Hexarelin, a Growth Hormone Secretagogue, Improves Lipid Metabolic Aberrations in Nonobese Insulin-Resistant Male MKR Mice

Despite the occurrence of dyslipidemia and its contribution to the development of insulin resistance in obese subjects, a growing number of studies have described abnormal lipid profiles among leaner persons. For example, individuals with an abnormal paucity or distribution of fat (lipodystrophy) develop severe insulin resistance, dyslipidemia, and hepatic steatosis. Deranged adipocyte metabolism and differentiation contribute to ectopic fat deposition and consequent development of insulin resistance. Growth hormone (GH) therapy has been shown to correct body composition abnormalities in some lipodystrophy patients. However, little is known about the effects of GH-releasing peptides in this regard. Hexarelin, a GH secretagogue, has recently been shown to have beneficial effects on fat metabolism via the CD36 receptor. In this study, the effects of twice daily intraperitoneal injections of hexarelin (200 μg/kg body weight) were examined in nonobese insulin-resistant MKR mice and corresponding wild-type FVB mice for 12 days. Hexarelin treatment significantly improved glucose and insulin intolerance and decreased plasma and liver triglycerides in MKR mice. These beneficial metabolic effects could be due to the improved lipid metabolism and enhanced adipocyte differentiation of white adipose tissue with hexarelin treatment. Interestingly, although food intake of hexarelin-treated MKR mice was significantly increased, this did not change total body weight. Moreover, hexarelin treatment corrected the abnormal body composition of MKR mice, as demonstrated by a decrease in fat mass and an increase in lean mass. Our results suggest a possible application of hexarelin in treatment of lipid disorders associated with the metabolic syndrome.

Effects of medicinal food plants on impaired glucose tolerance: A systematic review of randomized controlled trials

BACKGROUND

The objective of this systematic review was to assess available scientific data on the efficacy and safety of medicinal food plants for the treatment of impaired glucose tolerance.

METHODS

We included randomized controlled trials (RCTs) with a minimum follow-up period of 6weeks. The diagnosis was determined by fasting plasma glucose values after two-hour oral glucose tolerance testing (OGTT). Two authors independently extracted data and evaluated bias. The Cochrane tool of risk of Bias Tool was used.

RESULTS

This review included ten trials. Most studies were highly biased as data were incomplete or reporting was selective. The two-hour fasting plasma glucose after the curcumin extract intervention showed statistical significance after 3, 6 and 9months: p<0.01. Also, glycosylated haemoglobin levels A1c (HbA1c) values after curcumin extract intervention showed statistical significance after 3, 6 and 9months: p<0.01. Insulin resistance (HOMA-IR) after curcumin extract intervention showed statistical significance after 6months and after 9months: p<0.05 and p<0.01.

CONCLUSIONS

Curcumin has shown the confident results to be effective for the treatment of impaired glucose tolerance. Fenugreek and flaxseed may also be effective, but due to low quality of these studies the results must be interpreted with caution.

Protocol for a pilot randomised controlled trial of metformin in pre-diabetes after kidney transplantation: the Transplantation and Diabetes (Transdiab) study

INTRODUCTION

Post-transplant diabetes mellitus (PTDM) is a common complication of kidney transplantation and is associated with significant morbidity and mortality. In the general population, metformin has been used for diabetes prevention in high-risk individuals. Improving insulin sensitivity is one of many proven favourable effects of metformin. Despite the high incidence of PTDM in kidney transplant recipients, there is a lack of evidence for the role of metformin in the prevention of diabetes in this setting. METHODS AND ANALYSIS: Transplantation and Diabetes (Transdiab) is a single-centre, unblinded, pilot randomised controlled trial assessing the feasibility, tolerability and efficacy of metformin after renal transplantation in patients with impaired glucose tolerance (IGT). Participants will undergo an oral glucose tolerance test in the 4-12 weeks post-transplantation; those with IGT will be randomised to standard care or standard care and metformin 500 mg twice daily, and followed up for 12 months. The primary outcomes of the study will be the feasibility of recruitment, the tolerability of metformin assessed using the Gastrointestinal Symptom Rating Scale at 3 and 12 months, and the efficacy of metformin assessed by morning glucose and glycated haemoglobin at 3, 6, 9 and 12 months.

