Understanding the link between type 2 diabetes mellitus and Parkinson's disease:role of brain insulin resistance

Type 2 diabetes mellitus and Parkinson's disease are chronic diseases linked to a growing pandemic that affects older adults and causes significant socio-economic burden.Epidemiological data supporting a close relationship between these two aging-related diseases have resulted in the investigation of shared pathophysiological molecular mechanisms.Impaired insulin signaling in the brain has gained increasing attention during the last decade and has been suggested to contribute to the development of Parkinson's disease through the dysregulation of several pathological processes.The contribution of type 2 diabetes mellitus and insulin resistance in neurodegeneration in Parkinson's disease,with emphasis on brain insulin resistance,is extensively discussed in this article and new therapeutic strategies targeting this pathological link are presented and reviewed.

Novel insights into D-Pinitol based therapies:a link between tau hyperphosphorylation and insulin resistance

Alzheimer’s disease is a neurodegenerative disorder characterized by the amyloid accumulation in the brains of patients with Alzheimer’s disease.The pathogenesis of Alzheimer’s disease is mainly mediated by the phosphorylation and aggregation of tau protein.Among the multiple causes of tau hyperphosphorylation,brain insulin resistance has generated much attention,and inositols as insulin sensitizers,are currently considered candidates for drug development.The present narrative review revises the interactions between these three elements:Alzheimer’s disease-tau-inositols,which can eventually identify targets for new disease modifiers capable of bringing hope to the millions of people affected by this devastating disease.

Insulin resistance as the molecular link between diabetes and Alzheimer's disease

Diabetes mellitus(DM)and Alzheimer's disease(AD)are two major health concerns that have seen a rising prevalence worldwide.Recent studies have indicated a possible link between DM and an increased risk of developing AD.Insulin,while primarily known for its role in regulating blood sugar,also plays a vital role in protecting brain functions.Insulin resistance(IR),especially prevalent in type 2 diabetes,is believed to play a significant role in AD's development.When insulin signalling becomes dysfunctional,it can negatively affect various brain functions,making individuals more susceptible to AD's defining features,such as the buildup of beta-amyloid plaques and tau protein tangles.Emerging research suggests that addressing insulin-related issues might help reduce or even reverse the brain changes linked to AD.This review aims to explore the relationship between DM and AD,with a focus on the role of IR.It also explores the molecular mechanisms by which IR might lead to brain changes and assesses current treatments that target IR.Understanding IR's role in the connection between DM and AD offers new possibilities for treatments and highlights the importance of continued research in this interdisciplinary field.

Effects of axylitol-casein complex on insulin resistance and gut microbiota composition in high-fat-diet+streptozotocin-induced type 2 diabetes mellitus mice

This study investigated the effects of a xylitol-casein non-covalent complex(XC)on parameters related to type 2 diabetes mellitus(T2DM),in addition to related changes in gut microbiome composition and functions.High-fat-diet(HFD)+streptozotocin(STZ)-induced T2DM mice were treated with xylitol(XY),casein(CN),and XC,after which fecal samples were collected for gut microbiota composition and diversity analyses based on 16S rRNA high-throughput sequencing and multivariate statistics.XC decreased body weight and improved glucose tolerance,insulin sensitivity,pancreas impairment,blood lipid levels,and liver function in T2DM mice compared to XY-and CN-treated mice.Furthermore,XC modulated theα-diversity,β-diversity and gut microbiota composition.Based on Spearman’s correlation analysis,the relative abundances of Alistipes,Bacteroides,and Faecalibaculum were positively correlated and those of Akkermansia,Lactobacillus,Bifidobacterium,and Turicibacter were negatively correlated with the phenotypes related to the improvement of T2DM.In conclusion,we found that XC alleviated insulin resistance by restoring the gut microbiota of T2DM mice.Our results provide strong evidence for the beneficial effects of XC on T2DM and motivation for further investigation in animal models and,eventually,human trials.

