Liver-fat accumulation and insulin resistance in obese women with previous gestational diabetes

The effects of long-term almond consumption on whole-body insulin sensitivity, postprandial glucose responses, and 48 h continuous glucose concentrations in males and females with prediabetes: a randomized controlled trial

PURPOSE

Findings concerning the effects of almond consumption on glucose metabolism are inconsistent which might relate to body weight gain. The effects of long-term almond consumption on glucose metabolism are investigated in a free-living setting without detailed dietary instructions in males and females with overweight/obesity and prediabetes.

METHODS

Forty-three participants volunteered in this randomized, cross-over trial with a 5-months control and intervention period and a 2-months wash-out. In the intervention period participants daily consumed 50 g whole almonds. At the end of both periods insulin sensitivity was assessed by a hyperinsulinemic euglycemic clamp, and postprandial glucose responses, and 48 h continuous glucose concentrations were measured.

RESULTS

Almond consumption significantly decreased insulin sensitivity (P = 0.002), and increased postprandial glucose concentrations (P = 0.019), as well as fasting insulin concentrations (P = 0.003) as compared to the control period. The AUCs for 24 h glucose concentrations were not significantly different between control and intervention (P = 0.066). Almond consumption also significantly increased BMI (P = 0.002), and waist circumference (P = 0.013), supported by the concurrent increased energy intake (P = 0.031). The effects on glucose metabolism could only partly be explained by the observed weight gain as the almond effect remained after correcting for BMI changes.

CONCLUSIONS

In participants with prediabetes, long-term almond consumption showed adverse effects on insulin sensitivity and glucose metabolism. As almonds seemed not to have fully replaced other food items, it might be necessary to provide more supporting guidelines on how to incorporate energy-dense nuts into healthy diets to prevent type 2 diabetes development.

CLINICAL TRIAL REGISTRATION

This clinical trial was registered in February 2018 as NCT03419702.

Aetiology of Type 2 diabetes in people with a 'normal' body mass index: testing the personal fat threshold hypothesis

Weight loss in overweight or obese individuals with Type 2 diabetes (T2D) can normalize hepatic fat metabolism, decrease fatty acid oversupply to β cells and restore normoglycaemia. One in six people has BMI <27 kg/m2 at diagnosis, and their T2D is assumed to have different aetiology. The Personal Fat Threshold hypothesis postulated differing individual thresholds for lipid overspill and adverse effects on β-cell function. To test this hypothesis, people with Type 2 diabetes and body mass index <27kg/m2 (n = 20) underwent repeated 5% weight loss cycles. Metabolic assessments were carried out at stable weight after each cycle and after 12 months. To determine how closely metabolic features returned to normal, 20 matched normoglycemic controls were studied once. Between baseline and 12 months: BMI fell (mean ± SD), 24.8 ± 0.4 to 22.5 ± 0.4 kg/m2 (P<0.0001) (controls: 21.5 ± 0.5); total body fat, 32.1 ± 1.5 to 27.6 ± 1.8% (P<0.0001) (24.6 ± 1.5). Liver fat content and fat export fell to normal as did fasting plasma insulin. Post-meal insulin secretion increased but remained subnormal. Sustained diabetes remission (HbA1c < 48 mmol/mol off all glucose-lowering agents) was achieved by 70% (14/20) by initial weight loss of 6.5 (5.5-10.2)%. Correction of concealed excess intra-hepatic fat reduced hepatic fat export, with recovery of β-cell function, glycaemic improvement in all and return to a non-diabetic metabolic state in the majority of this group with BMI <27 kg/m2 as previously demonstrated for overweight or obese groups. The data confirm the Personal Fat Threshold hypothesis: aetiology of Type 2 diabetes does not depend on BMI. This pathophysiological insight has major implications for management.

Magnetic resonance study of visceral, subcutaneous, liver and pancreas fat changes after 12 weeks intermittent fasting in obese participants with prediabetes

BACKGROUND

It is not clear whether there are differences in proportions of fat loss from visceral:subcutaneous depots by probiotic supplementation, ethnicity or sex during weight loss; or whether visceral/pancreatic fat depot changes are related to changes in HbA1c. Our objective is to investigate whether weight loss from different fat depots is related to these factors during weight loss achieved by intermittent fasting.

METHOD

Prediabetes participants on 5:2 intermittent fasting were randomized 1:1 to either daily probiotic or placebo for 12 weeks. Twenty-four patients had magnetic resonance imaging data at baseline and 12 weeks.

RESULTS

After 12 weeks of intermittent fasting, subcutaneous fat (%) changed from 35.9 ± 3.1 to 34.4 ± 3.2, visceral fat (%) from 15.8 ± 1.3 to 14.8 ± 1.2, liver fat (%) from 8.7 ± 0.8 to 7.5 ± 0.7 and pancreatic fat (%) from 7.7 ± 0.5 to 6.5 ± 0.5 (all p< 0.001). Changes in weight, HbA1c, SAT, VAT, LF and PF did not differ significantly between probiotic and placebo groups.

CONCLUSION

Overall weight loss was correlated with fat loss from subcutaneous depots. Losses from different fat depots did not correlate with changes in HbA1c or differ by probiotic supplementation, ethnicity or sex.

Dysregulation of Lipid and Glucose Metabolism in Nonalcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease (NAFLD) is a highly prevalent condition affecting approximately a quarter of the global population. It is associated with increased morbidity, mortality, economic burden, and healthcare costs. The disease is characterized by the accumulation of lipids in the liver, known as steatosis, which can progress to more severe stages such as steatohepatitis, fibrosis, cirrhosis, and even hepatocellular carcinoma (HCC). This review focuses on the mechanisms that contribute to the development of diet-induced steatosis in an insulin-resistant liver. Specifically, it discusses the existing literature on carbon flux through glycolysis, ketogenesis, TCA (Tricarboxylic Acid Cycle), and fatty acid synthesis pathways in NAFLD, as well as the altered canonical insulin signaling and genetic predispositions that lead to the accumulation of diet-induced hepatic fat. Finally, the review discusses the current therapeutic efforts that aim to ameliorate various pathologies associated with NAFLD.

Adipose tissue function in healthy pregnancy, gestational diabetes mellitus and pre-eclampsia

Gestational diabetes mellitus (GDM) is a common disorder of pregnancy with short- and long-term consequences for mother and baby. Pre-eclampsia is of major concern to obstetricians due to its sudden onset and increased morbidity and mortality for mother and baby. The incidence of these conditions continues to increase due to widespread maternal obesity. Maternal obesity is a risk factor for GDM and pre-eclampsia, yet our understanding of the role of adipose tissue and adipocyte biology in their aetiology is very limited. In this article, available data on adipose tissue and adipocyte function in healthy and obese pregnancy and how these are altered in GDM and pre-eclampsia are reviewed. Using our understanding of adipose tissue and adipocyte biology in non-pregnant populations, a role for underlying adipocyte dysfunction in the pathological pathways of these conditions is discussed.

The impact of high intensity interval training on liver fat content in overweight or obese adults: A meta-analysis

Liver fat is a marker of the metabolic derangements associated with obesity for which exercise training is a potential therapy. We therefore performed a systematic meta-analysis to investigate the effect of high intensity interval training (HIIT) on liver fat content in overweight or obese adults with metabolic disorders. PubMed, Scopus, Web of Science and the Cochrane were searched up to October 2020 for HIIT vs. Control (CON) or HIIT vs. moderate intensity interval training (MICT) studies on liver fat content in overweight and obese individuals with metabolic disorders. Standardized mean differences (SMD) and 95% confidence intervals (95% CIs) were calculated. Ten studies involving 333 participants were included in the meta-analysis. Based on studies that directly compared HIIT and CON (6 studies), HIIT was beneficial for promoting a reduction in liver fat [-0.51 (95% CI: -0.85 to -0.17), p = 0.003]. However, there were no significant evidence for an effect of HIIT on liver fat [-0.07 (95% CI: -0.33 to 0.19), p = 0.59], when compared with MICT (7 studies). These results suggest that a HIIT could induce improvements in liver fat of overweight and obese adults with metabolic disorders despite no weight loss.

