronic diseases among adults living in Canada.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3310-8) contains supplementary material, which is available to authorized users.

Relationship between body mass index and mean arterial pressure in normotensive and chronic hypertensive pregnant women: a prospective, longitudinal study

Background

Being overweight is associated with both higher systolic blood pressure (SBP) and diastolic blood pressure (DBP) during pregnancy and increased risk of gestational hypertensive disorders. The objective of this study was to determine and quantify the effect of body mass index (BMI) on mean arterial pressure (MAP) at several time points throughout pregnancy in normotensive (NT) and chronic hypertensive pregnant (HT) women.

Methods

A prospective longitudinal study was carried out in 461 singleton pregnancies (429 low-risk and 32 with chronic arterial hypertension), with measurements taken at the 1^st, 2^nd, and 3^rd trimesters and at delivery. Linear mixed-effects regression models were used to evaluate the time-progression of BMI, SBP, DBP and MAP during pregnancy (NT vs. HT). The longitudinal effect of BMI on MAP, adjusted for the hypertensive status, was investigated by the same methodology.

Results

BMI consistently increased with time in both NT and HT women. In contrast, MAP decreased during the first half of pregnancy, after which it increased until the moment of delivery in both groups. A 5-unit increase in BMI was predicted to produce an increase of approximately 1 mmHg in population MAP values. This effect is independent from the time period and from hypertensive status.

Conclusions

In both NT and HT pregnant women, MAP is strongly (and significantly) influenced by increases in BMI.

Health Benefits of Exercise for People Living With HIV: A Review of the Literature

With life expectancy increasing and the symptomatology of HIV being altered since the advent of antiretroviral therapy (ART), we now have begun to see metabolic changes with negative implications among people living with HIV/AIDS (PLWHA). Some of these changes include increased blood lipids, central fat accumulation, lipodystrophy, and decreased aerobic capacity. All of which are known risk factors for cardiovascular disease, cancer, and all-cause mortality. A common practice among healthy and other clinical populations to help modify these risk factors is some form of aerobic exercise, resistance exercise, or a combination of both. It has been demonstrated that PLWHA could respond in a similar manner, which in turn may enhance life expectancy and/or quality of life. The purpose of this literature review was to examine the evidence of health benefits of routine exercise training among PLWHA since the advent of ART. Although limited in strength because of small sample sizes and limited intervention durations, there is overall consistency in the general findings. An overview of the findings would indicate that physical activity and exercise are both safe and effective in improving cardiorespiratory fitness, metabolic profile, and quality of life among PLWHA.

Obesity and diabetes: newer concepts in imaging

Quantifying body fat is currently an area of active research. Recent studies have shown that the quantity and location of fat in different compartments have varying clinical significance. This information can now be obtained from computed tomography (CT) or magnetic resonance (MR), and it can inform clinical decision making for patient management. Diabetes patients with insulin resistance and hyperinsulinemia have nonalcoholic fatty liver disease (NAFLD) ranging from steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis, typically diagnosed by liver biopsy or serum markers. There is now an emerging role of noninvasive imaging tests such as MR imaging or MR spectroscopy or elastography, which can provide quantitative information and have potential to avoid biopsy. Obese patients with diabetes are also at risk for cardiovascular disease and cancer. There is an emerging role for imaging in early detection of not only structural but also functional abnormalities of myocardium at a subclinical stage. Screening for cancer is currently recommended only for breast, colon, prostate, and cervix. Given wider availability and advances in imaging techniques such as positron emission tomography/CT (faster scans with higher resolution and less ionizing radiation) and better understanding of molecular biology and risk-stratification, more and more cancers are being detected in early stages with better clinical outcomes. Concerns related to cost, overdiagnosis, and unnecessary interventions must be addressed before population-based screening for other cancers is recommended. Based on ongoing imaging research, it is expected that it will be possible to provide more precise measurement of body fat and detect cardiovascular disease and cancers earlier in their course.

