Importance of obesity for the metabolic abnormalities associated with an abdominal fat distribution

Influence of b2 adrenergic receptor polymorphism (rs1042713 and rs1042714) on anthropometric, hormonal and lipid profiles in polycystic ovarian syndrome

BACKGROUND

Polycystic ovarian syndrome (PCOS) is a frequently encountered disorder. This study aimed to identify polymorphisms in ADRB2 in Saudi PCOS development and to study its influence on lipids, hormones, and anthropometric parameters.

METHODS

Saudi females (100) suffering from PCOS and healthy controls (100) were investigated. The estimation of cholesterol, triglycerides, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), plasma glucose, leptin Insulin, and ghrelin were carried out. The DNA was extracted, and ADRB2 fragment carrying the exon 1 was amplified and sequenced.

RESULTS

The waist, W/H ratio, lipids, glucose, and insulin were significantly higher in the obese PCOS compared to the normal weight group. The leptin and ghrelin were not different. Two single nucleotide polymorphisms (SNPs): rs1042713 (Arg16Gly; A>G) and rs1042714 (Gln27Glu; C>G) were identified. The genotype and allele frequency of rs1042713 did not differ in the total PCOS and normal weight, and obese PCOS compare to the controls. However, rs1042714 was significantly associated with PCOS development, where the minor G allele was protective against PCOS development.

CONCLUSIONS

The rs1042714 polymorphism of the ADRB associates with PCOS development in Saudis, while rs1042713 does not. However, the GG genotype of rs1042713 associates significantly with elevated BMI, waist, hip, W/H, and leptin, and decreased ghrelin. On the other hand, rs1042714 genotypes do not associate with any abnormality except the homozygous GG have higher triglycerides and lower HDL-C. Interestingly, glucose showed different correlation patterns in individuals carrying different genotypes of the two studied SNP, indicating clearly that the metabolic responses to a normal nutrient are significantly influenced by the genotypes of the SNPs in ADRB2.

Cytokines and the immune response in obesity-related disorders

The increasing prevalence of obesity and the associated morbidity and mortality are important public health problems globally. There is an important relationship between an unhealthy lifestyle and increased serum inflammatory cytokines. Adipocytes secrete several pro-inflammatory cytokines involved in the recruitment and activation of macrophages resulting in chronic low-grade inflammation. Increased cytokines in obese individual are related to the progression of several disorders including cardiovascular disease, hypertension, and insulin resistance. In present review we have summarized the crucial roles of cytokines and their inflammatory functions in obesity-related immune disorders.

Type 2 diabetes mellitus in women with polycystic ovary syndrome during a 24-year period: importance of obesity and abdominal fat distribution

STUDY QUESTION

What are the predictive factors for later development of type 2 diabetes (T2DM) in women with polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Obesity and abdominal fat distribution in women with PCOS in the mid-fertile years were the major risk factors for T2DM development 24 years later when lifestyle factors were similar to controls.

WHAT IS KNOWN ALREADY

Women with PCOS have an increased prevalence of T2DM.

STUDY DESIGN SIZE DURATION

A longitudinal and cross-sectional study was performed. Women with PCOS were examined in 1992 and in 2016. Randomly selected, age-matched women from the general population served as controls.

PARTICIPANTS/MATERIALS SETTING METHODS

Women with PCOS (n = 27), attending an outpatient clinical at a tertiary care centre for infertility or hirsutism were diagnosed in 1992 (mean age 30 years) and re-examined in 2016 (mean age 52 years). Women from the World Health Organization MONItoring of trends and determinants for CArdiovascular disease (WHO MONICA-GOT) 2008, aged 38-68 years, served as controls (n = 94), and they were previously examined in 1995. At both at baseline and at follow-up, women had blood samples taken, underwent a clinical examination and completed structured questionnaires, and the women with PCOS also underwent a glucose clamp test at baseline.

MAIN RESULTS AND THE ROLE OF CHANCE

None of women with PCOS had T2DM at baseline. At the 24-year follow-up, 19% of women with PCOS had T2DM versus 1% of controls (P < 0.01). All women with PCOS who developed T2DM were obese and had waist-hip ratio (WHR) >0.85 at baseline. No difference was seen between women with PCOS and controls regarding use of high-fat diet, Mediterranean diet or amount of physical activity at follow-up at peri/postmenopausal age. However, women with PCOS had a lower usage of a high-sugar diet as compared to controls (P = 0.01). The mean increases in BMI and WHR per year were similar in women with PCOS and controls during the follow-up period.

LIMITATIONS REASONS FOR CAUTION

The small sample size of women with PCOS and the fact that they were recruited due to infertility or hirsutism make generalization to women with milder forms of PCOS uncertain.

WIDER IMPLICATIONS OF THE FINDINGS

Obesity and abdominal fat distribution, but not hyperandrogenism per se, in women with PCOS in the mid-fertile years were the major risk factors for T2DM development 24 years later when peri/postmenopausal. Lifestyle factors were similar to controls at that time.

STUDY FUNDING/COMPETING INTERESTS

The study was financed by grants from the Swedish state under the agreement between the Swedish government and the country councils, the ALF-agreement (ALFGBG-718611), the Gothenburg Medical Association GLS 694291 and 780821, the Swedish Heart Lung Foundation and Hjalmar Svensson Foundation. The authors have no conflict of interest.

Nutrition, insulin resistance and dysfunctional adipose tissue determine the different components of metabolic syndrome

Obesity is an excessive accumulation of body fat that may be harmful to health. Today, obesity is a major public health problem, affecting in greater or lesser proportion all demographic groups. Obesity is estimated by body mass index (BMI) in a clinical setting, but BMI reports neither body composition nor the location of excess body fat. Deaths from cardiovascular diseases, cancer and diabetes accounted for approximately 65% of all deaths, and adiposity and mainly abdominal adiposity are associated with all these disorders. Adipose tissue could expand to inflexibility levels. Then, adiposity is associated with a state of low-grade chronic inflammation, with increased tumor necrosis factor-α and interleukin-6 release, which interfere with adipose cell differentiation, and the action pattern of adiponectin and leptin until the adipose tissue begins to be dysfunctional. In this state the subject presents insulin resistance and hyperinsulinemia, probably the first step of a dysfunctional metabolic system. Subsequent to central obesity, insulin resistance, hyperglycemia, hypertriglyceridemia, hypoalphalipoproteinemia, hypertension and fatty liver are grouped in the so-called metabolic syndrome (MetS). In subjects with MetS an energy balance is critical to maintain a healthy body weight, mainly limiting the intake of high energy density foods (fat). However, high-carbohydrate rich (CHO) diets increase postprandial peaks of insulin and glucose. Triglyceride-rich lipoproteins are also increased, which interferes with reverse cholesterol transport lowering high-density lipoprotein cholesterol. In addition, CHO-rich diets could move fat from peripheral to central deposits and reduce adiponectin activity in peripheral adipose tissue. All these are improved with monounsaturated fatty acid-rich diets. Lastly, increased portions of ω-3 and ω-6 fatty acids also decrease triglyceride levels, and complement the healthy diet that is recommended in patients with MetS.

