Pathophysiology and pharmacological treatment of insulin resistance

Recent research progress on the correlation between metabolic syndrome and Helicobacter pylori infection

Background

Globally, metabolic syndrome (MS) and Helicobacter pylori (HP) infection, which have gained an epidemic status, are major challenges to human health, society, and medical professionals. Recent studies have demonstrated that MS is closely related to HP infection. Additionally, HP is an important risk factor for gastric cancer. However, systematic reviews on HP are lacking. This review aimed to summarize and analyze the potential correlation of HP infection with MS and its components, as well as the underlying mechanism, to provide reference and strategies for clinical prevention and treatment.

Methodology

Previous studies examining the correlation between HP and MS since 1990 were retrieved from the PubMed, Web of Science, and Embase databases. The potential correlation between HP infection and MS and its components was comprehensively analyzed. The keywords "Helicobacter pylori," "HP," "metabolic syndrome," "hypertension," "obesity," "diabetes," or "dyslipidemia" were used in all fields. No language restrictions were imposed.

Results

MS was strongly correlated to HP infection. The inflammatory response and inflammatory factors produced during HP infection are important etiological factors for insulin resistance and MS. The co-occurrence of long-term chronic inflammation and immune dysfunction with MS may be the predisposing factor for HP infection. MS components, such as diabetes, hypertension, dyslipidemia, and obesity were also correlated with HP infection in one or both directions.

Conclusions

HP infection and MS may promote the pathogenesis of each other. The contribution of HP infection and MS to gastric cancer cannot be ruled out based on co-occurrence. The MS components diabetes and obesity may be bidirectionally correlated with HP infection.

Function of sildenafil on diseases other than urogenital system: An umbrella review

Background: To investigate the function of sildenafil on diseases other than urogenital system, an umbrella review was conducted. Methods: Meta-analysis and systematic reviews on this topic were comprehensively evaluated in this umbrella review. Quality of evidence was evaluated through AMSTAR and the Grading of Recommendations, Assessment, Development and Evaluation system to generate a reliable and valid conclusion. Results: 77 out of 1164 meta-analysis were enrolled. 33 significant outcomes and 41 non-significant outcomes were extracted from all eligible articles. We found sildenafil did significant help in reducing arterial systolic pressure, mean pulmonary arterial pressure, pulmonary arterial pressure, systolic pulmonary arterial pressure in patients with pulmonary and cardiovascular diseases. Besides, sildenafil also improved exercise capacity or performance in patients with pulmonary and cardiovascular diseases. Other than these patients, this drug contributed great help in pregnant women with fetal growth restriction and preeclampsia by increasing the weight of newborns and lowering uterine and umbilical pulsatility indices. Additionally, it was reported that utilization of sildenafil has brought increased risk of melanoma. Conclusion: We can conclude from our study that sildenafil played an important role in many fields, especially in vascular protection. This finding provides a strong evidence for further expansion of sildenafil utilization in other diseases.

Early-life determinants of childhood plasma insulin levels: implications for primordial prevention of diabetes

BACKGROUND

We earlier reported prematurity as an independent risk factor for elevated insulin levels. Investigation is still lacking on the influence of prenatal and perinatal factors on childhood insulin levels.

METHODS

In this secondary analysis of a prospective birth cohort, plasma insulin levels were measured at birth and early childhood. Regression models identified early-life factors associated with the primary outcome: log-transformed childhood plasma insulin levels.

RESULTS

One thousand one hundred and nine children had insulin levels at birth and 825 at both time points. Compared to term, preterm infants had higher plasma insulin levels (geometric mean) at birth (612, 95% CI 552-679 vs. 372, 95% CI 345-402 pmol/ml) and in early childhood (547, 95% CI 494-605 vs. 445, 95% CI 417-475 pmol/ml). Factors associated with higher early childhood insulin levels included higher insulin level at birth, black race, female sex, maternal smoking during pregnancy, maternal perceived stress, in utero drug exposure, maternal pregestational diabetes mellitus, and maternal preconception overweight and obesity.

CONCLUSIONS

In this high-risk US birth cohort, we identified multiple prenatal and perinatal risk factors for higher early childhood insulin levels, in addition to prematurity. These findings lend support to primordial preventive strategies for diabetes mellitus.

IMPACT

In this secondary analysis of a large prospective study from a high-risk racially diverse cohort, we identify biological and social factors that contribute to elevated levels of plasma insulin in early childhood. Our study also investigates factors affecting plasma insulin in preterm infants along with comorbidities commonly seen during the neonatal intensive care stay. Our work reaffirms the importance of Developmental Origins of Health and Disease with regards to in utero programming of insulin levels. Our work supports the possibility that primordial preventive strategies for diabetes mellitus in high-risk populations may need to begin as early as the prenatal period.

High-throughput drug screening models of mature adipose tissues which replicate the physiology of patients' Body Mass Index (BMI)

Obesity is a complex and incompletely understood disease, but current drug screening strategies mostly rely on immature in vitro adipose models which cannot recapitulate it properly. To address this issue, we developed a statistically validated high-throughput screening model by seeding human mature adipocytes from patients, encapsulated in physiological collagen microfibers. These drop tissues ensured the maintenance of adipocyte viability and functionality for controlling glucose and fatty acids uptake, as well as glycerol release. As such, patients' BMI and insulin sensitivity displayed a strong inverse correlation: the healthy adipocytes were associated with the highest insulin-induced glucose uptake, while insulin resistance was confirmed in the underweight and severely obese adipocytes. Insulin sensitivity recovery was possible with two type 2 diabetes treatments, rosiglitazone and melatonin. Finally, the addition of blood vasculature to the model seemed to more accurately recapitulate the in vivo physiology, with particular respect to leptin secretion metabolism.

Association of Helicobacter pylori infection with the risk of metabolic syndrome and insulin resistance: an updated systematic review and meta-analysis

BACKGROUND

Conflicting results of recent studies on the association between Helicobacter pylori (H. pylori) infection and the risk of insulin resistance and metabolic syndrome explored the need for updated meta-analysis on this issue. Therefore, this systematic review aimed to estimate the pooled effect of H. pylori infection on the risk of insulin resistance and metabolic syndrome.

METHODS

To identify case-control studies and cohort studies evaluating the association of H. pylori infection with insulin resistance and metabolic syndrome, a comprehensive literature search was performed from international databases including Medline (PubMed), Web of Sciences, Scopus, EMBASE, and CINHAL from January 1990 until January 2021. We used odds ratio with its 95% confidence interval to quantify the effect of case-control studies and risk ratio with its 95% CI for the effect of cohort studies.

RESULTS

22 studies with 206,911 participants were included for meta-analysis. The pooled estimate of odds ratio between H. pylori infection and metabolic syndrome in case-control studies was 1.19 (95% CI 1.05-1.35; I2 = 0%), and in cohort studies, the pooled risk ratio was 1.31 (95% CI 1.13-1.51; I2 = 0%). Besides, case-control studies showed the pooled odds ratio of 1.54 (95% CI 1.19-1.98; I2 = 6.88%) for the association between H. pylori infection and insulin resistance.

CONCLUSION

In this meta-analysis, the results showed that there was a possibility of metabolic syndrome and insulin resistance in case of H. pylori infection.

In vitro anti-diabetic activity, bioactive constituents, and molecular modeling studies with sulfonylurea receptor1 for insulin secretagogue activity of seed extract of Syzygium cumini (L.)

Introduction: Syzygium cumini (L.) has been known to be used for diabetes treatment in traditional Indian and Chinese medicine. The present study focuses on the evaluation for glucose uptake and insulin release in vitro and characterization of phytoconstituents of the hydro-ethanolic extract of Syzygium cumini seed (SCE). Further, this report covers the molecular docking findings of the bioactive constituents on the sulfonylurea receptor 1 (SUR1). Methods: A glucose uptake assay of SCE was used to estimate the glucose uptake from the cell lysates and the cell culture supernatants using insulin as the reference standard. Insulin release activity of SCE from RIN-5F cells was estimated using enzyme-linked immunosorbent assay. The phytoconstituents were isolated by preparative HPLC and characterized by mass spectrometry, nuclear magnetic resonance (NMR) and infrared spectroscopy. The molecular docking of bioactive constituents was carried on repaglinide bound to the SUR1. Results: In the presence of SCE, the glucose uptake through L6 myoblast cells increased by 19.91% at 40 µg/mL in comparison with the vehicle control (P < 0.05). Moreover, SCE showed 2.8-fold enhancement of insulin release at 40 µg/mL as compared to the vehicle controls (P < 0.05). Gallic and ellagic acids were the key phytoconstituents isolated from SCE. Molecular docking studies revealed that both gallic acid and ellagic acid bind to the repaglinide binding pocket of SUR1. Conclusion: SCE increases the release of insulin and enhances glucose uptake in vitro, which may contribute to its in vivo anti-diabetic activity. The presence of ellagic acid and gallic acid in SCE may be the cause for enhanced insulin release observed with SCE following binding to SUR1.

Investigating the relationship between insulin resistance and adipose tissue in a randomized Tehrani population

OBJECTIVES

Insulin resistance is the most common metabolic change associated with obesity. The present study aimed to investigate the relationship between insulin resistance and body composition especially adipose tissue in a randomized Tehrani population.

