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PubMed2006

Adiponectin and insulin resistance in young and healthy smokers.

Smoking is closely associated with insulin resistance, though the mechanism is not clear. Adiponectin, a novel anti-atherosclerotic and anti-inflammatory adipose tissue product, which is closely associated with insulin resistance, was reported to be low in smokers with cofactors for atherosclerosis. However, the effects of smoking on circulating adiponectin levels in otherwise healthy people are unknown. In this study, a case control design was implemented to search for the effect of smoking on plasma adiponectin and insulin sensitivities in healthy people. Sixty-four healthy male smokers, with no family history of hypertension and diabetes mellitus were compared with appropriate 36 age and body mass index matched controls. Both the patients and controls were the soldiers of a troop with regular daily physical activity. Plasma adiponectin, high sensitive C-reactive protein (hsCRP), insulin and lipid levels, and insulin sensitivity as assessed by homeostasis model assessment index (HOMA) of the smokers were measured and compared with those of the controls. The plasma adiponectin, hsCRP, insulin levels and HOMA indexes of the two groups were similar. These parameters were not affected by the amount of cigarettes per day. HDL-cholesterol levels were lower (p = 0.01) and systolic blood pressures were higher (p = 0.02) in the smokers. These results indicate that smoking may not affect plasma adiponectin and insulin levels in young and healthy men with high exercise capacity.

Adiponectin↗

PubMed2006

Associations between two single nucleotide polymorphisms of adiponectin gene and coronary artery diseases.

Adiponectin, an adipocyte-secreted protein, is known to have anti-atherogenic, anti-inflammatory and anti-diabetic properties and its serum levels are decreased in obesity, type 2 diabetes, and coronary artery disease. Several studies have been performed to investigate the association of genetic variations in the adiponectin with obesity, insulin resistance, and type 2 diabetes, but few studies were performed in association with coronary artery disease. Therefore we examined the associations between two single nucleotide polymorphisms (SNPs), +45T>G and +276G>T of the adiponectin gene, and coronary artery diseases (CAD). One hundred and fifty six subjects (mean age 57.4 yrs) were enrolled in which coronary angiograms were performed due to chest pain. Genotypings were done for two SNPs in the adiponectin gene by Taqman polymerase chain reaction (PCR) method. The presence of CAD was defined as a >50% reduction of coronary artery diameter. Among 156 subjects, the allele frequencies were 0.683 for G allele and 0.317 for T allele in SNP +276G>T and 0.705 for T allele and 0.295 for G allele in SNP +45T>G. Both genotypes were in compliance with Hardy-Weinberg equilibrium. No association with the presence of CAD was observed for adiponectin gene SNP276 and SNP45 (p = 0.954, p = 0.843). Also, no significant association was observed between the severity of CAD and either SNPs (p = 0.571, p = 0.955). Our study showed that SNP +276G>T and +45T>G in adiponectin gene were not associated with the presence of CAD. Further studies will be necessary to confirm the role of SNP 276G>T and 45T>G in the development of CAD.

Adiponectin↗

PubMed2005

Adiponectin: a key fat-derived molecule regulating inflammation.

Adiponectin is the abundant adipocyte-derived protein with well-established anti-atherogenic and insulin-sensitising properties. Besides these well characterised biological functions, recent evidence supports a strong anti-inflammatory function. Whereas initial studies demonstrated that adiponectin suppresses the production of the potent pro-inflammatory cytokine TNF-alpha, current studies showed that this adipokine also induces various anti-inflammatory cytokines, such as IL-10 or -1 receptor antagonists. These effects are paralleled by various other immune-regulatory properties, such as specific effects on endothelial cell functions. These in vitro effects are directly translated into various animal models of inflammation, demonstrating a potent anti-inflammatory effect for adiponectin. Thiazolidinediones selectively upregulate peroxisome-proliferator-activated receptor-gamma, leading to increased tissue and serum concentrations of adiponectin. Adiponectin has emerged as a key mediator regulating and affecting the balance between fat and inflammation. Therefore, either adiponectin itself or its inducing agents, such as thiazolidinediones, might be of key therapeutic interest in the near future far beyond diseases being associated with insulin resistance.