Palmitoleic acid on top of HFD ameliorates insulin resistance independent of diacylglycerols and alters gut microbiota in C57BL/6J mice

With the prevalence of obesity and obesity-related metabolic syndrome,such as insulin resistance in recent years,it is urgent to explore effective interventions to prevent the progression of obesity-related metabolic syndrome.Palmitoleic acid is a monounsaturated fatty acid that is available from dietary sources,mainly derived from marine products.P almitoleic acid plays a positive role in maintaining glucose homeostasis and reducing inflammation.However,it is still unknow the mechanism of palmitoleic acid in ameliorating insulin resistance.Here,we investigated the effects of palmitoleic acid on chow diet(CD)-fed and high-fat diet(HFD)-fed mice,which were fed CD or HFD for 12 weeks before administration.We administrated mice with BSA(control),oleic acid,or palmitoleic acid for 6 weeks on top of CD or HFD feeding.We found that palmitoleic acid only improved glucose homeostasis in HFD-fed obese mice by increasing glucose clearance and reducing HOMA-IR.Further study explored that palmitoleic acid changed the composition of gut microbiota by decreasing Firmicutes population and increasing Bacteroidetes population.In colon,palmitoleic acid increased intestinal tight junction integrity and reduced inflammation.Moreover,palmitoleic acid decreased macrophage infiltration in liver and adipose tissue and increase glucose uptake in adipose tissue.Diacylglycerol(DAG)in tissue(for example,liver)is found to positively correlated with HOMA-IR.HFD enhanced the levels of DAGs in liver but not in adipose tissue in this study.Palmitoleic acid did not reverse the high DAG levels induced by HFD in liver.Therefore,in HFD-fed mice,palmitoleic acid reduced insulin resistance by an independent-manner of DAGs.It might be associated with the beneficial effects of palmitoleic acid on altering the gut microbiota composition,improving of intestinal barrier function,and downregulating the inflammation in colon,liver,and adipose tissue.

Growth hormone improves insulin resistance in visceral adipose tissue after duodenal-jejunal bypass by regulating adiponectin secretion

BACKGROUND The mechanism of improvement of type 2 diabetes after duodenal-jejunal bypass(DJB)surgery is not clear.AIM To study the morphological and functional changes in adipose tissue after DJB and explore the potential mechanisms contributing to postoperative insulin sensitivity improvement of adipose tissue in a diabetic male rat model.METHODS DJB and sham surgery was performed in a-high-fat-diet/streptozotocin-induced diabetic rat model.All adipose tissue was weighed and observed under microscope.Use inguinal fat to represent subcutaneous adipose tissue(SAT)and mesangial fat to represent visceral adipose tissue.RNA-sequencing was utilized to evaluate gene expression alterations adipocytes.The hematoxylin and eosin staining,reverse transcription-quantitative polymerase chain reaction,western blot,and enzyme-linked immunosorbent assay were used to study the changes.Insulin resistance was evaluated by immunofluorescence.RESULTS After DJB,whole body blood glucose metabolism and insulin sensitivity in adipose tissue improved.Fat cell volume in both visceral adipose tissue(VAT)and SAT increased.Compared to SAT,VAT showed more significantly functional alterations after DJB and KEGG analysis indicated growth hormone(GH)pathway and downstream adiponectin secretion were involved in metabolic regulation.The circulating GH and adiponectin levels and GH receptor and adiponectin levels in VAT increased.Cytological experiment showed that GH stimulated adiponectin secretion and improve insulin sensitivity.CONCLUSION GH improves insulin resistance in VAT in male diabetic rats after receiving DJB,possibly by increasing adiponectin secretion.

Effects of vitamin family members on insulin resistance and diabetes complications

The following letter to the editor highlights the article“Effects of vitamin D supplementation on glucose and lipid metabolism in patients with type 2 diabetes mellitus and risk factors for insulin resistance”in World J Diabetes 2023 Oct 15;14(10):1514-1523.It is necessary to explore the role of vitamin family members in insulin resistance and diabetes complications.

Therapeutic effects of Lingguizhugan decoction in a rat model of high-fat diet-induced insulin resistance

BACKGROUND Lingguizhugan(LGZG)decoction is a widely used classic Chinese medicine formula that was recently shown to improve high-fat diet(HFD)-induced insulin resistance(IR)in animal studies.AIM To assess the therapeutic effect of LGZG decoction on HFD-induced IR and explore the potential underlying mechanism.METHODS To establish an IR rat model,a 12-wk HFD was administered,followed by a 4-wk treatment with LGZG.The determination of IR status was achieved through the use of biochemical tests and oral glucose tolerance tests.Using a targeted metabolomics platform to analyze changes in serum metabolites,quantitative real-time PCR(qRT-PCR)was used to assess the gene expression of the ribosomal protein S6 kinase beta 1(S6K1).RESULTS In IR rats,LGZG decreased body weight and indices of hepatic steatosis.It effectively controlled blood glucose and food intake while protecting islet cells.Metabolite analysis revealed significant differences between the HFD and HFDLGZG groups.LGZG intervention reduced branched-chain amino acid levels.Levels of IR-related metabolites such as tryptophan,alanine,taurine,and asparagine decreased significantly.IR may be linked to amino acids due to the contemporaneous increase in S6K1 expression,as shown by qRT-PCR.CONCLUSIONS Our study strongly suggests that LGZG decoction reduces HFD-induced IR.LGZG may activate S6K1 via metabolic pathways.These findings lay the groundwork for the potential of LGZG as an IR treatment.