Characteristics of metabolically obese normal-weight (MONW) subjects

The existence of a subgroup of normal-weight individuals displaying obesity-related phenotypic characteristics was first proposed in 1981. These individuals were identified as metabolically obese but normal weight (MONW). It was hypothesized that these individuals might be characterized by hyperinsulinemia and (or) insulin resistance, as well as by hypertriglyceridemia and high blood pressure despite having a body mass index (BMI) < 25 kg/m2. Such characteristics could confer upon MONW subjects a higher cardiovascular risk; however, scientific data on MONW subjects are scarce since only 9 publications are directly related to this topic. Despite differences in the criteria for identifying MONW subjects and the small number of subjects involved in most of these studies, their consistent results indicate that: (i) the prevalence of the MONW syndrome ranges between 5% and 45%, depending on the criteria used, age, BMI, and ethnicity; (ii) when compared with control subjects, MONW subjects display an altered insulin sensitivity, a higher abdominal and visceral adiposity, a more atherogenic lipid profile, a higher blood pressure, and a lower physical activity energy expenditure; and (iii) MONW subjects are at higher risks for type 2 diabetes and cardiovascular diseases.

Modification of skin composition by conjugated linoleic acid alone or with combination of other fatty acids in mice

The effects of conjugated linoleic acid (CLA), γ-linolenic acid (GLA), linoleic acid (LA), and their combinations, on skin composition in mice were investigated. Mice (8 weeks old) were orally administered with either LA, GLA, CLA, LA + GLA, LA + CLA, or CLA + GLA for 4 weeks. Then, the skin was analysed for triacylglycerol content, fatty acid composition and collagen content. Additionally, thicknesses of the dermis layer and subcutaneous tissue layer, and the size and number of adipocytes were measured histologically. The skin fatty acid composition was modified depending upon the fatty acid composition of supplemented oils. In each oil-alone group, skin triacylglycerol content was the highest in LA, followed by GLA and CLA treatments. Combinations with CLA had a similar triacylglycerol content compared with the CLA-alone group. No significant changes in collagen content were observed among any treatments. The effects on subcutaneous thickness were similar to the results obtained in the triacylglycerol contents, where groups supplemented with CLA alone or other fatty acids had significantly thinner subcutaneous tissue compared with the LA-alone group. However, no significant difference was detected in the thickness of the dermis layers. The number of adipocytes was highest in the LA + GLA group and tended to be reduced by CLA with or without the other fatty acids. These results suggest that CLA alone or in combination with other fatty acids strongly modifies skin composition in mice.

Beneficial effects of a Dietary Approaches to Stop Hypertension eating plan on features of the metabolic syndrome

OBJECTIVE

To determine the effects of a Dietary Approaches to Stop Hypertension (DASH) eating plan on metabolic risks in patients with the metabolic syndrome.

RESEARCH DESIGN AND METHODS

This was a randomized controlled outpatient trial conducted on 116 patients with the metabolic syndrome. Three diets were prescribed for 6 months: a control diet, a weight-reducing diet emphasizing healthy food choices, and the DASH diet with reduced calories and increased consumption of fruit, vegetables, low-fat dairy, and whole grains and lower in saturated fat, total fat, and cholesterol and restricted to 2,400 mg Na. The main outcome measures were the components of the metabolic syndrome.

RESULTS

Relative to the control diet, the DASH diet resulted in higher HDL cholesterol (7 and 10 mg/dl), lower triglycerides (-18 and -14 mg/dl), systolic blood pressure (SBP) (-12 and -11 mmHg), diastolic blood pressure (-6 and -7 mmHg), weight (-16 and -14 kg), fasting blood glucose (FBG) (-15 and -8 mg/dl), and weight (-16 and -15 kg), among men and women, respectively (all P < 0.001). The net reduction in triglycerides (-17 and -18 mg/dl), SBP (-11 and -11 mmHg), diastolic blood pressure (-5 and -6 mmHg), and FBG (-4 and -6 mg/dl), weight (-16 and -15 kg), and increase in HDL (5 and 10 mg/dl) among men and women, respectively, was higher in the DASH group (all P < 0.05). The weight-reducing diet resulted in significant change in triglycerides (-13 and -10 mg/dl), SBP (-6 and -6 mmHg), and weight (-13 and -12 kg) among men and women, respectively (all P < 0.05).

CONCLUSIONS

The DASH diet can likely reduce most of the metabolic risks in both men and women; the related mechanisms need further study.

Body mass index and weight change from adolescence into adulthood, waist-to-hip ratio and perceived work ability among young adults

OBJECTIVES

To study how body mass index (BMI, kg/m2) at 14 and 31 years (y) changes in BMI between 14 and 31 y, and waist-to-hip ratio (WHR) at 31 y are associated with poor perceived working ability at 31 y.

DESIGN AND SUBJECTS

A population-based cohort, originally 11637 people, born in Northern Finland in 1966 was resurveyed at 14 and 31 y.

MEASUREMENTS

Perceived work ability (measured by modified work ability index, WAI), BMI, WHR, alcohol intake, smoking, basic education and work history were recorded at 31 y and BMI also at 14 y.

RESULTS

Low WAI (15% of lowest values) at 31 y showed a U-shaped association with BMI at 14 y, and also with BMI at 31 y, except in obese males. Low WAI similarly had a U-shaped association with WHR, but in males only, while in females, the probability of low WAI increased almost linearly with WHR. Low WAI was more common among smokers and people with a low level of education. The pattern for alcohol intake was more equivocal, with a nonsignificant finding in males and an almost linear decrease of low WAI with increasing alcohol intake in females.

CONCLUSIONS

Work ability, health habits and anthropometric measures should be evaluated regularly in young workers, and preventive measures against diseases leading to premature retirement should be taken in time, for example by the occupational health-care service.

Validity and reliability of dual-energy X-ray absorptiometry for the assessment of abdominal adiposity

A number of methods exist for the estimation of abdominal obesity, ranging from waist-to-hip ratio to computed tomography (CT). Although dual-energy X-ray absorptiometry (DXA) was originally used to measure bone density and total body composition, recent improvements in software allow it to determine abdominal fat mass. Sixty-five men and women aged 18–72 yr participated in a series of studies to examine the validity and reliability of the DXA to accurately measure abdominal fat. Total body fat and abdominal regional fat were measured by DXA using a Lunar DPX-IQ. Multislice CT scans were performed between L1 and L4 vertebral bodies (region of interest) using a Picker PQ5000 CT scanner, and volumetric analyses were carried out on a Voxel Q workstation. Both abdominal total tissue mass ( P = 0.02) and abdominal fat mass ( P < 0.0001) in the L1–L4 region of interest were significantly lower as measured by DXA compared with multislice CT. However, Bland-Altman analysis demonstrated good concordance between DXA and CT for abdominal total tissue mass (i.e., limits of agreement = −1.56–2.54 kg) and fat mass (i.e., limits of agreement = −0.40–1.94 kg). DXA also showed excellent reliability among three different operators to determine total, fat, and lean body mass in the L1–L4 region of interest (intraclass correlations, R = 0.94, 0.97, and 0.89, respectively). In conclusion, the DXA L1–L4 region of interest compared with CT proved to be both reliable and accurate method to determine abdominal obesity.

Effect of two modes of antiandrogen treatment on insulin sensitivity and serum leptin in women with PCOS

Androgens are suggested to interact with leptin production and with insulin sensitivity in both polycystic ovary syndrome (PCOS) and obesity. The aim of the study was to follow these interactions along with two forms of antiandrogen treatment. Twenty women with PCOS were treated with ethinylestradiol and high dose of cyproteroneacetate (EE-CA) and 8 with the gonadotrophin-releasing hormone (GnRH) analogue goserelin for 6 months. The patients were divided into a low and a high body weight group and compared with a group of overweight women without PCOS. Both treatments resulted in a significant reduction of free testosterone but the concentration of leptin remained unchanged. EECA treatment resulted in deterioration and GnRH in improvement of insulin sensitivity. Serum leptin correlated only with body weight and body fat. It is concluded that leptin levels do not adequately reflect changes in insulin sensitivity or androgen levels after short-term antiandrogen or antigonadotropin treatment.

