Adiponectin is Associated with Impaired Fasting Glucose in the Non-Diabetic Population

Determination of risk factors associated with inflammation in hypertensive patients with type-2 diabetes mellitus in a Palestinian Diabetes Study

OBJECTIVE

To determine the risk factors associated with inflammation in hypertensive patients with type-2 diabetes mellitus.

METHODS

A total of 164 hypertensive patients with type 2 diabetes patients aged 38-60 years were selected from 7 primary healthcare centers in Gaza city, Palestine. Interview questionnaire were employed to collect data related to age, gender, smoking habits, and physical activity pattern. Laboratory biochemical tests included fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), interleukin 6 (IL-6), high sensitive C reactive protein (hs-CRP), and adiponectin were estimated in all patients.

RESULTS

The study involved 118 (72%) women and 46 (28%) men; the mean of age was 53.7 ± 0.46 years. A tertile of inflammation feature with hs-CRP was developed. The highest tertile of hs-CRP was significantly associated with women, higher obesity indices, metabolic dysregulation involving lipid profile markers, FBG and blood pressure, IL-6, and lower adiponectin. After adjusting for age, gender, smoking habits, and physical activity; the risk factor of high level of hs-CRP were the increased body mass index [OR: 1.17, p = .018], IL-6 [OR: 2.22, p = .025] and FBG [OR: 1.01, p = .007], as well as reduced adiponectin [OR: 0.81, p = .002].

CONCLUSION

The inflammation state was affected by obesity and had been related to altered adipokines levels of IL-6 and adiponectin, as well as affected by the glycemic control, as evidenced by higher serum level of FBG.

Insulin and Proinsulin Dynamics Progressively Deteriorate From Within the Normal Range Toward Impaired Glucose Tolerance

Context

Slight elevations in plasma glucose (PG) manifest in advance of diabetes onset, but abnormalities in immunoreactive insulin (IRI), proinsulin (Pro), and adiponectin dynamics during this stage remain poorly understood.

Objective

The objective of this work is to investigate whether IRI and Pro dynamics become abnormal as glucose tolerance deteriorates from within the normal range toward impaired glucose tolerance (IGT), as well as the relationship between PG, and these dynamics and serum adiponectin levels.

Design

A cross-sectional study was designed.

Setting

This study took place at Jichi Medical University in Japan.

Participants and Measurements

PG, IRI, and Pro levels were determined in 1311 young Japanese individuals (age < 40 years) with normal or IGT before and at 30, 60, and 120 minutes during a 75-g oral glucose tolerance test. Participants were assigned to 4 groups according to glucose tolerance, and then background factors, adiponectin levels, insulin sensitivity (SI), and insulin secretion (β) indexes were determined.

Results

PG levels as well as IRI and Pro levels 60 and 120 minutes after glucose-loading increased incrementally with deteriorating glucose tolerance. All measures of β and the SI measure index of insulin sensitivity (ISI)-Matsuda decreased incrementally. Serum adiponectin levels were not significantly different among the glucose tolerance groups, but were independently and negatively correlated with fasting glucose.

Conclusions

Early β decreased and postloading Pro levels became excessive in a progressive manner as glucose tolerance deteriorated from within the normal range toward IGT.

Obesity and inflammation: the linking mechanism and the complications

Obesity is the accumulation of abnormal or excessive fat that may interfere with the maintenance of an optimal state of health. The excess of macronutrients in the adipose tissues stimulates them to release inflammatory mediators such as tumor necrosis factor α and interleukin 6, and reduces production of adiponectin, predisposing to a pro-inflammatory state and oxidative stress. The increased level of interleukin 6 stimulates the liver to synthesize and secrete C-reactive protein. As a risk factor, inflammation is an imbedded mechanism of developed cardiovascular diseases including coagulation, atherosclerosis, metabolic syndrome, insulin resistance, and diabetes mellitus. It is also associated with development of non-cardiovascular diseases such as psoriasis, depression, cancer, and renal diseases. On the other hand, a reduced level of adiponectin, a significant predictor of cardiovascular mortality, is associated with impaired fasting glucose, leading to type-2 diabetes development, metabolic abnormalities, coronary artery calcification, and stroke. Finally, managing obesity can help reduce the risks of cardiovascular diseases and poor outcome via inhibiting inflammatory mechanisms.

