Increased intrahepatic triglyceride is associated with peripheral insulin resistance: in vivo MR imaging and spectroscopy studies

2007 ◽  
Vol 293 (6) ◽  
pp. E1663-E1669 ◽  
Author(s):  
Jong-Hee Hwang ◽  
Daniel T. Stein ◽  
Nir Barzilai ◽  
Min-Hui Cui ◽  
Julia Tonelli ◽  
...  

Recent studies have indicated that the mass/content of intramyocellular lipid (IMCL), intrahepatic triglyceride (IHTG), visceral fat (VF), and even deep abdominal subcutaneous fat (SF) may all be correlated with insulin resistance. Since simultaneous measurements of these parameters have not been reported, the relative strength of their associations with insulin action is not known. Therefore, the goals of this study were 1) to simultaneously measure IMCL, IHTG, VF, and abdominal SF in the same nondiabetic individuals using noninvasive 1H-magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) and 2) to examine how these fat stores are correlated with systemic insulin sensitivity as measured by whole body glucose disposal (Rd) during euglycemic-hyperinsulinemic clamp studies. Positive correlations were observed among IMCL, IHTG, and VF. There were significant inverse correlations between whole body Rd and both IMCL and VF. Notably, there was a particularly tight inverse correlation between IHTG and whole body Rd ( r = −0.86, P < 0.001), consistent with an association between liver fat and peripheral insulin sensitivity. This novel finding suggests that hepatic triglyceride accumulation has important systemic consequences that may adversely affect insulin sensitivity in other tissues.

2006 ◽  
Vol 100 (2) ◽  
pp. 609-614 ◽  
Author(s):  
Martin Torriani ◽  
Bijoy J. Thomas ◽  
Robert B. Barlow ◽  
Jamie Librizzi ◽  
Sara Dolan ◽  
...  

The human immunodeficiency virus (HIV)-lipodystrophy syndrome is associated with fat redistribution and metabolic abnormalities, including insulin resistance. Increased intramyocellular lipid (IMCL) concentrations are thought to contribute to insulin resistance, being linked to metabolic and body composition variables. We examined 46 women: HIV infected with fat redistribution ( n = 25), and age- and body mass index-matched HIV-negative controls ( n = 21). IMCL was measured by 1H-magnetic resonance spectroscopy, and body composition was assessed with computed tomography, dual-energy X-ray absorptiometry (DEXA), and magnetic resonance imaging. Plasma lipid profile and markers of glucose homeostasis were obtained. IMCL was significantly increased in tibialis anterior [135.0 ± 11.5 vs. 85.1 ± 13.2 institutional units (IU); P = 0.007] and soleus [643.7 ± 61.0 vs. 443.6 ± 47.2 IU, P = 0.017] of HIV-infected subjects compared with controls. Among HIV-infected subjects, calf subcutaneous fat area (17.8 ± 2.3 vs. 35.0 ± 2.5 cm2, P < 0.0001) and extremity fat by DEXA (11.8 ± 1.1 vs. 15.6 ± 1.2 kg, P = 0.024) were reduced, whereas visceral abdominal fat (125.2 ± 11.3 vs. 74.4 ± 12.3 cm2, P = 0.004), triglycerides (131.1 ± 11.0 vs. 66.3 ± 12.3 mg/dl, P = 0.0003), and fasting insulin (10.8 ± 0.9 vs. 7.0 ± 0.9 μIU/ml, P = 0.004) were increased compared with control subjects. Triglycerides ( r = 0.39, P = 0.05) and extremity fat as percentage of whole body fat by DEXA ( r = −0.51, P = 0.01) correlated significantly with IMCL in the HIV but not the control group. Extremity fat (β = −633.53, P = 0.03) remained significantly associated with IMCL among HIV-infected patients, controlling for visceral abdominal fat, abdominal subcutaneous fat, and antiretroviral medications in a regression model. These data demonstrate increased IMCL in HIV-infected women with a mixed lipodystrophy pattern, being most significantly associated with reduced extremity fat. Further studies are necessary to determine the relationship between extremity fat loss and increased IMCL in HIV-infected women.