KAT7/HMGN1 signaling epigenetically induces tyrosine phosphorylation-regulated kinase 1A expression to ameliorate insulin resistance in Alzheimer’s disease

BACKGROUND Epidemiological studies have revealed a correlation between Alzheimer’s disease(AD)and type 2 diabetes mellitus(T2D).Insulin resistance in the brain is a common feature in patients with T2D and AD.KAT7 is a histone acetyltransferase that participates in the modulation of various genes.AIM To determine the effects of KAT7 on insulin patients with AD.METHODS APPswe/PS1-dE9 double-transgenic and db/db mice were used to mimic AD and diabetes,respectively.An in vitro model of AD was established by Aβstimulation.Insulin resistance was induced by chronic stimulation with high insulin levels.The expression of microtubule-associated protein 2(MAP2)was assessed using immunofluorescence.The protein levels of MAP2,Aβ,dual-specificity tyrosine phosphorylation-regulated kinase-1A(DYRK1A),IRS-1,p-AKT,total AKT,p-GSK3β,total GSK3β,DYRK1A,and KAT7 were measured via western blotting.Accumulation of reactive oxygen species(ROS),malondialdehyde(MDA),and SOD activity was measured to determine cellular oxidative stress.Flow cytometry and CCK-8 assay were performed to evaluate neuronal cell death and proliferation,respectively.Relative RNA levels of KAT7 and DYRK1A were examined using quantitative PCR.A chromatin immunoprecipitation assay was conducted to detect H3K14ac in DYRK1A.RESULTS KAT7 expression was suppressed in the AD mice.Overexpression of KAT7 decreased Aβaccumulation and MAP2 expression in AD brains.KAT7 overexpression decreased ROS and MDA levels,elevated SOD activity in brain tissues and neurons,and simultaneously suppressed neuronal apoptosis.KAT7 upregulated levels of p-AKT and p-GSK3βto alleviate insulin resistance,along with elevated expression of DYRK1A.KAT7 depletion suppressed DYRK1A expression and impaired H3K14ac of DYRK1A.HMGN1 overexpression recovered DYRK1A levels and reversed insulin resistance caused by KAT7 depletion.CONCLUSION We determined that KAT7 overexpression recovered insulin sensitivity in AD by recruiting HMGN1 to enhance DYRK1A acetylation.Our findings suggest that KAT7 is a novel and promising therapeutic target for the resistance in AD.

Ghrelin regulates insulin resistance by targeting insulin-like growth factor-1 receptor via miR-455-5p in hepatic cells

Objective: To explore the mechanism by which ghrelin regulates insulin sensitivity through modulation of miR-455-5p in hepatic cells. Methods: HepG2 cells were treated with or without DAG (1 μM). Glucose consumption, intracellular glycogen content, phosphorylation of PI3K and Akt stimulated by insulin, expression of miR-455-5p, as well as IGF-1R protein level were analyzed. In addition, bioinformatic analysis, dual luciferase reporter assay, miR- 455-5p mimic or inhibitor treatment was conducted to investigate the molecular mechanisms. Results: High glucose treatment upregulated miR-455-5p expression but reduced glucose consumption and glycogen content. DAG reversed the effect of high glucose on glucose metabolism, increased protein level of IGF-1R and phosphorylation of PI3K/Akt stimulated by insulin, as well as downregulated miR-455-5p expression. Bioinformatic analysis indicated IGF-1R was the target of miR-455-5p. Dual luciferase reporter assay, as well as transfection with miR-455-5p mimic/inhibitor confirmed that DAG activated IGF-1R/PI3K/Akt signaling via inhibiting miR-455-5p. Conclusion: DAG improves insulin resistance via miR-455-5p- mediated activation of IGF-1R/PI3K/Akt system, suggesting that suppression of miR-455-5p or activation of DAG may be potential targets for T2DM therapy.

