scholarly journals Melatonin Treatment Improves Insulin Resistance and Pigmentation in Obese Patients with Acanthosis Nigricans

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Hang Sun ◽  
Xingchun Wang ◽  
Jiaqi Chen ◽  
Aaron M. Gusdon ◽  
Kexiu Song ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Acanthosis Nigricans ◽  
Resistance Index ◽  
Inflammatory Factors ◽  
Model Assessment ◽  
Obese Patients ◽  
Inflammatory Status ◽  
Before And After ◽  
Matsuda Index

Objective. This study aimed to determine the effects of melatonin on insulin resistance in obese patients with acanthosis nigricans (AN). Methods. A total of 17 obese patients with acanthosis nigricans were recruited in a 12-week pilot open trial. Insulin sensitivity, glucose metabolism, inflammatory factors, and other biochemical parameters before and after the administration of melatonin were measured. Results. After 12 weeks of treatment with melatonin (3 mg/day), homeostasis model assessment insulin resistance index (HOMA-IR) (8.99 ± 5.10 versus 7.77 ± 5.21, p<0.05) and fasting insulin (37.09 5 ± 20.26 μU/ml versus 32.10 ± 20.29 μU/ml, p<0.05) were significantly decreased. Matsuda index (2.82 ± 1.54 versus 3.74 ± 2.02, p<0.05) was significantly increased. There were also statistically significant declines in the AN scores of the neck and axilla, body weight, body mass index, body fat, visceral index, neck circumference, waist circumference, and inflammatory markers. Conclusions. It was concluded that melatonin could improve cutaneous symptoms in obese patients with acanthosis nigricans by improving insulin sensitivity and inflammatory status. This trial is registered with ClinicalTrials.gov NCT02604095.

scholarly journals The Relationship between Circulating Acetate and Human Insulin Resistance before and after Weight Loss in the DiOGenes Study

Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 339
Author(s):  
Manuel A. González Hernández ◽  
Emanuel E. Canfora ◽  
Kenneth Pasmans ◽  
A. Astrup ◽  
W. H. M. Saris ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Weight Loss ◽  
Insulin Sensitivity ◽  
Positive Association ◽  
Fat Free Mass ◽  
Model Assessment ◽  
Random Factor ◽  
Before And After ◽  
Homeostatic Model Assessment ◽  
Matsuda Index

Microbially-produced acetate has been reported to beneficially affect metabolic health through effects on satiety, energy expenditure, insulin sensitivity, and substrate utilization. Here, we investigate the association between sex-specific concentrations of acetate and insulin sensitivity/resistance indices (Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), circulating insulin and Matsuda Index) in the Diet, Obesity and Genes (DiOGenes) Dietary study at baseline and after a low-calorie diet (LCD, 800 kcal/d). In this analysis, 692 subjects (Body Mass Index >27 kg/m2) were included, who underwent an LCD for 8 weeks. Linear mixed models were performed, which were adjusted for mean acetate concentration, center (random factor), age, weight loss, and fat-free mass (FFM). At baseline, no associations between plasma acetate and insulin sensitivity/resistance indices were found. We found a slight positive association between changes in acetate and changes in HOMA-IR (stdβ 0.130, p = 0.033) in women, but not in men (stdβ −0.072, p = 0.310) independently of age, weight loss and FFM. We were not able to confirm previously reported associations between acetate and insulin sensitivity in this large European cohort. The mechanisms behind the sex-specific relationship between LCD-induced changes in acetate and insulin sensitivity require further study.

scholarly journals SAT0111 THE RELATIONSHIP BETWEEN THE ADMINISTRATION OF IL-6 INHIBITORS AND INSULIN RESISTANCE IN PATIENTS WITH ACTIVE RHEUMATOID ARTHRITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 989.3-989
Author(s):  
A. Jitaru ◽  
C. Pomirleanu ◽  
M. M. Leon-Constantin ◽  
F. Mitu ◽  
C. Ancuta
Keyword(s):  
Rheumatoid Arthritis ◽  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Beneficial Effect ◽  
Disease Activity ◽  
Interleukin 6 ◽  
Normal Weight ◽  
Diabetic Patients ◽  
Model Assessment ◽  
Inflammatory Status