Prospective study of gestational diabetes and fatty liver scores 9 to 16 years after pregnancy

BACKGROUND

Women with gestational diabetes mellitus (GDM) may be at an increased risk of liver complications because chronic hyperglycemia is a risk factor for liver fat accumulation and potential liver dysfunction. Large prospective studies examining liver fat accumulation following a GDM pregnancy are lacking.

METHODS

The Diabetes & Women's Health Study (2012-2014) examined the association between GDM and subsequent fatty liver scores among 607 women with and 619 women without GDM in the Danish National Birth Cohort. Nine to 16 years postpartum, a clinical examination was performed, with measurement of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and γ-glutamyl transferase, from which fatty liver scoring indices were calculated to assess liver fat score, fatty liver index, hepatic steatosis index, and liver fat percentage. Relative risks (RR) with 95% confidence intervals (CI) for elevated liver scoring indices by GDM status were assessed adjusting for major risk factors, including prepregnancy body mass index.

RESULTS

Women with prior GDM had higher adjusted ALT and AST levels than women without GDM (by 6.7% [95% CI 1.7-12.0] and 4.8% [95% CI 0.6-9.1], respectively). Women with GDM also had adjusted increased risks for elevated liver fat score (RR 2.34; 95% CI 1.68-3.27), fatty liver index (RR 1.59; 95% CI 1.27-1.99), and hepatic steatosis index (RR 1.44; 95% CI 1.21-1.71).

CONCLUSIONS

Women with GDM during pregnancy were at an increased risk for fatty liver 9 to 16 years postpartum. Gestational diabetes mellitus may serve as another risk indicator for the early identification and prevention of liver fat accumulation.

Transcriptional Regulation of Early Growth Response Gene-1 (EGR1) is Associated with Progression of Nonalcoholic Fatty Liver Disease (NAFLD) in Patients with Insulin Resistance

BACKGROUND The occurrence of nonalcoholic fatty liver disease (NAFLD) is closely related to type 2 diabetes, especially in patients with insulin resistance. The purpose of this research was to elucidate the major genes and transcriptional regulation of insulin resistance in the progression of NAFLD. MATERIAL AND METHODS We downloaded the gene expression matrix of GSE89632 from Gene Expression Omnibus. Then the principal component analysis was used to identify whether the samples were clustered. Differentially expressed genes were identified by limma R package. Enrichment analysis and protein‑protein interaction network was used to find potential function and screening hub genes. We further used ChIP-seq data from ENCODE to predict the transcriptional regulation of hub genes. Finally, we verified the functions of hub genes with clinical information. RESULTS These hub genes were significantly enriched in "response to insulin", "response to glucose", and "fat cell differentiation". ChIP-seq data showed that EGR1 (early growth response gene-1) may play an important role in the transcriptional regulation of SOCS1 (suppressor of cytokine signaling 1), SOCS3 (suppressor of cytokine signaling 3), and Fos gene family in the liver, as the low expression of EGR1 in patients with insulin resistance may promote the occurrence and development of NAFLD. Similarly, correlation analysis showed that EGR1 was positively correlated with the expression of SOCS1, SOCS3, and the genes of Fos gene family, and EGR1 was negatively correlated with the degree of steatosis. CONCLUSIONS Newly identified hub genes and their transcriptional regulation may promote understanding of the molecular mechanisms underlying insulin resistance related to the progression of NAFLD and provide a new therapy target and biomarkers.

Hepatic miR‑215 target Rictor and modulation of hepatic insulin signalling in rats

Increasing evidence has suggested that hepatic lipid accumulation is associated with hepatic insulin resistance; however, the underlying mechanism is yet to be determined. It was demonstrated that the levels of microRNA-215 (miR-215) expression in the liver of rats fed a high-fat diet were significantly increased compared with rats on a control diet. Additionally, it was revealed via luciferase assays and western blotting that miR-215 targets rapamycin-insensitive companion of mammalian target of rapamycin (Rictor), an important protein in the hepatic insulin signalling pathway. Following overexpression of miR-215 in the H4IIE rat hepatocarcinoma cell line, it was reported that the intracellular insulin signalling pathway was inhibited; conversely, inhibition of miR-215 expression induced this pathway. Furthermore, it was demonstrated via reverse transcription-quantitative polymerase chain reaction analysis that free fatty acids promoted the expression of miR-215. The present study provided a novel mechanistic insight into the association between nonalcoholic fatty liver and hepatic insulin resistance.

Non-alcoholic fatty liver disease in the first trimester and subsequent development of gestational diabetes mellitus

AIMS/HYPOTHESIS

Although there is substantial evidence that non-alcoholic fatty liver disease (NAFLD) is associated with impaired glucose homeostasis, the clinical significance of NAFLD in pregnant women has not been well determined. This study investigates the relationship between NAFLD in the first trimester and the subsequent development of gestational diabetes mellitus (GDM).

METHODS

A multicentre, prospective cohort study was conducted in which singleton pregnant Korean women were assessed for NAFLD at 10-14 weeks using liver ultrasound, fatty liver index (FLI) and hepatic steatosis index (HSI). Maternal plasma adiponectin and selenoprotein P concentrations were measured. Participants were screened for GDM using the two-step approach at 24-28 weeks.

RESULTS

Six hundred and eight women were included in the final analysis. The prevalence of NAFLD was 18.4% (112/608) and 5.9% (36/608) developed GDM. Participants who developed GDM had a higher prevalence of radiological steatosis (55.6% vs 16.1%; p < 0.001) and higher FLI (40.0 vs 10.7; p < 0.001) and HSI (35.5 vs 29.0; p < 0.001). The risk of developing GDM was significantly increased in participants with NAFLD and was positively correlated with the severity of steatosis. This relationship between NAFLD and GDM remained significant after adjustment for metabolic risk factors, including measures of insulin resistance. Maternal plasma adiponectin and selenoprotein P levels were also correlated with both NAFLD severity and the risk of developing GDM.

CONCLUSIONS/INTERPRETATION

NAFLD in early pregnancy is an independent risk factor for GDM. Adiponectin may be a useful biomarker for predicting GDM in pregnant women.

Gestational diabetes in young women predicts future risk of serious liver disease

AIMS/HYPOTHESIS

In common with type 2 diabetes, gestational diabetes mellitus (GDM) is associated with a propensity for hepatic fat deposition. We hypothesised that GDM predicts future lifetime risk of serious liver-disease outcomes, such as cirrhosis, liver failure and need for transplantation.

METHODS

From population-based administrative databases, we identified all women in Ontario, Canada, who had a pregnancy resulting in live birth between April 1994 and March 2002 (N = 698,078). This population was stratified into individuals with (n = 17,932) and without (n = 680,146) GDM, and both groups were further stratified according to subsequent development of type 2 diabetes in the years after delivery. The median follow-up for the development of serious liver disease (defined as hospitalisation for cirrhosis, liver failure or transplantation) was 14.0 years.

RESULTS

Women with GDM had a higher risk of serious liver disease than those without GDM (n = 680,146; HR = 1.40, 95% CI 1.01, 1.94). Compared with women who did not have GDM and did not develop diabetes (n = 635,998), those with GDM who subsequently developed type 2 diabetes (n = 8567) had a higher risk of serious liver disease (adjusted HR = 1.56, 95% CI 1.02, 2.39), as did those without GDM who developed type 2 diabetes (n = 44,148; adjusted HR = 2.48, 95% CI 2.10, 2.93), but not those with GDM who did not develop type 2 diabetes (n = 9365; adjusted HR = 1.15, 95% CI 0.69, 1.91).

CONCLUSION/INTERPRETATION

GDM is associated with future risk of serious liver disease in young women, the development of which may be dependent upon progression to non-gestational diabetes.

Hepatic fat and glucose tolerance in women with recent gestational diabetes

OBJECTIVE

Women with a history of gestational diabetes mellitus (GDM) have an elevated risk of ultimately developing pre-diabetes and diabetes later in life. They also have an increased prevalence of fatty liver, but recent studies have reported conflicting findings on whether hepatic fat affects their risk of pre-diabetes/diabetes. Thus, we sought to evaluate the associations of liver fat with glucose homeostasis and determinants thereof in women with and without recent gestational dysglycemia.