Prevalence of hyperinsulinemia associated with body mass index, genetic predisposition, and lifestyle in college freshmen students

OBJECTIVE

College lifestyle places an individual at greater risk for the development of insulin resistance (IR) and disease. The aim of this study was to establish a baseline measurement of insulin, and other variables influencing IR in college freshmen.

PARTICIPANTS

Twenty-two men and women, 18 to 19 years of age, during first month of college.

METHODS

Following 12-hour fast, subjects reported to the laboratory for determination of body mass index (BMI) and completion of questionnaire determining ethnicity, family history, and patterns of diet, exercise, and stress. Blood samples were obtained and analyzed for glucose and insulin.

RESULTS

Mean insulin value for men (14.9 ± 1.86 μU/mL) was normal, and that for women (17.3 ± 1.74 μU/mL) was slightly elevated. When subjects were grouped by BMI, genetic predisposition, and summated lifestyle risk, fasting insulin values were significantly different. Eight of 22 subjects were hyperinsulinemic (insulin >19 μU/mL).

CONCLUSION

Hyperinsulinemia is prevalent in this population and merits further investigation and intervention.

Oral dehydroepiandrosterone replacement in older adults: effects on central adiposity, glucose metabolism and blood lipids

OBJECTIVE

To determine the effects of dehydroepiandrosterone (DHEA) therapy on changes in central adiposity, insulin action and blood lipids. Many of the actions of DHEA in humans are thought to be mediated through its conversion to sex hormones, which are modulators of adiposity, muscularity and insulin sensitivity. The effects of DHEA replacement on regional tissue composition, glucose metabolism and blood lipid profile in older adults have been inconsistent.

DESIGN

A randomized, double-blinded, placebo-controlled trial. The intervention was oral DHEA 50 mg/day or placebo for 12 months.

PARTICIPANTS

Fifty-eighty women and 61 men, aged 60-88 years, with low serum DHEA sulphate (DHEAS) levels at study entry.

MEASUREMENTS

Computed tomography measures of abdominal fat areas, thigh muscle and fat areas, DXA-derived trunk fat mass, serum glucose and insulin responses to an oral glucose challenge, and fasted serum total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides were assessed before and after the intervention.

RESULTS

There were no significant (P > 0·05) differences between the DHEA and placebo groups in the changes in regional tissue composition or glucose metabolism. HDL-cholesterol (P = 0·01) and fasted triglycerides (P = 0·02) decreased in women and men taking DHEA.

CONCLUSION

Restoring serum DHEAS levels in older adults to young adult levels for 1 year does not appear to reduce central adiposity or improve insulin action. The benefit of DHEA on decreasing serum triglycerides must be weighed against the HDL-lowering effect.

Fat mass modifies the association of fat-free mass with symptom-limited treadmill duration in the Coronary Artery Risk Development in Young Adults (CARDIA) Study

BACKGROUND

The assessment of fat mass and fat-free mass in relation to the symptom-limited maximal exercise duration (Max(dur)) of a treadmill test allows for insight into the association of body composition with treadmill performance potential.

OBJECTIVE

We investigated the complex associations between fat mass and fat-free mass and Max(dur) in a population setting.

DESIGN

The Max(dur) of a graded exercise treadmill test and body composition by dual-energy X-ray absorptiometry were estimated in 2413 black and white men and women aged 38-50 y from the Coronary Artery Risk Development in Young Adults (CARDIA) cohort.

RESULTS

The mean Max(dur) was ≈7.5 s shorter per kilogram of fat mass in both men and women and independent of fat-free mass, height, race, television watching, physical activity, systolic blood pressure, lung function, and education. Fat mass modified the association of fat-free mass with the Max(dur) (2-way interaction P < 0.001), and the interaction was stronger in women than in men. In men in the lowest fat-mass quartile, the Max(dur) was 1.3 s longer per kilogram of fat-free mass and was 0.5 s shorter per kilogram of fat-free mass in the highest fat-mass quartile. In contrast, in women with the least fat mass, the Max(dur) was 2.7 s longer per kilogram of fat-free mass and was 2.8 s shorter per kilogram of fat-free mass in the highest fat-mass quartile.

