Predictors of impaired glucose regulation in patients with non-alcoholic fatty liver disease

Insulin receptor substrate 2 gene Gly1057Asp polymorphism is a risk factor for nonalcoholic fatty liver disease

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD), which is an emerging global chronic liver disease, has a close association with insulin resistance. We aimed to determine whether the Gly1057Asp (rs1805097) polymorphism of the insulin receptor substrate 2 (IRS2) gene is associated with NAFLD.

METHODS

Using the polymerase chain reaction-restriction fragment length polymorphism method, 135 patients with biopsy-proven NAFLD and 135 controls underwent IRS2 genotype analysis.

RESULTS

Genotype and allele distributions of the IRS2 gene Gly1057Asp variant conformed to the Hardy-Weinberg equilibrium in both the case and control groups (P > .05). The Asp/Asp genotype of IRS2 gene Gly1057Asp polymorphism compared with Gly/Gly genotype was associated with a 2.1-fold increased risk for NAFLD after adjustment for confounding factors (P = .029; odds ratio = 2.10, 95% CI = 1.23-3.97).

CONCLUSION

Our findings revealed for the first time that the Gly1057Asp Asp/Asp genotype of the IRS2 gene is a marker of increased NAFLD susceptibility; however, studies in other populations are required to confirm the results.

Global epidemiology of type 2 diabetes in patients with NAFLD or MAFLD: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD) shares common pathophysiological mechanisms with type 2 diabetes, making them significant risk factors for type 2 diabetes. The present study aimed to assess the epidemiological feature of type 2 diabetes in patients with NAFLD or MAFLD at global levels.

METHODS

Published studies were searched for terms that included type 2 diabetes, and NAFLD or MAFLD using PubMed, EMBASE, MEDLINE, and Web of Science databases from their inception to December 2022. The pooled global and regional prevalence and incidence density of type 2 diabetes in patients with NAFLD or MAFLD were evaluated using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

RESULTS

A total of 395 studies (6,878,568 participants with NAFLD; 1,172,637 participants with MAFLD) from 40 countries or areas were included in the meta-analysis. The pooled prevalence of type 2 diabetes among NAFLD or MAFLD patients was 28.3% (95% confidence interval 25.2-31.6%) and 26.2% (23.9-28.6%) globally. The incidence density of type 2 diabetes in NAFLD or MAFLD patients was 24.6 per 1000-person year (20.7 to 29.2) and 26.9 per 1000-person year (7.3 to 44.4), respectively.

CONCLUSIONS

The present study describes the global prevalence and incidence of type 2 diabetes in patients with NAFLD or MAFLD. The study findings serve as a valuable resource to assess the global clinical and economic impact of type 2 diabetes in patients with NAFLD or MAFLD.

Fibrosis and hepatic regeneration mechanism

Liver cirrhosis is the final stage of continuous hepatic inflammatory activity derived by viral, metabolic or autoimmune origin. In the last years, cirrhosis was considered a unique and static condition; recently was accepted some patients subgroups with different liver injury degrees that coexist under the same diagnosis, with implications about the natural disease history. The liver growth factor (LGF) is a potent in vivo and in vitro mitogenic agent and an inducer of hepatic regeneration (HR) through the hepatocytes DNA synthesis. The clinical implications of the LGF levels in cirrhosis, are not clear and even with having a fundamental role in the liver regeneration processes, the studies suggest that it could be a cirrhosis severity marker, in acute liver failure and in chronic hepatitis. Its role as predictor of mortality in fulminant hepatic insufficiency patients has been suggested. HR is one of the most enigmatic and fascinating biological phenomena. The rapid volume and liver function restoration after a major hepatectomy (>70%) or severe hepatocellular damage and its strict regulation of tissue damage response after the cessation, is an exclusive property of the liver. HR is the clinical applications fundament, such as extensive hepatic resections (>70% of the liver parenchyma), segmental transplantation or living donor transplantation, sequential hepatectomies, isolated portal embolization or associated with in situ hepatic transection, temporary artificial support in acute liver failure and the possible cell therapy clinical applications.