METHODS

This study used data of 2,160 individuals registered in a cross-sectional study on were randomly selected from among subjects who were referred to nutrition counseling clinic in Tehran, from April 2016 to September 2017. Insulin resistance was calculated by homeostasis model assessment formula. The odds ratio (95% CI) was calculated using logistic regression models.

RESULTS

The mean age of the men was 39 (±10) and women were 41 (±11) (the age ranged from 20 to 50 years). The risk of increased HOMA-IR was 1.03 (95% CI: 1.01-1.04) for an increase in one percent of Body fat, and 1.03 (95% CI: 1.00-1.05) for an increase in one percent of Trunk fat. Moreover, the odds ratio of FBS for an increase in one unit of Body fat percent and Trunk fat percent increased by 1.05 (adjusted odds ratio [95% CI: 1.03, 1.06]) and 1.05 (95% CI: 1.02, 1.08). Also, the risk of increased Fasting Insulin was 1.05 (95% CI: 1.03-1.07) for an increase in one unit of Body fat percent, and 1.05 (95% CI: 1.02-1.08) for an increase in one unit of Trunk fat percent.

CONCLUSIONS

The findings of the present study showed that there was a significant relationship between HOMA-IR, Fasting blood sugar, Fasting Insulin, and 2 h Insulin with percent of Body fat, percent of Trunk fat.

Efficacy and safety of imeglimin in Japanese patients with type 2 diabetes: A 24-week, randomized, double-blind, placebo-controlled, dose-ranging phase 2b trial

AIM

To assess the efficacy and safety of imeglimin monotherapy compared with placebo for 24 weeks in Japanese patients with type 2 diabetes (T2D).

MATERIALS AND METHODS

In this 24-week, randomized, double-blind, placebo-controlled, parallel-group, dose-ranging, phase 2b clinical trial, Japanese adults (age ≥ 20 years) with T2D either treatment-naïve or previously treated with one oral antidiabetes agent were eligible for participation. Patients were randomly assigned (1:1:1:1) to receive orally imeglimin 500, 1000 or 1500 mg, or placebo twice-daily over a 24-week period. The primary endpoint was the placebo-adjusted change at week 24 in HbA1c. Safety outcomes were assessed in all patients who received at least one dose of study drug.

RESULTS

A total of 299 patients were randomized to receive double-blind treatment with orally twice-daily placebo (n = 75), imeglimin 500 mg (n = 75), 1000 mg (n = 74) or 1500 mg (n = 75). At week 24, imeglimin significantly decreased HbA1c (difference vs. placebo: imeglimin 500 mg -0.52% [95% CI: -0.77%, -0.27%], imeglimin 1000 mg -0.94% [95% CI: -1.19%, -0.68%], imeglimin 1500 mg -1.00% [95% CI: -1.26%, -0.75%]; P < .0001 for all). Treatment-emergent adverse events were reported for 68.0%, 62.2%, 73.3% and 68.0% of patients receiving imeglimin 500, 1000 or 1500 mg and placebo, respectively. A small increase in gastrointestinal adverse effects (e.g. diarrhoea) occurred with the 1500 mg dose level. Hypoglycaemia was balanced among groups.

CONCLUSIONS

Imeglimin as monotherapy in Japanese patients with T2D was well tolerated and significantly improved glycaemic control with no significant increase in hypoglycaemic events versus placebo. Given the marginal increase in efficacy with the 1500 versus 1000 mg dose (along with the potential for gastrointestinal tolerability issues), a dose of 1000 mg twice-daily was selected for subsequent phase 3 studies.

Triglycerides to High-Density Lipoprotein Cholesterol Ratio Is the Best Surrogate Marker for Insulin Resistance in Nonobese Middle-Aged and Elderly Population: A Cross-Sectional Study

OBJECTIVE

Insulin resistance (IR) is closely associated with metabolic profiles, including obesity and dyslipidemia. The aim of the present study was to examine how lipid profiles were associated with IR in nonobese middle-aged and elderly Chinese population.

METHODS

This cross-sectional study included 1608 subjects. IR was defined by homeostasis model assessment of insulin resistance (HOMA-IR) of at least 2.5.

RESULTS

In nonobese subjects (body mass index (BMI) < 25 kg/m², n = 996), triglyceride (TG) to high-density lipoprotein cholesterol (HDL-C) ratio (odds ratio (OR) = 1.43, 95% confidence interval (CI) 1.13-1.81, P=0.003) was an independent risk factor for IR. The best marker for predicting IR in nonobese subjects was TG/HDL-C ratio with the areas under the receiver operating characteristic curves (AUC) of 0.73 (P < 0.001). The optimal cut-off point to identifying IR for TG/HDL-C ratio was ≥1.50 in the nonobese population. Other markers like BMI, TG, and total cholesterol (TC)/HDL-C also had acceptable discriminatory power for predicting IR in nonobese population (AUC ≥ 0.7 and P < 0.001). BMI had the highest AUC of 0.647 (P < 0.001) after being adjusted, but it was not effective enough to predict IR in obese subjects (BMI ≥ 25.0, n = 612).

CONCLUSIONS

The TG/HDL-C ratio may be the best reliable marker for predicting IR in the nonobese middle-aged and elderly Chinese population.

Association of the Ratio of Triglycerides to High-Density Lipoprotein Cholesterol Levels with the Risk of Type 2 Diabetes: A Retrospective Cohort Study in Beijing

BACKGROUND

Previous studies have shown that the ratio of triglyceride to high-density lipoprotein cholesterol level (TG/HDL-C) is a risk factor for type 2 diabetes mellitus (T2DM). The aim of this study was to investigate the nonlinear relationship between TG/HDL-C and the incidence of T2DM in a Chinese population.

METHODS

We used logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the incidence of T2DM among 7,791 participants from the Risk Evaluation of cAncers in Chinese diabeTic Individuals: a lONgitudinal (REACTION) cohort study at baseline.

RESULTS

After adjusting for age, sex, body mass index, smoking status, alcohol intake, low-density lipoprotein cholesterol level, strenuous activity, education level, family histories of T2DM and tumors, and the presence of hypertension, tumor, stroke, and coronary heart disease, we showed that TG/HDL-C was positively associated with the incidence of T2DM at the 4-year follow-up (OR = 1.49, 95%CI = 1.26-1.78). TG/HDL-C and incidence of T2DM showed a nonlinear relationship; the inflection point of TG/HDL-C was 1.50. The ORs (95% CI) on the left and right sides of the inflection point were 2.50 (1.70-3.67) and 0.96 (0.67-1.37), respectively. After adjusting for age, sex, and body mass index (BMI) in the linear relationship, the OR of the incidence of T2DM was 1.60 (95%CI = 1.37-1.87). When the TG/HDL-C was less than 1.50 or greater than 1.76, the ORs (95% CI) were 2.41 (1.82-3.18) or 0.81 (0.53-1.25), respectively. Subgroup analysis showed no relationships of T2DM incidence with sex, BMI, family history of T2DM, or TG/HDL-C.

CONCLUSION

TG/HDL-C is positively associated with diabetes risk. In our study, with each increasing quintile, the risk of T2DM after 4 years was 1.60 or 1.49 depending on the variables adjusted. In addition, our cohort study showed a nonlinear relationship between TG/HDL-C and T2DM incidence, with an inflection point of 1.76 or 1.50, depending on the variables adjusted. When the TG/HDL was less than 1.50, the ORs (95% CI) were 2.41 (1.82-3.18) and 2.50 (1.70-3.67). When the TG/HDL-C was greater than 1.76 or 1.50, there was no significant difference in the change in OR.

Insulin resistance and type 2 diabetes in children

Type 2 diabetes (T2D) is an emerging health risk in obese children and adolescents. Both environmental (lack of physical activity, excess nutritional intake, sedentary lifestyle) and genetic factors contribute to this global epidemic. The growing prevalence of T2D in youth is also associated with a consistently increased incidence of metabolic and cardiovascular complications. Insulin resistance (IR), i.e., whole-body decreased glucose uptake in response to physiological insulin levels, determines impaired glucose homeostasis and it is recognized as cardinal trigger of T2D and cardiovascular disease in both adults and children. In particular, IR and beta-cell dysfunction lead to the persistent hyperglycemia which characterizes T2D. Indeed, both pathological states influence each other and presumably play a crucial, synergistic role in the pathogenesis of T2D, although the precise mechanisms are not completely understood. However, beta-cell dysfunction and IR induce impaired glucose metabolism, thus leading to the progression to T2D. Therefore, understanding the mechanisms correlated with the decline of beta-cell function and IR is crucial in order to control, prevent, and treat T2D in youth. This review focuses on the current knowledge regarding IR and T2D in children and adolescents and showcases interesting opportunities and stimulating challenges for the development of new preventative approaches and therapeutic strategies for young patients with T2D.

Pharmacokinetics of Imeglimin in Subjects with Moderate Hepatic Impairment

BACKGROUND

Imeglimin is a novel oral antidiabetic drug used to treat type 2 diabetes, targeting the mitochondrial bioenergetics. Imeglimin is mainly excreted unchanged by the kidneys and is a substrate of organic cation transporters, which are expressed in the kidney and the liver.

OBJECTIVE

The aim of this study was to assess the effect of hepatic impairment on the pharmacokinetics of imeglimin.