Background:Rheumatoid arthritis (RA) is associated with an increased cardiovascular (CV) risk, due not only to the traditional risk factors (hypertension, insulin resistance/diabetes, obesity, smoking), but to the inflammatory status as well. The blockade of interleukin-6 (IL-6) can regulate the glucose metabolism, reducing the glucose level and insulin resistance (IR). This beneficial effect is seen more in patients with normal values of body mass index (BMI), compared to the obese population.Objectives:Given the mentioned existing data, we aim to demonstrate the positive effect of IL-6 inhibitors in active RA patients with normal or increased BMI.Methods:We recruited 56 consecutive patients with definite and active RA, non-responders/partial responders to conventional synthetic Drug Modifying Anti-Rheumatic Drugs (csDMARDs)/biological therapy. For a period of 52 weeks, patients received subcutaneous Tocilizumab (TCZ) in a dose of 162mg once a week, according to European League Anti Rheumatism (EULAR) recommendation and National Protocol. We assessed demographics, RA-related parameters (clinical, inflammatory and immune) and metabolic markers, as well as the peripheral response to insulin, quantified by Homeostasis Model Assessment for insulin resistance (HOMA-IR) and the Quantitative Insulin Sensitivity Check Index (QUICKI). We did not include in the study the patients known with diabetes mellitus (DM) and those undergoing glucocorticoids.Results:After 52 weeks of treatment, most of the patients showed a statistically significant reduction of HOMA-IR (3.61 ± 1.21 at the onset vs. 2.45 ± 1.46 at the end of the study, p<0.001), while QUICKI registered a slight increase (0.32 ± 0.01 at the onset vs. 0.33 ± 0.01 at the end of the study, p<0.001). Also, the decrease in insulin and glucose levels were more obvious in patients with normal BMI, strictly related to disease activity.Conclusion:Long-term administration of TCZ in active RA is associated with a significant reduction of disease activity and IR, especially in normal weight patients. This confirms that obesity, as a CV risk factor, represents one of the main causes of IR.References:[1]Castañeda S, Remuzgo-Martínez S, López-Mejías R et al. Rapid beneficial effect of the IL-6 receptor blockade on insulin resistance and insulin sensitivity in non-diabetic patients with rheumatoid arthritis.Clin Exp Rheumatol. 2019; 37(3):465-473.[2]Lehrskov LL, Christensen RH. The role of interleukin-6 in glucose homeostasis and lipid metabolism.Semin Immunopathol. 2019; 41(4):491-499.[3]Ursini F, Russo E, Ruscitti P, Giacomelli R, De Sarro G. The effect of non-TNF-targeted biologics and small molecules on insulin resistance in inflammatory arthritis.Autoimmun Rev. 2018 Apr;17(4):399-404.Disclosure of Interests:Alexandra Jitaru: None declared, Cristina Pomirleanu: None declared, Maria-Magdalena Leon-Constantin: None declared, Florin Mitu: None declared, CODRINA ANCUTA Consultant of: AbbVie, Pfizer, Roche, Novartis, UCB, Ewopharma, Merck Sharpe and Dohme, and Eli Lilly, Speakers bureau: AbbVie, Pfizer, Roche, Novartis, UCB, Ewopharma, Merck Sharpe and Dohme, and Eli Lilly

scholarly journals Insulin resistance and liver histopathology in metabolically unhealthy subjects do not correlate with the hepatic abundance of NLRP3 inflammasome nor circulating IL-1β levels

2021 ◽  
Vol 9 (1) ◽  
pp. e001975
Author(s):  
Nicolas Quezada ◽  
Ilse Valencia ◽  
Javiera Torres ◽  
Gregorio Maturana ◽  
Jaime Cerda ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Liver Damage ◽  
Nlrp3 Inflammasome ◽  
Low Grade ◽  
Model Assessment ◽  
Alcoholic Fatty Liver ◽  
Protein Levels ◽  
Liver Histopathology ◽  
Inflammatory Status