2018 ◽  
Vol 104 (5) ◽  
pp. 1855-1865 ◽  
Author(s):  
Kristina M Utzschneider ◽  
Steven E Kahn ◽  
David C Polidori

Abstract Context Total insulin clearance is decreased in nonalcoholic fatty liver disease (NAFLD), but the relationship between liver fat and hepatic insulin extraction (HIE) is unknown. Objective This cross-sectional study addresses the hypothesis that HIE is reduced in NAFLD and investigates metabolic and/or anthropometric characteristics most closely associated with insulin clearance. Participants Nondiabetic subjects with NAFLD (n = 13) and age- and body mass index (BMI)-matched controls with normal liver enzymes (n = 15) underwent abdominal CT, dual-energy X-ray absorptiometry, oral glucose tolerance test (OGTT), and labeled two-step hyperinsulinemic-euglycemic clamps. Outcome Measurements Liver fat was estimated by the CT liver/spleen ratio. Hepatic and extrahepatic insulin clearances were modeled using clamp and OGTT data. Results Extrahepatic insulin clearance and HIE were not different between NAFLD and controls and did not correlate with liver fat. HIE was positively correlated with insulin sensitivity [rate of glucose disposal (Rd; low r = +0.7, P &lt; 0.001; high r = +0.6, P = 0.001), adiponectin (r = +0.55, P = 0.004), and insulin-mediated suppression of clamp nonesterified free fatty acid (NEFA; r = +0.67, P &lt; 0.001)] but was not associated with fasting NEFA, insulin-mediated suppression of glucose production, or measures of adiposity. Extrahepatic insulin clearance was positively associated with percent body fat (r = +0.44, P = 0.02) and subcutaneous fat (r = +0.42, P = 0.03) but not BMI, intra-abdominal fat, liver fat, Rd, adiponectin, or NEFA. Conclusions HIE is not directly associated with hepatic steatosis but is associated with muscle and adipose tissue insulin resistance. The data suggest differential regulation of insulin clearance with extrahepatic insulin clearance being associated with body fat and not insulin sensitivity.


2005 ◽  
Vol 288 (4) ◽  
pp. E768-E774 ◽  
Author(s):  
Kirsi Hannele Pietiläinen ◽  
Aila Rissanen ◽  
Jaakko Kaprio ◽  
Sari Mäkimattila ◽  
Anna-Maija Häkkinen ◽  
...  

We determined whether acquired obesity is associated with increases in liver or intra-abdominal fat or impaired insulin sensitivity by studying monozygotic (MZ) twin pairs discordant and concordant for obesity. We studied nineteen 24- to 27-yr-old MZ twin pairs, with intrapair differences in body weight ranging from 0.1 to 24.7 kg [body mass index (BMI) range 20.0–33.9 kg/m2], identified from a population-based FinnTwin16 sample. Fat distribution was determined by magnetic resonance imaging, percent body fat by dual-energy X-ray absorptiometry, liver fat by proton spectroscopy, insulin sensitivity by measuring the fasting insulin concentration, and whole body insulin sensitivity by the euglycemic insulin clamp technique. Intrapair differences in BMI were significantly correlated with those in intra-abdominal fat ( r = 0.82, P < 0.001) and liver fat ( r = 0.57, P = 0.010). Intrapair differences in fasting insulin correlated with those in subcutaneous abdominal ( r = 0.60, P = 0.008), intra-abdominal ( r = 0.75, P = 0.0001) and liver ( r = 0.49, P = 0.048) fat. Intrapair differences in whole body insulin sensitivity correlated with those in subcutaneous abdominal ( r = −0.72, P = 0.001) and intra-abdominal ( r = −0.55, P = 0.015) but not liver ( r = −0.20, P = 0.20) fat. We conclude that acquired obesity is associated with increases in intra-abdominal and liver fat and insulin resistance, independent of genetic factors.


Gut ◽  
2020 ◽  
pp. gutjnl-2020-322073
Author(s):  
Giulia Angelini ◽  
Serenella Salinari ◽  
Lidia Castagneto-Gissey ◽  
Alessandro Bertuzzi ◽  
James Casella-Mariolo ◽  
...  