METHODS

An open-label, single-dose, parallel-group study was carried out in seven subjects with normal hepatic function and seven subjects with moderate hepatic impairment who received a single dose of imeglimin 1000 mg. Blood and urine samples were collected up to 48 h after imeglimin administration. Pharmacokinetics were determined using non-compartmental methods.

RESULTS

Imeglimin maximum observed plasma concentration (C_max) and area under the plasma concentration-time curve (AUC) in subjects with moderate hepatic impairment was 1.3-fold (90% confidence interval [CI] 1.05-1.60) and 1.5-fold (90% CI 1.19-1.82) higher than in subjects with normal hepatic function, but was not considered as clinically meaningful. Higher plasma exposure and amount of imeglimin renally excreted in moderate hepatic impaired subjects, associated with an unchanged elimination rate, suggests that this increase could be linked to a higher oral absorption and/or lower hepatic uptake in this population.

CONCLUSIONS

Imeglimin was safe and well tolerated in all subjects.

CLINICAL TRIAL REGISTRATION

EudraCT 2018-001950-83.

Treatment with Mammalian Ste-20-like Kinase 1/2 (MST1/2) Inhibitor XMU-MP-1 Improves Glucose Tolerance in Streptozotocin-Induced Diabetes Mice

Diabetes mellitus (DM) is one of the major causes of death in the world. There are two types of DM—type 1 DM and type 2 DM. Type 1 DM can only be treated by insulin injection whereas type 2 DM is commonly treated using anti-hyperglycemic agents. Despite its effectiveness in controlling blood glucose level, this therapeutic approach is not able to reduce the decline in the number of functional pancreatic β cells. MST1 is a strong pro-apoptotic kinase that is expressed in pancreatic β cells. It induces β cell death and impairs insulin secretion. Recently, a potent and specific inhibitor for MST1, called XMU-MP-1, was identified and characterized. We hypothesized that treatment with XMU-MP-1 would produce beneficial effects by improving the survival and function of the pancreatic β cells. We used INS-1 cells and STZ-induced diabetic mice as in vitro and in vivo models to test the effect of XMU-MP-1 treatment. We found that XMU-MP-1 inhibited MST1/2 activity in INS-1 cells. Moreover, treatment with XMU-MP-1 produced a beneficial effect in improving glucose tolerance in the STZ-induced diabetic mouse model. Histological analysis indicated that XMU-MP-1 increased the number of pancreatic β cells and enhanced Langerhans islet area in the severe diabetic mice. Overall, this study showed that MST1 could become a promising therapeutic target for diabetes mellitus.

Lack of Drug-Drug Interaction Between Cimetidine, a Renal Transporter Inhibitor, and Imeglimin, a Novel Oral Antidiabetic Drug, in Healthy Volunteers

BACKGROUND AND OBJECTIVE: Imeglimin is a novel oral antidiabetic drug to treat type 2 diabetes, targeting the mitochondrial bioenergetics. In vitro, imeglimin was shown to be a substrate of human multidrug and toxic extrusion transporters MATE1 and MATE2-K and organic cation transporters OCT1 and OCT2. The objective of the study was to assess the potential drug-drug interaction between imeglimin and cimetidine, a reference inhibitor of these transporters.

METHODS

A phase 1 study was carried out in 16 subjects who received a single dose of 1500 mg imeglimin alone on day 1 followed by a 6-day treatment (day 5 to day 10) with cimetidine 400 mg twice daily. On day 8, a single dose of imeglimin was co-administered with cimetidine. Blood and urine samples were collected up to 72 h after each imeglimin administration. Pharmacokinetic parameters were determined using non-compartmental methods.

RESULTS

Imeglimin maximum plasma concentration (C_max) and area under the plasma concentration-time curve (AUC) were 1.3-fold [90% CI (1.12-1.62) and (1.10-1.46) for C_max and AUC_0-last, respectively] higher when imeglimin was co-administered with cimetidine but this increase was not considered clinically relevant. This increase could be mainly explained by a reduction in renal elimination, mediated through the cimetidine inhibition of renal MATE1 transporter. Imeglimin taken alone or with cimetidine was safe and well tolerated in all subjects.

CONCLUSIONS

No clinically significant drug-drug interaction exists between imeglimin and cimetidine, a reference inhibitor of MATE1, MATE2-K, OCT1 and OCT2 transporters.

CLINICAL TRIAL REGISTRATION

EudraCT 2018-001103-36.

Absence of QTc prolongation in a thorough QT study with imeglimin, a first in class oral agent for type 2 diabetes mellitus

PURPOSE

Imeglimin is the first in a new class of oral antidiabetic agents, the glimins, currently in development to improve glycemic control in patients with type 2 diabetes mellitus. A thorough QT study was conducted to establish electrophysiological effects of therapeutic and supratherapeutic doses of imeglimin on cardiac repolarization.

METHODS

In this randomized, double-blind, four-period, placebo and active controlled crossover study, healthy subjects were administered a single dose of imeglimin 2250 mg, imeglimin 6000 mg, moxifloxacin 400 mg, and placebo. 12-Lead Holter ECGs were recorded from 1 h before dosing until at least 24 h after each dose. This study was performed at a single-center inpatient clinical pharmacology unit.

RESULTS

The upper bound of the two-sided 90% confidence interval for time-matched, placebo-subtracted, baseline-adjusted QTc intervals (ΔΔQTcF) did not exceed the regulatory threshold of 10 ms in any of the imeglimin dose groups. There were no QTcF values above 500 ms nor changes from pre-dose in QTcF above 60 ms in the imeglimin groups. Imeglimin did not exert a relevant effect on heart rate and PR or QRS intervals. Assay sensitivity was demonstrated by the effect of moxifloxacin 400 mg, with a lower bound two-sided 90% confidence interval for ΔΔQTcF of 10.6 ms.

CONCLUSION

This thorough QT study demonstrated that therapeutic and supratherapeutic exposures of imeglimin did not induce a QT/QTc prolongation with a strong confidence as evidenced by the assay sensitivity.

TRIAL REGISTRATION NUMBER/DATE

NCT02924337/ October 5, 2016.

RS1799817 in INSR associates with susceptibility to polycystic ovary syndrome

Background

Insulin and its receptor (INSR) have been implicated in the etiology of the polycystic ovarian syndrome (PCOS). Here, we investigate the association between INSR rs1799817 polymorphism and PCOS in Saudi Arabian women.

Methods

Study group included 126 PCOS women and 118 normo-ovulatory matched controls. The demographic data was recorded, and the plasma levels of glucose, lipids, leptin, E2, LH, FSH, T, SHBG, and insulin were determined. The genotypic and allele frequencies of rs1799817 were evaluated in both PCOS and control group. Polymerase chain reaction (PCR) was used to amplify Exon 17 of the INSR gene, and the amplified products were analyzed by direct sequencing. A single-nucleotide polymorphism (C to T) was found at locus 10923 (His1058) of rs1799817.

Results

In the PCOS group, the mutant allele T occurs at a significantly higher frequency (0.306) compared to the control group (0.174) (p<0.001). It shows a dominant effect and elevates the relative risk of PCOS even in the heterozygotes (RR=2.82). After stratification of the participants by body mass index, the frequency of T allele was significantly higher in the lean patients with PCOS compared to the lean control. The obese PCOS also had a higher frequency than the obese control, but the difference was not statistically significant. Several parameter values were affected by the INSR genotype, particularly W/H ratio, lipid, insulin and glucose levels and insulin resistance in PCOS patients.

Conclusions

The INSR gene polymorphism rs1799817 is a susceptibility locus associated with PCOS in Saudis and associated metabolic and hormonal changes, particularly, in the lean PCOS females.

Female infertility: which role for obesity?

Obesity is associated with infertility in women through multiple and complex mechanisms. Briefly, the adipose tissue through the production of many factors, such as leptin, free fatty acids (FFA), and cytokines may affect both ovarian and endometrium functions, with a final alteration in oocyte maturation and endometrial epithelium receptivity. In addition, through the development of peripheral insulin resistance obesity produces a condition of functional hyperandrogenism and hyperestrogenism that contribute to produce anovulation and to reduce endometrial receptivity and, therefore participate to cause infertility. Weight loss is able to restore fertility in most cases, but there are no practical indications to guide the clinician to choice the best method among increased physical activity, diet, drugs, and bariatric surgery.

The synergism of high-intensity intermittent exercise and every-other-day intermittent fasting regimen on energy metabolism adaptations includes hexokinase activity and mitochondrial efficiency

Visceral lipid accumulation, organ hypertrophy and a reduction in skeletal muscle strength are all signs associated with the severity of obesity-related disease. Intermittent fasting (IF) and high-intensity intermittent exercise (HIIE) are natural strategies that, individually, can prevent and help treat obesity along with metabolic syndrome and its associated diseases. However, the combinatorial effect of IF and HIIE on energetic metabolism is currently not well understood. We hypothesized that their combination could have a potential for more than strictly additive benefits. Here, we show that two months of every-other-day intermittent fasting regimen combined with a high-intensity intermittent exercise protocol (IF/HIIE) produced a synergistic effect, enhancing physical endurance (vs. control, HIIE and IF) and optimizing metabolic pathways of energy production in male Wistar rats. The IF/HIIE group presented enhanced glucose tolerance (vs. control, HIIE and IF), lower levels of plasma insulin (vs. control and HIIE), and a global activation of low Km hexokinases in liver (vs. control, HIIE and IF), heart (vs. control and HIIE) and skeletal muscle (vs. control, HIIE and IF). The IF/HIIE synergism, rather than a simply additive effect, is evidenced by increase in muscle mass and cross-section area, activation of the FoF1 ATP synthase, and the gain of characteristics suggestive of augmented mitochondrial mass and efficiency observed in this group. Finally, important reductions in plasma oxidative stress markers were present preferentially in IF/HIIE group. These findings provide new insights for the implementation of non-pharmaceutical strategies to prevent/treat metabolic syndrome and associated diseases.