Association between the level of circulating adiponectin and prediabetes: A meta-analysis

Aims/Introduction

Adiponectin has been proposed to have an essential role in the regulation of insulin sensitivity and metabolism, but previous studies on levels of adiponectin in prediabetes remain inconsistent. The present study aimed to assess the differences of adiponectin levels between prediabetes patients and healthy controls by carrying out a meta-analysis.

Materials and Methods

We carried out a systematic literature search of PubMed, EMBASE, and other databases for case–control studies and cohort studies measuring adiponectin levels in serum or plasma from prediabetes patients and healthy controls. The pooled weighted mean difference (WMD) and 95% confidence interval (CI) were used to estimate the association between adiponectin levels and prediabetes.

Results

Three cohort studies and 15 case–control studies with a total of 41,841 participants were included in the meta-analysis. The results showed that circulating adiponectin levels in prediabetes patients were significantly lower than that of healthy controls (WMD –1.694 μg/mL; 95% CI –2.151, –1.237; P < 0.001). Subgroup analysis showed more significant differences between prediabetes patients and healthy controls when the ratio of the homeostatic model assessment of insulin resistance was >2.12 (WMD −2.95 μg/mL; 95% CI –4.103, –1.806; P < 0.001) and average age was >60 years (WMD −2.20 μg/mL; 95% CI –3.207, –1.201; P < 0.001). Additionally, WMD in adiponectin showed a trend of direct correlation in subgroups of homeostatic model assessment of insulin resistance ratio, body mass index and age.

Conclusions

The present meta-analysis supports adiponectin levels in prediabetes patients being lower than that of healthy controls,indicating that the level of circulating adiponectin decreases before the onset of diabetes.

Comparison of salivary and plasma adiponectin and leptin in patients with metabolic syndrome

BACKGROUND

The relationship of saliva with plasma protein levels makes saliva an attractive diagnostic tool. Plasma levels of adiponectin and leptin in healthy individuals or diabetes mellitus patients have been previously reported. Nevertheless, salivary levels of these adipocytokines in patients with metabolic syndrome (MS) have never been investigated. This study was aimed to determine adiponectin and leptin levels in saliva and plasma from patients with metabolic syndrome, and evaluate any correlation of these levels with MS.

METHODS

Forty-six healthy and 82 MS patients were enrolled. Demographic data and blood biochemistries were recorded. Saliva and plasma adiponectin and leptin levels were analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Adiponectin and leptin were higher in plasma than in saliva (p < .001). Plasma adiponectin was decreased and plasma leptin increased in patients with MS (p < .001). Salivary adiponectin and salivary leptin were not different between healthy subjects and MS patients (p = .619 and p = .523). Correlation between salivary and plasma adiponectin showed significant association (r = .211, p = .018) while salivary and plasma leptin had no correlation (r = -.161, p = .069). Significant correlation was observed between the salivary adiponectin/salivary leptin ratio and plasma adiponectin (r = .371, p < .001), but not with any component of MS. Increased triglyceride and waist circumference were associated with risk of having a low level of plasma adiponectin (OR = 1.009; 95% CI 1.002-1.015 and OR = 1.125; 95% CI 1.029-1.230). For leptin, body mass index and high-density lipoprotein cholesterol (HDL-C) were associated with a high level of plasma leptin (OR = 1.621; 95% CI 1.212-2.168 and OR = .966; 95% CI .938-.996). The OR for MS as predicted by plasma adiponectin was .928 (95% CI .881-.977).

CONCLUSIONS

This study showed that salivary adiponectin and leptin do not correlate with MS. Although correlation between salivary and plasma adiponectin was observed, no association with MS was observed. Only plasma adiponectin may be useful for the prediction of MS.