METHODS

Two hundred and fifty-seven women underwent an antepartum oral glucose tolerance test (OGTT), which diagnosed 97 with GDM, 40 with gestational impaired glucose tolerance (GIGT), and 120 with normal glucose tolerance (NGT). At a mean of 4.8 years post partum, they underwent an OGTT (which revealed that 52 had progressed to pre-diabetes/diabetes) and hepatic ultrasound, on which liver fat was graded as none (n=164), mild (n=66), or moderate (n=27).

RESULTS

Liver fat was more prevalent in women with previous GDM than in those with GIGT or NGT (p=0.009) and in women with current pre-diabetes/diabetes than in those without (p=0.0003). As the severity of liver fat increased, there was a progressive worsening of insulin sensitivity and beta-cell function, coupled with rising fasting and 2-hour glucose (all p<0.0001). On multiple linear regression analyses, moderate liver fat was independently associated with lower insulin sensitivity (p=0.0002) and higher 2-hour glucose (p=0.009). Moreover, moderate liver fat emerged as an independent predictor of pre-diabetes/diabetes (OR=3.66, 95% CI 1.1 to 12.5).

CONCLUSION

The higher prevalence of liver fat in women with previous GDM is associated with their increased risk of pre-diabetes/diabetes.

Changes Over Time in Hepatic Markers Predict Changes in Insulin Sensitivity, β-Cell Function, and Glycemia

CONTEXT

Serum concentrations of liver enzymes and the hepatokine fetuin-A have been linked to the risk of type 2 diabetes, but their longitudinal impact on insulin resistance and β-cell dysfunction is unclear.

OBJECTIVE

To evaluate the impact of changes over 2 years in fetuin-A and the liver enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), and γ-glutamyltransferase (GGT) on changes in insulin sensitivity, β-cell function, and glycemia in women with varying degrees of previous gestational dysglycemia, reflecting a range of future diabetic risk.

DESIGN/SETTING/PARTICIPANTS

In total, 336 women underwent glucose challenge test (GCT) and oral glucose tolerance test (OGTT) in pregnancy, followed by repeat OGTT and measurement of ALT/AST/GGT/fetuin-A at both 1 year and 3 years postpartum. The antepartum GCT/OGTT identified four gestational glucose tolerance groups: gestational diabetes (n = 104), gestational impaired glucose tolerance (n = 59), abnormal GCT with normal OGTT (n = 98), and normal GCT/OGTT (n = 75).

RESULTS

At 1 and 3 years postpartum, ALT, AST, GGT, and fetuin-A did not differ across the four groups, but the intervening change in ALT/AST ratio was greater in the gestational dysglycemia groups (P = 0.05). Higher baseline ALT/AST (t = -1.99, P = 0.05) and fetuin-A (t = -3.17, P = 0.002) predicted lower insulin sensitivity (Matsuda) at 3 years, as did their respective changes from 1 to 3 years (ALT/AST: t = -5.47, P < 0.0001; fetuin-A: t = -3.56, P = 0.0004). Change in ALT/AST predicted lower β-cell function (t = -2.33, P = 0.02) and higher fasting glucose at 3 years (t = 2.55, P = 0.01). Moreover, baseline fetuin-A predicted prediabetes/diabetes at 3 years (OR, 1.38; 95% CI, 1.01 to 1.88).

CONCLUSION

Circulating hepatic markers, particularly ALT/AST ratio and fetuin-A, track with changes in insulin sensitivity and β-cell function, supporting a pathophysiologic basis in their prediction of diabetic risk.

Sex-Specific Association between Metabolic Abnormalities and Elevated Alanine Aminotransferase Levels in a Military Cohort: The CHIEF Study

The association of metabolic syndrome (MetS) components with elevated serum alanine aminotransferase (ALT) levels, a marker of hepatic injury, may differ between men and women. However, the sex-specific association in a military young population which has a low prevalence of MetS was unclear. We conducted a cross-sectional examination in 6738 men and 766 women, aged 18-50 years, from the cardiorespiratory fitness study in armed forces (CHIEF) in eastern Taiwan. The components of MetS were defined according to the updated International Diabetes Federation (IDF) ethnic criteria for Asians. Elevated ALT levels were defined as ≥40 U/L for both sexes and ≥30 U/L for women alternatively. Multivariate logistic regression analysis was performed to determine the sex-specific association between MetS components and elevated ALT. The prevalence of MetS and elevated ALT in men were 11.9% and 12.7% respectively, and in women were 3.5%, and 3.8% respectively. In men, high-density lipoprotein < 40 mg/dL, blood pressures ≥ 130/85 mmHg, serum triglycerides ≥ 150 mg/dL, and waist size ≥ 90 cm were associated with elevated ALT (odds ratios (OR) and 95% confidence intervals: 1.59 (1.34-1.90), 1.40 (1.19-1.65), 2.00 (1.68-2.39), and 1.68 (1.38-2.04); all p < 0.001); whereas in women, only fasting plasma glucose ≥ 100 mg/dL was associated with elevated ALT ≥ 40 U/L (OR: 7.59 (2.35-24.51), p = 0.001) and ALT ≥ 30 U/L (2.67 (0.89-7.95), p = 0.08). Our findings suggest that the relationship between metabolic abnormalities and elevated ALT may differ by sex, possibly due to the MetS more prevalent in young adult men than in women.

Serum γ-glutamyltransferase level and metabolic syndrome in children and adolescents: Korean National Health and Nutrition Examination Survey

AIMS/INTRODUCTION

Serum γ-glutamyltransferase (GGT) is positively related to cardiometabolic diseases, such as type 2 diabetes mellitus, hypertension and metabolic syndrome (MetS), in adult populations. Our aim was to investigate whether serum GGT is independently associated with MetS and its components in a nationally representative sample of Korean children and adolescents.

MATERIALS AND METHODS

The study included data from 1,618 participants (867 boys, 751 girls) aged 10-18 years from the 2010-2011 Korean National Health and Nutrition Examination Survey. MetS was diagnosed by the 2007 International Diabetes Federation criteria for children and adolescents. Participants were stratified using a cut-off value of the 75th percentile of serum GGT levels (19 IU/L for boys, 15 IU/L for girls). The odds ratios and 95% confidence intervals for MetS and its components were determined with multiple logistic regression analyses.

RESULTS

The mean values of most cardiometabolic variables were significantly higher in the upper stratum. Except for low high-density lipoprotein cholesterol in boys and elevated blood pressure in girls, participants in the upper GGT stratum had significantly higher odds of MetS and its components than those in the lower stratum. The multivariate-adjusted odds ratios for MetS for the upper stratum were 5.79 (95% confidence interval 1.21-27.02) in boys and 6.20 (95% confidence interval 1.71-22.47) in girls, after adjusting for age, household income and residential area.

CONCLUSIONS

Serum GGT was positively associated with MetS and its components in Korean children and adolescents. Serum GGT could be a useful measure for identifying children and adolescents with MetS.

Roles of Diacylglycerols and Ceramides in Hepatic Insulin Resistance

Although ample evidence links hepatic lipid accumulation with hepatic insulin resistance, the mechanistic basis of this association is incompletely understood and controversial. Diacylglycerols (DAGs) and ceramides have emerged as the two best-studied putative mediators of lipid-induced hepatic insulin resistance. Both lipids were first associated with insulin resistance in skeletal muscle and were subsequently hypothesized to mediate insulin resistance in the liver. However, the putative roles for DAGs and ceramides in hepatic insulin resistance have proved more complex than originally imagined, with various genetic and pharmacologic manipulations yielding a vast and occasionally contradictory trove of data to sort. In this review we examine the state of this field, turning a critical eye toward both DAGs and ceramides as putative mediators of lipid-induced hepatic insulin resistance.

Liver triacylglycerol content and gestational diabetes: effects of moderate energy restriction

AIMS/HYPOTHESIS

Women with a history of gestational diabetes mellitus (GDM) have raised liver triacylglycerol. Restriction of energy intake in type 2 diabetes can normalise glucose control and liver triacylglycerol concentration but it is not known whether similar benefits could be achieved in GDM. The aim of this work was to examine liver triacylglycerol accumulation in women with GDM and the effect of modest energy restriction.

METHODS

Sixteen women with GDM followed a 4 week diet (5 MJ [1200 kcal]/day). Liver triacylglycerol, before and after diet and postpartum, was measured by magnetic resonance. Insulin secretion and sensitivity were assessed before and after diet. Twenty-six women who underwent standard antenatal care for GDM (matched for age, BMI, parity and ethnicity) were used as a comparator group.