ETHICS AND DISSEMINATION

Despite the significant morbidity and mortality of PTDM, there are currently no randomised clinical trials assessing pharmacological interventions for its prevention after kidney transplantation. The Transdiab trial will thus provide important data on the feasibility, safety, tolerability and efficacy of metformin after renal transplantation in patients with IGT; this will facilitate undertaking larger multicentre trials of interventions to reduce the incidence or severity of diabetes after kidney transplantation. This study has been approved by the Northern B Health and Disability Ethics Committee of the Ministry of Health in New Zealand. On study completion, results are expected to be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry Number: ACTRN12614001171606.

Preclinical characterization of 55P0251, a novel compound that amplifies glucose-stimulated insulin secretion and counteracts hyperglycaemia in rodents

AIMS

55P0251 is a novel compound with blood glucose lowering activity in mice, which has been developed from a molecular backbone structure found in herbal remedies. We here report its basic pharmacological attributes and initial progress in unmasking the mode of action.

MATERIALS AND METHODS

Pharmacokinetic properties of 55P0251 were portrayed in several species. First efforts to elucidate the glucose lowering mechanism in rodents included numerous experimental protocols dealing with glucose tolerance, insulin secretion from isolated pancreatic islets and comparison to established drugs.

RESULTS

A single oral dose of 55P0251 improved glucose tolerance in mice with an ED₅₀ between 1.5 and 2 mg/kg (reductions in areas under the curve, 1 mg/kg, -18%; 5 mg/kg, -30%; 27 mg/kg, -47%). Pharmacokinetic studies revealed attractive attributes, including a plasma half-life of approximately 3 hours and a bioavailability of approximately 58% in rats. 55P0251 amplified glucose stimulated insulin release from isolated mouse islets and improved glucose tolerance via increased insulin secretion in rats (increase in area under the insulin curve, +184%). Unlike sulfonylureas and glinides, 55P0251 hardly stimulated insulin release under basal conditions and did not induce hypoglycaemia in vivo, but it amplified the secretory response to glucose and other insulinotropic stimuli (KCl, glucagon-like peptide-1). Comparison to established anti-diabetic agents and examination of interaction with molecular targets (K_ATP channel, dipeptidyl peptidase-4, glucagon-like peptide-1 receptor) excluded molecular mechanisms addressed by presently marketed drugs.

CONCLUSIONS

55P0251 is a novel compound that potently counteracts hyperglycaemia in rodents via amplification of glucose-stimulated insulin release.

Effect of Linagliptin Versus Metformin on Glycemic Variability in Patients with Impaired Glucose Tolerance

BACKGROUND

Impaired glucose tolerance (IGT) and glycemic variability may be associated with increased risk of micro- and macrovascular complications. The aim of this study was to assess the effect of linagliptin versus metformin on glycemic variability in patients with IGT.

MATERIAL AND METHODS

A randomized, double-blind clinical trial with parallel groups was carried out in 16 adult patients with IGT, overweight or obesity. All patients signed an informed consent. The therapies were randomly assigned: (a) metformin 500 mg bid (n = 8) or (b) linagliptin 5 mg a.m. and placebo p.m. (n = 8), both for 90 days. At the beginning of the trial and 3 months later, fasting glucose, glycated hemoglobin A1c, oral glucose tolerance test (OGTT), and glycemic variability [area under the curve (AUC) of glucose, mean amplitude of glycemic excursion (MAGE), standard deviation (SD) of glucose, coefficient of variation (CV) of glucose, and mean blood glucose (MBG)] were measured. Mann-Whitney U, Wilcoxon, and Fisher exact tests were used for statistical analyses.

RESULTS

Both groups were similar in basal characteristics. After linagliptin administration, a significant decrease in glucose levels at 120 min of OGTT (9.0 ± 0.9 vs. 6.9 ± 2.2 mmol/L, P = 0.012) was observed. Glycemic variability showed a similar behavior and there were no significant differences in the AUC, MAGE, SD of glucose, CV of glucose, and MBG between groups.