β-Arrestin Based Receptor Signaling Paradigms: Potential Therapeutic Targets for Complex Age-Related Disorders

G protein coupled receptors (GPCRs) were first characterized as signal transducers that elicit downstream effects through modulation of guanine (G) nucleotide-binding proteins. The pharmacotherapeutic exploitation of this signaling paradigm has created a drug-based field covering nearly 50% of the current pharmacopeia. Since the groundbreaking discoveries of the late 1990s to the present day, it is now clear however that GPCRs can also generate productive signaling cascades through the modulation of β-arrestin functionality. β-Arrestins were first thought to only regulate receptor desensitization and internalization - exemplified by the action of visual arrestin with respect to rhodopsin desensitization. Nearly 20 years ago, it was found that rather than controlling GPCR signal termination, productive β-arrestin dependent GPCR signaling paradigms were highly dependent on multi-protein complex formation and generated long-lasting cellular effects, in contrast to G protein signaling which is transient and functions through soluble second messenger systems. β-Arrestin signaling was then first shown to activate mitogen activated protein kinase signaling in a G protein-independent manner and eventually initiate protein transcription - thus controlling expression patterns of downstream proteins. While the possibility of developing β-arrestin biased or functionally selective ligands is now being investigated, no additional research has been performed on its possible contextual specificity in treating age-related disorders. The ability of β-arrestin-dependent signaling to control complex and multidimensional protein expression patterns makes this therapeutic strategy feasible, as treating complex age-related disorders will likely require therapeutics that can exert network-level efficacy profiles. It is our understanding that therapeutically targeting G protein-independent effectors such as β-arrestin will aid in the development of precision medicines with tailored efficacy profiles for disease/age-specific contextualities.

Association between Physical Fitness and Cardiometabolic Risk of Children and Adolescents in Korea

Background

This study aimed to investigate the association between physical fitness and cardiometabolic health of Korean children and adolescents.

Methods

In total, 168 participants (89 boys and 79 girls) aged 10–16 years were recruited for the Intervention for Childhood and Adolescent Obesity via Activity and Nutrition Study in 2016. The subjects were categorized into two groups using the definition of metabolic syndrome by the International Diabetes Federation: metabolically unhealthy (with at least two of the five criteria) and healthy groups (with less than one criterion). Correlation analysis of the participants’ general characteristics was performed. Odds ratios (ORs) of physical fitness for cardiometabolic risk were evaluated via logistic regression.

Results

Metabolically unhealthy children showed greater weight, height, and body mass index, higher Children’s Depression Inventory score, and longer screen time than did the metabolically healthy children. Metabolically healthy children showed greater upper and lower extremity muscular strength than did the metabolically unhealthy children (P=0.04 and P<0.001, respectively). In the multiple logistic regression analysis, lower extremity muscle strength was inversely related to the clustered cardiometabolic risk of the children and adolescents with or without adjustment for confounders (OR, 4.32; 95% confidence interval [CI], 1.87–9.97; OR, 7.64; 95% CI, 1.55– 37.74, respectively).

Conclusion

Physical fitness, especially lower extremity muscle strength, is significantly inversely associated with individual and clustered cardiometabolic risks in Korean children and adolescents.

Sodium acetate improves disrupted glucoregulation and hepatic triglyceride content in insulin-resistant female rats: involvement of adenosine deaminase and dipeptidyl peptidase-4 activities

Combined oral contraceptive (COC) treatment has been shown to be associated with glucose deregulation and increased triglyceride levels, but the mechanisms are elusive. Soluble dipeptidyl peptidase-4 (sDPP-4) and adenosine deaminase (ADA) are involved in the initiation and/or progression of cardiometabolic disorders. We therefore, hypothesized that increased DPP-4 and ADA activities are involved in glucose deregulation and hepatic triglyceride accumulation induced by COC treatment. This study also investigated whether short-chain fatty acid, acetate, would protect against COC-induced dysmetabolic effects. Female Wistar rats received (p.o.) vehicle and COC (1.0 μg ethinylestradiol plus 5.0 μg levonorgestrel) with or without sodium acetate (ACE; 200 mg) for 8 weeks. Treatment with COC led to increased plasma triglyceride-glucose index, 1-h postload glucose response, insulin, free fatty acid, insulin resistance, and impaired glucose tolerance. COC treatment also resulted in increased plasma and hepatic triglycerides (TG), TG/HDL-cholesterol ratio, malondialdehyde, uric acid, lactate dehydrogenase, DPP-4, ADA, and xanthine oxidase (XO) activities. On the other hand, COC led to reduction in nitric oxide level. However, ACE significantly ameliorated the alterations induced by COC treatment, but XO activity remains elevated during COC treatment. This result also demonstrates that increased DPP-4 and ADA activities are at least in part involved in glucose deregulation and hepatic TG accumulation induced by COC treatment. Therefore, sodium acetate would impact positively on cardiometabolic disorders, at least in part, by inhibition of DPP-4 and ADA activities.

Association between insulin resistance and the development of cardiovascular disease

For many years, cardiovascular disease (CVD) has been the leading cause of death around the world. Often associated with CVD are comorbidities such as obesity, abnormal lipid profiles and insulin resistance. Insulin is a key hormone that functions as a regulator of cellular metabolism in many tissues in the human body. Insulin resistance is defined as a decrease in tissue response to insulin stimulation thus insulin resistance is characterized by defects in uptake and oxidation of glucose, a decrease in glycogen synthesis, and, to a lesser extent, the ability to suppress lipid oxidation. Literature widely suggests that free fatty acids are the predominant substrate used in the adult myocardium for ATP production, however, the cardiac metabolic network is highly flexible and can use other substrates, such as glucose, lactate or amino acids. During insulin resistance, several metabolic alterations induce the development of cardiovascular disease. For instance, insulin resistance can induce an imbalance in glucose metabolism that generates chronic hyperglycemia, which in turn triggers oxidative stress and causes an inflammatory response that leads to cell damage. Insulin resistance can also alter systemic lipid metabolism which then leads to the development of dyslipidemia and the well-known lipid triad: (1) high levels of plasma triglycerides, (2) low levels of high-density lipoprotein, and (3) the appearance of small dense low-density lipoproteins. This triad, along with endothelial dysfunction, which can also be induced by aberrant insulin signaling, contribute to atherosclerotic plaque formation. Regarding the systemic consequences associated with insulin resistance and the metabolic cardiac alterations, it can be concluded that insulin resistance in the myocardium generates damage by at least three different mechanisms: (1) signal transduction alteration, (2) impaired regulation of substrate metabolism, and (3) altered delivery of substrates to the myocardium. The aim of this review is to discuss the mechanisms associated with insulin resistance and the development of CVD. New therapies focused on decreasing insulin resistance may contribute to a decrease in both CVD and atherosclerotic plaque generation.

CHRONIC UNPREDICTABLE MILD STRESS PROGRESSIVELY DISTURBS GLUCOSE METABOLISM AND APPETITE HORMONES IN RATS

Context

Chronic stress is characterized by increased release of catecholamines, glucocorticoids and other neurohumoral factors, predisposing individuals to obesity, insulin resistance and vascular disease, pathologies considered priority health problems. Study of alterations induced by stress on metabolism in association with food intake modulatory hormones (insulin, leptin and ghrelin) is mandatory.

Objective

This research studied temporal course during 60 days of chronic unpredictable mild stress (CUMS) on glucose and lipids metabolism, and on the neuroendocrine system that regulates appetite-satiety balance.

Materials and Methods

Wistar rats were exposed to CUMS for 20, 40 and 60 days. Corticosterone stayed high during 60 days of CUMS; after 40 days, body weight, cholesterol and triglycerides decreased and glucose intolerance was evident at day 60; insulin and ghrelin increased at 20 and 40 days, respectively; leptin decreased after day 20. Data suggest that 60 days of CUMS progressively disturb metabolism of carbohydrates and lipids as well as food intake regulatory hormones, affecting the metabolism, and can lead to the development of chronic degenerative diseases, such as cardiovascular disease, metabolic syndrome and type 2 diabetes.

LIPC variants as genetic determinants of adiposity status, visceral adiposity indicators, and triglyceride-glucose (TyG) index-related parameters mediated by serum triglyceride levels

BACKGROUND

Visceral adiposity indicators and the product of triglyceride and fasting plasma glucose (TyG) index-related parameters are effective surrogate markers for insulin resistance (IR) and are predictors of metabolic syndrome and diabetes mellitus. However, their genetic determinants have not been previously reported. Pleiotropic associations of LIPC variants have been observed in lipid profiles and atherosclerotic cardiovascular diseases. We aimed to investigate LIPC polymorphisms as the genetic determinants of adiposity status, visceral adiposity indicators and TyG index-related parameters.