CONCLUSIONS

The Max(dur) was negatively related to fat mass. Fat-free mass in obese people contributed little to the treadmill performance potential as assessed by the Max(dur), although the contribution of fat-free mass was positive in thinner people.

Comparison of dual-energy x-ray absorptiometric and anthropometric measures of adiposity in relation to adiposity-related biologic factors

Dual-energy x-ray absorptiometry (DXA) can provide accurate measurements of body composition. Few studies have compared the relative validity of DXA measures with anthropometric measures such as body mass index (BMI) and waist circumference (WC). The authors compared correlations of DXA measurements of total fat mass and fat mass percent in the whole body and trunk, BMI, and WC with obesity-related biologic factors, including blood pressure and levels of plasma lipids, C-reactive protein, and fasting insulin and glucose, among 8,773 adults in the National Health and Nutrition Examination Survey (1999-2004). Overall, the magnitudes of correlations of BMI and WC with the obesity-related biologic factors were similar to those of fat mass or fat mass percent in the whole body and trunk, respectively. These observations were largely consistent across different age, gender, and ethnic groups. In addition, in both men and women, BMI and WC demonstrated similar abilities to distinguish between participants with and without the metabolic syndrome in comparison with corresponding DXA measurements. These data indicate that the validity of simple anthropometric measures such as BMI and WC is comparable to that of DXA measurements of fat mass and fat mass percent, as evaluated by their associations with obesity-related biomarkers and prevalence of metabolic syndrome.

Gender Differences in the Association between Sleep Duration and Body Composition: The Cardia Study

Sleep duration has been inversely associated with body mass index (BMI). We examined the relationship between self-reported sleep duration and BMI, waist circumference, and percent body fat in Black and White individuals from the CARDIA study. Box-Tidwell regression models were adjusted for age and race (Model 1), additional lifestyle and demographic variables (Model 2), and physical activity (Model 3). There were significant interactions between sleep and gender for the main outcome variables. In men, there was a trend for an inverse relationship between reported sleep duration and BMI in Model 2 (beta = -0.20, P = .053) but not model 3 (beta = -0.139, P = .191). In women, inverse relationships were observed between sleep duration and BMI (beta = -0.294, P = .005) and waist circumference (beta = -0.442, P = .059), in Model 2. These associations became nonsignificant in model 3 (BMI: beta = -0.172, P = .084; waist circumference: beta = -0.161, P = .474). Our results are consistent with previous findings that sleep is associated with BMI and other body composition variables. However, the relationship between self-reported sleep duration and body composition may be stronger in women than in men.

Impact of Aerobic and Resistance Exercise on the Health of HIV-Infected Persons

Individuals infected with HIV experience numerous comorbidities caused by the disease progression and medications, lack of (or inability to perform) physical activity, malnutrition, or a combination of these causes. Common symptoms include loss of muscle mass, fatigue, lypodystrophy, lypoatrophy, and decreases in strength, functional capacity, and overall quality of life. Studies have shown that exercise is a potential treatment of many of these symptoms. Research suggests that exercise may produce beneficial physiological changes in the HIV-infected population such as improved body composition and increases in both strength and endurance. In addition, psychological conditions such as depression and anxiety have been shown to be positively affected by exercise. The purpose of this review is to examine the literature regarding effects of aerobic, resistance, and combined aerobic and resistance exercise training on HIV-infected individuals.

Childbearing may increase visceral adipose tissue independent of overall increase in body fat

OBJECTIVE

To examine whether childbearing is associated with increased visceral adiposity and whether the increase is proportionally larger than other depots.