CONCLUSION

Linagliptin administration resulted in better glycemic control according to the decrease of glucose levels by the OGTT at 120 min in patients with IGT. Meanwhile, glycemic variability was not modified in any of the study groups.

Effects of saxagliptin on glucose homeostasis and body composition of obese patients with newly diagnosed pre-diabetes

AIMS

To assess the effect of saxagliptin monotherapy on blood glucose and islet β-cell function in obese patients with newly diagnosed pre-diabetes and abnormal fat metabolism.

METHODS

A 24-week, randomized controlled trial was conducted involving 25 obese subjects with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) (mean age 45years) to receive lifestyle intervention only (control group) or combined with saxagliptin 2.5mg or 5mg daily (S2.5 or S5 group), metformin 1500mg daily (Met group). Anthropometrics, body fat and biochemical parameters were measured before and after 4, 12 and 24weeks intervention.

RESULTS

S5 group and Met group showed a significant decrease in fasting plasma glucose (FPG) and HbA1c compared with the control group (all P<0.05) after 24-week intervention. However, the decrease in 2h postprandial plasma glucose levels (2hPPG) in S5 group were greater compared with control group (P<0.01). Insulin resistance (HOMA-IR) was reduced in S5 group, Met group and control group (P<0.05), and the β-cell function (HOMA-β) was improved in all groups (P<0.05). However, the changes in obesity-related indicators including waist circumference, hip circumference, weight, BMI, body fat, percentage of body fat and waist-to-hip fat ratio were greate in Met group (all P<0.05) compared with other groups (P>0.05).

CONCLUSIONS

Saxagliptin monotherapy may prevent or delay the progression of IGT or IFG to type 2 diabetes mellitus in obese patients with newly diagnosed pre-diabetes. ClinicalTrials.gov: NCT01960205.

Dapagliflozin improves insulin resistance and glucose intolerance in a novel transgenic rat model of chronic glucose overproduction and glucose toxicity

AIM

To determine whether the excretion of glucose improves insulin resistance, impaired insulin secretion or both.

MATERIALS AND METHODS

Appropriate methods were used to assess insulin sensitivity (euglycaemic-hyperinsulinaemic clamp) and insulin secretion (hyperglycaemic clamp) in insulin-resistant and hyperglycaemic phosphoenolpyruvate carboxykinase (PEPCK) transgenic rats after treatment with the sodium-glucose co-transporter-2 (SGLT2) inhibitor dapagliflozin.

RESULTS

In 14-week-old rats with hyperglycaemia, insulin resistance and glucose intolerance, 6 weeks of dapagliflozin treatment resulted in lower weight gain, plasma glucose and insulin levels, and improved glucose tolerance, associated with enhanced insulin sensitivity (rate of glucose disappearance: 51.6 ± 2.3 vs 110.6 ± 3.9 µmol/min/kg; P < .005) and glucose uptake in muscle (0.9 ± 0.1 vs 1.7 ± 0.3 µmol/min/100 g; P < .05) and fat (0.23 ± 0.04 vs 0.55 ± 0.10 µmol/min/100 g, P < .05). Additionally, adipose tissue GLUT4 protein levels were increased (0.78 ± 0.05 vs 1.20 ± 0.09 arbitrary units; P < .05), adipocyte count was higher (221.4 ± 17.7 vs 302.3 ± 21.7 per mm² fat area; P < .05) and adipocyte size was reduced (4631.8 ± 351.5 vs 3397.6 ± 229.4 µm² , P < .05). There was no improvement, however, in insulin secretion. To determine whether earlier intervention is necessary, 5-week-old PEPCK transgenic rats were treated with dapagliflozin for 9 weeks and insulin secretion assessed. Dapagliflozin resulted in improved plasma glucose and insulin levels, and lower weight gain but, again, insulin secretion was not improved.

CONCLUSIONS

In this transgenic model of low-grade chronic hyperglycaemia, SGLT2 inhibitor treatment resulted in reduced blood glucose and insulin levels and enhanced glucose tolerance, associated with improved muscle and fat insulin resistance but not improved insulin secretory function.