ObjectiveTo assess the role of jejunum in insulin resistance in humans and in experimental animals.DesignTwenty-four subjects undergoing biliopancreatic diversion (BPD) or Roux-en-Y gastric bypass (RYGB) were enrolled. Insulin sensitivity was measured at baseline and at 1 week after surgery using oral glucose minimal model.We excluded the jejunum from intestinal continuity in pigs and created a jejunal loop with its vascular and nerve supply intact accessible from two cutaneous stomas, and reconnected the bowel with an end-to-end anastomosis. Glucose stable isotopes were given in the stomach or in the jejunal loop.In vitro studies using primary porcine and human hepatocytes or myoblasts tested the effects of plasma on gluconeogenesis or glucose uptake and insulin signalling.ResultsWhole-body insulin sensitivity (SI∙104: 0.54±0.12 before vs 0.82±0.11 after BPD, p=0.024 and 0.41±0.09 before vs 0.65±0.09/pM/min after RYGB, p=not significant) and Glucose Disposition Index increased only after BPD. In pigs, insulin sensitivity was significantly lower when glucose was administered in the jejunal loop than in the stomach (glucose rate of disappearance (Rd) area under the curve (AUC)/insulin AUC∙10: 1.82±0.31 vs 2.96±0.33 mmol/pM/min, p=0.0017).Metabolomics showed a similar pattern before surgery and during jejunal-loop stimulation, pointing to a higher expression of gluconeogenetic substrates, a metabolic signature of impaired insulin sensitivity.A greater hepatocyte phosphoenolpyruvate-carboxykinase and glucose-6-phosphatase gene expression was elicited with plasma from porcine jejunal loop or before surgery compared with plasma from jejunectomy in pigs or jejunal bypass in humans.Stimulation of myoblasts with plasma from porcine jejunal loop or before surgery reduced glucose uptake, Ser473-Akt phosphorylation and GLUT4 expression compared with plasma obtained during gastric glucose administration after jejunectomy in pigs or after jejunal bypass in humans.ConclusionProximal gut plays a crucial role in controlling insulin sensitivity through a distinctive metabolic signature involving hepatic gluconeogenesis and muscle insulin resistance. Bypassing the jejunum is beneficial in terms of insulin-mediated glucose disposal in obesity.Trial registration numberNCT03111953.


1985 ◽  
Vol 248 (5) ◽  
pp. E567-E574 ◽  
Author(s):  
D. E. James ◽  
A. B. Jenkins ◽  
E. W. Kraegen

The euglycemic hyperinsulinemic clamp technique in conscious unrestrained rats was used to examine the effect of insulin on glucose metabolism in metabolically distinct skeletal muscle in vivo. Tissue glucose metabolic rate (R'g) was estimated using 2-[3H]-deoxyglucose, and glucose disposal was examined by measuring glycogen content and [14C]glucose incorporation into glycogen in four different muscles. Insulin sensitivity varied among different muscle types in that the insulin concentration required for half-maximal stimulation of R'g was 80, 150, 280, and 320 mU/1 for soleus (SOL), red gastrocnemius (RG), white gastrocnemius (WG), and extensor digitorum longus, respectively. There were similar relative differences in the maximal effect of insulin on R'g in these muscles. Maximal insulin stimulation almost doubled muscle glycogen content in RG and SOL, whereas there was no change in WG. The relationship between R'g and glycogen synthesis indicated that increased glucose uptake resulted predominantly in glycogen storage. There was an excellent relationship between maximal R'g and blood flow in different muscles. We conclude that there is marked heterogeneity in insulin sensitivity and responsiveness among muscles of different fiber composition. Insulin-induced increases in total peripheral glucose disposal occur predominantly in muscles containing a high proportion of oxidative fibers. Therefore the relative proportion of oxidative to glycolytic muscle fibers may be important factors in determining whole body insulin sensitivity.


2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Anna Benrick ◽  
Manuel Maliqueo ◽  
Sun Miao ◽  
Jesus A. Villanueva ◽  
Yi Feng ◽  
...  