Mapping the global research landscape on nonalcoholic fatty liver disease and insulin resistance:A visualization and bibliometric study

BACKGROUND Nonalcoholic fatty liver disease(NAFLD)is a liver condition that is prevalent worldwide and associated with significant health risks and economic burdens.As it has been linked to insulin resistance(IR),this study aimed to perform a bibliometric analysis and visually represent the scientific literature on IR and NAFLD.AIM To map the research landscape to underscore critical areas of focus,influential studies,and future directions of NAFLD and IR.METHODS This study conducted a bibliometric analysis of the literature on IR and NAFLD indexed in the SciVerse Scopus database from 1999 to 2022.The search strategy used terms from the literature and medical subject headings,focusing on terms related to IR and NAFLD.VOSviewer software was used to visualize research trends,collaborations,and key thematic areas.The analysis examined publication type,annual research output,contributing countries and institutions,funding agencies,journal impact factors,citation patterns,and highly cited references.RESULTS This analysis identified 23124 documents on NAFLD,revealing a significant increase in the number of publications between 1999 and 2022.The search retrieved 715 papers on IR and NAFLD,including 573(80.14%)articles and 88(12.31%)reviews.The most productive countries were China(n=134;18.74%),the United States(n=122;17.06%),Italy(n=97;13.57%),and Japan(n=41;5.73%).The leading institutions included the Universitàdegli Studi di Torino,Italy(n=29;4.06%),and the Consiglio Nazionale delle Ricerche,Italy(n=19;2.66%).The top funding agencies were the National Institute of Diabetes and Digestive and Kidney Diseases in the United States(n=48;6.71%),and the National Natural Science Foundation of China(n=37;5.17%).The most active journals in this field were Hepatology(27 publications),the Journal of Hepatology(17 publications),and the Journal of Clinical Endocrinology and Metabolism(13 publications).The main research hotspots were“therapeutic approaches for IR and NAFLD”and“inflammatory and high-fat diet impacts on NAFLD”.CONCLUSION This is the first bibliometric analysis to examine the relationship between IR and NAFLD.In response to the escalating global health challenge of NAFLD,this research highlights an urgent need for a better understanding of this condition and for the development of intervention strategies.Policymakers need to prioritize and address the increasing prevalence of NAFLD.

Dynamics in the Prevalence of Insulin Resistance between 2005 and 2023 in Type 2 Diabetics in South Kivu in the East of the Democratic Republic of Congo: Cross-Sectional Studies

Aim: Sub-Saharan Africa is undergoing an epidemiological transition responsible for a change in the metabolic profile in favour of insulin resistance. The aim of this study was to assess the dynamics of the prevalence of insulin resistance and associated risk factors in diabetic patients in the Democratic Republic of Congo between 2005 and 2023. Method: We measured fasting blood glucose and insulin levels and looked for metabolic syndrome parameters (2009 criteria) in type 2 diabetes patients in 2005-2008 (n = 176) and in 2018-2023 (n = 303). The HOMA model was used to measure insulin sensitivity and islet β-cell secretory function. Results: Between 2005 and 2013, the trend was towards an increase in the prevalence of insulin resistance (from 13.1% to 50.8%;p Conclusion: This present study shows an increase in insulin resistance in Congolese urban areas and a persistence of atypical diabetes mellitus in Congolese rural areas, confirming the particularity of the pathophysiology of the disease in African areas currently influenced by the epidemiological transition. Further studies using an appropriate methodology are required.

Selenoprotein-p and insulin resistance in children and adolescents with obesity

BACKGROUND Insulin resistance and obesity present significant challenges in pediatric populations.Selenoprotein P1(SEPP1)serves as a biomarker for assessing selenium levels in the body.While its association with metabolic syndrome is established in adults,its relevance in children remains underexplored.AIM To ascertain SEPP1 blood levels in children and adolescents diagnosed with obesity and to assess its correlation with insulin resistance and adiposity indices.METHODS 170 children participated in this study,including 85 diagnosed with obesity and an equal number of healthy counterparts matched for age and sex.Each participant underwent a comprehensive medical evaluation,encompassing a detailed medical history,clinical examination,and anthropometric measurements like waist circumference and waist-to-height ratio.Furthermore,routine blood tests were conducted,including serum SEPP1,visceral adiposity index(VAI),and Homeostatic Model Assessment of Insulin Resistance(HOMA-IR)level.RESULTS Our findings revealed significantly lower serum SEPP1 levels in children with obesity compared to their healthy peers.Moreover,notable negative correlations were observed between serum SEPP1 levels and body mass index,VAI,and HOMA-IR.CONCLUSION The study suggests that SEPP1 could serve as a valuable predictor for insulin resistance among children and adolescents diagnosed with obesity.This highlights the potential utility of SEPP1 in pediatric metabolic health assessment and warrants further investigation.