The effect of basal insulin glargine on the fibrinolytic system and von Willebrand factor in people with dysglycaemia and high risk for cardiovascular events: Swedish substudy of the Outcome Reduction with an Initial Glargine Intervention trial

INTRODUCTION

Fibrinolytic factors, plasminogen activator inhibitor-1, tissue plasminogen activator, tissue plasminogen activator/plasminogen activator-complex and the haemostatic factor von Willebrand factor are known markers of cardiovascular disease. Their plasma levels are adversely affected in patients with dysglycaemia, and glucose normalization with insulin glargine might improve the levels of these factors.

METHODS

Prespecified Swedish substudy of the Outcome Reduction with an Initial Glargine Intervention trial (ClinicalTrials.gov number, NCT00069784). Tissue plasminogen activator activity, tissue plasminogen activator antigen, plasminogen activator inhibitor-1 antigen, tissue plasminogen activator/plasminogen activator inhibitor-1 complex and von Willebrand factor were analysed at study start, after 2 years and at the end of the study (median follow-up of 6.2 years).

RESULTS

Of 129 patients (mean age of 64 ± 7 years, females: 19%), 68 (53%) and 61 (47%) were randomized to the insulin glargine and standard care group, respectively. Allocation to insulin glargine did not significantly affect the studied fibrinolytic markers or von Willebrand factor compared to standard care. Likewise, there were no significant differences in plasminogen activator inhibitor-1, tissue plasminogen activator antigen and von Willebrand factor. During the whole study period, the within-group analysis revealed a curvilinear pattern and significant changes for tissue plasminogen activator/plasminogen activator inhibitor-1 complex, tissue plasminogen activator antigen and von Willebrand factor in the insulin glargine but not in the standard care group.

CONCLUSION

In people with dysglycaemia and other cardiovascular risk factors, basal insulin does not improve the levels of markers of fibrinolysis or von Willebrand factor compared to standard glucose-lowering treatments.

Treatment of sarcopenia and glucose intolerance through mitochondrial activation by 5-aminolevulinic acid

Recently, sarcopenia has attracted attention as therapeutic target because it constitutes a risk factor for metabolic and cardiovascular diseases. We focused 5-aminolevulinic acid (ALA) which act as electron carriers in the mitochondrial electron transport system. The mice that received ALA for 8 weeks gained muscle strength and endurance, and exhibited increased muscle mass and mitochondrial amount. Administration of ALA to sarcopenia mice aged 100 weeks and chronic kidney disease (CKD) model mice also increased muscle mass and improved physical performance. Metabolome analysis revealed increased branched-chain amino acids (BCAAs) levels in the skeletal muscle of ALA-treated mice. Quantitative PCR analysis revealed decreased expression levels in branched-chain amino acid transaminases (BCATs) that degrade BCAAs and other muscle-degrading factors, and increased levels of mitochondria-activating factors. We also studied in cultured myocytes and obtained compatible results. ALA-treated mice tended to increase body weight, but reduced blood glucose level. These suggested that ALA treatment not only activated muscle mitochondria but also enhanced muscle mass through an increase in BCAAs contents, as to improve muscle strength, endurance and glucose tolerance in mice. In these ways, muscle mitochondrial activation with ALA is suggested to be useful for the treatment of sarcopenia and glucose intolerance.

Effect of valsartan on kidney outcomes in people with impaired glucose tolerance

AIMS

To examine the effect of valsartan on kidney outcomes in patients with impaired glucose tolerance (IGT).

METHODS

In a double-blind randomized trial, 9306 patients with IGT were assigned to valsartan (160 mg daily) or placebo. The co-primary endpoints were the development of diabetes and two composite cardiovascular outcomes. Prespecified renal endpoints included: the composite of renal death, end-stage renal disease (ESRD) or doubling of serum creatinine; estimated glomerular filtration rate (eGFR) ≤30 mL/min/1.73 m² ; hospitalization for renal failure; and progression from normoalbuminuria to microalbuminuria, microalbuminuria to macroalbuminuria, and normoalbuminuria to macroalbuminuria. The median follow-up was 6.2 years.