Adipocytes↗

PubMed2005

Relationship between serum adiponectin concentration, pulse wave velocity and nonalcoholic fatty liver disease.

OBJECTIVES: We aimed to investigate the relationship between nonalcoholic fatty liver disease (NAFLD), serum adiponectin concentration and brachial-ankle pulse wave velocity (baPWV) as a risk marker for atherosclerosis. METHODS: A total of 213 nonalcoholic subjects (67 males, 146 females) participated in this study. Division of subjects into the NAFLD group or the normal group was based on the existence of fatty liver detected by sonography. RESULTS: Serum adiponectin levels in the NAFLD group were significantly lower than those in the normal group. After adjusting for age, body-mass index (BMI) and the homeostasis model of assessment (HOMA), there was a significant negative correlation between NAFLD and serum adiponectin level only in females (r = -0.22, P = 0.008). Multiple logistic regression analysis showed a tendency of inverse correlation between NAFLD and serum adiponectin level in females (P = 0.055). After adjustment for age, BMI and HOMA value, serum adiponectin levels were inversely correlated with serum alanine aminotransferase (ALT) and gamma-glutamyltranspeptidase (GGT) levels (r = -0.199 (P = 0.004) and r = -0.282 (P < 0.001)). On the other hand, baPWV in the NAFLD group was also significantly higher than that in the normal group in females (P = 0.005). Individual levels of serum ALT, aspatate aminotransferase (AST), alkaline phosphatase (ALP) and GGT were positively correlated with baPWV after adjusting for age, sex, BMI, HOMA and systolic blood pressure (P < 0.05). CONCLUSION: Serum adiponectin level and baPWV were significantly associated with NAFLD and various liver enzymes, especially in females.

Adiponectin↗

PubMed2006

Plasma adiponectin concentration and tumor necrosis factor-alpha system activity in lean non-diabetic offspring of type 2 diabetic subjects.

OBJECTIVE: There is growing evidence that adiponectin function is related to the pathogenesis of insulin resistance. Insulin resistance might be present even in lean subjects with a strong family history of type 2 diabetes. The aim of the study was to look for adiponectin's role in the pathogenesis of insulin resistance in offspring of type 2 diabetic patients, and its relation to the activity of the tumor necrosis factor (TNF)-alpha system. RESEARCH DESIGN AND METHODS: The study was carried out in 23 lean offspring of type 2 diabetic subjects and in 23 controls matched for age, sex and body mass index. The oral glucose tolerance test for glucose and insulin estimations and hyperinsulinemic, euglycemic clamp studies were performed in all patients. The plasma concentration of adiponectin, TNF-alpha, soluble TNF receptors 1 and 2 (sTNFR1, sTNFR2), HbA1c, total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein-cholesterol and triglycerides were estimated. RESULTS: The insulin sensitivity index, normalized for fat-free mass (M(ffm)) and adiponectin concentrations were markedly decreased in offspring of type 2 diabetic subjects compared with the control group (P = 0.0046 and P = 0.00058 respectively). TNF-alpha and sTNFR1 concentrations did not differ between the studied groups; however the concentration of sTNFR2 was markedly increased in the offspring of type 2 diabetic patients (P = 0.0002). Adiponectin concentration was positively correlated to the insulin sensitivity index (r = 0.34; P = 0.020) and to HDL-cholesterol (r = 0.29, P = 0.047) and was inversely related to sTNFR2 (r = -0.33, P = 0.027). CONCLUSIONS: The obtained results suggest that adiponectin could play a role in the pathogenesis of insulin resistance in lean offspring of type 2 diabetic subjects.