Hepatogenous Diabetes: A Primer

As liver is one of the primary organs involved in glucose homeostasis, it is not surprising that patients with liver dysfunction in chronic liver disease usually develop impaired glucose tolerance and subsequently overt diabetes later in their natural course. Diabetes that develops after the onset of cirrhosis of liver is usually referred to as hepatogenous diabetes (HD). It is an underrecognized and a hallmark endocrinological event in chronic liver disease. HD is associated with a higher risk of developing hepatic decompensations, such as ascites, variceal bleeding, hepatic encephalopathy, renal dysfunction, refractory ascites, and hepatocellular carcinoma along with reduced survival rates than normoglycemic patients with cirrhosis of liver. It is quite different from type 2 diabetes mellitus with the absence of classical risk factors, dissimilar laboratory profiles, and decreased incidence of microvascular complications. Furthermore, the management of patients with HD is challenging because of altered pharmacokinetics of most antidiabetic drugs and increased risk of hypoglycemia and other adverse effects. Hence, a clear understanding of the epidemiology, pathophysiology, clinical implications, laboratory diagnosis, and management of HD is essential for both hepatologists as well as endocrinologists, which is narrated briefly in this review.

Probiotics in Adolescent Prediabetes: A Pilot RCT on Glycemic Control and Intestinal Bacteriome

Dysbiosis of intestinal ecology could be implicated in prediabetes. The aim of this pilot randomized controlled trial (RCT) was to collect preliminary data on the effects of probiotic supplementation (Vivomixx©) on markers of glucose metabolism, intestinal microbiome composition, and intestinal health indices, of prediabetic adolescents. The intervention group was administered probiotic sachets twice daily for 4 months, while both intervention and control groups received weekly consultation sessions for a healthier lifestyle. Thirty-two participants were recruited (1.3 participants per month) and were randomized (16 in control and 16 in intervention group). Fifteen of them signed the inform consent and never entered the study (6 in control and 9 in intervention group). Thus, seventeen participants completed the study (10 in control and 7 in intervention group), with no serious adverse events. After the 4-month intervention, no difference was observed in the markers of glycemic control between the two groups, although a minor effect was observed for fasting glucose at 1-month, probably due to the initial higher adherence to the probiotic supplements. Modifications of the protocol procedures are warranted because of the high attrition rates and suboptimal compliance that were noted. Future studies and further RCTs with larger samples need to be conducted to fully elucidate the potential effects of probiotics in the glycemic control of prediabetic adolescents.

Regression to Normal Glucose Regulation in American Indians and Alaska Natives of a Diabetes Prevention Program

OBJECTIVE

This study evaluated whether regression from impaired glucose regulation (IGR) to normal glucose regulation (NGR) after 1 year of a lifestyle intervention reduces diabetes risk in American Indians and Alaska Natives (AI/ANs). In addition, we sought to identify predictors for regression to NGR and understand possible mechanisms for the association between NGR and future diabetes risk.

RESEARCH DESIGN AND METHODS

Data from participants enrolled from 2006 to 2009 in the Special Diabetes Program for Indians Diabetes Prevention Program with IGR at baseline and an oral glucose tolerance test at year 1 were analyzed (N = 1,443). Cox regression models were used to estimate the subsequent diabetes risk (year 1 to year 3) by year 1 glucose status. Mediation analysis was used to estimate the proportions of the association between year 1 glycemic status and diabetes risk explained by specific factors.

RESULTS

Those who reverted to NGR at year 1 (38%) had lower diabetes risk than those with sustained IGR (adjusted hazard ratio 0.28, 95% CI 0.12-0.67). The lower risk associated with regression to NGR was explained by both baseline risk factors and differences in weight loss. Metformin use, weight loss, and an increase in exercise were modifiable risk factors associated with higher odds of regression to NGR.

CONCLUSIONS

Patients with prediabetes who reverted to NGR had a reduced risk of developing type 2 diabetes over the next 2 years. Both baseline and modifiable risk factors explained the risk reduction associated with NGR.

GLP-2 Dysregulates Hepatic Lipoprotein Metabolism, Inducing Fatty Liver and VLDL Overproduction in Male Hamsters and Mice

Fundamental complications of insulin resistance and type 2 diabetes include the development of nonalcoholic fatty liver disease and an atherogenic fasting dyslipidemic profile, primarily due to increases in hepatic very-low-density lipoprotein (VLDL) production. Recently, central glucagon-like peptide-2 receptor (GLP2R) signaling has been implicated in regulating hepatic insulin sensitivity; however, its role in hepatic lipid and lipoprotein metabolism is unknown. We investigated the role of glucagon-like peptide-2 (GLP-2) in regulating hepatic lipid and lipoprotein metabolism in Syrian golden hamsters, C57BL/6J mice, and Glp2r-/- mice consuming either a normal chow or high-fat diet (HFD). In the chow-fed hamsters, IP GLP-2 administration significantly increased fasting dyslipidemia, hepatic VLDL production, and the expression of key genes involved in hepatic de novo lipogenesis. In HFD-fed hamsters and chow-fed mice, GLP-2 administration exacerbated or induced hepatic lipid accumulation. HFD-fed Glp2r-/- mice displayed reduced glucose tolerance, VLDL secretion, and microsomal transfer protein lipid transfer activity, as well as exacerbated fatty liver. Thus, we conclude that GLP-2 plays a lipogenic role in the liver by increasing lipogenic gene expression and inducing hepatic steatosis, fasting dyslipidemia, and VLDL overproduction. In contrast, the lack of Glp2r appears to interfere with VLDL secretion, resulting in enhanced hepatic lipid accumulation. These studies have uncovered a role for GLP-2 in maintaining hepatic lipid and lipoprotein homeostasis.