METHODS

A total of 592 participants from Taiwan were genotyped for three LIPC single nucleotide polymorphisms (SNPs).

RESULTS

The LIPC SNPs rs2043085 and rs1532085 were significantly associated with body mass index (BMI), waist circumference (WC), lipid accumulation product, visceral adiposity index, and TyG index-related parameters [including the TyG index, TyG with adiposity status (TyG-BMI), and TyG-WC index], whereas the rs1800588 SNP was only significantly associated with the TyG index. The associations became nonsignificant after further adjustment for serum TG levels. No significant association was observed between any the studied LIPC SNPs and IR status.

CONCLUSION

Our data revealed a pleiotropic association between the LIPC variants and visceral adiposity indicators and TyG index-related parameters, which are mediated by serum TG levels.

β-Adrenergic Receptor and Insulin Resistance in the Heart

Insulin resistance is characterized by the reduced ability of insulin to stimulate tissue uptake and disposal of glucose including cardiac muscle. These conditions accelerate the progression of heart failure and increase cardiovascular morbidity and mortality in patients with cardiovascular diseases. It is noteworthy that some conditions of insulin resistance are characterized by up-regulation of the sympathetic nervous system, resulting in enhanced stimulation of β-adrenergic receptor (βAR). Overstimulation of βARs leads to the development of heart failure and is associated with the pathogenesis of insulin resistance in the heart. However, pathological consequences of the cross-talk between the βAR and the insulin sensitivity and the mechanism by which βAR overstimulation promotes insulin resistance remain unclear. This review article examines the hypothesis that βARs overstimulation leads to induction of insulin resistance in the heart.

Impact of weight loss-associated changes in detailed body composition as assessed by whole-body MRI on plasma insulin levels and homeostatis model assessment index

BACKGROUND/OBJECTIVES

We assessed the effect of weight loss-associated changes in detailed body composition on plasma insulin levels and homeostatic model assessment (HOMA) index to calculate the magnitude of reduction in different adipose tissue depots required to improve insulin sensitivity.

SUBJECTS/METHODS

A total of 50 subjects aged 20-69 years were studied. The participants were compiled from low-calorie diet interventions and bariatric surgery and differed in their baseline body mass index (BMI; range 21.6-54.4 kg/m²) and degree of weight losses (range -3.3 to -56.9 kg). Detailed body composition and liver fat were measured using whole-body magnetic resonance imaging (MRI). Insulin resistance was assessed by HOMA.

RESULTS

Mean body weight decreased by -16.0±13.6 kg. Significant changes were observed in total adipose tissue (TAT_MRI, range -0.5 to -36.0 kg), total subcutaneous adipose tissue (SAT_MRI), visceral adipose tissue (VAT_MRI), skeletal muscle, liver fat, plasma insulin levels and HOMA. Decreases in insulin and HOMA were correlated with reductions in TAT_MRI, SAT_MRI, VAT_MRI (just with HOMA) and liver fat. Losses of 2.9 and 6.5 kg body weight, 2.0 and 5.0 kg TAT_MRI as well as 1.6 and 6% liver fat were required to decrease plasma insulin levels by 1 μU/ml and HOMA_{adjusted for baseline HOMA} by 1 point. Multiple regression analysis showed that baseline liver fat and changes in liver fat explained 49.7% and 55.1% of the variance in weight loss-associated changes in plasma insulin and HOMA, respectively.

CONCLUSIONS

Decreases of adipose tissues and liver fat are the major determinants of reduction in plasma insulin levels and improvement in HOMA index.

Hypoglycemic and anti-hyperglycemic activity of Triphalādi granules in mice

Background:

Triphalādi kvātha is well known herbal Ayurvedic formulation used in Prameha (~type 2 diabetes mellitus). In the present study, kvātha was converted into granules and assessed for its hypoglycemic and anti-hyperglycemic effects in albino mice.

Materials and Methods:

Triphalādi granules (650 mg/kg, p.o.) were administered in normal albino mice for assessment of hypoglycemic activity. Anti-hyperglycemic activity of Triphalādi granules was assessed in glucose (5 g/kg, p.o.) solution overloaded mice. The blood sugar level (BSL) was measured with the help of one touch easy glucometer.

Results:

Triphalādi granules produced significant decrease in blood glucose level after one hour in comparison to initial values while decreasing BSL by 27.92% in comparison to control group in normal albino mice. In hyperglycemic study, Triphalādi granules produced significant decrease the BSL after 2 hr. of administration compared to control group.

Conclusion:

Triphalādi granules have significant hypoglycemic and anti-hyperglycemic activity in mice with minimal effect on BSL below normal range. The studies suggest the potential role of Triphalādi granules as an alternative adjuvant therapy in diabetic individuals for the control of the blood glucose level.

Molecular characterization of insulin resistance and glycolytic metabolism in the rat uterus

Peripheral insulin resistance and hyperandrogenism are the primary features of polycystic ovary syndrome (PCOS). However, how insulin resistance and hyperandrogenism affect uterine function and contribute to the pathogenesis of PCOS are open questions. We treated rats with insulin alone or in combination with human chorionic gonadotropin (hCG) and showed that peripheral insulin resistance and hyperandrogenism alter uterine morphology, cell phenotype, and cell function, especially in glandular epithelial cells. These defects are associated with an aberration in the PI3K/Akt signaling pathway that is used as an indicator for the onset of insulin resistance in classical metabolic tissues. Concomitantly, increased GSK3β (Ser-9) phosphorylation and decreased ERK1/2 phosphorylation in rats treated with insulin and hCG were also observed. We also profiled the expression of glucose transporter (Glut) isoform genes in the uterus under conditions of insulin resistance and/or hyperandrogenism. Finally, we determined the expression pattern of glycolytic enzymes and intermediates during insulin resistance and hyperandrogenism in the uterus. These findings suggest that the PI3K/Akt and MAPK/ERK signaling pathways play a role in the onset of uterine insulin resistance, and they also suggest that changes in specific Glut isoform expression and alterations to glycolytic metabolism contribute to the endometrial dysfunction observed in PCOS patients.

Long-term in vivo polychlorinated biphenyl 126 exposure induces oxidative stress and alters proteomic profile on islets of Langerhans

It has been recently proposed that exposure to polychlorinated biphenyls (PCBs) is a risk factor to type 2 diabetes mellitus (DM2). We investigated this hypothesis using long-term in vivo PCB126 exposure to rats addressing metabolic, cellular and proteomic parameters. Male Wistar rats were exposed to PCB126 (0.1, 1 or 10 μg/kg of body weight/day; for 15 days) or vehicle by intranasal instillation. Systemic alterations were quantified by body weight, insulin and glucose tolerance, and blood biochemical profile. Pancreatic toxicity was measured by inflammatory parameters, cell viability and cycle, free radical generation, and proteomic profile on islets of Langerhans. In vivo PCB126 exposure enhanced the body weight gain, impaired insulin sensitivity, reduced adipose tissue deposit, and elevated serum triglycerides, cholesterol, and insulin levels. Inflammatory parameters in the pancreas and cell morphology, viability and cycle were not altered in islets of Langerhans. Nevertheless, in vivo PCB126 exposure increased free radical generation and modified the expression of proteins related to oxidative stress on islets of Langerhans, which are indicative of early β-cell failure. Data herein obtained show that long-term in vivo PCB126 exposure through intranasal route induced alterations on islets of Langerhans related to early end points of DM2.

Agrimonia eupatoria L. and Cynara cardunculus L. Water Infusions: Comparison of Anti-Diabetic Activities

Diabetes mellitus (DM) is frequently diagnosed at a time when patients already suffer from several cardiovascular complications. Our previously published data (Molecules 201520 (11): 20538-50) on the anti-oxidative properties of Agrimonia eupatoria L. (AE) and Cynara cardunculus L. (CC) prompted us to extend the available evidence on their possible protective activities on selected DM-related parameters in a streptozotocin-induced DM rat model and in a series of in vitro experiments. Male rats were divided into four groups: control group, untreated diabetic group, AE and CC treated diabetic groups. During a five-week period, changes in blood glucose and body weight were monitored. Then, rats were sacrificed and subjected to the assessment of changes in the reactivity of aortas and measurement of butyrylcholinesterase activity. To complete the panel of experiments, α-glucosidase activity was assessed in vitro. Our results demonstrate that both tested extracts exert similar anti-diabetic activities. However, better anti-oxidant activity of the A. eupatoria extract indicates its higher clinical potential in the prevention and/or adjuvant therapy of developing cardiovascular complications related to DM and diseases associated with oxidative stress.

Triglyceride Glucose-Body Mass Index Is a Simple and Clinically Useful Surrogate Marker for Insulin Resistance in Nondiabetic Individuals

Background

Insulin resistance (IR) and the consequences of compensatory hyperinsulinemia are pathogenic factors for a set of metabolic abnormalities, which contribute to the development of diabetes mellitus and cardiovascular diseases. We compared traditional lipid levels and ratios and combined them with fasting plasma glucose (FPG) levels or adiposity status for determining their efficiency as independent risk factors for IR.

Methods

We enrolled 511 Taiwanese individuals for the analysis. The clinical usefulness of various parameters—such as traditional lipid levels and ratios; visceral adiposity indicators, visceral adiposity index (VAI), and lipid accumulation product (LAP); the product of triglyceride (TG) and FPG (the TyG index); TyG with adiposity status (TyG-body mass index [BMI]) and TyG-waist circumference index [WC]); and adipokine levels and ratios—was analyzed to identify IR.