Gender effects on adrenergic receptor expression and lipolysis in white adipose tissue of rats

OBJECTIVE

To investigate the effects of short-term (15 days) cafeteria-diet feeding on the expression of alpha- and beta-adrenergic receptors (AR) and its association with lipolytic stimulation in isolated retroperitoneal white adipocytes.

RESEARCH METHODS AND PROCEDURES

Six female and 6 male Wistar rats (4 weeks old) were fed a cafeteria diet plus standard diet for 15 days. The remaining 12 age- and sex-matched rats received a standard diet only. White retroperitoneal adipose tissue was isolated and used for the determination of both alpha(2) and beta-AR expression and for in vitro studies of lipolytic activity.

RESULTS

In female control rats, we found higher lipolytic capacities located at the postreceptor level and a lower alpha(2)/beta(3)-AR ratio than male rats. Cafeteria-diet feeding for 15 days decreased lipolytic activity in both male and female rats and altered the alpha(2A)- and beta(3)-AR protein levels with an increase of alpha(2A)-AR in males and a beta(3)-AR decrease in females.

DISCUSSION

Our results indicate that a 15-day cafeteria-diet feeding induced an increase in the alpha(2)/beta(3)-AR balance and impaired adipose tissue lipolytic activity, which was higher in males and may contribute to the development of increased fat mass. The higher functionality of alpha(2)-AR, together with the minor role developed by beta(3)-AR and lower lipolytic capacities located at the postreceptor level in cafeteria-diet-fed male rats compared with female rats, may be responsible for the gender-dependent differences observed in this study.

Risk factors for coronary heart disease in obese non-diabetic subjects

OBJECTIVE

To examine relationships between body mass index (BMI) and coronary risk factors in obese subjects presenting to a dedicated obesity clinic.

STUDY DESIGN

Cross-sectional population survey from a single centre.

SUBJECTS

Three hundred and eighty-six consecutive non-diabetic obese subjects (301 women, 85 men) attending an obesity clinic for the first time (mean BMI 43.3 kg/m(2); range 30.6-71.5), aged 17-69 y (mean 40.1).

MEASUREMENTS

Height, weight, resting blood pressure, fasting plasma cholesterol, triglyceride, glucose and uric acid concentrations.

RESULTS

All variables measured showed an increase with higher BMI (triglycerides, P=0.04; glucose, P=0.007; urate, P<0.001; systolic BP, P<0.001; diastolic BP, P<0.001) as measured by one-way ANOVA, except cholesterol concentration which showed no relationship with BMI. In comparison with the group of subjects with BMI 30-35 kg/m(2) mean values for all variables were higher in the more obese subjects.

CONCLUSIONS

Non-diabetic subjects with BMI>35 kg/m(2) carry a burden of common coronary risk factors which appears to increase with greater obesity. The risk factor pattern observed echoes that described in insulin resistance syndromes. Plasma cholesterol concentration appears not to be related to BMI.

Changes in patterns of fatness in adult men in relation to serum indices of cardiovascular risk: the Normative Aging Study

BACKGROUND

Overweight and/or excessive weight gain, as well as changes in central fat deposition, have been implicated in increased incidence of coronary disease and type 2 diabetes.

OBJECTIVE

We related adiposity (BMI, kg/m2, and waist circumference, WC, cm) to biochemical risk factors (cholesterol, triglyceride and glucose concentrations) for cardiovascular disease and diabetes.

DESIGN

Associations were examined both cross-sectionally and longitudinally, among 867 men enrolled in the Normative Aging Study (NAS). We included all participants with complete anthropometric and clinical data at both enrollment (average age 45 y) and after approximately 15 y of follow-up (average age 60 y). We used multiple linear regression analysis to test relationships between body fatness and change in body fatness and the biochemical indices.

RESULTS

In adulthood, concurrent BMI and waist circumference related significantly to triglyceride and glucose concentrations and to 2 h glucose responses at two time points. Measures of fatness 15 y earlier were also predictive of later triglyceride and glucose measures. When included together, BMI, but not WC, remained independently associated with triglycerides at both time points, while WC, but not BMI, remained significantly associated with fasting glucose concentrations and glucose response at the follow-up observation. In contrast, gains in weight and abdominal fat from entry to follow-up related more strongly to serum cholesterol concentrations than did concurrent measures.

CONCLUSION

Attained weight, weight gain, and location of weight contribute differentially to these indices of cardiovascular and diabetes risk.

Relation of leptin and insulin to adiposity-associated elevations in sympathetic activity with age in humans

OBJECTIVE

To determine whether plasma leptin and insulin concentrations are related to adiposity-associated elevations in muscle sympathetic nerve activity (MSNA) with age in healthy adult humans.

DESIGN

Cross-sectional investigation of young and older adult men.

SUBJECTS

Thirty healthy adult men, 16 young (25+/-1 y, mean+/-s.e.) and 14 older (61+/-1 y).

MEASUREMENTS/RESULTS

The older men had higher (P<0.05) levels of body mass, BMI, total fat mass and truncal fat mass (dual energy X-ray absorptiometry) than the young men. MSNA burst frequency (microneurography) was approximately 75% higher in the older men (P<0.001). Plasma leptin concentrations were approximately 150% higher (P<0.01), whereas plasma insulin concentrations were approximately 70% higher (P<0.05) in the older subjects. MSNA was related to both total (r=0.51, P<0.01) and truncal (r=0.56, P<0.01) fat mass. Plasma leptin concentrations were related to total and truncal fat mass (both r=0.83, P<0.001), and to MSNA (r=0.49, P<0.01). Plasma insulin concentrations were related to MSNA (r=0.38, P<0.05). We used partial correlation analyses to assess whether leptin and/or insulin are potential contributors to the relation between body fat and MSNA. Adjusting for the effects of plasma leptin, but not insulin, concentrations eliminated the significant relations between MSNA and total and truncal fat mass.

CONCLUSION

Our results: (1) demonstrate a positive relation between MSNA and plasma leptin concentrations in young and older healthy men; and (2) support the concept that circulating leptin concentrations may act as a humoral signal contributing to adiposity-associated elevations in MSNA with age in adult humans.

Body fat distribution and cardiovascular risk in normal weight women. Associations with insulin resistance, lipids and plasma leptin

OBJECTIVE

To systematically examine the correlations between insulin resistance, plasma leptin concentration, obesity and the distribution of fat assessed by anthropometry and magnetic resonance imaging in Asian women.

DESIGN

A cross sectional study of non-diabetic, normal weight women.

SUBJECTS

Twenty-one healthy women aged 38.8 y (s.d. 11.7) and BMI 22.6 kg/m2 (s.d. 2.3).

MEASUREMENTS

Intraperitoneal, retroperitoneal and subcutaneous abdominal fat volume was assessed by magnetic resonance imaging. Anthropometric data were collected. Total fat mass was assessed by bioelectric impedance analysis. Fasting serum lipids, insulin and plasma leptin were assayed.

RESULTS

Generalized obesity correlated with subcutaneous abdominal fat mass (r=0.83, P<0.001), but not with intra-abdominal fat mass. Both intraperitoneal fat mass and retroperitoneal fat mass increased with age (r=0.58, P=0.005 and r=0. 612, P=0.003, respectively). Abdominal subcutaneous fat mass was the most important determinant of insulin resistance and plasma leptin. Of the serum lipids, only fasting triglyceride correlated significantly with the waist-to-hip ratio.