IntroductionSystemic chronic low-grade inflammation has been linked to insulin resistance (IR) and non-alcoholic steatohepatitis (NASH). NOD-like receptor protein 3 (NLRP3) inflammasome and its final product, interleukin (IL)-1β, exert detrimental effects on insulin sensitivity and promote liver inflammation in murine models. Evidence linking hepatic NLRP3 inflammasome, systemic IR and NASH has been scarcely explored in humans. Herein, we correlated the hepatic abundance of NLRP3 inflammasome components and IR and NASH in humans.Research design and methodsMetabolically healthy (MH) (n=11) and metabolically unhealthy (MUH) (metabolic syndrome, n=21, and type 2 diabetes, n=14) subjects were recruited. Insulin sensitivity (homeostatic model assessment of IR (HOMA-IR) and Oral Glucose Sensitivity (OGIS120)), glycemic (glycated hemoglobin), and lipid parameters were determined by standard methods. Plasma cytokines were quantified by Magpix. Hepatic NLRP3 inflammasome components were determined at the mRNA and protein levels by reverse transcription–quantitative PCR and western blot, respectively. Liver damage was assessed by histological analysis (Non-alcoholic Fatty Liver Disease Activity Score (NAS) and Steatosis, Inflammatory Activity, and Fibrosis (SAF) scores). IR and liver histopathology were correlated with NLRP3 inflammasome components as well as with liver and plasma IL-1β levels.ResultsBody Mass Index, waist circumference, and arterial hypertension frequency were significantly higher in MUH subjects. These patients also had increased high-sensitivity C reactive protein levels compared with MH subjects. No differences in the plasma levels of IL-1β nor the hepatic content of Nlrp3, apoptosis-associated speck-like (Asc), Caspase-1, and IL-1β were detected between MUH and MH individuals. MUH subjects had significantly higher NAS and SAF scores, indicating more severe liver damage. However, histological severity did not correlate with the hepatic content of NLRP3 inflammasome components nor IL-1β levels.ConclusionOur results suggest that NLRP3 inflammasome activation is linked neither to IR nor to the inflammatory status of the liver in MUH patients.

scholarly journals The Relationship between Insulin Resistance and the Cardiovascular Biomarker Growth Differentiation Factor-15 in Obese Patients

2011 ◽  
Vol 57 (2) ◽  
pp. 309-316 ◽  
Author(s):  
Greisa Vila ◽  
Michaela Riedl ◽  
Christian Anderwald ◽  
Michael Resl ◽  
Ammon Handisurya ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Gastric Bypass ◽  
Insulin Sensitivity ◽  
Oral Glucose ◽  
Model Assessment ◽  
Obese Patients ◽  
Growth Differentiation Factor 15 ◽  
Homeostatic Model Assessment ◽  
Homeostatic Model ◽  
The Relationship

BACKGROUND Growth differentiation factor-15 (GDF-15) is a stress-responsive cytokine linked to obesity comorbidities such as cardiovascular disease, inflammation, and cancer. GDF-15 also has adipokine properties and recently emerged as a prognostic biomarker for cardiovascular events. METHODS We evaluated the relationship of plasma GDF-15 concentrations with parameters of obesity, inflammation, and glucose and lipid metabolism in a cohort of 118 morbidly obese patients [mean (SD) age 37.2 (12) years, 89 females, 29 males] and 30 age- and sex-matched healthy lean individuals. All study participants underwent a 75-g oral glucose tolerance test; 28 patients were studied before and 1 year after Roux-en-Y gastric bypass surgery. RESULTS Obese individuals displayed increased plasma GDF-15 concentrations (P &lt; 0.001), with highest concentrations observed in patients with type 2 diabetes. GDF-15 was positively correlated with age, waist-to-height ratio, mean arterial blood pressure, triglycerides, creatinine, glucose, insulin, C-peptide, hemoglobin A1c, and homeostatic model assessment insulin resistance index and negatively correlated with oral glucose insulin sensitivity. Age, homeostatic model assessment index, oral glucose insulin sensitivity, and creatinine were independent predictors of GDF-15 concentrations. Roux-en-Y gastric bypass led to a significant reduction in weight, leptin, insulin, and insulin resistance, but further increased GDF-15 concentrations (P &lt; 0.001). CONCLUSIONS The associations between circulating GDF-15 concentrations and age, insulin resistance, and creatinine might account for the additional cardiovascular predictive information of GDF-15 compared to traditional risk factors. Nevertheless, GDF-15 changes following bariatric surgery suggest an indirect relationship between GDF-15 and insulin resistance. The clinical utility of GDF-15 as a biomarker might be limited until the pathways directly controlling GDF-15 concentrations are better understood.