Results

For all lipid ratios, the TG/high-density lipoprotein cholesterol (HDL-C) ratio had the highest additional percentage of variation in the homeostasis model assessment of insulin resistance (HOMA-IR; 7.0% in total); for all variables of interest, TyG-BMI and leptin-adiponectin ratio (LAR) were strongly associated with HOMA-IR, with 16.6% and 23.2% of variability, respectively. A logistic regression analysis revealed similar patterns. A receiver operating characteristic (ROC) curve analysis indicated that TG/HDL-C was a more efficient IR discriminator than other lipid variables or ratios. The area under the ROC curve (AUC) for VAI (0.734) and TyG (0.708) was larger than that for TG/HDL-C (0.707). TyG-BMI and LAR had the largest AUC (0.801 and 0.801, respectively).

Conclusion

TyG-BMI is a simple, powerful, and clinically useful surrogate marker for early identification of IR.

Efficacy and safety of dapagliflozin in addition to insulin therapy in Japanese patients with type 2 diabetes: Results of the interim analysis of 16-week double-blind treatment period

Introduction

Dapagliflozin treatment when added to insulin therapy in Japanese patients with type 2 diabetes remains to be evaluated.

Materials and Methods

This was a multicenter, randomized, double‐blind, parallel‐group, placebo‐controlled study to evaluate efficacy (at 16 weeks) and long‐term safety (at 52 weeks) of dapagliflozin in addition to insulin therapy. The interim analysis was carried out at week 16 to assess the efficacy and safety profiles. The patients receiving insulin (n = 182) were randomized to either dapagliflozin 5 mg or a placebo at a 2:1 ratio. The primary efficacy end‐point was the change in hemoglobin A1c (HbA1c) from baseline at week 16.

Results

Patients in the dapagliflozin group showed an adjusted decrease in HbA1c of −0.55% from baseline, whereas the placebo showed a marginal increase of 0.05%. The placebo‐corrected mean change of HbA1c from baseline to week 16 in dapagliflozin was −0.60% (P < 0.0001). In addition, the placebo‐corrected mean change of fasting plasma glucose and bodyweight from baseline to week 16 in the dapagliflozin group was −22.7 mg/dL (P < 0.0001) and −1.21 kg (P < 0.0001), respectively. The placebo‐corrected mean daily insulin dose in the dapagliflozin group was numerically decreased (treatment difference: −0.72 IU/day; P = 0.0743). No major episodes or discontinuations as a result of hypoglycemia were reported during the study period.

Conclusions

Dapagliflozin used as add‐on treatment to insulin therapy showed significantly greater reduction of HbA1c, fasting plasma glucose and bodyweight without severe hypoglycemia compared with the placebo at week 16. These results show the clinical benefit of prescribing dapagliflozin for Japanese patients with insufficient glycemic control even with insulin therapy.

Prediabetes linked to excess glucagon in transgenic mice with pancreatic active AKT1

Protein kinase B/AKT has three isoforms (AKT1-3) and is renowned for its central role in the regulation of cell growth and proliferation, due to its constitutive activation in various cancers. AKT2, which is highly expressed in insulin-responsive tissues, has been identified as a primary regulator of glucose metabolism as Akt2 knockout mice (Akt2(-/-)) are glucose-intolerant and insulin-resistant. However, the role of AKT1 in glucose metabolism is not as clearly defined. We previously showed that mice with myristoylated Akt1 (AKT1(Myr)) expressed through a bicistronic Pdx1-TetA and TetO-MyrAkt1 system were susceptible to islet cell carcinomas, and in this study we characterized an early onset, prediabetic phenotype. Beginning at weaning (3 weeks of age), the glucose-intolerant AKT1(Myr) mice exhibited non-fasted hyperglycemia, which progressed to fasted hyperglycemia by 5 months of age. The glucose intolerance was attributed to a fasted hyperglucagonemia, and hepatic insulin resistance detectable by reduced phosphorylation of the insulin receptor following insulin injection into the inferior vena cava. In contrast, treatment with doxycycline diet to turn off the transgene caused attenuation of the non-fasted and fasted hyperglycemia, thus affirming AKT1 hyperactivation as the trigger. Collectively, this model highlights a novel glucagon-mediated mechanism by which AKT1 hyperactivation affects glucose homeostasis and provides an avenue to better delineate the molecular mechanisms responsible for diabetes mellitus and the potential association with pancreatic cancer.

Short-term, high-fat diet accelerates disuse atrophy and protein degradation in a muscle-specific manner in mice

BACKGROUND

A short-term high-fat diet impairs mitochondrial function and the ability of skeletal muscle to respond to growth stimuli, but it is unknown whether such a diet alters the ability to respond to atrophy signals. The purpose of this study was to determine whether rapid weigh gain induced by a high-fat (HF) diet accelerates denervation-induced muscle atrophy.

METHODS

Adult, male mice (C57BL/6) were fed a control or HF (60 % calories as fat) diet for 3 weeks (3wHF). Sciatic nerve was sectioned unilaterally for the final 5 or 14 days of the diet. Soleus and extensor digitorum longus (EDL) muscles were removed and incubated in vitro to determine rates of protein degradation and subsequently homogenized for determination of protein levels of LC3, ubiquitination, myosin heavy chain (MHC) distribution, and mitochondrial subunits.

RESULTS

When mice were fed the 3wHF diet, whole-body fat mass more than doubled, but basal (innervated) muscle weights, rates of protein degradation, LC3 content, mitochondrial protein content, and myosin isoform distribution were not significantly different than with the control diet in either soleus or EDL. However in the 14 day denervated soleus, the 3wHF diet significantly augmented loss of mass, proteolysis rate, amount of the autophagosome marker LC3 II, and the amount of overall ubiquitination as compared to the control fed mice. On the contrary, the 3wHF diet had no significant effect in the EDL on amount of mass loss, proteolysis rate, LC3 levels, or ubiquitination. Fourteen days denervation also induced a loss of mitochondrial proteins in the soleus but not the EDL, regardless of the diet.

CONCLUSIONS

Taken together, a short-term, high-fat diet augments denervation muscle atrophy by induction of protein degradation in the mitochondria-rich soleus but not in the glycolytic EDL. These findings suggest that the denervation-induced loss of mitochondria and HF diet-induced impairment of mitochondrial function may combine to promote skeletal muscle atrophy.

Helicobacter pylori Infection Increases Insulin Resistance and Metabolic Syndrome in Residents Younger than 50 Years Old: A Community-Based Study

This study aimed to analyze the influence of H. pylori infection on insulin resistance and metabolic syndrome (MS) by multivariate analysis of a community-based cohort study. From January 2013 to February 2014,811 subjects were enrolled in a community-based cohort study from the northeastern region of Taiwan. All subjects received a demographic survey and blood tests, including an H. pylori antibody test, liver biochemistry tests, lipid profiles, sugar/insulin levels for Homeostatic model assessment (HOMA-IR index), and measurements of adipokines and inflammatory cytokines. A total of 264 men and 547 women were included in this study. The mean age was 59.2 ± 12.7 years. Subjects seropositive for H. pylori antibodies exhibited higher rates of hypertension, an increased incidence of a HOMA-IR index > 2.5 and a higher level of tumor necrosis factor-α than those without H. pylori antibodies. We found a significant difference in the presence of H. pylori antibodies between subjects with MS and those without MS (76.7% vs. 53.7%, p = 0.007) among subjects < 50 y/o. A HOMA-IR index >2.5, H. pylori antibody presence and leptin were predictors for MS in subjects < 50 y/o. The estimated odds ratio of MS for a subject with H. pylori antibodies was 3.717 (95% CI = 1.086–12.719) times that of a subject without H. pylori antibodies. In addition, no difference in H. pylori antibody status was detected for MS prediction in subjects that were ≧ 50 y/o (p = 0.861). In conclusion, subjects with H. pylori antibodies had a higher incidence of a HOMA-IR >2.5 than those without H pylori antibodies. For subjects aged < 50 y/o, the H. pylori antibody was a predictor for MS.

Regulation of hepatic TRB3/Akt interaction induced by physical exercise and its effect on the hepatic glucose production in an insulin resistance state

To maintain euglycemia in healthy organisms, hepatic glucose production is increased during fasting and decreased during the postprandial period. This whole process is supported by insulin levels. These responses are associated with the insulin signaling pathway and the reduction in the activity of key gluconeogenic enzymes, resulting in a decrease of hepatic glucose production. On the other hand, defects in the liver insulin signaling pathway might promote inadequate suppression of gluconeogenesis, leading to hyperglycemia during fasting and after meals. The hepatocyte nuclear factor 4, the transcription cofactor PGC1-α, and the transcription factor Foxo1 have fundamental roles in regulating gluconeogenesis. The loss of insulin action is associated with the production of pro-inflammatory biomolecules in obesity conditions. Among the molecular mechanisms involved, we emphasize in this review the participation of TRB3 protein (a mammalian homolog of Drosophila tribbles), which is able to inhibit Akt activity and, thereby, maintain Foxo1 activity in the nucleus of hepatocytes, inducing hyperglycemia. In contrast, physical exercise has been shown as an important tool to reduce insulin resistance in the liver by reducing the inflammatory process, including the inhibition of TRB3 and, therefore, suppressing gluconeogenesis. The understanding of these new mechanisms by which physical exercise regulates glucose homeostasis has critical importance for the understanding and prevention of diabetes.