Adiponectin↗

PubMed2005

Renal insulin resistance syndrome, adiponectin and cardiovascular events in patients with kidney disease: the mild and moderate kidney disease study.

The relationship among insulin resistance, adiponectin, and cardiovascular (CV) morbidity in patients with mild and moderate kidney disease was investigated. Insulin sensitivity (Homeostasis Model Assessment of Insulin Resistance [HOMA-IR]) and adiponectin plasma levels were assessed in 227 nondiabetic renal patients at different degrees of renal dysfunction and in 76 healthy subjects of similar age and gender distribution and body mass index. In renal patients, association with prevalent CV events was evaluated, and incident CV events were evaluated in a prospective study. HOMA-IR was markedly higher in patients than in healthy subjects (3.59 +/- 3.55 versus 1.39 +/- 0.51; P < 0.01). In renal patients, HOMA-IR was significantly correlated with body mass index (r = 0.477; P < 0.01), triglycerides (r = 0.384; P < 0.01), adiponectin plasma levels (r = -0.253; P < 0.01), and age (r = 0.164; P < 0.05), but not with renal function (GFR by iod-thalamate clearance). Patients with previous CV events were significantly older, had higher HOMA-IR and serum triglycerides, and had lower adiponectin plasma levels (all P < 0.05). Logistic regression analysis revealed age (P < 0.001) and adiponectin (P < 0.002) as independent variables related to prevalent CV events. In the prospective study, median follow-up was 54 mo. Patients who experienced CV events had significantly higher serum glucose and lower adiponectin plasma levels (both P < 0.05). In patients with chronic kidney diseases, a syndrome of insulin resistance is present even in the earliest stage of renal dysfunction, and several components of this syndrome are associated with CV events. Moreover, hypoadiponectinemia is a novel putative CV risk factor in patients with mild and moderate renal failure.

Adiponectin↗

PubMed2003

Antimicrobial periodontal treatment decreases serum C-reactive protein, tumor necrosis factor-alpha, but not adiponectin levels in patients with chronic periodontitis.

BACKGROUND: Elevated levels of C-reactive protein (CRP) and decreased plasma adiponectin are associated with increased risk of atherosclerosis. Furthermore, recent observations suggested that adiponectin and tumor necrosis factor-alpha (TNF-alpha) suppressed each other's production. Since periodontal disease has been suggested to act as a risk factor for atherosclerosis, we examined the effects of antimicrobial periodontal treatment on CRP, adiponectin, and TNF-alpha levels. METHODS: Fifteen chronic periodontitis patients with various systemic conditions at high risk for atherosclerosis were enrolled in the study. Patients were non-surgically treated with topical application of antibiotics and mechanical debridement of calculus once a week for 1 month. Before and after therapy, CRP, adiponectin, and TNF-alpha levels were measured. RESULTS: Both CRP and TNF-alpha levels were significantly decreased after treatment (P<0.01 and P<0.03, respectively), while adiponectin levels did not change significantly. CONCLUSIONS: Periodontal treatment is effective in reducing CRP and TNF-alpha, while adiponectin does not appear to be influenced by periodontal treatment. Elevated levels of CRP and TNF-alpha may be associated with increased risk for future development of atherosclerosis in periodontitis patients.

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PubMed2006

Adiponectin suppression of high-glucose-induced reactive oxygen species in vascular endothelial cells: evidence for involvement of a cAMP signaling pathway.