RESULTS

Valsartan reduced the incidence of diabetes but not cardiovascular events. In the valsartan group, 25/4631 patients (0.5%), vs 26/4675 (0.6%) patients in the placebo group, developed ESRD or experienced doubling of serum creatinine (hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.55-1.66; P  = .87). Few patients in either group developed an eGFR of ≤30 mL/min/1.73 m² or had a renal hospitalization. Fewer patients on valsartan (237/4084 [5.8%]) than on placebo (342/4092 [8.4%]) developed microalbuminuria (HR 0.68, 95% CI 0.57-0.80; P  < .0001), and fewer valsartan-treated patients developed macroalbuminuria. Overall, urinary albumin-to-creatinine ratio (UACR) was 11% lower with valsartan (95% CI 8-13; P  < .0001) and 9% lower (95% CI 6-11; P  < .0001) after adjusting for both glucose and blood pressure.

CONCLUSIONS

The effect of valsartan on UACR was not wholly explained by change in blood pressure or glucose. Valsartan reduced the incidence of microalbuminuria in IGT without increasing the incidence of hyperkalaemia or renal dysfunction compared with placebo.

Determinants of the increase in ketone concentration during SGLT2 inhibition in NGT, IFG and T2DM patients

AIM

To examine metabolic factors that influence ketone production after sodium-glucose cotransport inhibitor (SGLT2) administration.

RESEARCH DESIGN AND METHODS

Fasting plasma glucose (FPG), insulin, glucagon, free fatty acid and ketone concentrations were measured in 15 type 2 diabetes mellitus (T2DM) and 16 non-diabetic subjects before and at day 1 and day 14 after treatment with empagliflozin.

RESULTS

Empagliflozin caused a 38 mg/dL reduction in FPG concentration in T2DM patients. However, it caused only a small but significant (7 mg/dL) reduction in the FPG concentration in impaired fasting glucose (IFG) subjects and did not affect FPG concentration in normal glucose tolerant (NGT) subjects. Empagliflozin caused a significant increase in mean plasma glucagon, free fatty acid (FFA) and ketone concentrations in T2DM subjects. However, empagliflozin did not cause a significant change in mean plasma insulin, glucagon or ketone concentrations in non-diabetic subjects. An index that integrates change in plasma glucose, insulin and FFA concentration at day 1 strongly correlates with plasma ketone concentration at day 1 (r = 0.85, P < .001) and day 14 (r = 0.63, r = 0.01) and predicts, with 86% sensitivity and 83% specificity, subjects at the top tertile for plasma ketone concentration after empagliflozin treatment.

CONCLUSION

Results of the present study demonstrate that SGLT2 inhibition exerts different metabolic effects in non-diabetic individuals as compared to diabetic patients.

Pectic Bee Pollen Polysaccharide from Rosa rugosa Alleviates Diet-Induced Hepatic Steatosis and Insulin Resistance via Induction of AMPK/mTOR-Mediated Autophagy

Despite it is used as a nutraceutical against diabetes and obesity, the mechanism of action of bee pollen is still unclear. Pectic bee pollen polysaccharide (RBPP-P) was isolated from Rosa rugosa, and its structure was characterized by ¹³C-NMR and Fourier transform-infrared spectroscopy (FT-IR). Using high glucose and fatty acids-treated HepG2 cells and high fat diet (HFD)-induced obesity mice, we detected its effect on insulin function and lipid metabolism based on autophagy. RBPP-P contained arabinogalactan, rhamnogalacturonan I, and homogalacturonan domains. In vivo studies demonstrated that RBPP-P markedly ameliorated insulin resistance, glucose intolerance, and liver steatosis in obese mice. The suppressive effects of RBPP-P on liver steatosis and triglyceride content were mediated by increased autophagy and lipase expression in liver. In AMPK knockdown cells (prkaa 1/2^−/− MEF) and HFD-fed mice tissues (liver, gonadal white adipose, and inguinal white adipose), RBPP-P enhanced autophagy in AMPK/mTOR-dependent way in liver, but not in adipose tissue. These findings demonstrated that bee pollen polysaccharide alleviated liver steatosis and insulin resistance by promoting autophagy via an AMPK/mTOR-mediated signaling pathway, suggesting that RBPP-P could be a novel therapeutic agent used for the treatment of obesity and diabetes.