Polycystic ovary syndrome (PCOS) is a reproductive and metabolic disorder associated with obesity and insulin resistance that often precedes the development of type-2 diabetes. Rats continuously exposed to dihydrotestosterone from prepuberty display typical reproductive and metabolic PCOS characteristics including anovulation, polycystic ovaries, insulin resistance, and obesity. Our aim was to investigate if resveratrol improves reproductive and metabolic functions in PCOS rats. The effect was compared to exercise. Control and PCOS rats were treated with vehicle or resveratrol (400 mg · kg−1 · day−1) for 5-6 weeks. Another group of PCOS rats received vehicle treatment and exercised for 5-6 weeks. Insulin sensitivity was determined by euglycemic-hyperinsulinemic clamp. The glucose infusion rate was lower in the PCOS-vehicle group compared to control-vehicle rats (P<0.05). Exercise increased insulin sensitivity compared with PCOS-vehicle rats (P<0.05), but resveratrol did not. Resveratrol treatment and exercise resulted in smaller adipocytes, upregulated estrogen-related receptorαgene expression in subcutaneous fat, and improved estrus cyclicity in the previously acyclic PCOS rats. Although resveratrol had positive effects on adiposity and cyclicity in a similar manner to exercise, resveratrol does not seem to be a good candidate for treating insulin resistance associated with PCOS because no improvement in insulin sensitivity was observed in PCOS rats on normal chow.


2008 ◽  
Vol 36 (5) ◽  
pp. 891-900 ◽  
Author(s):  
Mary C. Sugden ◽  
Mark J. Holness

In healthy individuals, a hyperbolic relationship exists between whole-body insulin-sensitivity and insulin secretion. Thus, for any difference in insulin-sensitivity, a reciprocal proportionate change occurs in insulin secretion. Such a feedback loop is evident in healthy individuals ingesting diets high in saturated fat and in late pregnancy where, despite lipid-induced insulin resistance, glucose tolerance is maintained through augmented GSIS (glucose-stimulated insulin secretion). NRs (nuclear receptors) are members of a superfamily of ligand-regulated and orphan transcription factors. On activation by a cognate ligand, many ligand-activated NRs recruit the RXR (retinoid X receptor) for heterodimer formation. Such NRs include the PPARs (peroxisome-proliferator-activated receptors), which are involved in lipid sensing and liporegulation. PPARs exert important lipid-lowering effects in vivo, thereby opposing the development of lipid-induced insulin resistance by relieving the inhibition of insulin-stimulated glucose disposal by muscle and lowering the necessity for augmented GSIS to counter lipid-induced insulin resistance. Long-chain fatty acids are proposed as natural PPAR ligands and some specific endogenous pathways of lipid metabolism are believed to generate PPAR agonists. Other NRs, e.g. the LXR (liver X receptor), which senses expansion of the metabolically active pool of cholesterol, and the FXR (farnesoid X receptor; NR1H4), which, like the LXR, is involved in sterol metabolism, also modulate systemic lipid levels and insulin-sensitivity. In this review, we discuss how these NRs impact insulin secretion via effects on the insulin-sensitivity–insulin secretion feedback loop and, in some cases, via direct effects on the islet itself. In addition, we discuss interactions between these nutrient/metabolite-responsive NRs and NRs that are central to the action of metabolically important hormones, including (i) the glucocorticoid receptor, critical for maintaining glucose homoeostasis in stress, inflammation and during fasting, and (ii) the thyroid hormone receptors, vital for maintenance of oxidative functions. We present data indicating that the RXR occupies a key role in directly modulating islet function and that its heterodimerization with at least two of its partners modulates GSIS.


2019 ◽  
Vol 8 (5) ◽  
pp. 623 ◽  
Author(s):  
Alice Tang ◽  
Adelle C. F. Coster ◽  
Katherine T. Tonks ◽  
Leonie K. Heilbronn ◽  
Nicholas Pocock ◽  
...  