Plasma MOTS-c levels are associated with insulin sensitivity in lean but not in obese individuals

2018 ◽  
Vol 66 (6) ◽  
pp. 1019-1022 ◽  
Author(s):  
Luis Rodrigo Cataldo ◽  
Rodrigo Fernández-Verdejo ◽  
José Luis Santos ◽  
Jose Eduardo Galgani
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
High Energy ◽  
12S Rrna ◽  
Model Assessment ◽  
Metabolic Homeostasis ◽  
Reading Frame ◽  
Homeostatic Model Assessment ◽  
Matsuda Index ◽  
Insight Into

Mitochondrial open reading frame of the 12S rRNA-c (MOTS-c) is a mitochondrial-derived peptide that attenuates weight gain and hyperinsulinemia when administered to high fat-fed mice. MOTS-c is therefore a potential regulator of metabolic homeostasis under conditions of high-energy supply. However, the effect of insulin resistance and obesity on plasma MOTS-c concentration in humans is unknown. To gain insight into MOTS-c regulation, we measured plasma MOTS-c concentration and analyzed its relationship with insulin sensitivity surrogates, in lean and obese humans (n=10 per group). Obese individuals had impaired insulin sensitivity as indicated by low Matsuda and high Homeostatic Model Assessment (HOMA) indexes. Although plasma MOTS-c concentration was similar in lean and obese individuals (0.48±0.16 and 0.52±0.15 ng/mL; p=0.60), it was correlated with HOMA (r=0.53; p<0.05) and Matsuda index (r=−0.46; p<0.05). Notably, when the groups were analyzed separately, the associations remained only in lean individuals. We conclude that plasma MOTS-c concentration is unaltered in human obesity. However, MOTS-c associates positively with insulin resistance mostly in lean individuals, indicating that plasma MOTS-c concentration depends on the metabolic status in this population. Such dependence seems altered when obesity settles. The implications of plasma MOTS-c for human metabolic homeostasis deserve future examination.

scholarly journals Serum vaspin levels in hypothyroid patients

2011 ◽  
Vol 165 (4) ◽  
pp. 563-569 ◽  
Author(s):  
Neşe Çinar ◽  
Neşe Ersöz Gülçelik ◽  
Kadriye Aydín ◽  
Şafak Akín ◽  
Aydan Usman ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Animal Studies ◽  
Fasting Glucose ◽  
Resistance Index ◽  
The Body ◽  
Model Assessment ◽  
Free Triiodothyronine ◽  
Significant Difference ◽  
Before And After ◽  
Hypothyroid Patients

ObjectiveTo elucidate the link between TSH and obesity, the relationship between TSH and adipocytokines were previously studied. Animal studies demonstrated a possible relationship between vaspin levels and thyroid functions. In this study, we aimed to investigate vaspin levels in hypothyroid states and its relationship with insulin resistance parameters in humans.DesignProspective observational study.MethodsWe enrolled 27 overt hypothyroid, 33 subclinical hypothyroid and 41 euthyroid patients. We measured the body mass index (BMI), fasting glucose, fasting insulin, homeostasis model assessment of insulin resistance index (HOMA-IR), lipid profile, TSH, free triiodothyronine, free thyroxine and vaspin levels. The change in vaspin levels in 12 overt hypothyroid patients after establishment of euthyroidism was analysed.ResultsAll groups were age-matched. Overt hypothyroid group had higher BMI values (P<0.05) than other groups. No significant difference was observed in insulin levels and HOMA-IR among the groups (P>0.05). Adjusted vaspin levels for BMI and age were similar among the groups. Mean vaspin levels in overt, subclinical and euthyroid patients were 1.20±1.17, 1.48±0.93 and 0.95±0.75 ng/ml respectively (P>0.05). There was no significant association between vaspin levels and BMI, fasting glucose, insulin and HOMA-IR (P>0.05). Establishing euthyroidism in hypothyroid patients did not result in a significant change in vaspin levels (before and after treatment, 1.35±1.06 and 1.25±0.68 ng/ml, respectively; P>0.05).ConclusionWe herein present novel data indicating vaspin levels are neither altered in overt and subclinical hypothyroidism nor have a relationship with features of insulin resistance in hypothyroid patients.

scholarly journals Elevated circulating microRNA-122 is associated with obesity and insulin resistance in young adults

2015 ◽  
Vol 172 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Rui Wang ◽  
Jie Hong ◽  
Yanan Cao ◽  
Juan Shi ◽  
Weiqiong Gu ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Young Adults ◽  
Insulin Sensitivity ◽  
Hdl Cholesterol ◽  
Circulating Microrna ◽  
Model Assessment ◽  
Obese Patients ◽  
Serum Samples ◽  
Functional Studies ◽  
Control Subjects