Increased liver AGEs induce hepatic injury mediated through an OST48 pathway

The protein oligosaccharyltransferase-48 (OST48) is integral to protein N-glycosylation in the endoplasmic reticulum (ER) but is also postulated to act as a membrane localised clearance receptor for advanced glycation end-products (AGE). Hepatic ER stress and AGE accumulation are each implicated in liver injury. Hence the objective of this study was to increase the expression of OST48 and examine the effects on hepatic function and structure. Groups of 8 week old male mice (n = 10-12/group) over-expressing the gene for OST48, dolichyl-diphosphooligosaccharide-protein glycosyltransferase (DDOST+/-), were followed for 24 weeks, while randomised to diets either low or high in AGE content. By week 24 of the study, either increasing OST48 expression or consumption of high AGE diet impaired liver function and modestly increased hepatic fibrosis, but their combination significantly exacerbated liver injury in the absence of steatosis. DDOST+/- mice had increased both portal delivery and accumulation of hepatic AGEs leading to central adiposity, insulin secretory defects, shifted fuel usage to fatty and ketoacids, as well as hepatic glycogen accumulation causing hepatomegaly along with hepatic ER and oxidative stress. This study revealed a novel role of the OST48 and AGE axis in hepatic injury through ER stress, changes in fuel utilisation and glucose intolerance.

Associations Between Sleep Habits and Dysglycemia in Adults in the United States: A Cross-Sectional Analysis

OBJECTIVES

To examine the independent and joint associations between sleep duration and quality with glycated hemoglobin (A1C) levels and dysglycemia in non-institutionalized adults living in the United States.

METHODS

Data from the United States National Health and Nutrition Examination Survey (2005-2008) were used (N=9478; ≥20 years). Information on sleep quantity and quality were derived from the Sleep Disorders Questionnaire and used to classify sleep quality as good, fair, poor, or very poor.

RESULTS

Overall, sleep quantity and quality were related to A1C levels in our unadjusted models. In general, a U-shaped relationship between sleep quantity and A1C levels was observed. Compared to those who slept for 7 to 8 hours per night, sleeping for 4 hours or fewer was associated with higher A1C levels (mean, 95% CI; 5.49%, 5.45 to 5.53 vs. 5.69%, 5.60 to 5.77; p<0.05), whereas only those reporting good and very poor sleep quality had higher A1C levels than poor sleepers (mean, 95% CI: 5.63%, 5.57 to 5.69; 5.56%, 5.52 to 5.60 vs. 5.46%, 5.42 to 5.50; p<0.05). The relationships among sleep duration and quality and the joint effects of sleep quality and quantity and dysglycemia were not significant after multivariable adjustment.

CONCLUSIONS

Between 7 and 8 hours of sleep and fair/poor sleep quality were associated with optimal A1C levels, while sleeping for fewer or more hours appeared to increase dysglycemia, without adjustment for covariates. These relationships were attenuated following multivariable adjustment. Future research is necessary to refine our understanding of the sleep/glycemic-control relationship to provide a context for the clinical significance of these findings for longer-term A1C control in adults with diabetes.

The Correlation and Risk Factors between Carotid Intima-Media Thickening and Alcoholic Liver Disease Coupled with Helicobacter pylori Infection

The aim of this study was to explore the associations and differences in influencing factors between alcoholic liver disease (ALD) coupled with Helicobacter pylori infection and atherosclerosis and to determine whether there is a "double hit phenomenon" in atherosclerosis patients with ALD and H. pylori infections. Included cases (n = 160) were categorized into 4 groups: 41 cases of ALD coupled with H. pylori infections (group A), 35 cases of H. pylori infections without ALD (group B), 37 cases of ALD without H. pylori infections (group C), and 47 normal control cases (group D). CIMT was significantly greater in group A than in groups B and D (P = 0.005 and P = 0.001, respectively). The GLM univariate analysis found that CIMT was significantly greater in group A than in groups B, C and D (P = 0.018, P = 0.001 and P = 0.009, respectively). We found that BMI and ALT, AST and ApoB levels were independent predictors of CIMT (P = 0.000, P = 0.000, P = 0.012 and P = 0.014, respectively). ALD coupled with H. pylori infection may result in significant CIMT thickening, but H. pylori infection without ALD and ALD without H. pylori infection does not, suggesting that a "double hit phenomenon" occurs. Additionally, BMI, and ALT, AST and ApoB levels were independent risk factors for increased CIMT.