RESULTS

Fourteen women, who completed the study, achieved a weight loss of 1.6 ± 1.7 kg over the 4 week dietary period. Mean weight change was -0.4 kg/week in the study group vs +0.3 kg/week in the comparator group (p = 0.002). Liver triacylglycerol level was normal but decreased following diet (3.7% [interquartile range, IQR 1.2-6.1%] vs 1.8% [IQR 0.7-3.1%], p = 0.004). There was no change in insulin sensitivity or production. Insulin was required in six comparator women vs none in the study group (eight vs two required metformin). Blood glucose control was similar for both groups. The hypo-energetic diet was well accepted.

CONCLUSIONS/INTERPRETATION

Liver triacylglycerol in women with GDM was not elevated, unlike observations in non-pregnant women with a history of GDM. A 4 week hypo-energetic diet resulted in weight loss, reduced liver triacylglycerol and minimised pharmacotherapy. The underlying pathophysiology of glucose metabolism appeared unchanged.

Effects of exercise training on intrahepatic lipid content in humans

Non-alcoholic fatty liver (NAFL) is the most common liver disorder in western society. Various factors may play a role in determining hepatic fat content, such as delivery of lipids to the liver, de novo lipogenesis, hepatic lipid oxidation, secretion of intrahepatic lipids to the circulation or a combination of these. If delivery of lipids to the liver outweighs the sum of hepatic lipid oxidation and secretion, the intrahepatic lipid (IHL) content starts to increase and NAFL may develop. NAFL is closely related to obesity and insulin resistance and a fatty liver increases the vulnerability to type 2 diabetes development. Exercise training is a cornerstone in the treatment and prevention of type 2 diabetes. There is a large body of literature describing the beneficial metabolic consequences of exercise training on skeletal muscle metabolism. Recent studies have started to investigate the effects of exercise training on liver metabolism but data is still limited. Here, first, we briefly discuss the routes by which IHL content is modulated. Second, we review whether and how these contributing routes might be modulated by long-term exercise training. Third, we focus on the effects of acute exercise on IHL metabolism, since exercise also might affect hepatic metabolism in the physically active state. This will give insight into whether the effect of exercise training on IHL could be explained by the accumulated effect of acute bouts of exercise, or whether adaptations might occur only after long-term exercise training. The primary focus of this review will be on observations made in humans. Where human data is missing, data obtained from well-accepted animal models will be used.

Hepatic fat and abdominal adiposity in early pregnancy together predict impaired glucose homeostasis in mid-pregnancy

Hepatic fat and abdominal adiposity individually reflect insulin resistance, but their combined effect on glucose homeostasis in mid-pregnancy is unknown. A cohort of 476 pregnant women prospectively underwent sonographic assessment of hepatic fat and visceral (VAT) and total (TAT) adipose tissue at 11–14 weeks' gestation. Logistic regression was used to assess the relation between the presence of maternal hepatic fat and/or the upper quartile (Q) of either VAT or TAT and the odds of developing the composite outcome of impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or gestational diabetes mellitus at 24–28 weeks' gestation, based on a 75 g OGTT. Upon adjusting for maternal age, ethnicity, family history of DM and body mass index (BMI), the co-presence of hepatic fat and quartile 4 (Q4) of VAT (adjusted odds ratio (aOR) 6.5, 95% CI: 2.3–18.5) or hepatic fat and Q4 of TAT (aOR 7.8 95% CI 2.8–21.7) were each associated with the composite outcome, relative to women with neither sonographic feature. First-trimester sonographic evidence of maternal hepatic fat and abdominal adiposity may independently predict the development of impaired glucose homeostasis and GDM in mid-pregnancy.

Proposed cut-off value of the intrahepatic lipid content for metabolically normal persons assessed by proton magnetic resonance spectroscopy in a Japanese population

AIMS

To determine the threshold intrahepatic lipid (IHL) content separating metabolically normal from abnormal in a Japanese population based on proton magnetic resonance spectroscopy ((1)H-MRS).

METHODS

A total of 305 Japanese subjects aged 20-69years were investigated. The subjects underwent general examination, blood tests, and (1)H-MRS of the liver after an overnight fast. They completed a questionnaire about daily drinking habits and their daily alcohol intake was calculated.

RESULTS

The median IHL content was 4.7% in men and 1.7% in women, and it increased along with the number of features of metabolic syndrome (MetS). The optimum IHL cut-off value for separating normal subjects from those with at least one feature of MetS was 6.5% in men (AUC of ROC: 0.727, 95%-CI: 0.649-0.804) and 1.8% in women (0.765, 0.685-0.844). Alcohol intake was not correlated with the IHL content according to multiple logistic regression analysis.

CONCLUSION

This study demonstrated a close association of IHL with features of MetS and identified IHL content cut-off values for metabolic normality in Japanese subjects.

Non-Alcoholic Fatty Liver Disease in Early Pregnancy Predicts Dysglycemia in Mid-Pregnancy: Prospective Study

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is mediated by insulin resistance, as is gestational diabetes mellitus (GDM). NAFLD has not been studied in relation to GDM. The objective of this study was to assess the association between first-trimester sonographic findings of NAFLD, and both dysglycemia and GDM in mid-pregnancy.

METHODS

We followed a prospective cohort design at a large obstetrics clinic in Toronto, Ontario with 476 women enrolled in early pregnancy. NAFLD was assessed by ultrasound at 11-14 weeks gestation, and standardized images were independently scored by two ultrasonographers for the presence of hepatorenal contrast (one finding) and/or blurring of the intrahepatic vessels (one finding), relative to neither being present. Logistic regression analysis was used to generate odds ratios (ORs) and 95% confidence interval (CI) for the relation between 0, 1, or 2 sonographic findings of NAFLD and the composite outcome of impaired fasting glucose, impaired glucose tolerance, or GDM at 24-28 weeks gestation, determined by a fasting 75-g oral glucose tolerance test. ORs were adjusted (aOR) for maternal age, ethnicity, first-degree relative with type 2 DM, body mass index (BMI) at 11-14 weeks gestation, and change in BMI from 11-14 to 24-28 weeks gestation.

RESULTS

Fifty out of 476 women (10.5%) developed the composite outcome. The presence of 1 (aOR 2.0, 95% CI: 1.0-4.1) or 2 (aOR 2.9, 95% CI: 1.0-18.4) sonographic features of NAFLD predicted the composite outcome. Limiting the analysis to ≥1 feature vs. none, the aOR was 2.2 (95% CI: 1.1-4.3).

CONCLUSIONS

Sonographic assessment of NAFLD is a semiquantitative measure, with limited ability to detect small amounts of hepatic steatosis, or to distinguish various stages of NAFLD. First-trimester sonographic evidence of NAFLD predicts dysglycemia in mid-pregnancy.

Convergence in insulin resistance between very severely obese and lean women at the end of pregnancy

AIMS

Disrupted intermediary metabolism may contribute to the adverse pregnancy outcomes in women with very severe obesity. Our aim was to study metabolism in such pregnancies.

METHODS

We recruited a longitudinal cohort of very severely obese (n = 190) and lean (n = 118) glucose-tolerant women for anthropometric and metabolic measurements at early, mid and late gestation and postpartum. In case-control studies of very severely obese and lean women we measured glucose and glycerol turnover during low- and high-dose hyperinsulinaemic-euglycaemic clamps (HEC) at early and late pregnancy and in non-pregnant women (each n = 6-9) and body fat distribution by MRI in late pregnancy (n = 10/group).

RESULTS

Although greater glucose, insulin, NEFA and insulin resistance (HOMA-IR), and greater weight and % fat mass (FM) was observed in very severely obese vs lean participants, the degree of worsening was attenuated in the very severely obese individuals with advancing gestation, with no difference in triacylglycerol (TG) concentrations between very severely obese and lean women at term. Enhanced glycerol production was observed in early pregnancy only in very severely obese individuals, with similar intrahepatic FM in very severely obese vs lean women by late gestation. Offspring from obese mothers were heavier (p = 0.04).