METHODS AND PROCEDURES

This prospective study examined changes in adiposity assessed via computed tomography (CT) and dual-energy X-ray absorptiometry among 122 premenopausal women (50 black, 72 white) examined in 1995-1996 and again in 2000-2001. During the 5-year interval, 14 women had one interim birth and 108 had no interim births. Multiple linear regression models estimated mean (95% confidence interval (CI)) 5-year changes in anthropometric and adiposity measures by interim births adjusted for age, race, and changes in total and subcutaneous adiposity.

RESULTS

We found no significant differences between one interim birth and no interim births for 5-year changes in weight, BMI, total body fat, subcutaneous adipose tissue, or total abdominal adipose tissue. Visceral adipose tissue increased by 40 and 14% above initial levels for 1 birth and 0 birth groups, respectively. Having 1 birth vs. 0 births was associated with a greater increase in visceral adipose tissue of 18.0 cm2 (4.8, 31.2), P<0.01; gain of 27.1 cm2 (14.5, 39.7) vs. 9.2 cm2 (4.8, 13.6), and a borderline greater increase in waist girth of 2.3 cm (0, 4.5), P=0.05; gain of 6.3 cm (4.1, 8.5) vs. 4.0 cm (3.2, 4.8), controlling for gain in total body fat and covariates.

DISCUSSION

Pregnancy may be associated with preferential accumulation of adipose tissue in the visceral compartment for similar gains in total body fat. Further investigation is needed to confirm these findings and determine whether excess visceral fat deposition with pregnancy adversely affects metabolic risk profiles among women.

Trimester-specific blood pressure levels in relation to maternal pre-pregnancy body mass index

We evaluated the influence of maternal pre-pregnancy body mass index (BMI), based on reported pre-pregnancy weight and height, on blood pressure (BP) levels during pregnancy by using information from a prospective cohort of 1733 women recruited before 20 weeks' gestation. Maternal antenatal BP values were abstracted from medical records, and we evaluated the mean BP differences according to BMI group in regression models, using generalised estimating equations to account for repeated BP records within each pregnancy. In each trimester, mean systolic BP (SBP) and diastolic BP (DBP) values were positively associated with maternal pre-gestational BMI. This association persisted after adjustment for maternal age, parity, smoking, education, marital status and physical activity. Overweight women (25-29 kg/m(2)) had first-, second- and third-trimester mean SBPs that were 8.1, 7.7 and 8.2 mmHg, respectively, higher than values observed in lean women (<20 kg/m(2)). Mean DBP values were 4.5, 5.4 and 5.6 mmHg higher for each successive trimester in overweight vs. lean women. Obese (>30 kg/m(2)) women consistently had the highest mean SBP and DBP values. Trimester-specific mean SBP values were 10.7-12.0 mmHg higher among obese women vs. lean women. Corresponding trimester-specific mean DBP values were 6.9-7.4 mmHg higher in obese vs. lean women. Similar patterns were observed when trimester-specific average mean arterial pressures were evaluated. Elevated pregnancy BPs associated with maternal pre-gestational BMI are consistent with a large body of literature that documents increased pre-eclampsia risk among overweight and obese women.

Physical activity in young adults and incident hypertension over 15 years of follow-up: the CARDIA study

OBJECTIVE

We sought to examine the relation between physical activity and incident hypertension in young adults over 15 years of follow-up in the Coronary Artery Risk Development in Young Adults study.

METHODS

A total of 3993 Black and White men and women aged 18 to 30 years were examined at baseline, and 2, 5, 7, 10, and 15 years later. Blood pressure and physical activity were measured at each exam. Hypertension was defined as systolic 140 mm Hg or higher, diastolic 90 mm Hg or higher, or antihypertensive medication use. Average physical activity and incident hypertension over 15 years of follow-up were analyzed.