Analysis of the Correlation Between Visceral Fat Area and Insulin Resistance in Patients with Type 2 Diabetes and Abdominal Obesity

Objective: To analyze the correlation between visceral fat area and insulin resistance index (HOMA-IR) in patients with type 2 diabetes mellitus (T2DM) and abdominal obesity and to provide a reference for screening and related research of such patients. Methods: Two hundred patients with T2DM admitted to Guandu People’s Hospital of Kunming were included. The study was carried out from October 2022 to December 2023. The patients were divided into three groups according to different abdominal visceral fat areas (VFA): Group A (n = 65) was less than 75cm2, Group B (n = 75) was 75-100 cm2, and Group C (n = 60) was greater than 100 cm2. The subjects in the three groups were all tested for glycated hemoglobin (HbA1c), fasting insulin (FINS), and fasting blood glucose (FPG). Height and weight were measured to calculate body mass index (BMI). The HOMA-IR and TYG (fasting triglyceride and glycemic index) were also calculated. Changes in the BMI, VFA, HOMA-IR, and TYG levels were observed in the three groups. Results: The VFA, BMI, HbA1c, FPG, FINS, HOMA-IR, and TYG of the patients all increased, with a more significant increase in the BMI, FINS, HOMA-IR, and TYG levels (P < 0.01). Multiple linear stepwise regression analyses used visceral fat area (VFA) as the dependent variable. The results showed that VFA was closely related to BMI, FINS, HOMA-IR, and TYG. Conclusion: Early reduction of VFA to reduce insulin resistance may be a better treatment and effective method for T2DM, providing powerful measures and new strategies for effective blood sugar control and early prevention in the treatment of metabolic diseases.

Adiponectin Gene Variation -4522C/T Is Associated with Type 2 Diabetic Obesity and Insulin Resistance in Chinese

The authors investigated the possible association of -4522C/T variation of adiponectin gene with coronary heart disease （CHD） and type 2 diabetes mellitus （T2DM）. Genotyping of SNP --4522C/T in 304 patients with CHD, 389 patients with T2DM, and 405 age and sex-matched healthy control subjects was carried out by means of PCR-RFLP approach. No significant difference in the genotype or allele frequencies was found, either between patients with CHD and control subjects, or between patients with T2DM and control subjects. However, in the subgroup analysis, an association of the TAr genotype and T allele with type 2 diabetes combined with obesity （BMI ≥ 25 kg/m2） was found （P = 0.014 and P = 0.034, respectively）. Also the homeostasis model assessment of insulin resistance （HOMA-IR） in T2DM patients with T/T genotype was significantly higher than that in T2DM patients carrying C allele （P = 0.0069）. The authors＇ findings for the first time demonstrated that SNP --4522 in the adiponectin gene was associated with T2DM that combined with obesity and higher insulin resistance index in patients with T2DM. This indicated that the variation might associate with an increased susceptibility to type 2 diabetic obesity and insulin resistance. But -4522C/T polymorphism did not contribute to the susceptibility of CHD.

Effect of Milrinone Induced Insulin Resistance on Glucose and Lipid Metabolism in Rats