CONCLUSIONS/INTERPRETATION

Pregnancies complicated by obesity demonstrate attenuation in weight gain and insulin resistance compared with pregnancies in lean women. Increased glycerol production is confined to obese women in early pregnancy and obese and lean individuals have similar intrahepatic FM by term. When targeting maternal metabolism to treat adverse pregnancy outcomes, therapeutic intervention may be most effective applied early in pregnancy.

Associations between visceral fat and liver fat with insulin sensitivity and metabolic risk in obese adolescents

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.

Caloric restriction for treatment of geriatric obesity: Do the benefits outweigh the risks?

Most evidence for the health benefits of prescribing caloric restriction (CR) for weight loss is derived from randomized, controlled trials (RCTs) in young/middle-aged adults; there are very few RCTs in older adults in which the isolated effects of CR can be deciphered. The purpose of this review is to summarize the RCT evidence of the benefits (and potential risks) of CR for the treatment of obesity in older adults. We identified only 19 published papers from 10 RCTs ranging from 3 to 18 months that met the criteria of independent effects of a CR component and were conducted in adults with a mean age ≥65 yrs. Overall, the results show a beneficial treatment effect for improving some metabolic, functional and body composition outcomes with few documented risks. However, all outcomes were assessed immediately after treatment cessation. Thus, until additional scientifically rigorous evidence with long-term follow-up is available, the risk-to-benefit ratio of CR for the treatment of obesity in older adults remains unclear.

Android and gynoid fat percentages and serum lipid levels in United States adults

CONTEXT

Accumulating evidence suggests that fat distribution is a better predictor of cardiovascular disease than body mass index (BMI).

OBJECTIVE

The aim of this study was to investigate the association of android and gynoid fat percentages with lipid profiles to determine whether android and/or gynoid fat percentages are associated with serum lipid levels.

DESIGN

A population-based cross-sectional study.

PATIENTS

Five thousand six hundred and ninety-six adults (20 years and older) who participated in the National Health and Nutrition Examination Survey 2003-2006.

MEASUREMENT

The regional body composition in the android and gynoid regions was defined by dual energy X-ray absorptiometry (DXA). The estimation of lipid risk profiles included total cholesterol, high-density lipoprotein (HDL) -cholesterol, low-density lipoprotein (LDL) -cholesterol and triglycerides (TG).

RESULTS

Regardless of gender, android and gynoid body fat percentages were positively and significantly correlated with BMI and waist circumference. After adjustment for age, ethnicity, education, smoking, alcohol consumption, dyslipidaemia and BMI, increases in android fat percentage were significantly associated with total cholesterol, TG and HDL cholesterol in males, and total cholesterol, HDL cholesterol and LDL cholesterol in females. The gynoid fat percentages showed a positive correlation with total cholesterol in males, whereas gynoid fat accumulation in females showed a favourable association with TG and HDL cholesterol. The observed associations differed according to ethnic groups.

CONCLUSION

Our results suggest that regional fat distribution in the android and gynoid regions have different effects on lipid profiles, and that fat in the android region, rather than the gynoid region, may be an important factor in determining the risk of cardiovascular disease.

Ageing, adipose tissue, fatty acids and inflammation

A common feature of ageing is the alteration in tissue distribution and composition, with a shift in fat away from lower body and subcutaneous depots to visceral and ectopic sites. Redistribution of adipose tissue towards an ectopic site can have dramatic effects on metabolic function. In skeletal muscle, increased ectopic adiposity is linked to insulin resistance through lipid mediators such as ceramide or DAG, inhibiting the insulin receptor signalling pathway. Additionally, the risk of developing cardiovascular disease is increased with elevated visceral adipose distribution. In ageing, adipose tissue becomes dysfunctional, with the pathway of differentiation of preadipocytes to mature adipocytes becoming impaired; this results in dysfunctional adipocytes less able to store fat and subsequent fat redistribution to ectopic sites. Low grade systemic inflammation is commonly observed in ageing, and may drive the adipose tissue dysfunction, as proinflammatory cytokines are capable of inhibiting adipocyte differentiation. Beyond increased ectopic adiposity, the effect of impaired adipose tissue function is an elevation in systemic free fatty acids (FFA), a common feature of many metabolic disorders. Saturated fatty acids can be regarded as the most detrimental of FFA, being capable of inducing insulin resistance and inflammation through lipid mediators such as ceramide, which can increase risk of developing atherosclerosis. Elevated FFA, in particular saturated fatty acids, maybe a driving factor for both the increased insulin resistance, cardiovascular disease risk and inflammation in older adults.

Gestational diabetes mellitus and cardiovascular risk after pregnancy

Gestational diabetes mellitus (GDM) affects many women in pregnancy and is enhanced by epidemic conditions of obesity, increasing age at the time of the first pregnancy, stressful life conditions, a sedentary lifestyle with less physical activity and unhealthy nutrition with highly processed, high-calorie food intake. GDM does not affect the mother and offspring in pregnancy alone, as there is compelling evidence of the long-term effects of the hyperglycemic state in pregnancy postpartum. Type 2 diabetes mellitus, cardiovascular disease and metabolic syndrome are more common in GDM women, and even the offspring of GDM women are reported to have higher obesity rates and a higher risk for noncommunicable diseases. Early prevention of risk factors seems to be key to overcoming the vicious cycle of cardiometabolic disease onset.

Clinical association between serum γ-glutamyltransferase levels and the development of insulin resistance in Korean men: a 5-year follow-up study

AIMS

In recent years, γ-glutamyltransferase has emerged as a predictor of cardiovascular disease, Type 2 diabetes mellitus, the metabolic syndrome and hypertension. However, it is not yet certain whether γ-glutamyltransferase is a predictor for insulin resistance. The aim of this study was to examine the longitudinal association between baseline γ-glutamyltransferase level and the development of insulin resistance in Korean men.

METHODS

We performed a prospective cohort study, involving 22 931 healthy Korean men without baseline insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR < 2.7) for 5 years. We checked the HOMA-IR serially to monitor the development of insulin resistance (incidence of HOMA-IR ≥ 2.7). A Cox proportional hazards model was used to determine hazard ratios for insulin resistance by quartile groups of baseline serum γ-glutamyltransferase levels.

RESULTS

During 81 208.6 person-years of follow-up, 3856 (16.8%) cases of insulin resistance developed between 2006 and 2010. After adjusting for multiple covariates, including baseline HOMA-IR, the hazard ratios (95% CI) for incident insulin resistance comparing the second to the fourth quartile of baseline serum γ-glutamyltransferase levels with the first quartile were 1.19 (1.06-1.33), 1.38 (1.23-1.53) and 1.58 (1.41-1.77), respectively (P for trend < 0.001).

CONCLUSIONS

Our findings show that serum γ-glutamyltransferase level could be a predictor of the development of insulin resistance in Korean men.

Effects of taurine supplementation on hepatic markers of inflammation and lipid metabolism in mothers and offspring in the setting of maternal obesity

Maternal obesity is associated with obesity and metabolic disorders in offspring. However, intervention strategies to reverse or ameliorate the effects of maternal obesity on offspring health are limited. Following maternal undernutrition, taurine supplementation can improve outcomes in offspring, possibly via effects on glucose homeostasis and insulin secretion. The effects of taurine in mediating inflammatory processes as a protective mechanism has not been investigated. Further, the efficacy of taurine supplementation in the setting of maternal obesity is not known. Using a model of maternal obesity, we examined the effects of maternal taurine supplementation on outcomes related to inflammation and lipid metabolism in mothers and neonates. Time-mated Wistar rats were randomised to either: 1) control : control diet during pregnancy and lactation (CON); 2) CON supplemented with 1.5% taurine in drinking water (CT); 3) maternal obesogenic diet (high fat, high fructose) during pregnancy and lactation (MO); or 4) MO supplemented with taurine (MOT). Maternal and neonatal weights, plasma cytokines and hepatic gene expression were analysed. A MO diet resulted in maternal hyperinsulinemia and hyperleptinemia and increased plasma glucose, glutamate and TNF-α concentrations. Taurine normalised maternal plasma TNF-α and glutamate concentrations in MOT animals. Both MO and MOT mothers displayed evidence of fatty liver accompanied by alterations in key markers of hepatic lipid metabolism. MO neonates displayed a pro-inflammatory hepatic profile which was partially rescued in MOT offspring. Conversely, a pro-inflammatory phenotype was observed in MOT mothers suggesting a possible maternal trade-off to protect the neonate. Despite protective effects of taurine in MOT offspring, neonatal mortality was increased in CT neonates, indicating possible adverse effects of taurine in the setting of normal pregnancy. These data suggest that maternal taurine supplementation may ameliorate the adverse effects observed in offspring following a maternal obesogenic diet but these effects are dependent upon prior maternal nutritional background.