RESULTS

There were 634 cases of incident hypertension over 15 years of follow-up. Those who were more versus less physically active experienced a reduced risk (hazard rate ratio = 0.83; 95% confidence interval = 0.73, 0.93) for incident hypertension, after adjustment for race, sex, age, education, and family history of high blood pressure.

CONCLUSIONS

Physical activity merits attention in the prevention of incident hypertension among young adults, particularly as they move into middle age.

Adult Weight Change, Weight Cycling, and Prepregnancy Obesity in Relation to Risk of Preeclampsia

BACKGROUND

Preeclampsia has been shown to be associated with obesity, with other risk factors for cardiovascular disease, and with subsequent cardiovascular disease itself. However, the possible association with weight gain and weight cycling has not been evaluated.

METHODS

In this prospective study of a cohort of 1644 pregnant women, we assessed adult weight change, intentional weight cycling, and prepregnancy obesity in relation to preeclampsia risk. Net weight change from age 18 years to the period 3 months before conception was determined for each participant. Weight cycling was defined as intentional weight loss and unintentional regain of at least 15 pounds during periods not related to pregnancy or lactation. We used multivariate regression procedures to calculate risk ratios (RRs) and 95% confidence intervals (CIs).

RESULTS

Relative to women with stable weight (gained or lost < 2.5 kg) women who gained 5.0-9.9 kg experienced a 2.6-fold increased risk of preeclampsia (95% CI = 1.0-6.7). The corresponding risk ratio (RR) for women who gained > or = 10 kg was 5.1 (2.2-12.2). Intentional weight cycling, after controlling for weight at age 18 years, adult weight change, and other risk factors, was not associated with increased risk of preeclampsia (RR = 1.1; CI = 0.6-1.8). RRs increased monotonically with increasing prepregnancy body mass index greater than 19.8 kg/m. After adjusting for confounders, the RR for prepregnancy overweight women and obese women were 1.7 (0.6-4.9) and 3.4 (1.5-7.6) respectively.

CONCLUSIONS

These results suggest that adult weight gain and prepregnancy overweight and obesity status are associated with an increased risk of preeclampsia.

Waist circumference correlates with metabolic syndrome indicators better than percentage fat

OBJECTIVE

Percent fat is often considered the reference for establishing the magnitude of adipose tissue accumulation and the risk of excess adiposity. However, the increasing recognition of a strong link between central adiposity and metabolic disturbances led us to test whether waist circumference (WC) is more highly correlated with metabolic syndrome components than percent fat and other related anthropometric measures such as BMI.

RESEARCH METHODS AND PROCEDURES

BMI, WC, and percent fat, measured by DXA, were evaluated in 1010 healthy white and African-American men and women [age, 48.3 +/- 17.2 (standard deviation) years; BMI, 27.0 +/- 5.3 kg/m(2)]. The associations of BMI, WC, and percent fat with age and laboratory-adjusted health risk indicators (i.e., serum glucose, insulin, triglycerides, high-density lipoprotein cholesterol, blood pressure) in each sex and ethnicity group were examined.

RESULTS

For 18 of 24 comparisons, the age- and laboratory-adjusted correlations were lowest for percent fat and in 16 of 24 comparisons were highest for WC. Fifteen of the between-method differences reached statistical significance. With health risk indicator as the dependent variable and anthropometric measures as the independent variable, the contribution of percent fat to the WC regression model was not statistically significant; in contrast, adding WC to the percent fat regression model did make a significant independent contribution for most health risk indicators.

DISCUSSION

WC had the strongest associations with health risk indicators, followed by BMI. Although percent fat is a useful measure of overall adiposity, health risks are best represented by the simply measured WC.

Abdominal obesity predicts declining insulin sensitivity in non-obese normoglycaemics: the Insulin Resistance Atherosclerosis Study (IRAS)

AIM

Cross-sectional studies have demonstrated a relationship between obesity and insulin sensitivity (S(I)); however, there is a lack of evidence from longitudinal studies.