Adiponectin is an abundant adipocyte-derived plasma protein with antiatherosclerotic effects. Vascular signal transduction by adiponectin is poorly understood and may involve 5'-AMP-activated protein kinase (AMPK), cAMP signaling, and other pathways. Hyperglycemia sharply increases the production of reactive oxygen species (ROS), which play a key role in endothelial dysfunction in diabetes. Because the recombinant globular domain of human adiponectin (gAd) reduces the generation of endothelial ROS induced by oxidized LDL, we sought to determine whether adiponectin could also suppress ROS production induced by high glucose in cultured human umbilical vein endothelial cells. Incubation in 25 mmol/l glucose for 16 h increased ROS production 3.8-fold (P<0.05), using a luminol assay. Treatment with gAd for 16 h suppressed glucose-induced ROS in a dose-dependent manner up to 81% at 300 nmol/l (P<0.05). The AMPK activator 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR; 1 mmol/l, 16 h) only partially decreased glucose-induced ROS by 22% (P<0.05). Cell pretreatment with AMPK inhibitors, however, failed to block the effect of gAd to suppress glucose-induced ROS, suggesting that the action of gAd was independent of AMPK. Interestingly, activation of cAMP signaling by treatment with forskolin (2 micromol/l) or dibutyryl-cAMP (0.5 mmol/l) reduced glucose-induced ROS generation by 43 and 67%, respectively (both P<0.05). Incubation with the cAMP-dependent protein kinase (PKA) inhibitor H-89 (1 micromol/l) fully abrogated the effect of gAd, but not that of AICAR, on ROS induced by glucose. gAd also increased cellular cAMP content by 70% in an AMPK-independent manner. Full-length adiponectin purified from a eukaryotic expression system also suppressed ROS induced by high glucose or by treatment of endothelial cells with oxidized LDL. Thus, adiponectin suppresses excess ROS production under high-glucose conditions via a cAMP/PKA-dependent pathway, an effect that has implications for vascular protection in diabetes.

AMP-Activated Protein Kinases↗

PubMed2006

Adiponectin increases fatty acid oxidation in skeletal muscle cells by sequential activation of AMP-activated protein kinase, p38 mitogen-activated protein kinase, and peroxisome proliferator-activated receptor alpha.

Adiponectin has recently received a great deal of attention due to its beneficial effects on insulin resistance and metabolic disorders. One of the mechanisms through which adiponectin exerts such effects involves an increase in fatty acid oxidation in muscle and liver. In the present study, we demonstrate that 5'-AMP-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase (MAPK) are involved in the activation of peroxisome proliferator-activated receptor (PPAR)alpha by adiponectin in muscle cells. Adiponectin increases the transcriptional activity of PPARalpha and the expression of its target genes, including ACO, CPT1, and FABP3 in C2C12 myotubes. These effects were suppressed by the overexpression of a dominant-negative form of AMPK. Moreover, chemical inhibitors of AMPK and p38 MAPK potently repressed fatty acid oxidation and the induction of PPARalpha target gene expression by adiponectin. Interestingly, araA, an AMPK inhibitor, prevented the activation of p38 MAPK, whereas SB203580, a p38 MAPK inhibitor, did not affect AMPK activation, suggesting that p38 MAPK is a downstream signaling factor of AMPK. Taken together, these results suggest that adiponectin stimulates fatty acid oxidation in muscle cells by the sequential activation of AMPK, p38 MAPK, and PPARalpha.

AMP-Activated Protein Kinases↗

PubMed2006

Associations of adiponectin levels with incident impaired glucose metabolism and type 2 diabetes in older men and women: the hoorn study.