Anti-Obesity and Anti-Diabetic Effect of Neoagarooligosaccharides on High-Fat Diet-Induced Obesity in Mice

Neoagarooligosaccharides (NAOs), mainly comprising neoagarotetraose and neoagarohexaose, were prepared by hydrolyzing agar with β-agarase DagA from Streptomyces coelicolor, and the anti-obesity and anti-diabetic effects of NAOs on high-fat diet (HFD)-induced obesity in mice were investigated after NAOs-supplementation for 64 days. Compared to the HFD group, the HFD-0.5 group that was fed with HFD + NAOs (0.5%, w/w) showed remarkable reduction of 36% for body weight gain and 37% for food efficiency ratios without abnormal clinical signs. Furthermore, fat accumulation in the liver and development of macrovesicular steatosis induced by HFD in the HFD-0.5 group were recovered nearly to the levels found in the normal diet (ND) group. NAOs intake could also effectively reduce the size (area) of adipocytes and tissue weight gain in the perirenal and epididymal adipose tissues. The increased concentrations of total cholesterol, triglyceride, and free fatty acid in serum of the HFD group were also markedly ameliorated to the levels found in serum of the ND group after NAOs-intake in a dose dependent manner. In addition, insulin resistance and glucose intolerance induced by HFD were distinctly improved, and adiponectin concentration in the blood was notably increased. All these results strongly suggest that intake of NAOs can effectively suppress obesity and obesity-related metabolic syndromes, such as hyperlipidemia, steatosis, insulin resistance, and glucose intolerance, by inducing production of adiponectin in the HFD-induced obese mice.

Erythropoietin (EPO) ameliorates obesity and glucose homeostasis by promoting thermogenesis and endocrine function of classical brown adipose tissue (BAT) in diet-induced obese mice

Erythropoietin (EPO), clinically used as a hematopoietic drug, has received much attention due to its nonhematopoietic effects. EPO reportedly has beneficial effects on obesity and diabetes mellitus. We investigated whether interscapular brown adipose tissue (iBAT: main part of classical BAT) could play a role in EPO’s anti-obesity and anti-diabetic effects in diet-induced obese mice. Four-week-old male C57BL/6J mice were fed a high-fat diet (HFD-Con), and half were additionally given an intraperitoneal injection of recombinant human EPO (200 IU/kg) (HFD-EPO) thrice a week for four weeks. At 8 weeks, EPO-injected mice showed significantly reduced body weight with reduced epididymal and subcutaneous white fat mass and unchanged caloric intake and locomotor activity. HOMA-IR (insulin resistance index) and glucose levels during intraperitoneal glucose tolerance test (IPGTT) were significantly lower in HFD-EPO mice than in HFD-Con mice. EPO-injected mice also showed increased oxygen consumption, indicative of metabolic rate, and skin temperature around iBAT tissue masses. EPO significantly upregulated the PRD1-BF1-RIZ1 homologous domain containing 16 (PRDM16), a transcriptional factor with a crucial role in brown adipocyte differentiation. EPO significantly increased phosphorylated signal transducer and activator of transcription 3 (STAT3), which is downstream of erythropoietin receptor (EpoR) and known to stabilize PRDM16. EPO’s suppression of myocyte enhancer factor 2c (Mef2c) and microRNA-133a (miR-133a) via β3-adrenergic receptor caused PRDM16 upregulation. EPO-mediated enhancement of EpoR/STAT3 and β-adrenergic receptor/Mef2c/miR-133 pathways dramatically increases total uncoupling protein 1 (UCP1), an essential enzyme for BAT thermogenesis. Furthermore, EPO activated BAT’s endocrine functions. EPO facilitated fibroblast growth factor 21 (FGF21) production and excretion in iBAT, associated with reduction of liver gluconeogenesis-related genes. Thus, EPO’s improvement of obesity and glucose homeostasis can be attributed to increased iBAT thermogenic capacity and activation of BAT’s endocrine functions.