METHODS

The Insulin Resistance Atherosclerosis Study (IRAS) estimated S(I) (x10(-4)/min.microU/ml) directly using a frequently sampled intravenous glucose tolerance test with minimal model analysis in 504 normoglycaemic subjects. Partial correlation coefficients (r) were calculated to compare the relationship of change in S(I) from baseline to 5 years later (DeltaS(I)) with baseline waist circumference (waist) as a measure of abdominal obesity and body mass index (BMI) as a measure of overall obesity. Mean DeltaS(I) was -1.06 (SD = 1.85).

RESULTS

Higher baseline waist (r = -0.16; p = 0.0005), but not BMI (r = -0.005; p = 0.91), was associated with (-) DeltaS(I) in models including sex, ethnicity, clinical centre and baseline S(I), BMI, waist, age and physical activity. The waist-DeltaS(I) relationship differed across the levels of baseline BMI, being significant only in normal weight (r = -0.21) and overweight subjects (r = -0.16), but not in obese subjects. DeltaS(I) was correlated with a 5-year change in either obesity measure (Deltawaist: r = -0.22 and DeltaBMI: r = -0.20; p = 0.0001).

CONCLUSIONS

Among non-diabetics, waist circumference was a strong predictor of declining S(I) among lean subjects, a modest predictor among overweight subjects, but was not predictive among obese individuals. Waist circumference should be considered, in addition to BMI, when identifying individuals at high risk of diabetes or the insulin resistance syndrome.

Comparison of visceral adipose tissue mass in adult African Americans and whites

OBJECTIVE

Previous studies have reported racial differences in the amount of visceral adipose tissue (VAT), a risk factor for metabolic diseases. These results are equivocal and have not controlled for hormonal influences on VAT mass. This study was designed to measure the extent to which race is associated with VAT, controlling for total adipose tissue (TAT) mass and testosterone.

RESEARCH METHODS AND PROCEDURES

Using a cross-sectional study design, we measured TAT mass using DXA, VAT and subcutaneous adipose tissue mass using magnetic resonance imaging, and sex hormones using radioimmunoassay in 224 African-American and white men and women.

RESULTS

White men had increased VAT mass, even when controlling for TAT and age, compared with African-American men. White women also had a higher VAT mass compared with African-American women, but only when controlling for TAT and age. When multiple linear regression was used to evaluate the racial differences in VAT mass in a subset of subjects (n=80), controlling for sex hormones, it was found that white men, but not women, had increased VAT mass compared with their African-American counterparts.

DISCUSSION

Based on the results of this study, we conclude that, when controlling for TAT, sex hormone levels, and age, white men, but not women, have more VAT mass than African-American men and women. Additional studies are needed to explore possible environmental and genetic influences on fat distribution relative to race and sex.

Serum adiponectin in young adults--interactions with central adiposity, circulating levels of glucose, and insulin resistance: the CARDIA study

PURPOSE

To study adiponectin, a circulating adipocytokine secreted by adipocytes inversely associated with diabetes and insulin resistance, and factors affecting its levels in the Coronary Artery Risk Development in Young Adults (CARDIA) study.

METHODS

Adiponectin in serum was measured by radioimmunoassay in 3355 participants (ages: 23-45 years) categorized by fasting glucose levels as normal, impaired fasting glucose, or diabetes mellitus.

RESULTS

Levels of adiponectin were higher in women, in white participants, and with age. Waist circumference, estimating visceral fat, strongly and inversely correlated with levels of adiponectin, more than body mass index. Adiponectin values adjusted for gender and race were lower with higher fasting glucose values in the normal range and still lower with impaired fasting glucose and untreated diabetes mellitus, even further adjusting for waist circumference and fasting insulin levels (p < 0.0001). Gender- and race-adjusted adiponectin levels were inversely associated with insulin resistance at year 15 and with insulin resistance measured 15 years previously and with its change from baseline to year 15 (p < 0.0001).