OBJECTIVE: Adiponectin is an adipose tissue-derived protein. Low levels are associated with obesity, insulin resistance, and type 2 diabetes. Our objective was to investigate the prospective association between adiponectin levels and the 6.4-year risk of type 2 diabetes and of impaired glucose metabolism (IGM). RESEARCH DESIGN AND METHODS: The Hoorn Study is a cohort study among Caucasians, aged 50-75 years. BMI, waist-to-hip ratio (WHR), fasting glucose, 2-h glucose, triglycerides, HDL cholesterol, LDL cholesterol, alanine aminotransferase, leptin, and adiponectin were measured at baseline. Lifestyle (alcohol intake, smoking, and physical activity) was assessed by questionnaires. After a mean follow-up of 6.4 years, glucose tolerance was assessed by a 75-g oral glucose tolerance test. Analyses were performed in 1,264 subjects (584 men and 680 women) without type 2 diabetes at baseline. For analyses of incident IGM, 239 subjects with IGM at baseline and/or type 2 diabetes at follow-up were excluded. RESULTS: Age- and lifestyle-adjusted odds ratios and 95% CIs comparing highest with lowest adiponectin quartile were 0.52 (0.23-1.18) in men and 0.15 (0.06-0.39) in women for type 2 diabetes and 0.90 (0.51-1.61) and 0.28 (0.16-0.48) for IGM, respectively. The risks were only slightly reduced after adjustment for WHR and leptin as markers of (abdominal) adiposity. Adjustment for baseline fasting and postload glucose levels (potential mediators) substantially diminished these inverse associations with type 2 diabetes (0.79 [0.32-1.91] and 0.62 [0.21-1.81]) and with IGM (1.20 [0.61-2.35] and 0.48 [0.26-0.90]), respectively. CONCLUSIONS: A high adiponectin level was strongly associated with a lower risk of IGM and type 2 diabetes, particularly in women. These results suggest that adiponectin is involved in the pathophysiology linking obesity to type 2 diabetes.

Adiponectin↗

PubMed2002

Genetic variation in the gene encoding adiponectin is associated with an increased risk of type 2 diabetes in the Japanese population.

An adipocyte-derived peptide, adiponectin (also known as GBP28), is decreased in subjects with type 2 diabetes. Recent genome-wide scans have mapped a diabetes susceptibility locus to chromosome 3q27, where the adiponectin gene (APM1) is located. Herein, we present evidence of an association between frequent single nucleotide polymorphisms at positions 45 and 276 in the adiponectin gene and type 2 diabetes (P = 0.003 and P = 0.002, respectively). Subjects with the G/G genotype at position 45 or the G/G genotype at position 276 had a significantly increased risk of type 2 diabetes (odds ratio 1.70 [95% CI 1.09-2.65] and 2.16 [1.22-3.95], respectively) compared with those having the T/T genotype at positions 45 and 276, respectively. In addition, the subjects with the G/G genotype at position 276 had a higher insulin resistance index than those with the T/T genotype (1.61 +/- 0.05 vs. 1.19 +/- 0.12, P = 0.001). The G allele at position 276 was linearly associated with lower plasma adiponectin levels (G/G: 10.4 +/- 0.85 microg/ml, G/T: 13.7 +/- 0.87 microg/ml, T/T: 16.6 +/- 2.24 microg/ml, P = 0.01) in subjects with higher BMIs. Based on these findings together with the observation that adiponectin improves insulin sensitivity in animal models, we conclude that the adiponectin gene may be a susceptibility gene for type 2 diabetes.

Adiponectin↗

PubMed2002

Association of adiponectin mutation with type 2 diabetes: a candidate gene for the insulin resistance syndrome.

Adiponectin, also referred to as AdipoQ or ACRP30, is a plasma protein produced and secreted exclusively from adipose tissue. The protein contains a collagen-like domain and a C1q-like globular domain. A protease-generated globular segment enhances fatty acid oxidation in muscles, thereby modulating lipid and glucose metabolism. Plasma adiponectin levels are inversely correlated with the severity of insulin resistance. A recent genome-wide scan study mapped a susceptibility locus for type 2 diabetes and the metabolic syndrome to chromosome 3q27, where the adiponectin gene is located. Here, we screened Japanese patients with type 2 diabetes and age- and BMI-matched nondiabetic control subjects for mutations in adiponectin gene. We identified four missense mutations (R112C, I164T, R221S, and H241P) in the globular domain. Among these mutations, the frequency of I164T mutation was significantly higher in type 2 diabetic patients than in age- and BMI- matched control subjects (P < 0.01). Furthermore, plasma adiponectin concentrations of subjects carrying I164T mutation were lower than those of subjects without the mutation. All the subjects carrying I164T mutation showed some feature of metabolic syndrome, including hypertension, hyperlipidemia, diabetes, and atherosclerosis. Our findings suggest that I164T mutation is associated with low plasma adiponectin concentration and type 2 diabetes.