CD36 is important for adipocyte recruitment and affects lipolysis

OBJECTIVE

The scavenger receptor CD36 facilitates the cellular uptake of long-chain fatty acids. As CD36-deficiency attenuates the development of high fat diet (HFD)-induced obesity, the role of CD36-deficiency in preadipocyte recruitment and adipocyte function was set out to characterize.

DESIGN AND METHODS

Fat cell size and number were determined in gonadal, visceral, and subcutaneous adipose tissue of CD36(-/-) and WT mice after 6 weeks on HFD. Basal lipolysis and insulin-inhibited lipolysis were investigated in gonadal adipose tissue.

RESULTS

CD36(-/-) mice showed a reduction in adipocyte size in all fat pads. Gonadal adipose tissue also showed a lower total number of adipocytes because of a lower number of very small adipocytes (diameter <50 μm). This was accompanied by an increased pool of preadipocytes, which suggests that CD36-deficiency reduces the capacity of preadipocytes to become adipocytes. Regarding lipolysis, in adipose tissue from CD36(-/-) mice, cAMP levels were increased and both basal and 8-bromo-cAMP stimulated lipolysis were higher. However, insulin-mediated inhibition of lipolysis was more potent in CD36(-/-) mice.

CONCLUSIONS

These results indicate that during fat depot expansion, CD36-deficiency negatively affects preadipocyte recruitment and that in mature adipocytes, CD36-deficiency is associated with increased basal lipolysis and insulin responsiveness.

Polycystic ovary syndrome and nonalcoholic fatty liver in obese adolescents: association with metabolic risk profile

OBJECTIVE

To investigate the relationship between liver fat and in vivo insulin sensitivity, body composition, abdominal adiposity, and lipid metabolism in obese adolescent girls with polycystic ovary syndrome (PCOS).

DESIGN

Cross-sectional case-control study.

SETTING

Research center.

PATIENT(S)

Thirty Tanner stage V obese girls with PCOS.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Liver fat, abdominal adiposity, in vivo insulin-stimulated glucose disposal, whole-body lipolysis, fat oxidation, lipoprotein particle size and concentration, and liver enzymes (alanine aminotransferase and aspartate aminotransferase). Fatty liver index <1 is indicative of fatty liver.

RESULT(S)

Fatty liver was present in 6.7% of the individuals (6.7%). Levels of alanine aminotransferase and aspartate aminotransferase were not different between those with fatty liver vs. without. Fatty liver index was associated with age (r = -0.53), body mass index (r = -0.41), total (r = -0.43) and subcutaneous (r = -0.41) abdominal adiposity, insulin-stimulated glucose disposal (r = 0.36), and small, medium small, and very small low-density lipoprotein concentrations (r ≥ -0.43). In a multiple regression analysis, age, total T, race, and insulin-stimulated glucose disposal explained 43% of the variance (R(2) = 0.43) in fatty liver index, with age (R(2) = 0.28) and total T (R(2) = 0.11) being independent contributors.

CONCLUSION(S)

Liver fat is associated with increasing age, even in the narrow adolescent age range, increasing abdominal adiposity, worsening insulin sensitivity, and dyslipoproteinemia in obese adolescent girls with PCOS. Targeting these abnormalities early in the course of PCOS may halt future nonalcoholic fatty liver disease in adulthood.

Independent association of liver fat accumulation with insulin resistance

BACKGROUND

To examine the association of intrahepatic fat with homeostasis model assessment-insulin resistance (HOMA-IR), a marker of insulin resistance, in Japanese adults, and whether intrahepatic fat is associated with insulin resistance independent of waist circumference and other measures of obesity.

METHODS

Fifty-three individuals aged 37-69 were studied. Spectrum obtained using a 3-T magnetic resonance imager was analysed with LCModel to quantify intrahepatic fat. Blood levels of insulin, glucose and other biochemical markers were obtained after 8h or more fasting. Percent body fat was estimated by a bioelectrical impedance analyzer. HOMA-IR and intrahepatic fat content were log-transformed in the analysis.

RESULTS

We found a positive correlation between intrahepatic fat and HOMA-IR, which was independent of the anthropometric measures of obesity. In contrast, significant and positive correlations of body mass index, percent body fat, and waist circumference with HOMA-IR were largely explained by their associations with intrahepatic fat. Intrahepatic fat was positively associated with alanine transaminase and triglycerides even after adjustment for HOMA-IR.

CONCLUSION

Intrahepatic fat was associated with insulin resistance independent of age, sex, and measures of obesity in Japanese adults. Hypertriglyceridemia and liver injury may directly occur subsequent to intrahepatic fat accumulation.

A history of previous gestational diabetes mellitus is associated with adverse changes in insulin secretion and VLDL metabolism independently of increased intrahepatocellular lipid

AIMS/HYPOTHESIS

We have previously reported a high prevalence of non-alcoholic fatty liver disease (NAFLD) among women with previous gestational diabetes mellitus (pGDM). We wanted to confirm that intrahepatocellular lipid (IHCL) is associated with pGDM independently of adiposity and determine: (1) if VLDL metabolism is dysregulated; and (2) the extent to which NAFLD and IHCL account for the dysmetabolic phenotype in pGDM.

METHODS

We analysed data from a cohort of 234 women (114 with pGDM) and identified effects of pGDM on lipid and glucoregulation that were independent of ultrasound-diagnosed NAFLD. We then measured IHCL by MR spectroscopy in a representative subgroup (n = 36) and conducted detailed metabolic studies (IVGTT, VLDL apolipoprotein B [apoB] kinetics and palmitate turnover) and measurement of regional body fat by MRI to demonstrate effects of IHCL that were independent of a history of pGDM.

RESULTS

pGDM was associated with increased IHCL (p = 0.04) after adjustment for adiposity. Independently of IHCL, pGDM was associated with a lower IVGTT disposition index (p = 0.02) and acute insulin response to glucose (pGDM+/NAFLD-, 50% lower; pGDM+/NAFLD+, 36% lower; effect of pGDM, p = 0.03), increased VLDL apoB pool size (pGDM+/NAFLD-, 3.1-fold higher; pGDM+/NAFLD+, 1.2-fold higher; effect of pGDM, p = 0.02) and, at borderline significance (p = 0.05), increased rate of VLDL apoB synthesis.

CONCLUSIONS/INTERPRETATION

pGDM is associated with increased IHCL independently of adiposity. The increased liver fat contributes to the phenotype, but pGDM status is independently associated with diminished insulin secretion and (shown for the first time) augmented VLDL metabolism. IHCL with pGDM may compound a dysmetabolic phenotype.

Whole body fat: content and distribution

Obesity and its co-morbidities, including type II diabetes, insulin resistance and cardiovascular diseases, have become one of the biggest health issues of present times. The impact of obesity goes well beyond the individual and is so far-reaching that, if it continues unabated, it will cause havoc with the economies of most countries. In order to be able to fully understand the relationship between increased adiposity (obesity) and its co-morbidity, it has been necessary to develop proper methodology to accurately and reproducibly determine both body fat content and distribution, including ectopic fat depots. Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) have recently emerged as the gold-standard for accomplishing this task. Here, we will review the use of different MRI techniques currently being used to determine body fat content and distribution. We also discuss the pros and cons of MRS to determine ectopic fat depots in liver, muscle, pancreas and heart and compare these to emerging MRI techniques currently being put forward to create ectopic fat maps. Finally, we will discuss how MRI/MRS techniques are helping in changing the perception of what is healthy and what is normal and desirable body-fat content and distribution.