CONCLUSIONS

It is possible that the large size of the subcutaneous depot compared to the intra-abdominal depot overwhelms any metabolic differences between adipose tissue from these two sites, resulting in the stronger correlation between insulin resistance and subcutaneous abdominal fat mass rather than intra-abdominal fat mass. On the other hand, the distribution of fat between subcutaneous fat depots may be important in the metabolic syndrome given the correlation of fasting triglyceride with waist to hip ratio but not with abdominal fat. However, the study population was small, younger and leaner compared to previous studies and we may not be able to generalize these results to all segments of the population. We confirm that subcutaneous fat mass is the major determinant of plasma leptin.

Continuation of growth hormone (GH) therapy in GH-deficient patients during transition from childhood to adulthood: impact on insulin sensitivity and substrate metabolism

The appropriate management of GH-deficient patients during transition from childhood to adulthood has not been reported in controlled trials, even though there is evidence to suggest that this phase is associated with specific problems in relation to GH sensitivity. An issue of particular interest is the impact of GH substitution on insulin sensitivity, which normally declines during puberty. We, therefore, evaluated insulin sensitivity (euglycemic glucose clamp) and substrate metabolism in 18 GH-deficient patients (6 females and 12 males; age, 20 +/- 1 yr; body mass index, 25 +/- 1 kg/m2) in a placebo-controlled, parallel study. Measurements were made at baseline, where all patients were on their regular GH replacement, after 12 months of either continued GH (0.018 +/- 0.001 mg/kg day) or placebo, and finally after 12 months of open phase GH therapy (0.016 mg/kg x day). Before study entry GH deficiency was reconfirmed by a stimulation test. During the double-blind phase, insulin sensitivity and fat mass tended to increase in the placebo group [deltaM-value (mg/kg x min), -0.7 +/- 1.1 (GH) vs. 1.3 +/- 0.8 (placebo), P = 0.18; deltaTBF (kg), 0.9 +/- 1.2 (GH) vs. 4.4 +/- 1.6 (placebo), P = 0.1]. Rates of lipid oxidation decreased [delta lipid oxidation (mg/kg x min), 0.02 +/- 0.14 (GH) vs. -0.32 +/- 0.13 (placebo), P < 0.05], whereas glucose oxidation increased in the placebo-treated group (P < 0.05). In the open phase, a decrease in insulin sensitivity was found in the former placebo group, although they lost body fat and increased fat-free mass [M-value (mg/kg x min), 5.1 +/- 0.7 (placebo) vs. 3.4 +/- 1.0 (open), P = 0.09]. In the group randomized to continued GH treatment almost all hormonal and metabolic parameters remained unchanged during the study. In conclusion, 1) discontinuation of GH therapy for 1 yr in adolescent patients induces fat accumulation without compromising insulin sensitivity; and 2) the beneficial effects of continued GH treatment on body composition in terms of decrease in fat mass and increase in fat-free mass does not fully balance the direct insulin antagonistic effects.

Preperitoneal fat thickness determined by ultrasonography is correlated with coronary stenosis and lipid disorders in non-obese male subjects

OBJECTIVE

To investigate the relationship between preperitoneal fat thickness (PFT) determined by ultrasonography and the risk of coronary arterial disease, 130 non-obese patients with ischemic heart disease (77 men and 53 women) were examined.

RESULTS

There was a positive correlation between PFT and coronary artery stenosis score (r = 0.212, P < 0.05). After dividing the patients by gender, the correlation was recognized only in men (r = 0.246, P< 0.05). Also, PFT was positively correlated to serum total cholesterol (r = 0.259, P < 0.01), triglyceride (r = 0.205, P < 0.05) and low density lipoprotein (LDL)-cholesterol (r = 0.205, P < 0.05), and negatively correlated to serum high density lipoprotein (HDL)-cholesterol (r = -0.261, P < 0.01). Again, these correlations were found only in men, not in women.

CONCLUSION

PFT shows good correlations with coronary artery stenosis score and dyslipidemia, and may lead to the development of coronary artery disease in non-obese male subjects.

Diabetes, hypertension and erectile dysfunction

Diabetes mellitus (DM) and hypertension are independent risk factors for erectile dysfunction (ED), macrovascular disease and microangiopathy. ED is very common among diabetic patients. Men with DM have ED at an earlier age and with a significantly higher prevalence (as high as 75%). The prevalence of DM also tends to be higher in patients with Peyronie's disease. DM impairs neurogenic and endothelium-mediated relaxation of penile smooth muscle. It is impossible to separate DM from hypertension and from the other vascular risk factors. Good glycaemic and hypertension control in diabetics is very important since these factors increase the risk of both microvascular and macrovascular complications, possibly including ED.

Obesity and cardiovascular disease

Obesity, diabetes mellitus, and hypertension are common, interrelated medical problems in Westernized, industrialized societies. These interrelated medical conditions are associated with an increased risk of cardiovascular disease and are more prevalent in several minority groups, including African-American and Hispanic populations. The associated cardiovascular risks of these problems are more thoroughly addressed in another review in this supplement. Obesity markedly enhances the development of Type 2 diabetes. Moreover, it enhances the cardiovascular risk associated with other risk factors, such as hypertension and dyslipidemia. Weight reduction in association with an aerobic exercise program improves metabolic abnormalities and reduces blood pressure in individuals with diabetes and hypertension.

Diet-induced insulin resistance precedes other aspects of the metabolic syndrome

This study was designed to examine the effects of a high-fat refined-sugar (HFS) or a low-fat complex-carbohydrate (LFCC) diet on insulin-stimulated skeletal muscle glucose transport, plasma insulin, blood pressure, plasma triglycerides, plasma glycerol, body weight, and body fat in female Fischer rats. Insulin-stimulated glucose transport was significantly reduced in the HFS group at 2 wk, 2 mo, and 2 yr, whereas serum insulin was significantly elevated at all time points. Blood pressure was not significantly elevated in the HFS group until 12 mo, and all HFS animals were hypertensive by 18 mo. Glycerol, triglycerides, and abdominal fat cell size were not significantly different at 2 wk but were significantly elevated in the HFS rats at 2 and 6 mo. Body weight was similar in both groups until 20 wk on the diet, when the HFS rats started to gain more weight. These results demonstrate that insulin resistance and hyperinsulinemia occur before the other manifestations of the metabolic syndrome and that diet, not obesity, is the underlying cause.

Computed axial tomographic scan measurement of abdominal fat distribution and its correlation with anthropometry and insulin secretion in healthy Asian Indians

Asian Indians have high insulin resistance, hyperinsulinemia, a high prevalence of diabetes, and a high waist to hip ratio (WHR), although the rate of obesity is low. WHR and visceral fat (VF) are highly correlated, and both are associated with insulin resistance. This study was performed to determine the normal ranges of abdominal fat distribution (subcutaneous [SF] and VF) in nondiabetic South Indians and also to study its correlations with WHR, plasma insulin, and metabolic profiles. Fat areas were measured by computed axial tomographic scan at the L4 to L5 level. Mean areas of SF and VF in men and women in this study were similar to the values in white populations. Women had significantly less VF than men. Gender differences were observed in the contribution of fat areas to anthropometric, hormonal, and metabolic variables. In general, in men, total fat (TF) area showed significant independent correlation with body mass index (BMI), WHR, and total cholesterol, and VF correlated with insulin secretion. In women, TF and BMI were correlated and SF showed a correlation with total cholesterol. Insulin secretion in women did not show a correlation with fat areas.