Proteomic analysis in type 2 diabetes patients before and after a very low calorie diet reveals potential disease state and intervention specific biomarkers

Very low calorie diets (VLCD) with and without exercise programs lead to major metabolic improvements in obese type 2 diabetes patients. The mechanisms underlying these improvements have so far not been elucidated fully. To further investigate the mechanisms of a VLCD with or without exercise and to uncover possible biomarkers associated with these interventions, blood samples were collected from 27 obese type 2 diabetes patients before and after a 16-week VLCD (Modifast ∼450 kcal/day). Thirteen of these patients followed an exercise program in addition to the VCLD. Plasma was obtained from 27 lean and 27 obese controls as well. Proteomic analysis was performed using mass spectrometry (MS) and targeted multiple reaction monitoring (MRM) and a large scale isobaric tags for relative and absolute quantitation (iTRAQ) approach. After the 16-week VLCD, there was a significant decrease in body weight and HbA1c in all patients, without differences between the two intervention groups. Targeted MRM analysis revealed differences in several proteins, which could be divided in diabetes-associated (fibrinogen, transthyretin), obesity-associated (complement C3), and diet-associated markers (apolipoproteins, especially apolipoprotein A-IV). To further investigate the effects of exercise, large scale iTRAQ analysis was performed. However, no proteins were found showing an exercise effect. Thus, in this study, specific proteins were found to be differentially expressed in type 2 diabetes patients versus controls and before and after a VLCD. These proteins are potential disease state and intervention specific biomarkers.

Trial Registration

Controlled-Trials.com ISRCTN76920690

Correlation of insulin resistance by various methods with fasting insulin in obese

BACKGROUND

Several studies indicate that obesity is closely related to insulin resistance (IR). However, this relationship has not been adequately explored.

AIMS

This study aims to evaluate the prevalence of IR among obese using some indirect methods for assessment of IR.

MATERIALS AND METHODS

We analyzed the correlation of fasting insulin (FI) with body mass index. We examined 100 obese and overweight. Anthropometric measurements were done for all individuals. Blood lipids parameters, glucose, and insulin were assayed after a 10 h fast. The indices McAuley (McA), homeostasis model assessments (HOMA), quantitative insulin sensitivity check index (QUICKI) were used to assess IR.

RESULTS

In this study, the correlations of FI with McA, HOMA and QUICKI were significant (P < 0.05). FI test had significant sensitivity and specificity when compared with McA, HOMA and QUICKI indices. FI gives parallel results to the assessment of IR by other methods. Validity of FI was further analyzed by Cohen's kappa test and had a satisfactory agreement (χ =0.940).

CONCLUSION

Altogether, this study suggested that FI was sensitive and also specific as McA in assessment of IR in obese. Thus, FI can be used as an easy test to detect IR also in obese.

Prevalence of insulin resistance in siblings of type 2 diabetics of north west punjabi population

CONTEXT

Insulin resistance a physiological condition is marked by hyperglycemia and failure of cells to respond to normal action thus hyperinsulinemia. It is prevalent in individuals having genetic predisposition and family history of type 2 diabetes mellitus. Physically inactive individuals having sedentary life style are also at a risk of developing insulin resistance.

AIM

The present study was planned to observe the prevalence of insulin resistance or pre diabetes in various age groups of North West Punjabi population.

MATERIALS AND METHODS

A total of 400 families comprising of 1159 offsprings of diabetic patients and siblings amongst each were included in the present study. All these 400 families had history of type 2 diabetes mellitus in the present or past generation. Written consent was taken from the head of the family for inclusion in the study. Fasting samples were collected and analysed for Glucose, Glycosylated Hb, complete lipid profile, Insulin and c-peptide. Body mass index, waist hip ratio and HOMA-IR were calculated. Comparison of mean of various parameters was done using student t-test. Analysis of variance (ANOVA) was applied for comparison between groups followed by Bonferroni post hoc analysis. Pearson's correlation method was used for quantitative variables. Statistical significance was defined as p<0.05 (two tailed).

RESULTS

Prevalence of impaired fasting glucose both in males and females increased with advancing age. Hyperglycemia along with hyperinsulinemia, hypercholesterolemia and hypertriglyceridemia was observed in individuals having impaired fasting glucose. Individuals belonging to age group of >18-35 years were more prone to insulin resistance as compared to other age groups.

CONCLUSION

Insulin resistance at a young age of 18-35 years predisposes these individuals to coronary events. Females in reproductive years are more prone to insulin resistance or pre diabetes as compared to males of the same age group.

High-throughput screening of FDA-approved drugs using oxygen biosensor plates reveals secondary mitofunctional effects

Repurposing of FDA-approved drugs with effects on mitochondrial function might shorten the critical path to mitochondrial disease drug development. We improved a biosensor-based assay of mitochondrial O2 consumption, and identified mitofunctional defects in cell models of LHON and FXTAS. Using this platform, we screened a 1600-compound library of clinically used drugs. The assay identified drugs known to affect mitochondrial function, such as metformin and decoquinate. We also identified several drugs not previously known to affect mitochondrial respiration including acarbose, metaraminol, gallamine triethiodide, and acamprosate. These previously unknown 'mitoactives' represent novel links to targets for mitochondrial regulation and potentially therapy, for mitochondrial disease.

Transdermal delivery of insulin by amidated pectin hydrogel matrix patch in streptozotocin-induced diabetic rats: effects on some selected metabolic parameters

PURPOSE

Studies in our laboratory are concerned with developing optional insulin delivery routes based on amidated pectin hydrogel matrix gel. We therefore investigated whether the application of pectin insulin (PI)-containing dermal patches of different insulin concentrations sustain controlled release of insulin into the bloodstream of streptozotocin (STZ)-induced diabetic rats with concomitant alleviation of diabetic symptoms in target tissues, most importantly, muscle and liver.

METHODS

Oral glucose test (OGT) responses to PI dermal matrix patches (2.47, 3.99, 9.57, 16.80 µg/kg) prepared by dissolving pectin/insulin in deionised water and solidified with CaCl2 were monitored in diabetic rats given a glucose load after an 18-h fast. Short-term (5 weeks) metabolic effects were assessed in animals treated thrice daily with PI patches 8 hours apart. Animals treated with drug-free pectin and insulin (175 µg/kg, s.c.) acted as untreated and treated positive controls, respectively. Blood, muscle and liver samples were collected for measurements of selected biochemical parameters.

RESULTS

After 5 weeks, untreated diabetic rats exhibited hyperglycaemia and depleted hepatic and muscle glycogen concentrations. Compared to untreated STZ-induced diabetic animals, OGT responses of diabetic rats transdermally applied PI patches exhibited lower blood glucose levels whilst short-term treatments restored hepatic and muscle glycogen concentrations. Plasma insulin concentrations of untreated diabetic rats were low compared with control non-diabetic rats. All PI treatments elevated plasma insulin concentrations of diabetic rats although the levels induced by high doses (9.57 and 16.80 µg/kg) were greater than those caused by low doses (2.47 and 3.99 µg/kg) but comparable to those in sc insulin treated animals.

CONCLUSIONS

The data suggest that the PI hydrogel matrix patch can deliver physiologically relevant amounts of pharmacologically active insulin.

NOVELTY OF THE WORK

A new method to administer insulin into the bloodstream via a skin patch which could have potential future applications in diabetes management is reported.

The TG/HDL-C Ratio Might Be a Surrogate for Insulin Resistance in Chinese Nonobese Women

Obejective. To examine the discriminatory power of triglyceride (TG) and triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) for insulin resistance (IR) in a normoglycaemic Chinese population. Methods. The data were collected from 711 individuals. The normoglycaemic individuals were eventually included in the study (n = 533, age: 62.8 ± 6.6 years, male: 56.8%), who were with a fasting plasma glucose < 6.1 mmol/L and without a history of diabetes. IR was defined as the upper quintile (≥1.6) of homeostasis model assessment of IR. Area under the receiver operating characteristic curve (AROC) was used to examine the discriminatory power. Results. The discriminatory power of TG/HDL-C for IR was acceptable in women with a BMI < 24 kg/m(2) or waist circumference < 80 cm (AROCs: 0.718 and 0.713, resp.); however, the discriminatory power was not acceptable in the obese women. TG/HDL-C was not an acceptable marker of IR in men. The discriminatory power of TG for IR was not acceptable in both men and women. Conclusions. The discriminatory power of TG/HDL-C for IR differs by gender and obesity index in the normoglycaemic Chinese population, and TG/HDL-C could discriminate IR in the nonobese and normoglycaemic women.