Adiponectin as predictor for diabetes among pre-diabetic groups

Adiponectin is found to associate with diabetes in studies apart from cohort studies. This prospective cohort study is to evaluate the predictive role of adiponectin in diabetes among participants with impaired fasting glucose (IFG). A total of 42,845 participants who visited 7 health examination centers located in Seoul and Kyunggi province, South Korea, during 2004-2008 were first included. Of the 42,845 participants, 5,085 participants had IFG. IFG was categorized as stage 1 (fasting glucose 100-109 mg/dL) or stage 2 (110-125 mg/dL). The incidence rates of diabetes were followed up to December, 2011. Hazard ratios (HRs) and 95 % confidence intervals (CI) were performed by Cox proportional hazard model. Of the 5,085 participants, 652 participants developed diabetes during a mean follow-up of 4.4 years. Low adiponectin was associated with diabetes among men with stage 2 IFG (HR, 1.78; 95 %CI, 1.33-2.38) while it was associated with diabetes among women with stage 1 IFG (HR, 2.64; 95 %CI, 1.38-5.03) and stage 2 IFG (HR, 2.17; 95 %CI, 1.07-4.42). When combined men and women, the association between adiponectin and diabetes was statistically significant in stage 2 IFG with an increase of about 82 % (HR, 1.82; 95 %CI, 1.40-2.39) after adjusting for age, sex, body mass index, waist circumference, and fasting serum glucose. There was an interaction by sex and stage 1 IFG in the association between adiponectin and risk of diabetes (P < 0.001). Adiponectin was independently associated with diabetes among participants with IFG. This association was apparent in stage 2 IFG. Adiponectin may be used as a predictor of diabetes in patients having IFG.

Association between ADIPOQ SNPs with plasma adiponectin and glucose homeostasis and adiposity phenotypes in the IRAS Family Study

CONTEXT

Adiponectin is an adipocytokine associated with a variety of metabolic traits. These associations in human studies, in conjunction with functional studies in model systems, have implicated adiponectin in multiple metabolic processes.

OBJECTIVE

We hypothesize that genetic variants associated with plasma adiponectin would also be associated with glucose homeostasis and adiposity phenotypes.

DESIGN AND SETTING

The Insulin Resistance Atherosclerosis Family Study was designed to identify the genetic and environmental basis of insulin resistance and adiposity in the Hispanic- (n=1,424) and African-American (n=604) population.

MAIN OUTCOME MEASURES

High quality metabolic phenotypes, e.g. insulin sensitivity (S(I)), acute insulin response (AIR), disposition index (DI), fasting glucose, body mass index (BMI), visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and waist circumference, were explored.

RESULTS

Based on association analysis of more than 40 genetic polymorphisms in the adiponectin gene (ADIPOQ), we found no consistent association of ADIPOQ variants with plasma adiponectin levels and adiposity phenotypes. However, there were two promoter variants, rs17300539 and rs822387, associated with plasma adiponectin levels (P=0.0079 and 0.021, respectively) in the Hispanic-American cohort that were also associated with S(I) (P=0.0067 and 0.013, respectively). In contrast, there was only a single promoter SNP, rs17300539, associated with plasma adiponectin levels (P=0.0018) and fasting glucose (P=0.042) in the African-American cohort. Strikingly, high impact coding variants did not show evidence of association.

CONCLUSIONS

The lack of consistent patterns of association between variants, adiponectin levels, glucose homeostasis, and adiposity phenotypes suggests a reassessment of the influence of adiponectin in these pathways.

Attenuation of plasma annexin A1 in human obesity

Obesity-related metabolic disorders are characterized by mild chronic inflammation, leukocyte infiltration, and tissue fibrosis as a result of adipocytokine production from the expanding white adipose tissue. Annexin A1 (AnxA1) is an endogenous glucocorticoid regulated protein, which modulates systemic anti-inflammatory processes and, therefore, may be altered with increasing adiposity in humans. Paradoxically, we found that plasma AnxA1 concentrations inversely correlated with BMI, total percentage body fat, and waist-to-hip ratio in human subjects. Plasma AnxA1 was also inversely correlated with plasma concentrations of the acute-phase protein, C-reactive protein (CRP), and the adipocytokine leptin, suggesting that as systemic inflammation increases, anti-inflammatory AnxA1 is reduced. In addition, AnxA1 gene expression and protein were significantly up-regulated during adipogenesis in a human adipocyte cell line compared to vehicle alone, demonstrating for the first time that AnxA1 is expressed and excreted from human adipocytes. These data demonstrate a failure in the endogenous anti-inflammatory system to respond to increasing systemic inflammation resulting from expanding adipose tissue, a condition strongly linked to the development of type 2 diabetes and cardiovascular disease. These data raise the possibility that a reduction in plasma AnxA1 may contribute to the chronic inflammatory phenotype observed in human obesity.