Prevalence of hyperinsulinemia in young, nonobese Japanese men

OBJECTIVE

To clarify the prevalence of hyperinsulinemic subjects among young, nonobese, Japanese men, and to evaluate characteristics, in particular, of sympathetic nerve system activity and lipid fractions in hyperinsulinemic subjects.

METHODS

Norepinephrine, plasma insulin, and lipid fractions were measured in 512 normotensive, 124 borderline hypertensive (BHT) and 88 established hypertensive (EHT) subjects, matched for age and body mass index, after they had fasted overnight.

RESULTS

Hyperinsulinemia defined as mean fasting plasma insulin + 2SD in normotensives or more was found in 8% of all subjects (normotensive and hypertensive subjects, P = 0.018), 6% of normotensives, 10% of BHT (P = 0.28, versus normotensives), 18% of EHT (P = 0.005, versus normotensives), and 12% of hypertensives (P = 0.019, versus normotensives). The hyperinsulinemic (fasting insulin > or = mean + 2SD in normotensive) subjects had higher plasma norepinephrine levels in all blood pressure groups than did nonhyperinsulinemic (< mean + 2SD) subjects (normotensives P < 0.05, BHT P < 0.01, and EHT P < 0.05). Hyperinsulinemic normotensives had higher blood pressure levels than did nonhyperinsulinemic ones (P < 0.05); however, blood pressure levels in hyperinsulinemic BHT and EHT were similar to those in nonhyperinsulinemic subjects. Triglyceride in BHT and EHT was greater than that in normotensives (P < 0.05), and that in hyperinsulinemic subjects was greater than that in nonhyperinsulinemic subjects (P < 0.05). On the other hand, high-density lipoprotein cholesterol in hyperinsulinemic BHT and EHT was significantly lower than that in nonhyperinsulinemic BHT (P < 0.05) and EHT (P < 0.01).

CONCLUSION

These results demonstrated that the prevalence of hyperinsulinemia among the present sample of young, nonobese, Japanese men was 12% and that the prevalence increased with blood pressure elevation. Furthermore, hypertriglyceridemia and sympathetic nerve hyperactivity appear to be related to hyperinsulinemia and the emergence of hypertension.

Therapeutic challenges in the obese diabetic patient with hypertension

Obesity, diabetes mellitus, and hypertension are common and interrelated medical problems in Westernized, industrialized societies. These medical conditions are associated with an increased risk of cardiovascular disease and are more prevalent among minorities, such as African-American and Hispanic populations. The associated cardiovascular risks of these problems are more thoroughly addressed in another review in this supplement. Obesity markedly enhances the development of type II diabetes. Moreover, it enhances the cardiovascular risk associated with other risk factors, such as hypertension and dyslipidemia. Weight reduction in association with an aerobic exercise program improves metabolic abnormalities and reduces blood pressure in individuals with diabetes and hypertension. Frequently, however, pharmacologic treatment is required to lower blood pressure. Individual therapy with an angiotensin-converting enzyme (ACE) inhibitor is preferred initially in these individuals, with the addition of either a low dose diuretic or a nondihydropyridine calcium antagonist if additional blood pressure reduction is required. These additive agents are recommended, since each has been shown individually to reduce cardiovascular morbidity and to preserve renal function among diabetic patients. Other issues, such as aggressive therapy of lipids and adequate glycemic control, are also important strategies for reducing cardiovascular and renal morbidity and mortality in this very high-risk population.

Sex differences in cardiovascular risk factors independent of abdominal fat distribution

OBJECTIVE

To investigate sex differences in cardiovascular risk factors within a healthy middle-aged population.

DESIGN

Cross-sectional, observational study.

SETTING

Primary health care in Dalby, Sweden.

PARTICIPANTS

19 males and 19 postmenopausal females, selected for normotension, and matched for age (58 years) and body mass index (26 kg/m2).

MAIN OUTCOME MEASURES

At two visits, with a five year interval, subjects were investigated according to height, weight, and blood pressure (ambulant and in the doctor's surgery). The fat-free mass was calculated using the von Döbeln formula. Glucose metabolism was evaluated with an oral glucose tolerance test (glucose, insulin, C-peptide). Lipid levels, liver enzymes, and hormonal variables (cortisol, sex hormones) were also measured.

RESULTS

Males showed higher levels than females of glucose, insulin, triglycerides, and liver enzymes at the first visit, even after elimination of the influence of differences in weight. At the follow-up visit, males also had a higher 24-hour diastolic blood pressure than females (79.4 vs. 71.8 mm Hg; p < 0.01), as well as higher triglyceride levels (1.45 vs. 0.95 mmol/l; p < 0.05), even after elimination of the influence of abdominal fat distribution. No differences in smoking or daily intake of nutrients (per 1000 kcal) were seen, but alcohol intake differed in absolute terms (males 8.5 vs. females 2.3 g/d; p < 0.05).

CONCLUSION

Healthy middle-aged males differ in an unfavourable way from matched postmenopausal females in several cardiovascular risk factors. This is not fully explained by differences in abdominal fat distribution and sex hormone levels, nor by the influence of food intake and smoking habits.

Obesity and high-density lipoprotein cholesterol in black and white 9- and 10-year-old girls: The National Heart, Lung, and Blood Institute Growth and Health Study

It has been hypothesized that the role of obesity in the pathogenesis of coronary heart disease (CHD) may be mediated in part through its inverse relationship with high-density lipoprotein cholesterol (HDL-C). Obesity is inversely correlated with HDL-C, and HDL-C has been shown to be protective against CHD. Defining obesity as excess weight due to excess fat, the purpose of this analysis was to determine whether the effects of obesity are due to increased weight or to increased adiposity. Using baseline lipid and anthropometric data from the National Heart, Lung, and Blood Institute Growth and Health Study, cross-sectional associations among body mass, adiposity, HDL-C, and related lipid parameters (apolipoprotein [apo] AI and triglycerides [TGs]) were assessed in 821 white and 763 black 9- and 10-year-old girls, using multivariate linear regression models. Equations predicting HDL-C, apo AI, and TGs from age, race, race, sexual maturation stage, adiposity (sum of truncal--subscapular and suprailiac--skinfolds), and ponderosity (a ratio of weight to height) revealed that adiposity, not ponderosity, was the significant body composition variable to explain the variability of each of the lipids assessed. The amount of variance explained in each of the models was small (R2 Collapse

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MESH Headings

• Anthropometry
• Apolipoprotein A-I/blood
• Black People
• Body Composition/physiology
• Child
• Cholesterol, HDL/blood
• Cholesterol, HDL/physiology
• Female
• Humans
• Linear Models
• National Institutes of Health (U.S.)
• Obesity/blood
• Obesity/etiology
• Obesity/physiopathology
• Triglycerides/blood
• United States
• White People
• Black or African American

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Grants

• N01-HC-55023-26 NHLBI NIH HHS

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Affiliation(s)

J A Morrison Division of Cardiology, Children's Hospital Medical Center, Cincinnati, Ohio, USA
D Sprecher
R P McMahon
J Simon
G B Schreiber
P R Khoury

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Growth hormone-deficient adults are insulin-resistant