Aim To investigate the effects of milrinone (a selective phosphodiesteraseIII inhibitor PDE_3 ) on insulin secretion, blood glucose, plasma free fatty acids (FFA) anddose-response relationship, and assess possible effects of milrinone on glucose metabolism andinsulin sensitivity in conscious rats. Methods The catheterized nonstressed rats were administeredvarious doses of milrinone (1, 5, 25μmoL·kg^(-1)) and were compared with controls. Ahyperinsulinaemic-eugly-caemic clamp was established in counscious rats, andmilrinone(25μmoL·kg^(-1)) and 25% dimethyl sulfoxide (DMSO, as a control) were given at 120 minduring hyperinsulinaemic-euglycaemic clamping. Glucose turnover was determind with by gaschromatograph mass spectrometer (GC-MS). Results After dosing, plasma FFA levels in 3 milrinonegroups significantly increased, compared with the controls and before dosing. The percentages ofelevation of FFA by the different milrinone doses were very similar, 50%, and 52% , 55% for 1, 5,and 25 μmoL·kg^(-1), repectively, at 2 min after dosing. Plasma insulin levels were significantlyelevated in the 5 and 25 μmoL·kg^(-1) groups, and the effect of milrione on glucose concentrationwas detectable only in 25μmoL·kg^(-1) group. During hyperinsulinaemic clamping, there weresignificant increase, in plasma FFA (from 173 +- 15 to 634 +- 87μmoL·kg^(-1)) and hepatic glucoseproduction (HGP), and a significant decrease in glucose infusion rates (GIR) to about 21% and aslight increase in plasma insulin after milrinone treatment. Conclusion Milrinone impaires theability of insulin to suppress lipolysis and HGP, and insulin-mediated glucose utilization inperipheral tissue. Therefore, milrinone administration may induce an acute insulin resistance invivo.

Berberine reverses free-fatty-acid-induced insulin resistance in 3T3-L1 adipocytes through targeting IKKβ

AIM: To investigate the effects and molecular mechanisms of berberine on improving insulin resistance induced by free fatty acids (FFAs) in 3T3-L1 adipocytes. METHODS: The model of insulin resistance in 3T3-L1 adipocytes was established by adding palmic acid (0.5 mmol/L) to the culture medium. Berberine treatment was performed at the same time. Glucose uptake rate was determined by the 2-deoxy-[3H]-D-glucose method. The levels of IkB kinase beta (IKKβ) Ser181 phosphorylation, insulin receptor substrate-1(IRS-1) Ser307 phosphorylation, expression of IKKβ, IRS-1, nuclear transcription factor kappaB p65 (NF-κB p65), phosphatidylinositol-3-kinase p85 (PI-3K p85) and glucose transporter 4 (GLUT4) proteins were detected by Western blotting. The distribution of NF-κB p65 proteins inside the adipocytes was observed through confocal laser scanning microscopy (CLSM). RESULTS: After the intervention of palmic acid for 24 h, the insulin-stimulated glucose transport in 3T3-L1 adipocytes was inhibited by 67%. Meanwhile, the expression of IRS-1 and PI-3K p85 protein was reduced, while the levels of IKKβ Ser181 and IRS-1 Ser307 phosphorylation, and nuclear translocation of NF-κB p65 protein were increased. However, the above indexes, which indicated the existence of insulin resistance, were reversed by berberine although the expression of GLUT4, IKKβ and total NF-κB p65 protein were not changed during this study. CONCLUSION: Insulin resistance induced by FFAs in 3T3-L1 adipocytes can be improved by berberine. Berberine reversed free-fatty-acid-induced insulin resistance in 3T3-L1 adipocytes through targeting IKKβ.

Yi-Qi-Zeng-Min-Tang,a Chinese medicine,ameliorates insulin resistance in type 2 diabetic rats