Significance of oral glucose tolerance tests in non-alcoholic fatty liver disease patients with a fasting plasma glucose level of <126 mg/dL and HbA1c level of ≤ 6.4% in Japan

OBJECTIVE

The aim of this study was to clarify the indications for oral glucose tolerance tests (OGTT) in non-alcoholic fatty liver disease (NAFLD) subjects with a HbA1c level of ≤6.4%, fasting plasma glucose (FPG) level of <126 mg/dL and no history of diabetes.

PATIENTS

A total of 569 NAFLD subjects underwent 75-g OGTT. The plasma glucose and insulin levels were analyzed periodically for three hours during the OGTT examinations. Impaired fasting glucose (IFG) was defined as a plasma glucose level of ≥100 mg/dL to <126 mg/dL. Diabetes was defined as a two-hour post-load plasma glucose level of ≥200 mg/dL. Elevated insulin resistance was defined as a homeostasis model assessment-insulin resistance (HOMA-IR) of ≥2.5. Insulin secretory insufficiency was defined as an insulinogenic index of <0.4.

RESULTS

The prevalence of diabetes on the OGTT was 7.7% (44/569) among the NAFLD patients with an HbA1c level of ≤6.4%, FPG level of <126 mg/dL and no history of diabetes. A multivariate analysis showed that diabetes occurred more frequently when the subjects had IFG [odds ratio (OR) 5.13; 95% confidential interval (CI) 3.01-8.76; p<0.001] and an HbA1c level of 5.7-6.4% (OR 5.45; 95% CI 3.33-8.93; p<0.001). Of the NAFLD subjects with both IFG and an HbA1c level of 5.7-6.4%, 22.8% (28/123) exhibited a pattern of diabetes on OGTT. Regarding insulin dynamics, among the NAFLD subjects with both IFG and an HbA1c level of 5.7-6.4%, 25.2% (31/123) had elevated IR alone, 25.2% (31/123) had insulin secretory deficiency alone and 27.6% (34/123) had both elevated insulin resistance and insulin secretory deficiency.

CONCLUSION

NAFLD subjects with IFG and an HbA1c level of 5.7-6.4% should undergo OGTT in order to determine whether they have diabetes and/or abnormal insulin dynamics.

Curcumin inhibits gene expression of receptor for advanced glycation end-products (RAGE) in hepatic stellate cells in vitro by elevating PPARγ activity and attenuating oxidative stress

BACKGROUND AND PURPOSE

Diabetes is characterized by hyperglycaemia, which facilitates the formation of advanced glycation end-products (AGEs). Type 2 diabetes mellitus is commonly accompanied by non-alcoholic steatohepatitis, which could lead to hepatic fibrosis. Receptor for AGEs (RAGE) mediates effects of AGEs and is associated with increased oxidative stress, cell growth and inflammation. The phytochemical curcumin inhibits the activation of hepatic stellate cells (HSCs), the major effectors during hepatic fibrogenesis. The aim of this study was to explore the underlying mechanisms of curcumin in the elimination of the stimulating effects of AGEs on the activation of HSCs. We hypothesize that curcumin eliminates the effects of AGEs by suppressing gene expression of RAGE.

EXPERIMENTAL APPROACH

Gene promoter activities were evaluated by transient transfection assays. The expression of rage was silenced by short hairpin RNA. Gene expression was analysed by real-time PCR and Western blots. Oxidative stress was evaluated.

KEY RESULTS

AGEs induced rage expression in cultured HSCs, which played a critical role in the AGEs-induced activation of HSCs. Curcumin at 20 µM eliminated the AGE effects, which required the activation of PPARγ. In addition, curcumin attenuated AGEs-induced oxidative stress in HSCs by elevating the activity of glutamate-cysteine ligase and by stimulating de novo synthesis of glutathione, leading to the suppression of gene expression of RAGE.

CONCLUSION AND IMPLICATIONS

Curcumin suppressed gene expression of RAGE by elevating the activity of PPARγ and attenuating oxidative stress, leading to the elimination of the AGE effects on the activation of HSCs.

LINKED ARTICLE

This article is commented on by Stefanska, pp. 2209-2211 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2012.01959.x.