Patients with growth hormone deficiency (GHD) have traditionally been described as having increased insulin sensitivity with a tendency toward fasting hypoglycemia, at least in children. In other studies, impaired glucose tolerance has been found. To evaluate basal insulin sensitivity, a hyperinsulinemic, normoglycemic clamp was performed with an insulin rate of 40 mU/m2/min after an overnight fast. Fifteen patients (four women and 11 men aged 20 to 62 years) with GHD for at least 1 year were compared with 15 healthy controls matched for sex, age, and body mass index (BMI). Thirteen patients had complete pituitary deficiency and were being treated with conventional hormone replacement therapy. Two men had isolated GHD since childhood. Four men were being treated with bromocriptin. There were no significant differences between fasting blood glucose (4.4 +/- 0.1 v 4.7 +/- 0.2 [mean +/- SEM] mmol/L) or fasting plasma insulin (9.5 +/- 1.4 v 8.8 +/- 1.1 mU/L) in patients and controls, respectively. Fasting free fatty acid (FFA) levels were lower in patients (444 +/- 35 v 796 +/- 94 mumol/L, P < .01). Blood glucose levels during the clamp were similar (4.6 +/- 0.1 v 4.9 +/- 0.1 mmol/L), as were insulin levels (81 +/- 4 v 93 +/- 4 mU/L). A decrease in glucose infusion rate (GIR) was seen during the clamp in GHD subjects (3.9 +/- 0.5 v 9.9 +/- 0.7 mg/kg body weight/min) as compared with controls (P = .001). Even if corrections were made for body fat, there was a significant difference (GIR corrected per lean body mass, 5.8 +/- 0.8 v 13.9 +/- 0.9 mg/kg lean body mass/min, P < .001). The results suggest that adults with GHD are insulin-resistant. Despite this finding, normal fasting plasma insulin levels were seen.

Interrelation between risk factors for cardiovascular disease in men aged 33-42. A study from Habo in Skaraborg County, Sweden

OBJECTIVES

The main purpose was to study associations between different risk factors for coronary heart disease in order to find out whether such associations already exist during the fourth decade of life.

SETTING

A study carried out by the primary healthcare staff in the community of Habo in Skaraborg County in south-western Sweden.

SUBJECTS

All men living in Habo aged 33-42 years who were willing to participate in the study--in total 652 men (participation rate 86%).

MAIN OUTCOME MEASURES

Risk factors for coronary heart disease considered as markers of lifestyle: body-mass index as a measure of general obesity, waist-to-hip circumference ratio as a measure of central obesity, arterial blood pressure, serum cholesterol concentration and serum triglyceride concentration.

RESULTS

There were statistically significant correlations between all the factors analysed including anthropometric data, blood pressure and serum lipids.

CONCLUSIONS

The results indicate associations between different risk factors at an early age and emphasises the need for a multifactorial view on risk as early as at the ages which were the focus of this study.

Excess catecholamines and the metabolic syndrome: should central imidazoline receptors be a therapeutic target?

A sympathetic overactivity plays a major role in the pathogenesis of cardiovascular diseases in Westernized affluent societies. Of importance is an increased caloric intake and psychosocial stress which are associated with a raised central sympathetic outflow and unfavourable changes in metabolic parameters. Normalization of central sympathetic outflow could thus be a major therapeutic target. The newly developed antihypertensive drugs moxonidine and rilmenidine reduce the excitatory activity of neurons of the rostral ventrolateral medulla (RVLM) via binding to imidazoline receptors. Using radio telemetry, it is shown that, in contrast to the first generation centrally acting drug clonidine, moxonidine did not result in rebound of blood pressure after drug withdrawal in rats with spontaneous hypertension. In accordance, moxonidine is characterized by a low affinity for alpha-adrenoceptors and exhibits few side-effects. It is proposed that normalization of central sympathetic outflow represents a causal approach for improving crucial features of the metabolic syndrome.

Impaired glucose and insulin metabolism in borderline hypertension

This study investigated glucose and insulin metabolism in borderline hypertension (BHT) defined as repeated diastolic blood pressures (DBP) of 85-94 mmHg. Seventy-five BHT and 75 age-matched normotensive (NT, DBP < or = 80 mmHg) men were recruited from a population screening programme. Plasma lipoproteins were determined and an oral glucose tolerance test was performed (WHO criteria). Fasting insulin was significantly higher in the BHT group (17.2 vs 14.2 mU/ml, p < 0.001), whereas fasting blood glucose levels were similar in the two groups, indicating a reduced insulin sensitivity. The BHT group had significantly lower levels of HDL cholesterol and higher levels of plasma triglycerides, VLDL cholesterol and VLDL triglycerides. When adjusted for BMI these differences disappeared, whereas the basal insulin levels remained significantly elevated (F = 10.7, p < 0.001). These results indicate that an altered glucose and insulin metabolism is present already in the early stages of hypertension. They also suggest that these disturbances are only partly dependent on BMI. This supports the hypothesis that reduced insulin sensitivity could be of importance in the early phases of essential hypertension.

High fibrinogen and plasminogen activator inhibitor activity in growth hormone-deficient adults

Hypopituitary patients on routine replacement therapy except growth hormone (GH) have an increased risk of death from cardiovascular diseases compared with healthy subjects. Untreated GH deficiency might explain the premature death from vascular disease. Plasminogen activator inhibitor (PAI-1) activity, fibrinogen, insulin, blood lipid, and blood pressure levels were studied in 20 GH-deficient adults (10 men, 10 women) 50 +/- 11 years old with routine hormone replacement therapy (except GH) and compared with 20 healthy control subjects matched for sex, age, and body mass index. GH-deficient subjects had a higher waist-to-hip circumference ratio (P < .001), serum triglycerides (P < .02), PAI-1 activity (13.2 +/- 10.6 versus 6.8 +/- 4.8 U/mL [P < .05]), and fibrinogen (3.2 +/- 0.7 versus 2.4 +/- 0.6 g/L [P < .001]) and lower blood glucose (P < .05) compared with control subjects. Blood pressure, insulin, and cholesterol levels were similar. The aberrations found in this study might contribute to an increased atherothrombotic propensity and play a role in the pathogenesis of cardiovascular disease.

Differential effects of body fatness and body fat distribution on risk factor for cardiovascular disease in women. Impact of weight loss

This study examines the role of obesity and body fat distribution (ie, waist-to-hip ratio [WHR]) on cardiovascular disease (CVD) risk factors in 50 nondiabetic, obese (body mass index [BMI], 31 +/- 2 kg/m2, mean +/- SD), 45 +/- 10-year-old women. The data obtained at baseline and after weight loss were analyzed after dividing subjects by WHR into upper-body (WHR > 0.80) and lower-body (WHR < or = 0.80) groups and by median-split BMI into more obese (BMI > or = 31) and less obese (BMI < 31) groups. At baseline, the upper-body obese women, when compared with lower-body obese women, had higher plasma triglycerides (TGs) (175 +/- 85 versus 111 +/- 47 mg/dL, respectively; P < .001) and lower high-density lipoprotein cholesterol (HDL-C) (44 +/- 10 versus 54 +/- 11, respectively; P < .01) but similar total and low-density lipoprotein cholesterol levels and blood pressure. There were no significant differences in these CVD risk factors at baseline by BMI split. Although weight loss (-9 +/- 5 kg) lowered blood pressure and TGs irrespective of WHR or BMI, only upper-body obese women raised HDL-C. Moreover, the magnitude of the changes was greatest in women with an upper-body fat distribution. In women with WHR > 0.80, HDL-C increased by 11%, to 49 mg/dL (P < .001), and TGs decreased by 24%, to 134 mg/dL (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin resistance and risk factors for coronary heart disease

In this presentation an effort has been made to review the impact of resistance to insulin-mediated glucose uptake and/or hyperinsulinaemia on various metabolic end-points and clinical syndromes. Insulin resistance is present in the great majority of patients with states of glucose intolerance, but frank decompensation of glucose homoeostasis does not occur if individuals can maintain a state of compensatory hyperinsulinaemia. Although compensatory hyperinsulinaemia may prevent the development of NIDDM in insulin-resistant individuals, there is substantial evidence that insulin resistance and/or hyperinsulinaemia is associated with higher plasma concentrations of triglyceride, uric acid and plasminogen activator inhibitor 1 and with lower HDL cholesterol concentrations. Obesity, decreased physical activity and possibly cigarette smoking accentuate the degree of insulin resistance and its manifestations, and a genetic basis is also involved. Resistance to insulin-mediated glucose uptake and/or hyperinsulinaemia have been shown to be associated with high blood pressure, microvascular angina and CHD. Thus, resistance to insulin-mediated glucose uptake is a common phenomenon, which makes a major contribution to the aetiology and clinical course of common and serious diseases. Based on the above considerations, it is difficult to over-emphasize the health-related implication of a defect in insulin-mediated glucose uptake.