Adiponectin↗

PubMed2004

Discrimination between obesity and insulin resistance in the relationship with adiponectin.

Insulin resistance and obesity are both associated with lower plasma adiponectin concentrations. Since insulin resistance and obesity are related, the extent to which the association of adiponectin with insulin resistance is dependent on its relationship with obesity is unclear. To address this issue, fasting plasma adiponectin concentrations were measured in 60 nondiabetic subjects, stratified into four equal groups on the basis of both their degree of adiposity and insulin resistance. Insulin resistance was quantified by determining the steady-state plasma glucose (SSPG) concentration in response to an infusion of octreotide, glucose, and insulin, and degree of adiposity was assessed by BMI. Subjects were defined as obese (BMI >/=30.0 kg/m(2)) or nonobese (<27.0 kg/m(2)) and as either insulin sensitive (SSPG <100 mg/dl) or insulin resistant (>190 mg/dl). Insulin-resistant subjects had significantly (P<0.001) lower (mean +/- SD) adiponectin concentrations, whether they were obese (17.1 +/- 5.9 micro g/ml) or nonobese (16.3 +/- 7.5 micro g/ml) as compared with either obese, insulin-sensitive (34.3 +/- 13.1 micro g/ml) or nonobese, insulin-sensitive (29.8 +/- 15.3 micro g/ml) subjects. Finally, adiponectin levels in insulin-sensitive subjects varied to a significantly greater degree than in insulin-resistant subjects. These results suggest that adiponectin concentrations are more closely related to differences in insulin-mediated glucose disposal than obesity.

Adiponectin↗

PubMed2004

Restoration of adiponectin pulsatility in severely obese subjects after weight loss.

Diurnal variations of adiponectin levels have been studied in normal-weight men and in diabetic and nondiabetic obese subjects, but no data have been reported in obese subjects after weight loss. We collected blood samples at 1-h intervals over 24 h from seven severely obese subjects before and after massive weight loss consequent to surgical operation (bilio-pancreatic diversion [BPD]) to measure adiponectin, insulin, glucose, and cortisol levels. Insulin sensitivity was assessed by euglycemic-hyperinsulinemic clamp (M value). Studies of diurnal variations and pulsatility of adiponectin, insulin, and cortisol were performed. The pulsatility index (PI) of adiponectin increased after BPD from 0.04 to 0.11 microg/min (P = 0.01). Insulin PI significantly increased after the operation (1.50 vs. 1.08 pmol.l(-1).min(-1), P = 0.01), while cortisol PI did not significantly change. The adiponectin clearance rate changed from 0.001 +/- 10(-4).min(-1) before BPD to 0.004 +/- 8. 10(-4).min(-1) after BPD (P = 0.03). Insulin clearance increased from 0.006 +/- 6. 10(-4).min(-1) before BPD to 0.009 +/- 4.10(-4). min(-1) after BPD (P = 0.02). The M value doubled after surgery (27.08 +/- 8.5 vs. 53.34 +/- 9.3 micromol.kg(FFM)(-1).min(-1); P < 0.001) becoming similar to the values currently reported for normal-weight subjects. In conclusion, in formerly severely obese subjects, weight loss paired with the reversibility of insulin resistance restores homeostatic control of the adiponectin secretion, contributing to the reduction of cardiovascular risk already described in these patients.

Adiponectin↗

PubMed2005

Adipocytokines and VLDL metabolism: independent regulatory effects of adiponectin, insulin resistance, and fat compartments on VLDL apolipoprotein B-100 kinetics?