Background: Large cohort longitudinal studies have almost unanimously concluded that metabolic health in obesity is a transient phenomenon, diminishing in older age. We aimed to assess the fate of insulin sensitivity per se over time in overweight and obese individuals. Methods: Individuals studied using the hyperinsulinaemic-euglycaemic clamp at the Garvan Institute of Medical Research from 2008 to 2010 (n = 99) were retrospectively grouped into Lean (body mass index (BMI) < 25 kg/m2) or overweight/obese (BMI ≥ 25 kg/m2), with the latter further divided into insulin-sensitive (ObSen) or insulin-resistant (ObRes), based on median clamp M-value (M/I, separate cut-offs for men and women). Fifty-seven individuals participated in a follow-up study after 5.4 ± 0.1 years. Hyperinsulinaemic-euglycaemic clamp, dual-energy X-ray absorptiometry and circulating cardiovascular markers were measured again at follow-up, using the same protocols used at baseline. Liver fat was measured using computed tomography at baseline and proton magnetic resonance spectroscopy at follow-up with established cut-offs applied for defining fatty liver. Results: In the whole cohort, M/I did not change over time (p = 0.40); it remained significantly higher at follow-up in ObSen compared with ObRes (p = 0.02), and was not different between ObSen and Lean (p = 0.41). While BMI did not change over time (p = 0.24), android and visceral fat increased significantly in this cohort (ptime ≤ 0.0013), driven by ObRes (p = 0.0087 and p = 0.0001, respectively). Similarly, systolic blood pressure increased significantly over time (ptime = 0.0003) driven by ObRes (p = 0.0039). The best correlate of follow-up M/I was baseline M/I (Spearman’s r = 0.76, p = 1.1 × 10−7). Conclusions: The similarity in insulin sensitivity between the ObSen and the Lean groups at baseline persisted over time. Insulin resistance in overweight and obese individuals predisposed to further metabolic deterioration over time.


2015 ◽  
Vol 93 (5) ◽  
pp. 466-471 ◽  
Author(s):  
Ruth E. Brown ◽  
Jennifer L. Kuk ◽  
Ingrid Libman ◽  
Michelle Rivera-Vega ◽  
SoJung Lee

We examined the joint and independent associations between VAT and LF with insulin sensitivity (IS) and lipids in seventy-one obese adolescents (BMI ≥ 95th, 14.9 ± 1.8 years). VAT was assessed by magnetic resonance imaging, and LF was quantified by proton magnetic resonance spectroscopy. IS was evaluated by a 3 -h hyperinsulinemic (80 mU·m−2·min−1) euglycemic clamp. Independent associations between VAT and LF on metabolic variables were assessed in mutually adjusted multivariate models. The joint association between VAT and LF on metabolic variables was assessed by categorizing participants into a low VAT + low LF group (n = 35), high VAT + low LF group (n = 26), or high VAT + high LF group (n = 10), based on a VAT median split (1.17 kg) and high (≥5%) and low (<5%) LF. Both VAT and LF were independently associated with fasting insulin, 2 h insulin, insulin AUC, IS, and triglycerides (P < 0.05). Adolescents with high VAT + high LF had higher 2 h glucose, glucose AUC, 2 h insulin, triglycerides, and lower insulin sensitivity compared to adolescents with high VAT only (P < 0.025 for all). In obese adolescents, VAT and LF were independently associated with insulin sensitivity and dyslipidemia, and the concomitant presence of VAT and LF is strongly associated with metabolic risk factors.


2001 ◽  
Vol 280 (4) ◽  
pp. E576-E583 ◽  
Author(s):  
Mattias Soop ◽  
Jonas Nygren ◽  
Peter Myrenfors ◽  
Anders Thorell ◽  
Olle Ljungqvist

Postoperative insulin resistance is a well-characterized metabolic state that has been shown to correlate with the length of postoperative stay in hospital. Preoperative intravenous or oral carbohydrate treatment has been shown to attenuate the development of postoperative insulin resistance measured 1 day after surgery. To study the effects of preoperative oral carbohydrate treatment on postoperative changes in insulin resistance and substrate utilization, in the absence of postoperative confounding factors, 15 patients were double-blindly treated with either a carbohydrate-rich beverage (12.5%) ( n = 8) or placebo ( n = 7) before undergoing total hip replacement surgery. Insulin sensitivity, endogenous glucose release, and substrate oxidation rates were measured before and immediately after surgery. Whole body insulin sensitivity decreased by 18% in the treatment group vs. 43% in the placebo group ( P < 0.05, Student's t-test for unpaired data). In both groups, the major mechanism of insulin resistance was an inhibition of insulin-induced nonoxidative glucose disposal after surgery. The better preservation of insulin sensitivity in the treatment group was attributable to a less reduced glucose disposal in peripheral tissues and increased glucose oxidation rates.


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