Low blood pressure and blood glucose levels in Alzheimer's disease. Evidence for a hypometabolic disorder?

OBJECTIVE

To test possible differences between patients with Alzheimer's disease (AD) and patients with other forms of dementia and the healthy population concerning body composition, blood pressure, metabolic data and leukoaraiosis (LA).

DESIGN

Retrospective study on data collected according to a predefined protocol.

SETTING

A geriatric, neuropsychiatric diagnostic unit.

SUBJECTS

Seventy-one consecutive patients with dementia.

MAIN OUTCOME MEASURES

Body mass index, blood pressure, metabolism and LA in AD compared to other dementia forms.

RESULTS

Mean blood pressure and fasting blood glucose levels were lower in patients with AD, 94 +/- 12 mmHg and 4.3 +/- 0.5 mmol l-1, compared to patients with unspecified dementia (NUD), 100 +/- 10 mmHg and 5.5 +/- 2.5 mmol l-1 (P < 0.05) and vascular dementia (VAD), 114 +/- 12 mmHg and 5.6 +/- 1.6 mmol l-1 (P < 0.001) and the age-matched healthy population. Body mass index, serum cholesterol and cortisol were similar in all groups of dementia patients whereas triglycerides were highest in the VAD group. No cases of diabetes or treatment for hypertension were found in the AD group while the prevalence was 21% and 36% for diabetes in the NUD and VAD groups and 8% in the population from the same region. There were 16% with antihypertensive treatment in dementia NUD, 50% in VAD, and 30% in the general population. Treated or newly detected hypothyreosis was present in 11% of the AD patients, none in the other dementia groups and 2% in the general population. Smoking was least common in AD. Degree of LA correlated with blood pressure and blood glucose levels.

CONCLUSIONS

AD was clearly different to other dementia patients. They had lower blood pressure, blood glucose and higher prevalence of hypothyreosis than the healthy, age-matched population. These findings may indicate that AD could be a hypometabolic disorder.

Benefit from hypocaloric diet in obese men depends on the extent of weight-loss regarding cholesterol, and on a simultaneous change in body fat distribution regarding insulin sensitivity and glucose tolerance

Obesity and an android body fat distribution are related to metabolic disorders. We investigated the interdependences between metabolism, overweight, and body fat distribution in 40 moderately obese men before and after weight-loss. Correlations between metabolic parameters and body mass index (BMI) or waist to hip ratio (WHR) were much weaker in this exclusively obese population than in subjects of all weight categories, but the association between BMI and glucose tolerance (r = -.46, P less than .01) increased significantly after weight-loss. The improvement of metabolic parameters was much stronger in men who achieved normal weight (BMI less than 27 kg/m2) than in those who remained obese (BMI greater than 30 kg/m2, P less than .05). The WHR decreased during the diet (P less than .001), and this decrease and the extent of weight-loss were significantly correlated to an increase in insulin sensitivity (r = -.41, P less than .01) and a decrease in glucose area after an oral glucose load (r = .34, P less than .05). The decrease in apolipoprotein B, total cholesterol, and low-density lipoprotein (LDL) cholesterol was significantly correlated only to the extent of weight-loss (r = .34, .31, and .39, respectively; P less than .05). We conclude that it is best to reach normal weight for the normalization of metabolic aberrations. The reduction of cholesterol appears to be dependent on the extent of weight-loss, while the improvement in insulin sensitivity and glucose tolerance apparently is related to both the extent of weight-loss and to a change toward a less android body fat distribution.

The effects of gender and age on associations between blood lipid levels and obesity in Danish men and women aged 35-65 years

The purpose of the study was to assess the influence of gender and age on the associations between different measures of obesity, and blood lipid levels. Overall obesity (body fat, body fat percentage and body mass index) or abdominal obesity (waist/hip-ratio, waist/thigh-ratio and waist-circumference) and lipid levels [high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), total cholesterol and triglyceride level] were measured in 1987/88 in a random Danish population sample of men and women (N = 2987), aged 35, 45, 55 and 65 yr. All lipid levels were dependent on gender and age. The associations between most measures of obesity and HDL or LDL were independent of gender and age, whereas, with a few exceptions, associations between measures of obesity and total cholesterol, VLDL or triglycerides were dependent on gender and/or age. Compared to levels of HDL, LDL and total cholesterol, abdominal obesity specifically affected levels of VLDL or triglycerides, whereas overall obesity affected HDL, LDL, VLDL, total cholesterol and triglyceride levels more evenly. When men and women were compared, associations between the measures of obesity and blood lipids were stronger in men than in women of the same age, except for the associations between measures of abdominal obesity and VLDL or triglycerides in 45-year-old women. No age trend was found for associations between the measures of obesity and VLDL or triglycerides, whereas young age-groups showed stronger associations between obesity and total cholesterol than older age-groups. Failure to consider age/gender effects induces bias and may lead to misleading conclusions regarding the bivariate association between obesity and lipids, and further may make results from population studies incomparable.

Glycerol production in subcutaneous adipose tissue in lean and obese humans

To estimate the regional subcutaneous glycerol production rate in normal and obese humans, the venous arterialized plasma glycerol, interstitial glycerol in the subcutaneous adipose tissue together with adipose tissue blood flow (ATBF, ml/100 g.min) were measured in the postabsorptive state and for 2 h after ingestion of 100 g of oral glucose. Eight lean and eight obese men with normal oral glucose tolerance tests were investigated with the subcutaneous microdialysis technique and 133Xe clearance. In the postabsorptive state, the interstitial glycerol concentrations in lean and obese subjects were 170 +/- 21 vs. 282 +/- 28 microM (P less than 0.01) and 156 +/- 23 vs. 225 +/- 12 microM (P less than 0.05) in the abdominal and femoral subcutaneous adipose tissue, respectively. The corresponding arterial glycerol levels were 54 +/- 4 vs. 75 +/- 14 microM (NS). Abdominal ATBF was greater in lean subjects (3.2 +/- 0.6 vs. 1.6 +/- 0.3; P less than 0.05), whereas femoral ATBF was similar in both groups (2.7 +/- 0.4 vs. 2.4 +/- 0.7). Estimated mean local glycerol release (mumol/100 g.min) was similar in the lean and obese group (0.16 +/- 0.03 vs. 0.20 +/- 0.05 and 0.18 +/- 0.02 vs. 0.17 +/- 0.04) in the abdominal and femoral site, respectively. We conclude that glycerol production from the subcutaneous tissue is increased in obesity, irrespective of adipose tissue distribution. This enhancement is due to the increased adipose tissue mass.