CONCLUSIONS

These data suggest complex and significant physiologic interactions among circulating levels of adiponectin and measures of insulin action throughout young adulthood, even from several years earlier. Central obesity, as measured with waist circumference, is a primary factor affecting levels of circulating adiponectin. Furthermore, levels of glucose and levels of adiponectin may directly influence one another.

Management of metabolic complications associated with antiretroviral therapy for HIV-1 infection: recommendations of an International AIDS Society-USA panel

OBJECTIVE

Alterations in glucose and lipid metabolism, lactic acidemia, bone disorders, and abnormal body fat distribution have been recognized recently as frequent complications associated with HIV-1 infection and potent antiretroviral therapy, but limited data are available regarding the appropriate management of these disorders. These recommendations were developed to guide physicians actively involved in HIV care in the management of metabolic complications that occur primarily within the context of potent antiretroviral therapy.

PARTICIPANTS

A 12-member panel representing international expertise in HIV-1 patient care, antiretroviral therapy, and endocrine and metabolic disorders was selected in the spring of 2000 by the International AIDS Society-USA, a not-for-profit physician education organization. Panel members met in closed meetings beginning in May 2000. All work was funded by the International AIDS Society-USA; the panel members are not compensated for their participation.

EVIDENCE

The panel reviewed published results of clinical, epidemiologic, and basic science studies and data and abstracts presented at research conferences, primarily from 1997 to 2002. The panel also considered studies of the pathophysiology and treatment of similar metabolic abnormalities in noninfected persons. Emphasis was placed on results from prospective, randomized, controlled clinical trials when available.

PROCESS

For each metabolic complication, 1 or more member(s) reviewed and presented all available evidence to the panel, and then wrote a summary of the evidence and preliminary recommendations. Final recommendations were determined by full group consensus. The summaries were combined into a single working document and all panel members edited and approved all subsequent drafts.

CONCLUSIONS

Carefully controlled studies to determine the incidence, etiology, risk factors, and most appropriate treatments for metabolic complications in HIV-1 infection are urgently needed. In the absence of these data, and to prevent acute illness and mitigate long-term risks, the panel recommends routine assessment and monitoring of glucose and lipid levels and assessment and monitoring of lactic acidemia and bone abnormalities if clinical signs or symptoms are detected. With the exception of body fat distribution abnormalities, specific treatments for these complications are also recommended. Successful long-term antiretroviral therapy will require diligent monitoring and preemptive treatment of metabolic complications to optimize the risk-benefit ratio of antiretroviral therapies.

Differences in resting metabolic rate between white and African-American young adults

OBJECTIVE

A reported lower resting metabolic rate (RMR) in African-American women than in white women could explain the higher prevalence of obesity in the former group. Little information is available on RMR in African-American men.

RESEARCH METHODS AND PROCEDURES

We assessed RMR by indirect calorimetry and body composition by DXA in 395 adults ages 28 to 40 years (100 African-American men, 95 white men, 94 African-American women, and 106 white women), recruited from participants in the Coronary Artery Risk Development in Young Adults (CARDIA), Birmingham, Alabama, and Oakland, California, field centers.

RESULTS

Using linear models, fat-free mass, fat mass, visceral fat, and age were significantly related to RMR, but the usual level of physical activity was not. After adjustment for these variables, mean RMR was significantly higher in whites (1665.07 +/- 10.78 kcal/d) than in African Americans (1585.05 +/- 11.02 kcal/d) by 80 +/- 16 kcal/d (p < 0.0001). The ethnic x gender interaction was not significant (p = 0.9512), indicating that the difference in RMR between African-American and white subjects was similar for men and women.

DISCUSSION

RMR is approximately 5% higher in white than in African-American participants in CARDIA. The difference was the same for men and women and for lean and obese individuals. The prevalence of obesity is not higher in African-American men than in white men. Because of these reasons, we believe that RMR differences are unlikely to be a primary explanation for why African-American women are more prone to obesity than white women.