ObjectiveMicroRNAs (miRNAs) are involved in the regulation of adiposity, but functional studies have yielded inconclusive results. Examining the associations of circulating miRNAs levels with obesity and insulin sensitivity in humans may lead to improved insights.Design and methodsSerum samples collected from 112 obese and control subjects (50.0% men) were randomly divided and combined into four pools (28 samples in each obese or control pool). The genome-wide circulating miRNA profiles were detected via microarray. Elevated miR-122 was selected and validated in individual serum samples from 123 obese (46.7% men) and 107 control (50.0% men) young adults. Associations between circulating miR-122 levels and parameters related to adiposity, insulin resistance, lipid profiles and hepatic enzymes were further assessed.ResultsThirty-four miRNAs were found to be expressed differently in the sera of obese patients compared with control subjects (P<0.001). Further analyses confirmed that obese patients had 3.07-fold higher circulating miR-122 levels than controls (P<0.001). Serum miR-122 levels were correlated with BMI (r=0.469), alanine aminotransferase (r=0.634), triglycerides (r=0.448), HDL-cholesterol (r=−0.351) and homeostasis model assessment of insulin resistance (r=0.401, allP<0.01). After controlling for confounding factors, miR-122 remained as an independent risk factor for insulin resistance (OR=3.379, 95% CI=1.141–10.007,P=0.028).ConclusionsElevated circulating miR-122 is positively associated with obesity and insulin resistance in young adults. These findings provide a better understanding regarding the role of miRNAs in adiposity and insulin sensitivity.

scholarly journals Plasma Osteopontin Increases After Bariatric Surgery and Correlates with Markers of Bone Turnover But Not with Insulin Resistance

2008 ◽  
Vol 93 (6) ◽  
pp. 2307-2312 ◽  
Author(s):  
Michaela Riedl ◽  
Greisa Vila ◽  
Christina Maier ◽  
Ammon Handisurya ◽  
Soheila Shakeri-Manesch ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Bariatric Surgery ◽  
Resistance Index ◽  
Model Assessment ◽  
Obese Patients ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Insulin Resistance Index ◽  
Homeostatic Model Assessment ◽  
Homeostatic Model

Abstract Context: Osteopontin (OPN) is a multifunctional protein involved in bone metabolism, cardiovascular disease, diabetes, and obesity. OPN levels are elevated in the plasma and adipose tissue of obese subjects, and are decreased with diet-induced weight loss. Objective: We investigated the effect of bariatric surgery on plasma OPN concentrations in morbidly obese patients. Setting: The study was performed at a university hospital. Subjects: We investigated 40 obese patients aged 43.1 ± 1.8 yr, scheduled to undergo bariatric surgery. Roux-en-Y gastric bypass (RYGB) was performed in 30 subjects (27 females, three males), and laparoscopic adjustable gastric banding (LAGB) in 10 subjects (eight females, two males). Study Design: All patients were studied before and 1 yr (10.3–14.8 months) after the intervention. Main Outcome Measures: OPN, leptin, C-reactive protein, insulin, the homeostatic model assessment insulin resistance index, calcium, 25-hydroxyvitamin D, C telopeptide, and osteocalcin were determined. Results: Both bariatric procedures significantly reduced body weight, body mass index, insulin, leptin, and C-reactive protein 1 yr after surgery. Plasma OPN increased from 31.4 ± 3.8 to 52.8 ± 3.7 ng/ml after RYGB (P &lt; 0.001) and from 29.8 ± 6.9 to 46.4 ± 10.6 ng/ml after LAGB (P = 0.042). Preoperative OPN correlated with age, insulin, the homeostatic model assessment insulin resistance index, and postoperative OPN. Postoperative OPN correlated with C telopeptide and osteocalcin. Conclusions: One year after RYGB and LAGB, plasma OPN levels significantly increased and correlated with biomarkers of bone turnover. Unlike other proinflammatory cytokines, OPN does not normalize but increases further after bariatric surgery.

scholarly journals Comparison of Various Indices in Identifying Insulin Resistance and Diabetes in Chronic Spinal Cord Injury