We investigated the relationship of plasma adipocytokine concentrations with VLDL apolipoprotein B (apoB)-100 kinetics in men. Plasma adiponectin, leptin, resistin, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) concentrations were measured using enzyme immunoassays and insulin resistance by homeostasis model assessment (HOMA) score in 41 men with BMI of 22-35 kg/m(2). VLDL apoB kinetics were determined using an intravenous infusion of 1-[(13)C]leucine, gas chromatography-mass spectrometry, and compartmental modeling. Visceral and subcutaneous adipose tissue mass (ATM) were determined using magnetic resonance imaging, and total ATM was measured by bioelectrical impedance. In univariate regression, plasma adiponectin and leptin concentrations were inversely and directly associated, respectively, with plasma triglyceride; HOMA score; and visceral, subcutaneous, and total ATMs. Conversely, adiponectin and leptin were directly and inversely correlated, respectively, with VLDL apoB catabolism and HDL cholesterol concentration (P < 0.05). Resistin, IL-6, and TNF-alpha were not significantly associated with any of these variables. In multivariate regression, adiponectin was the most significant predictor of plasma VLDL apoB concentration (P = 0.001) and, together with total or subcutaneous ATM, was an independent predictor of VLDL apoB catabolism (P < 0.001); HOMA score was the most significant predictor of VLDL apoB hepatic secretion (P < 0.05). Leptin was not an independent predictor of VLDL apoB kinetics. In conclusion, plasma VLDL apoB kinetics may be differentially controlled by adiponectin and insulin resistance, with adiponectin regulating catabolism and insulin resistance regulating hepatic secretion in men. Total body fat may also independently determine the rate of VLDL catabolism, but leptin, resistin, IL-6, and TNF-alpha do not have a significant effect in regulating apoB kinetics.

Adiponectin↗

PubMed2002

Young men with high-normal blood pressure have lower serum adiponectin, smaller LDL size, and higher elevated heart rate than those with optimal blood pressure.

OBJECTIVE: Three measures--heart rate, a global index of the influence of the autonomic nervous system on the heart; circulating concentrations of adiponectin, an adipose-specific protein; and C-reactive protein (CRP), a sensitive marker of inflammation--have been reported to be closely associated with insulin resistance. Patients with borderline hypertension are known to be more insulin resistant and dyslipidemic than those with normal blood pressure (BP). BP can be classified into three categories: optimal, normal, and high-normal. The present study examined whether those with high-normal BP have any of these three conditions as compared with those with optimal BP in young healthy men. RESEARCH DESIGN AND METHODS: Anthropometric, blood pressure, heart rate, and blood tests, including tests for adiponectin and CRP, were conducted in 198 male students, ages 18-26 years, who had fasted overnight. Insulin resistance (IR) and insulin secretion (beta-cell levels) were calculated using the homeostasis model assessment (HOMA), and LDL size was measured by PAGE. RESULTS: Compared with the 90 men who had optimal BP, the 46 men with high-normal BP had increased heart rate, BMI, percent body fat, and serum leptin levels. In addition, they had greater serum insulin, HOMA IR, and beta-cell levels, lower adiponectin levels, and comparable CRP levels. Furthermore, the 46 men with high-normal BP had higher serum triglyceride and apolipoprotein (apo) B levels, and smaller LDL size; however, there was no difference in LDL and HDL cholesterol and apoA-I between men with optimal and high-normal BP. After adjusting for BMI, differences were still significant in serum adiponectin, heart rate, and LDL particle size. As BP rose, there was an increase in heart rate (BMI-adjusted least square means were 63, 65, and 70 bpm in men with optimal, normal, and high-normal BP, respectively; P = 0.005), whereas serum adiponectin (7.5, 6.6, and 6.4 mg/l; P = 0.007) and LDL particle size (271, 269, and 269 A; P = 0.008) decreased. CONCLUSIONS: Young men with high-normal BP have a faster heart rate, lower serum adiponectin levels, and smaller LDL size than men with optimal BP, even after adjustment for BMI. These results suggest the necessity of preventing further development of cardiac and metabolic diseases in young people who have high-normal BP.