Body fat distribution in white and black women: different patterns of intraabdominal and subcutaneous abdominal adipose tissue utilization with weight loss

BACKGROUND

Intraabdominal adipose tissue (IAAT) is the body fat depot most strongly related to disease risk. Weight reduction is advocated for overweight people to reduce total body fat and IAAT, although little is known about the effect of weight loss on abdominal fat distribution in different races.

OBJECTIVE

We compared the effects of diet-induced weight loss on changes in abdominal fat distribution in white and black women.

DESIGN

We studied 23 white and 23 black women, similar in age and body composition, in the overweight state [mean body mass index (BMI; in kg/m(2)): 28.8] and the normal-weight state (mean BMI: 24.0) and 38 never-overweight control women (mean BMI: 23.4). We measured total body fat by using a 4-compartment model, trunk fat by using dual-energy X-ray absorptiometry, and cross-sectional areas of IAAT (at the fourth and fifth lumbar vertebrae) and subcutaneous abdominal adipose tissue (SAAT) by using computed tomography.

RESULTS

Weight loss was similar in white and black women (13.1 and 12.6 kg, respectively), as were losses of total fat, trunk fat, and waist circumference. However, white women lost more IAAT (P < 0.001) and less SAAT (P < 0.03) than did black women. Fat patterns regressed toward those of their respective control groups. Changes in waist circumference correlated with changes in IAAT in white women (r = 0.54, P < 0.05) but not in black women (r = 0.19, NS).

CONCLUSIONS

Despite comparable decreases in total and trunk fat, white women lost more IAAT and less SAAT than did black women. Waist circumference was not a suitable surrogate marker for tracking changes in the visceral fat compartment in black women.

Predictive values of waist circumference for dyslipidemia, type 2 diabetes and hypertension in overweight White, Black, and Hispanic American adults

Waist circumferences (WC) >/=102 cm for men and >/=88 cm for women have been proposed by an expert panel as cut-points for identifying increased risk for the development of obesity comorbidities for most adults. The aim of this investigation was to examine the predictive values of these WC cut-points for hypercholesterolemia, low concentration of high (HDL-C), and high concentration of low (LDL-C) density lipoprotein cholesterol, hypertriglyceridemia, type 2 diabetes, and hypertension in overweight American adults. Data from NHANES III were utilized for the analysis. Predictive abilities were determined by calculating sensitivity, specificity, positive (PV+) and negative (PV-) predictive values in overweight subjects with BMI 25-29.9 kg/m(2). Sensitivity of WC cut-point was stronger for high LDL-C compared to other risk factors with the highest values recorded in the 40-59 and 60-69 year age groups in men and women, respectively. PV+ of WC cut-points for dyslipidemia, type 2 diabetes, and hypertension were low in men compared to women. PV+ tended to increase with age, from 19-39, 40-59 to 60-90 year age groups in Whites, Blacks, and Hispanic men. In men, the highest PV+ were recorded for hypertriglyceridemia in the 60-90 years old groups, with values of 71.6%, 52.5%, and 43.3% in Whites, Blacks, and Hispanics, respectively. The CVD risk factor associated with the highest PV+ in women was diabetes with values of 97.2% in Whites and 88.9% in Blacks, and hypertriglyceridemia with a value of 93.8% in the 17-39 year age group in Hispanics. Among Black men 40-59 years of age, only 32% of a population of overweight hypertensives were detected by the WC cut-points, and among Black women, 40-59 years of age, only 54% were detected. Given the low sensitivity of these cut-points for detecting hypertension, one of the major co-morbidities of obesity, these cut-points failed to provide adequate evidence for the use of WC in determining or evaluating patients as to co-morbid states. We recommend further studies to determine a set of specific cut-points associated with increased risk of CVD in different population groups.