Insulin resistance, hyperinsulinemia, and cardiovascular disease. The need for novel dietary prevention strategies

Insulin resistance associated with hyperinsulinemia (metabolic syndrome) emerged in recent years as an important health risk which is present in approximately 25% of the normal population in western industrialized societies. Insulin resistance as assessed for the whole body arises from a reduced glucose utilization of skeletal muscle. If the metabolic syndrome persists over a prolonged period of time, detrimental influences on the cardiovascular system become apparent involving diabetes mellitus, hypertension, and arteriosclerosis. Of particular pathogenic relevance is an unbalanced influence of insulin arising either from a diminished or enhanced insulin action depending on whether the various tissues of the body exhibit a reduced or unchanged insulin sensitivity. Since insulin resistance and hyperinsulinemia appear to be affected by various lifestyle factors, the unique opportunity exists of reducing cardiovascular mortality by correcting this syndrome at a time when degenerative changes have not occurred in the cardiovascular system. Of great importance is the finding that dietary factors can have a modulatory action on insulin sensitivity. In animal experiments, an increased intake of (saturated) fat and refined carbohydrates increased insulin resistance. Since psychosocial distress is expected to be associated with a sustained activation of the sympathoadrenal axis, it is likely also to aggravate the metabolic syndrome. A factor with a beneficial action appears to be physical exercise. In view of the high incidence of cardiovascular diseases, further research on lifestyle factors with an insulin-sensitizing or insulin-desensitizing action is required. Of prime importance is the reevaluation of established dietary recommendations and diets should be designed which take into account the individual cardiovascular risk factor profile.

Epidemiologic and clinical aspects of insulin resistance and hyperinsulinemia

Epidemiologic studies have shown that insulin is a risk factor for coronary heart disease (CHD). Clinical studies have also demonstrated positive correlations between insulin and blood pressure, triglycerides, total cholesterol, fibrinogen, and plasminogen activator inhibitor. Moreover, there is an inverse correlation between insulin and high-density lipoprotein (HDL). These studies have provided evidence in support of the biologic plausibility of epidemiologic observations, but they have not clearly established insulin's role in the pathogenesis of human cardiovascular diseases (CVD) such as hypertension. In fact, there is considerable evidence that insulin resistance (abnormal nonoxidative glucose disposal), not hyperinsulinemia, is the primary insulin-related abnormality in human hypertension, and that hyperinsulinemia occurs as a response to insulin resistance. Skeletal muscle appears to be the primary site of insulin resistance in essential hypertension, although other organs, such as the kidneys and liver--key sites for cell and water homeostasis and lipoprotein regulation, respectively--may respond normally to insulin. Adipocytes also appear to be a site of insulin resistance. Thus, the putative interrelationship between hyperinsulinemia and insulin resistance, on the one hand, and with blood pressure and lipoproteins, on the other, is a complex one and may involve organ-specific insulin resistance. Altered cation transport is one of several mechanisms by which insulin resistance might raise blood pressure. The Na+, K(+)-ATPase and Ca(2+)-ATPase pumps are insulin sensitive. Thus, when insulin resistance is present, the activity of these pumps in the smooth muscle of the arterial wall might be reduced. This would lead to an intracellular accumulation of sodium and calcium, thereby sensitizing the vascular wall to pressor substances. Moreover, secondary hyperinsulinemia will occur, and insulin has been shown to stimulate sympathetic nervous system activity and to increase renal tubular absorption of sodium. Insulin is also a growth factor and therefore might have a trophic effect on the vessel wall, one that could initiate and/or sustain hypertension as well as atherosclerosis. Abnormal lipoprotein metabolism is yet another possible explanation for the accelerated atherosclerosis that has been observed in persons with abnormal carbohydrate tolerance and insulin resistance. Hyperinsulinemia and insulin resistance both play a role in the expression of elevated very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) levels as well as in the depression of HDL levels. Coronary risk reduction has been disappointing when blood pressure has been lowered with treatment regimens based on thiazide diuretics and/or beta blockers. Thiazides and some beta blockers may further impair tissue insulin sensitivity and often cause blood lipoprotein abnormalities.(ABSTRACT TRUNCATED AT 400 WORDS)

Asymptomatic hyperglycemia and cardiovascular risk factors in the elderly

We studied the levels of cardiovascular risk factors in a population sample of 511 men and 920 women aged 65-74 years and living in East Finland. Altogether 312 men and 515 women had normal glucose tolerance, 84 men and 158 women impaired glucose tolerance (IGT), 33 men and 59 women newly diagnosed non-insulin-dependent diabetes (NIDDM) detected at the survey, and 82 men and 188 women previously diagnosed NIDDM. Subjects with IGT or newly diagnosed NIDDM had higher levels of total triglycerides and apolipoprotein B and lower levels of HDL cholesterol and apolipoprotein A1 than subjects with normal glucose tolerance, similarly as in previously diagnosed NIDDM. Furthermore, subjects with IGT or newly diagnosed NIDDM were more obese, had higher waist-hip ratio, and more frequently hypertension than subjects with normal glucose tolerance. Thus, asymptomatic hyperglycemia in the elderly is not a benign phenomenon, but is associated with similar adverse changes in cardiovascular risk factors as in middle-aged subjects.

Central adipose distribution is related to coronary atherosclerosis

A "male" distribution of adipose tissue in women (excess of fat in the abdomen compared with that in the hips; i.e., elevated waist/hip ratio) has been related to symptomatic cardiovascular disease. An elevated waist/hip ratio has also been related to symptomatic cardiovascular and cerebrovascular diseases in men, as well as to risk factors for these diseases and various metabolic conditions. To determine whether adipose distribution was related to coronary atherosclerosis, we performed a case-control study in patients with angiographically documented coronary atherosclerosis (cases) and in angiographically normal hospital and neighborhood controls. The data show that distribution of adiposity as assessed by waist/hip ratio is significantly related to coronary atherosclerosis in both females and males. Waist/hip ratio is significantly greater in female cases compared with either control group; in males, waist/hip ratio is significantly greater in cases compared with asymptomatic neighborhood controls but not compared with patients with normal coronary arteries. These results persist after control for age, plasma concentrations of lipids and lipoproteins, body mass index, history of hypertension, history of diabetes, and smoking status. The connection between the male adipose distribution in females and coronary atherosclerosis partly explains the greater likelihood of symptomatic cardiovascular disease in them. Males with excess deposition of fat in the abdominal region are also likely to experience increased risk.

Close correlation of intra-abdominal fat accumulation to hypertension in obese women

The relation between intra-abdominal visceral fat accumulation and blood pressure was investigated in 67 obese women (mean body mass index, 33.6 +/- 3.1; average age, 50 +/- 11 years). As an index of intra-abdominal fat accumulation, the ratio of the intra-abdominal visceral fat area to subcutaneous fat area was determined using a computed tomographic section at the level of the umbilicus. When the obese subjects were divided into a hypertensive group and a normotensive group, the ratio of the intra-abdominal visceral fat area to subcutaneous fat area in the hypertensive group was significantly higher (0.53 +/- 0.33 versus 0.29 +/- 0.12, p less than 0.01). Significant correlations between the ratio of intra-abdominal visceral fat area to subcutaneous fat area and systolic blood pressure (r = 0.62, p less than 0.001) and diastolic blood pressure (r = 0.53, p less than 0.001) also were found. However, no significant difference existed in either the body mass index or the waist-to-hip circumference ratio between the hypertensive and normotensive groups. Plasma renin activity, aldosterone, epinephrine, and norepinephrine levels were not significantly different between the two groups. Moreover, the correlation between the ratio of the intra-abdominal visceral fat area to subcutaneous fat area ratio and blood pressure was found independent of age and body mass index by multiple regression analyses. We conclude that intra-abdominal fat accumulation itself may play an important role in the pathogenesis of hypertension in obesity.