AIM:To investigate the effects of the Chinese herbal decoction,Yi-Qi-Zeng-Min-Tang(YQZMT),on insulin resistance in type 2 diabetic rats.METHODS:Sprague-Dawley rats were divided into two dietary regiments by feeding either normal pellet diet(NPD) or high fat diet(HFD).Four weeks later,the HFD-fed rats were injected intraperitoneally with lowdose streptozotocin(STZ).Rats with non-fasting blood glucose level ≥ 16.67 mmol/L were considered type 2 diabetic and further divided into five subgroups:the type 2 diabetes model group,low-dose,medium-doseand high-dose YQZMT groups,and rosiglitazone group.Age-matched NPD-fed rats served as controls.YQZMT or rosiglitazone were administered for 8 wk.Intraperitoneal glucose and insulin tolerance tests were performed before and after the treatment to measure the glucose tolerance and insulin sensitivity.Serum levels of biochemical parameters,adipocytokines,such as tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),as well as free fatty acids(FFAs),were also analyzed.RESULTS:There was significant elevation of insulin resistance and serum levels of fasting glucose(12.82 ± 1.08 mmol/L vs 3.60 ± 0.31 mmol/L,P < 0.01),insulin(7197.36 ± 253.89 pg/mL vs 4820.49 ± 326.89 pg/mL,P < 0.01),total cholesterol(TC)(8.40 ± 0.49 mmol/L vs 2.14 ± 0.06 mmol/L,P < 0.01),triglyceride(2.24 ± 0.12 mmol/L vs 0.78 ± 0.05 mmol/L,P < 0.01),low-density lipoprotein cholesterol(LDL-c)(7.84 ± 0.51 mmol/L vs 0.72 ± 0.04 mmol/L,P < 0.01) and decrease in high-density lipoprotein cholesterol(HDL-c)(0.57 ± 0.03 mmol/L vs 1.27 ± 0.03 mmol/L,P < 0.01) in the low-dose STZ and high-fat diet induced type 2 diabetic group when compared with the control group.Administration of YQZMT induced dose-and timedependent changes in insulin resistance,glucose and lipid profile,and reduced levels of FFA,TNF-α and IL-6 in the type 2 diabetic rats.After the treatment,compared with the diabetic group,the insulin resistance was ameliorated in the high-dose YQZMT(2.82 g/100 g per day) group,with a significant reduction in serum glucose(12.16 ± 1.00 mmol/L vs 17.65 ± 2.22 mmol/L,P < 0.01),homeostasis model assessment of basal insulin resistance(22.68 ± 2.37 vs 38.79 ± 9.02,P < 0.05),triglyceride(0.87 ± 0.15 mmol/L vs 1.99 ± 0.26 mmol/L,P < 0.01),TC(3.31 ± 0.52 mmol/L vs 6.50 ± 1.04 mmol/L,P < 0.01) and LDL-c(2.47 ± 0.50 mmol/L vs 6.00 ± 1.07 mmol/L,P < 0.01),and a signif icant increase in HDL-c(0.84 ± 0.08 mmol/L vs 0.50 ± 0.03 mmol/L,P < 0.01).But the body weight was not changed signif icantly.CONCLUSION:YQZMT,which ameliorates insulin resistance and does not cause increase in body weight,may be a suitable therapeutic adjunct for the treatment of type 2 diabetes.

Insulin resistance is associated with hepatocellular carcinoma in chronic hepatitis C infection

AIM:To elucidate the role of insulin resistance(IR) and serum adiponectin level in hepatocellular carcinoma(HCC) associated with chronic hepatitis C.METHODS:Clinical and biochemical characteristics were collected from 165 consecutive patients with newly diagnosed HCC.Homeostasis model assessment of IR(HOMA-IR) and serum adiponectin level were investigated in 188 patients with different stages of hepatitis C virus(HCV) infection.RESULTS:Among HCC patients,type 2 diabetics(DM) was more prevalent in HCV subjects(35.6%,n = 59) compared to hepatitis B virus(HBV;12.7%,n = 63) or non-HBV,non-HCV cases(7.1%,n = 28).In patients with chronic hepatitis C,HCC subjects had higher blood sugar(P < 0.001),insulin level(P = 0.003) and HOMAIR(P = 0.018) than those with chronic hepatitis and advanced fibrosis.Age,male sex and body mass index were significantly associated with serum adiponectin level,whereas HOMA-IR was not.Based on stepwise logistic regression analysis,age(OR:1.124,P < 0.001),serum insulin level(OR:1.585,P < 0.001),HOMA-IR(OR:0.495,P = 0.001),DM(OR:11.601,P = 0.002) and male sex(OR:3.877,P = 0.016) were independently associated with HCC.This result was similar even if the diabetic subjects were excluded for analysis.CONCLUSION:Insulin resistance measured by HOMAIR,regardless of the presence of diabetes,is significantly associated with HCC development in patients with chronic HCV infection.

Adiponectin and its association with insulin resistance and type 2 diabetes

Adiponectin is an adipokine, which is expressed in adipose tissue and is thought to play an important role in glucose metabolism. Hypoadiponectinemia can cause reduction of fatty acid oxidation, decreased glucose uptake in skeletal muscle cells, and increased gluconeogenesis in hepatic cells. The level of plasma glucose can be increased. On the other hand, the decrease of fatty acid oxidation increases the level of free fatty acid （FFA）, which increases the insulin resistance, and then decreases the glucose uptake, which ultimately causes increased plasma glucose and type 2 diabetes （T2D）. This review describes the process from hypoadiponectinemia to T2D and the genesis of hypoadiponectinemia at a molecular level.