Accelerated metabolic susceptibility to type 2 diabetes in older women with a history of gestational diabetes

The purpose of this study is to compare central obesity, insulin sensitivity, and cardiovascular disease risk factors between premenopausal and postmenopausal women with a history of gestational diabetes mellitus (GDM), controls, and women with type 2 diabetes (T2DM). Subjects were 73 overweight/obese and sedentary women who had a history of GDM (n=31) and were either premenopausal (n=11, 44±1 years, X±s.e.m.), postmenopausal (n=20, 58±1 years), or without a history of GDM as healthy postmenopausal controls (n=27, 57±1 years) or postmenopausal with T2DM (n=16, 59±1 years). The premenopausal GDM women had higher maximal oxygen uptake and lower visceral fat than the other three groups (P<0.05). BMI, %body fat, subcutaneous abdominal fat, and intramuscular fat did not differ significantly among the four groups. Glucose utilization (M, 3 h 40 mU/m(2) per min hyperinsulinemic-euglycemic clamps) was 27% higher (P=0.05) in pre- than postmenopausal GDM and was not different between premenopausal GDM and postmenopausal controls. M was 28% lower (P=0.06) in postmenopausal GDM than controls and was not significantly different between postmenopausal GDM and T2DM groups. Thus, despite being younger and more physically fit, premenopausal women with prior GDM display similar central obesity, glucose, and metabolic profiles as postmenopausal controls. Postmenopausal women with prior GDM are more insulin resistant than controls of similar age, adiposity, and fitness levels and display comparable glucose utilization rates as similar as women with T2DM suggesting that a prior history of GDM may be an early manifestation of increased risk of later T2DM.

Metabolic syndrome in youth: chimera or useful concept?

Metabolic syndrome (MetS) is a cluster of cardiometabolic risk factors associated with an increased risk for the development of cardiovascular diseases and type 2 diabetes. The prevalence of the MetS is not particularly high in the overall pediatric population (3 %-4 %) but it is as high as 30 %-50 % among overweight youth. Several definitions of the MetS have been used, thus, generating confusion and difficulties in defining the true prevalence of this syndrome. The recent definition of the International Diabetes Federation has tried to standardize the diagnostic criteria. However, there are still some concerns about use of cut-offs values and dichotomous variables, and some debate as to whether a continuous cardiometabolic risk score could be more appropriate for the pediatric population. Although there are some studies that have shown the association between childhood and adolescent MetS with long-term outcomes, further prospective studies are needed to clarify the true value of diagnosing MetS in youth.

The value of pre-operative magnetic resonance spectroscopy in the assessment of steatohepatitis in patients with colorectal liver metastasis

BACKGROUND & AIMS

Neoadjuvant chemotherapy prior to liver surgery for colorectal metastases can cause marked steatosis (≥ 33%) and steatohepatitis defined by non-alcoholic fatty liver disease activity score (NAS) as adverse effects on liver parenchyma. The aim of this study was to evaluate the steatosis level prior to liver resection using proton magnetic resonance spectroscopy ((1)H MRS) and to compare it with digital quantification of steatosis (DQS) and "classical" histopathology.

METHODS

(1)H MRS at 3T evaluated steatosis in 35 patients with colorectal liver metastasis, planned for liver resection. Non-tumorous liver parenchyma samples were obtained after surgery for classical histopathology and DQS utilising automated software for quantification of histopathological slides using image processing.

RESULTS

Classical histopathology defined marked steatosis in nine patients. Histopathology was less reliable than DQS (interclass correlation coefficient - ICC 0.771) or (1)H MRS (ICC 0.722) in steatosis estimation. (1)H MRS showed very similar steatosis levels and high reliability compared to DQS (ICC 0.955). Steatohepatitis was observed in seven patients (NAS ≥ 4) and (1)H MRS was able to predict it with 100% sensitivity and 89% specificity at threshold 10.9%, without knowing lobular inflammation or hepatocyte ballooning. BMI was significantly higher in the groups with marked steatosis and steatohepatitis. Standard blood tests or chemotherapy had no predictive value.

CONCLUSIONS

(1)H MRS is a reliable non-invasive tool for steatosis assessment, and interestingly, it was able to predict steatohepatitis defined by NAS ≥ 4 in patients planned for liver resection of colorectal metastases after neoadjuvant chemotherapy.

Nonalcoholic fatty liver disease markers are associated with insulin resistance in type 1 diabetes

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has been associated with the insulin resistance.

AIMS

To explore the relationship between markers of NAFLD, namely concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALK), γ-glutamyltransferase (GGT), ferritin and bilirubin and insulin resistance in type 1 diabetes.

METHODS

Our study included 353 patients with type 1 diabetes. Insulin sensitivity was measured with estimated glucose disposal rate calculated using the equation: eGDR = 24.31 - (12.22 × WHR) - (3.29 × HT) - (0.57 × HbA1c); WHR = waist to hip ratio, HT = hypertension. Correlations and multiple logistic regressions analysis were performed to identify the relationships between NAFLD associated markers and eGDR, individual components of insulin resistance and risk of insulin resistance.

RESULTS

AST, ALT, AST-to-ALT ratio, ALK and ferritin significantly correlated with insulin resistance measured by eGDR (r = -0.13, -0.14, 0.13, -0.18, and -0.24, respectively; all P < 0.05), and with individual components of insulin resistance, most notably WHR. In a multiple logistic regression model adjusted according to age, sex, duration of diabetes and BMI, increased levels of AST, ALT and ALK resulted in an increased risk for the development of insulin resistance in our subjects (OR = 1.03, 1.02, and 1.01, respectively; all P < 0.05).

CONCLUSIONS

These findings indicate that higher levels of ALT, AST and ALK are additional markers of insulin resistance in type 1 diabetes and suggest that those subjects must be considered as potentially affected not only by a hepatic but also by a multisystemic disease through altered insulin sensitivity.

Visceral abdominal and subfascial femoral adipose tissue have opposite associations with liver fat in overweight and obese premenopausal caucasian women

Abdominal obesity has been associated with liver fat storage. However, the relationships between other body composition depots and metabolic syndrome features with hepatic fat are still unclear. We examined abdominal and thigh adipose tissue (AT) compartments associations with liver fat in 140 overweight and obese premenopausal Caucasian women. Blood lipids and, proinflammatory and atherothrombotic markers associations with hepatic fat were also analyzed. A larger visceral AT (VAT) was related with liver fat (P < 0.05). Contrarily, thigh subfascial AT was inversely related to liver fat (P < 0.05). Increased fasting insulin, triglycerides, PAI-1 concentrations, and a higher total-cholesterol/HDL-cholesterol ratio were also associated with hepatic fat, even after adjustment for VAT (P < 0.05). Thigh subfascial adiposity was inversely associated with liver fat, suggesting a potential preventive role against ectopic fat storage in overweight and obese women. These results reinforce the contribution of an abdominal obesity phenotype associated with a diabetogenic and atherothrombotic profile to liver lipotoxicity.

Does physical inactivity cause nonalcoholic fatty liver disease?

While physical activity represents a key element in the prevention and management of many chronic diseases, we and others believe that physical inactivity is a primary cause of obesity and associated metabolic disorders. Unfortunately, accumulating evidence suggests that we have engineered physical activity out of our normal daily living activity. One such consequence of our sedentary and excessive lifestyle is nonalcoholic fatty liver disease (NAFLD), which is now considered the most common cause of chronic liver disease in Westernized societies. In this review, we will present evidence that physical inactivity, low aerobic fitness, and overnutrition, either separately or in combination, are an underlying cause of NAFLD.

Body and liver fat mass rather than muscle mitochondrial function determine glucose metabolism in women with a history of gestational diabetes mellitus

OBJECTIVE

Ectopic lipid storage in muscle (intramyocellular lipids [IMCL]) and liver (hepatocellular lipids [HCL]) coexists with impaired myocellular flux through ATP synthase (fATPase) in certain cohorts with increased risk of type 2 diabetes. Because women with a history of gestational diabetes mellitus (pGDM) have elevated ectopic lipids and diabetes risk, we tested whether deteriorated energy metabolism contributes to these abnormalities.

RESEARCH DESIGN AND METHODS

A total of 23 glucose-tolerant nonobese pGDM and eight women with normal glucose metabolism during pregnancy with similar age, body mass, and physical activity underwent oral glucose tolerance tests (OGTT) and intravenous glucose tolerance tests at 4-5 years after delivery. OGTT values <463 mL ⋅ min(-1) ⋅ m(-2) were considered to indicate insulin resistance. pGDM were further stratified into insulin-resistant (pGDM-IR) and insulin-sensitive (pGDM-IS) groups. IMCL, HCL, and fATPase were measured with (1)H/(31)P magnetic resonance spectroscopy.