Ankylosing spondylitis and other inflammatory spondyloarthritis increase the risk of developing type 2 diabetes in an Asian population

This study evaluated whether people with ankylosing spondylitis (AS) and spondyloarthritis are at higher risk of type 2 diabetes mellitus (T2DM). We used a sub-dataset of the National Health Insurance Research Database from 1996 to 2010 to established a AS cohort consisting new patients with AS or spondyloarthritis (N = 7,778) and a non-AS cohort without the diseases (N = 31,112). Incidences of T2DM in the two cohorts, hazard ratios (HRs) of risk of T2DM in association with AS, and cumulative probability of having T2DM were estimated by the end of 2010. The incidence of T2DM was 1.17-fold higher in the AS cohort than in the non-AS cohort (13.5 vs. 11.5, per 1,000 person-years), with an adjusted HR of 1.16 (95 % CI = 1.05-1.29). The T2DM incidence was higher for women than for men; while the Cox model measured sex-specific adjusted HR of T2DM was higher for men than for women. The incidence rate of T2DM increased with age in both cohorts, while the age-specific measures showed that the adjusted HR of T2DM was higher in young AS patients (≤50 years of age) than older ones, compared to their peers of non-AS group. The plot of Kaplan-Meier analysis showed that the overall probability of having T2DM was 2 % higher in the AS cohort than in the non-AS cohort (log-rank test: p < 0.0001). Patients with AS and spondyloarthritis have an increased risk of developing T2DM.

Hypoglycemic Activity and Antioxidative Stress of Extracts and Corymbiferin from Swertia bimaculata In Vitro and In Vivo

The present study was to investigate the anti-diabetic activities of Swertia bimaculata. Based on the glucose consumption of S. bimaculata extractsand different fractions (petroleum, dichloromethane, ethyl acetate, n-butanol and water extracts) in 3T3-L1 adipocyte assay, ethanol (ETH) and dichloromethane (DTH) extracts had the most effective potency. Furthermore, ETH, DTH and corymbiferin (the most abundant component of DTH) were evaluated for anti-diabetic effects in high fat and sucrose fed combined with low dose streptozocin induced diabetic rats. DTH and corymbiferin displayed remarkable anti-diabetic activities. The fasting blood glucose levels were significantly decreased, while the serum insulin levels were obviously increased. The oral glucose tolerance was also improved. The lowed serum total cholesterol, low density lipoprotein (LDL) and triglyceride levels and increased ratio of HDL (high density lipoprotein)/LDL were observed. The insulin sensitivity was improved on the basis of increased expressions of insulin-receptor substrate-2, phosphatidylinositol 3-kinase and Ser/Thr kinase AKT2. And also DTH and corymbiferin improved antioxidant capacity and carbohydrate metabolism in diabetic rats, along with the improvement of histopathology of livers and pancreatic β cells. Corymbiferin was one of active constituents, responsible for anti-diabetic properties. Therefore, S. bimaculata could be considered as an alternative agent against diabetes mellitus.

Current insights and new perspectives on the roles of hyperglucagonemia in non-insulin-dependent type 2 diabetes

Type 2 diabetes is well recognized as a noninsulin-dependent diabetic disease. Clinical evidence indicates that the level of circulating insulin may be normal, subnormal, and even elevated in type 2 diabetic patients. Unlike type 1 diabetes, the key problem for type 2 diabetes is not due to the absolute deficiency of insulin secretion, but because the body is no longer sensitive to insulin. Thus, insulin resistance is increased and the sensitivity to insulin is reset, so increasing levels of insulin are required to maintain body glucose and metabolic homeostasis. How insulin resistance is increased and what factors contribute to its development in type 2 diabetes remain incompletely understood. Overemphasis of insulin deficiency alone may be too simplistic for us to understand how type 2 diabetes is developed and should be treated, since glucose metabolism and homeostasis are tightly controlled by both insulin and glucagon. Insulin acts as a YIN factor to lower blood glucose level by increasing cellular glucose uptake, whereas glucagon acts as a YANG factor to counter the action of insulin by increasing glucose production. Furthermore, other humoral factors other than insulin and glucagon may also directly or indirectly contribute to increased insulin resistance and the development of hyperglycemia. The purpose of this article is to briefly review recently published animal and human studies in this field, and provide new insights and perspectives on recent debates as to whether hyperglucagonemia and/or glucagon receptors should be targeted to treat insulin resistance and target organ injury in type 2 diabetes.

Adipokines and hepatic insulin resistance

Obesity is a major risk factor for insulin resistance and type 2 diabetes. Adipose tissue is now considered to be an active endocrine organ that secretes various adipokines such as adiponectin, leptin, resistin, tumour necrosis factor-α, and interleukin-6. Recent studies have shown that these factors might provide a molecular link between increased adiposity and impaired insulin sensitivity. Since hepatic insulin resistance plays the key role in the whole body insulin resistance, clarification of the regulatory processes about hepatic insulin resistance by adipokines in rodents and human would seem essential in order to understand the mechanism of type 2 diabetes and for developing novel therapeutic strategies to treat it.

Comprehensive Evaluation of Anti-hyperglycemic Activity of Fractionated Momordica charantia Seed Extract in Alloxan-Induced Diabetic Rats

The present study evaluates anti-hyperglycemic activity of fractionated Momordica charantia (bitter gourd) seed extracts. Fasting blood glucose levels were evaluated before and after administration of different fractions of the seed extract. Among the three fractions tested, fraction Mc-3 (15 mg/kg b.wt.) showed the maximum anti-hyperglycemic activity and reduced blood glucose levels in experimental diabetic rats significantly. The activities of the key regulatory enzymes of glucose metabolism (hexokinase, pyruvate kinase, lactate dehydrogenase, and glucose-6-phosphate dehydrogenase) were determined in Mc-3-treated diabetic animals. Once-daily administration of the fraction Mc-3 for prolonged period of 18 days to the experimental diabetic animals did not result in any nephrotoxicity or hepatotoxicity as evident from insignificant changes in biochemical parameters indicative of liver and kidney functions. Further fractionation of the fraction Mc-3 by size exclusion chromatography resulted in a fraction, designated Mc-3.2, possessing anti-hyperglycemic activity. The fraction Mc-3.2 showed the presence of a predominant protein band of ~11 kDa on SDS-PAGE. Loss in anti-hyperglycemic activity of the Mc-3.2 upon protease treatment indicates the proteinaceous nature of the anti-hyperglycemic principles. Overall, the results suggest that Momordica charantia seeds contain an effective anti-hyperglycemic protein(s) which may find application in treatment of diabetes without evident toxic effects.

Linagliptin improves insulin sensitivity and hepatic steatosis in diet-induced obesity

Linagliptin (tradjenta™) is a selective dipeptidyl peptidase-4 (DPP-4) inhibitor. DPP-4 inhibition attenuates insulin resistance and improves peripheral glucose utilization in humans. However, the effects of chronic DPP-4 inhibition on insulin sensitivity are not known. The effects of long-term treatment (3–4 weeks) with 3 mg/kg/day or 30 mg/kg/day linagliptin on insulin sensitivity and liver fat content were determined in diet-induced obese C57BL/6 mice. Chow-fed animals served as controls. DPP-4 activity was significantly inhibited (67–89%) by linagliptin (P<0.001). Following an oral glucose tolerance test, blood glucose concentrations (measured as area under the curve) were significantly suppressed after treatment with 3 mg/kg/day (–16.5% to –20.3%; P<0.01) or 30 mg/kg/day (–14.5% to –26.4%; P<0.05) linagliptin (both P<0.01). Liver fat content was significantly reduced by linagliptin in a dose-dependent manner (both doses P<0.001). Diet-induced obese mice treated for 4 weeks with 3 mg/kg/day or 30 mg/kg/day linagliptin had significantly improved glycated hemoglobin compared with vehicle (both P<0.001). Significant dose-dependent improvements in glucose disposal rates were observed during the steady state of the euglycemic–hyperinsulinemic clamp: 27.3 mg/kg/minute and 32.2 mg/kg/minute in the 3 mg/kg/day and 30 mg/kg/day linagliptin groups, respectively; compared with 20.9 mg/kg/minute with vehicle (P<0.001). Hepatic glucose production was significantly suppressed during the clamp: 4.7 mg/kg/minute and 2.1 mg/kg/minute in the 3 mg/kg/day and 30 mg/kg/day linagliptin groups, respectively; compared with 12.5 mg/kg/minute with vehicle (P<0.001). In addition, 30 mg/kg/day linagliptin treatment resulted in a significantly reduced number of macrophages infiltrating adipose tissue (P<0.05). Linagliptin treatment also decreased liver expression of PTP1B, SOCS3, SREBP1c, SCD-1 and FAS (P<0.05). Other tissues like muscle, heart and kidney were not significantly affected by the insulin sensitizing effect of linagliptin. Long-term linagliptin treatment reduced liver fat content in animals with diet-induced hepatic steatosis and insulin resistance, and may account for improved insulin sensitivity.

The role of insulin resistance in the development of muscle wasting during cancer cachexia

BACKGROUND

Cancer cachexia is a complex syndrome associated with multiple metabolic abnormalities. Insulin resistance is present in many cancer patients and may be one mechanism through which muscle wasting occurs.

METHODS AND RESULTS

The present review examines evidence in support of a role for insulin resistance in the development of muscle wasting during cancer cachexia and identifies areas for future research. Patients suffering from cancer cachexia tend to exhibit insulin resistance and improvements in insulin resistance have the potential to improve cachexia symptoms. In addition, evidence suggests that insulin resistance may occur prior to the onset of cachexia symptoms.

CONCLUSIONS

Further investigation of the role of insulin resistance in cancer cachexia is needed. The use of translational research in this area is strongly encouraged, and has important implications for clinical research and the treatment and prevention of cancer cachexia.