2021 ◽  
Vol 10 (23) ◽  
pp. 5591
Author(s):  
Gary J. Farkas ◽  
Phillip S. Gordon ◽  
Nareka Trewick ◽  
Ashraf S. Gorgey ◽  
David R. Dolbow ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Glucose Metabolism ◽  
Diagnostic Study ◽  
Model Assessment ◽  
Linear Regression Models ◽  
Post Injury ◽  
Intravenous Glucose ◽  
Cord Injury ◽  
Matsuda Index

The purpose of this screening and diagnostic study was to examine the accord among indices of glucose metabolism, including the Homeostatic Model Assessment for Insulin Resistance (HOMA), HOMA2, Matsuda Index, Quantitative Insulin-sensitivity Check Index (QUICKI), hemoglobin A1C (HbA1C), and fasting plasma glucose (FPG) against intravenous glucose tolerance test-measured insulin sensitivity (Si) in individuals with chronic motor complete SCI. Persons with chronic (≥12-months post-injury) SCI (n = 29; 79% men; age 42.2 ± 11.4; body mass index 28.6 ± 6.4 kg/m2; C4-T10) were included. Measures were compared using adjusted R2 from linear regression models with Akaike information criterion (AIC, a measure of error). QUCKI had the greatest agreement with Si (adjusted R2 = 0.463, AIC = 91.1, p = 0.0001), followed by HOMA (adjusted R2 = 0.378, AIC = 95.4, p = 0.0008), HOMA2 (adjusted R2 = 0.256, AIC = 99.7, p = 0.0030), and the Matsuda Index (adjusted R2 = 0.356, AIC = 95.5, p = 0.0004). FPG (adjusted R2 = 0.056, AIC = 107.5, p = 0.1799) and HbA1C (adjusted R2 = 0.1, AIC = 106.1, p = 0.0975) had poor agreement with Si. While HbA1C and FPG are commonly used for evaluating disorders of glucose metabolism, QUICKI demonstrates the best accord with Si compared to the other measures.

scholarly journals Disruption of GIP/GIPR Axis in Human Adipose Tissue Is Linked to Obesity and Insulin Resistance

2014 ◽  
Vol 99 (5) ◽  
pp. E908-E919 ◽  
Author(s):  
Victòria Ceperuelo-Mallafré ◽  
Xavier Duran ◽  
Gisela Pachón ◽  
Kelly Roche ◽  
Lourdes Garrido-Sánchez ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Stem Cells ◽  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
Human Adipose Tissue ◽  
Fat Cells ◽  
Model Assessment ◽  
Adipose Derived Stem Cells ◽  
Obese Patients ◽  
Insulin Sensitizer

Context: Glucose-dependent insulinotropic peptide (GIP) has a central role in glucose homeostasis through its amplification of insulin secretion; however, its physiological role in adipose tissue is unclear. Objective: Our objective was to define the function of GIP in human adipose tissue in relation to obesity and insulin resistance. Design: GIP receptor (GIPR) expression was analyzed in human sc adipose tissue (SAT) and visceral adipose (VAT) from lean and obese subjects in 3 independent cohorts. GIPR expression was associated with anthropometric and biochemical variables. GIP responsiveness on insulin sensitivity was analyzed in human adipocyte cell lines in normoxic and hypoxic environments as well as in adipose-derived stem cells obtained from lean and obese patients. Results: GIPR expression was downregulated in SAT from obese patients and correlated negatively with body mass index, waist circumference, systolic blood pressure, and glucose and triglyceride levels. Furthermore, homeostasis model assessment of insulin resistance, glucose, and G protein-coupled receptor kinase 2 (GRK2) emerged as variables strongly associated with GIPR expression in SAT. Glucose uptake studies and insulin signaling in human adipocytes revealed GIP as an insulin-sensitizer incretin. Immunoprecipitation experiments suggested that GIP promotes the interaction of GRK2 with GIPR and decreases the association of GRK2 to insulin receptor substrate 1. These effects of GIP observed under normoxia were lost in human fat cells cultured in hypoxia. In support of this, GIP increased insulin sensitivity in human adipose-derived stem cells from lean patients. GIP also induced GIPR expression, which was concomitant with a downregulation of the incretin-degrading enzyme dipeptidyl peptidase 4. None of the physiological effects of GIP were detected in human fat cells obtained from an obese environment with reduced levels of GIPR. Conclusions: GIP/GIPR signaling is disrupted in insulin-resistant states, such as obesity, and normalizing this function might represent a potential therapy in the treatment of obesity-associated metabolic disorders.

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