RESULTS

pGDM had 36% higher fat mass and 12% lower insulin sensitivity. Log-transformed fATPase was lower in pGDM (10.6 ± 3.8 µmol ⋅ mL muscle(-1) ⋅ min(-1) vs. 12.1 ± 1.4 µmol ⋅ mL muscle(-1) ⋅ min(-1), P < 0.03) and related to plasma adiponectin after adjustment for body fat (r = 0.44, P < 0.04). IMCL were 61% and 69% higher in pGDM-IR (P < 0.05 vs. pGDM-IS) and insulin resistant women (P < 0.003 vs. insulin sensitive), respectively. HCL were doubled (P < 0.05) in pGDM and insulin resistant women, and correlated positively with body fat mass (r = 0.50, P < 0.01) and inversely with insulin sensitivity (r = -0.46, P < 0.05).

CONCLUSIONS

Glucose-tolerant pGDM show increased liver fat but only slightly lower muscular insulin sensitivity and ATP synthesis. This suggests that alteration of hepatic lipid storage represents an early and predominant abnormality in this cohort.

Gestational diabetes: emerging concepts in pathophysiology

Gestational diabetes affects 3 to 5% of pregnancies in the United Kingdom, contributing to significant maternal and fetal morbidity. Understanding the pathophysiology is important as it guides diagnostic screening and treatment. The insulin resistance of normal pregnancy facilitates provision of metabolic substrates to the fetus and is multifactorial in origin. Recent identification of hepatic and skeletal muscle lipid deposition in Type 2 diabetics, demonstrated by novel magnetic resonance spectroscopy techniques, is likely to be the underlying cause of pathological insulin resistance. Similar mechanisms almost certainly underlie gestational diabetes, although further studies are required to prove this. Women who develop gestational diabetes have demonstrable insulin resistance prior to pregnancy that is part of a chronic process of lipid accumulation ultimately leading to type 2 diabetes later in life. The importance of lifestyle advice and dietary modification and the rationale behind the use of metformin are thus explained.

Fitness versus fatness: moving beyond weight loss in nonalcoholic fatty liver disease

The rapid emergence of nonalcoholic fatty liver disease (NAFLD) as a cause of both liver-related morbidity and mortality and cardiometabolic risk has led to the search for effective lifestyle strategies to reduce liver fat. Lifestyle intervention comprising dietary restriction in conjunction with increased physical activity has shown clear hepatic benefits when weight loss approximating 3%-10% of body weight is achieved. Yet, the poor sustainability of weight loss challenges the current therapeutic focus on body weight and highlights the need for alternative strategies for NAFLD management. Epidemiologic data show an independent relationship between liver fat, physical activity, and fitness, and a growing body of longitudinal research demonstrates that increased physical activity participation per se significantly reduces hepatic steatosis and serum aminotransferases in individuals with NAFLD, independent of weight loss. Mechanistic insights to explain this interaction are outlined, and recommendations for the implementation of lifestyle intervention involving physical activity are discussed. In light of the often poor sustainability of weight loss strategies, and the viability of physical activity therapy, clinicians should assess physical fitness and physical activity habits, educate patients on the benefits of fitness outside of weight loss, and focus on behavior change which promotes physical activity adoption.

Insulin resistance and metabolic syndrome in the pediatric population

The metabolic syndrome is a constellation of specific anthropometric, physiological, and biochemical abnormalities predisposing affected individuals to the development of diabetes and cardiovascular disease. The syndrome is well described in the adult literature. However, its description in the pediatric literature is more limited. Due in large part to the normal physiological changes that occur in children and adolescents with respect to growth and puberty, investigators have also struggled to establish a standard definition of the syndrome in the pediatric age group, hindering coordinated research efforts. However, whatever definition of the syndrome is used, the prevalence of the metabolic syndrome in the pediatric age group has increased worldwide. Insulin resistance is the principal metabolic abnormality that is common to the development of the metabolic syndrome in both children and adults. This review summarizes current research regarding the pathophysiology of insulin resistance and how this may contribute to specific abnormalities seen in children and adolescents with the metabolic syndrome. Specifically, insulin resistance in pediatric patients is correlated with cardiovascular risk factors such as elevated blood pressure, dyslipidemia, and type 2 diabetes mellitus, all of which are significant risk factors for adult disease. In addition, current treatment and prevention strategies, including lifestyle modifications, pharmacologic agents, and certain surgical therapies, are highlighted. The need for collaborative changes at the family, school, city, state, and national levels to address the growing prevalence of the metabolic syndrome in the pediatric age group is also reviewed.

Feasibility of assessing liver lipid by proton magnetic resonance spectroscopy in healthy normal and overweight prepubertal children

BACKGROUND

Intramyocellular and intrahepatic (IHL) lipids are significantly associated with insulin resistance in adults and adolescents and may represent an early marker for developing the metabolic syndrome or type 2 diabetes.

METHODS

During the pilot phase of a larger cross-sectional study, we used proton magnetic resonance spectroscopy ((1)H-MRS) to determine the feasibility of noninvasively evaluating IHL in 11 male (n = 4) and female (n = 7) prepubertal children using a standard clinical system and to determine whether IHL is correlated with adiposity, fasting insulin and glucose, and liver enzymes.

RESULTS

Body mass index (BMI) (range, 13.4-32.4 kg/m(2)) and IHL stores (range, 0.07-3.2% relative to an oil phantom) were variable. IHL was correlated with body mass (r = 0.66, P = 0.037), BMI (r = 0.73, P = 0.016), percentage body fat (r = 0.73, P = 0.01, n = 10), waist circumference (r = 0.85, P = 0.016), and serum lactate dehydrogenase concentration (r = 0.77, P = 0.03) but was not significantly correlated with other markers of liver damage, including aspartate aminotransferase activity (r = 0.59, P = 0.09, n = 9) and alkaline phosphatase concentrations (r = 0.60, P = 0.087). IHL was also (P < 0.01) correlated with fasting insulin concentration (r = 0.85, P = 0.03, n = 6) and insulin resistance (r = 0.94, P = 0.006, n = 6), but these correlations were driven by the results for one child.

CONCLUSIONS

These preliminary data suggest that (1)H-MRS obtained in a standard pediatric clinical environment may be used to determine IHL in healthy normal and overweight prepubertal youth. This noninvasive technique may prove useful in identifying early markers of the metabolic syndrome in at-risk youth.

Liver fat and lipid oxidation in humans

BACKGROUND

Studies in animals show that changes in hepatic fatty acid oxidation alter liver fat content. Human data regarding whole-body and hepatic lipid oxidation are controversial and based on studies of only a few subjects.

AIMS

We examined whether whole-body and hepatic lipid oxidation are altered in subjects with non-alcoholic fatty liver disease (NAFLD) compared with controls.

METHODS

In vivo measurements of rates of substrate oxidation and insulin sensitivity (using the euglycaemic hyperinsulinaemic clamp technique in combination with indirect calorimetry and infusion of [3-(3)H]glucose) were performed in subjects with NAFLD [mean liver fat 14.0% (interquartile range 7.5-20.5%), n=29] and in control subjects [1.6% (1.0-3.0%), n=29]. Liver fat was measured using proton magnetic resonance spectroscopy. Plasma concentrations of 3-hydroxybutyrate (3-OHB) were measured as markers of hepatic lipid oxidation.

RESULTS

In the basal state, substrate oxidation rates and serum 3-OHB concentrations were comparable in subjects with and without NAFLD. Plasma 3-OHB concentrations were similarly suppressed by insulin in both the groups. During the insulin infusion, whole-body lipid oxidation was inversely correlated with insulin-stimulated glucose disposal (r=-0.48, P<0.0001), which was lower in subjects with NAFLD [3.7+/-0.2 mg/(kg fat-free mass min)] than in the control subjects [5.0+/-0.3 mg/(kg fat-free mass min), P=0.0008].

CONCLUSIONS

Hepatic lipid oxidation is unchanged in NAFLD. Whole-body lipid oxidation is increased because of peripheral insulin resistance. These data imply that alterations in hepatic fatty acid oxidation do not contribute to liver fat content in humans.