Adiponectin↗

PubMed2003

Plasma adiponectin and endogenous glucose production in humans.

OBJECTIVE: High plasma adiponectin is associated with reduced risk of type 2 diabetes, probably a consequence of its insulin-sensitizing properties. In vivo data in rodents suggest that the insulin-sensitization responsible for improvement of glycemia occurs in muscle and liver. Whereas associations of plasma adiponectin with muscle insulin sensitivity in humans have been examined, this has not been done for the liver. RESEARCH DESIGN AND METHODS: We therefore analyzed the relationship between fasting plasma adiponectin and basal endogenous glucose production [EGP]-basal) and insulin-suppressed EGP (EGP-insulin, isotope dilution technique) in 143 Pima Indians (94 with normal glucose tolerance, 36 with impaired glucose tolerance, and 16 with type 2 diabetes). RESULTS: Fasting plasma adiponectin concentrations were negatively correlated with EGP-basal and EGP-insulin before (P = 0.006 and P < 0.0001, respectively) as well as after adjustment for age, sex, percent body fat, and insulin-stimulated whole-body glucose uptake (P = 0.007 and P = 0.0005, respectively). CONCLUSIONS: These findings are compatible with the hypothesis that adiponectin increases hepatic insulin sensitivity. Consistent with data in animals, adiponectin may have generalized insulin-sensitizing effects in humans.

Adiponectin↗

PubMed2004

Plasma adiponectin, insulin sensitivity, and subclinical inflammation in women with prior gestational diabetes mellitus.

OBJECTIVE: Women with prior gestational diabetes mellitus (pGDM) are at increased risk of developing type 2 diabetes and associated vasculopathy. Because increased fat mass and inflammatory processes are angiopathic risk factors, the relationship between insulin sensitivity, parameters of subclinical inflammation, and plasma concentrations of adipocytokines was investigated in pGDM both at 3 months and 12 months after delivery. RESEARCH DESIGN AND METHODS: Insulin sensitivity (through a frequently sampled intravenous glucose tolerance test) and plasma concentrations of ultrasensitive C-reactive protein (CRP), adiponectin, plasminogen activator inhibitor (PAI)-1, tumor necrosis factor-alpha, leptin, and interleukin-6 were measured in 89 pGDM (BMI 26.9 +/- 0.5 kg/m(2), age 32 +/- 0.5 years) and in 19 women with normal glucose tolerance during pregnancy (NGT) (23.7 +/- 0.9 kg/m(2), 31 +/- 1.3 years). RESULTS: pGDM showed lower (P < 0.0001) plasma adiponectin (6.7 +/- 0.2 microg/ml) than NGT (9.8 +/- 0.6 microg/ml) and a decreased (P < 0.003) insulin sensitivity index (S(i)) and disposition index (P < 0.03), but increased plasma leptin (P < 0.003), PAI-1 (P < 0.002), and CRP (P < 0.03). After adjustment for body fat mass, plasma adiponectin remained lower in pGDM (P < 0.004) and correlated positively with S(i) (P < 0.003) and HDL cholesterol (P < 0.0001) but negatively with plasma glucose (2-h oral glucose tolerance test [OGTT]) (P < 0.0001), leptin (P < 0.01), CRP (P < 0.007), and PAI-1 (P < 0.0001). On regression analysis, only HDL cholesterol, postload (2-h OGTT) plasma glucose, and S(i) remained significant predictors of plasma adiponectin, explaining 42% of its variability. Of note, adiponectin further decreased (P < 0.05) only in insulin-resistant pGDM despite unchanged body fat content and distribution after a 1-year follow-up. CONCLUSIONS: Lower plasma adiponectin concentrations characterize women with previous GDM independently of the prevailing insulin sensitivity or the degree of obesity and are associated with subclinical inflammation and atherogenic parameters.

Adiponectin↗