Exogenous thyroxine improves glucose intolerance in insulin-resistant rats

Both hypothyroidism and hyperthyroidism are associated with glucose intolerance, calling into question the contribution of thyroid hormones (TH) on glucose regulation. TH analogues and derivatives may be effective treatment options for glucose intolerance and insulin resistance (IR), but their potential glucoregulatory effects during conditions of impaired metabolism are not well described. To assess the effects of thyroxine (T4) on glucose intolerance in a model of insulin resistance, an oral glucose tolerance test (oGTT) was performed on three groups of rats (n = 8): (1) lean, Long Evans Tokushima Otsuka (LETO), (2) obese, Otsuka Long Evans Tokushima Fatty (OLETF) and (3) OLETF + T4 (8.0 µg/100 g BM/day × 5 weeks). T4 attenuated glucose intolerance by 15% and decreased IR index (IRI) by 34% in T4-treated OLETF compared to untreated OLETF despite a 31% decrease in muscle Glut4 mRNA expression. T4 increased the mRNA expressions of muscle monocarboxylate transporter 10 (Mct10), deiodinase type 2 (Di2), sirtuin 1 (Sirt1) and uncoupling protein 2 (Ucp2) by 1.8-, 2.2-, 2.7- and 1.4-fold, respectively, compared to OLETF. Activation of AMP-activated protein kinase (AMPK) and insulin receptor were not significantly altered suggesting that the improvements in glucose intolerance and IR were independent of enhanced insulin-mediated signaling. The results suggest that T4 treatment increased the influx of T4 in skeletal muscle and, with an increase of DI2, increased the availability of the biologically active T3 to upregulate key factors such SIRT1 and UCP2 involved in cellular metabolism and glucose homeostasis.

Gut microbial degradation of organophosphate insecticides-induces glucose intolerance via gluconeogenesis

BACKGROUND

Organophosphates are the most frequently and largely applied insecticide in the world due to their biodegradable nature. Gut microbes were shown to degrade organophosphates and cause intestinal dysfunction. The diabetogenic nature of organophosphates was recently reported but the underlying molecular mechanism is unclear. We aimed to understand the role of gut microbiota in organophosphate-induced hyperglycemia and to unravel the molecular mechanism behind this process.

RESULTS

Here we demonstrate a high prevalence of diabetes among people directly exposed to organophosphates in rural India (n = 3080). Correlation and linear regression analysis reveal a strong association between plasma organophosphate residues and HbA1c but no association with acetylcholine esterase was noticed. Chronic treatment of mice with organophosphate for 180 days confirms the induction of glucose intolerance with no significant change in acetylcholine esterase. Further fecal transplantation and culture transplantation experiments confirm the involvement of gut microbiota in organophosphate-induced glucose intolerance. Intestinal metatranscriptomic and host metabolomic analyses reveal that gut microbial organophosphate degradation produces short chain fatty acids like acetic acid, which induces gluconeogenesis and thereby accounts for glucose intolerance. Plasma organophosphate residues are positively correlated with fecal esterase activity and acetate level of human diabetes.

CONCLUSION

Collectively, our results implicate gluconeogenesis as the key mechanism behind organophosphate-induced hyperglycemia, mediated by the organophosphate-degrading potential of gut microbiota. This study reveals the gut microbiome-mediated diabetogenic nature of organophosphates and hence that the usage of these insecticides should be reconsidered.

Dapagliflozin once-daily and exenatide once-weekly dual therapy: A 24-week randomized, placebo-controlled, phase II study examining effects on body weight and prediabetes in obese adults without diabetes

AIMS

To explore the effects of dual therapy with dapagliflozin and exenatide on body weight, body composition, glycaemic variables and systolic blood pressure (SBP) in obese adults without diabetes.

MATERIALS AND METHODS

In this single-centre, double-blind trial, we randomized 50 obese adults without diabetes (aged 18-70 years; body mass index 30-45 kg/m² ) to oral dapagliflozin 10 mg once daily plus subcutaneous long-acting exenatide 2 mg once weekly or placebo. MRI was used to assess change in body composition. Participants were instructed to follow a balanced diet and exercise moderately.

RESULTS

Of 25 dapagliflozin/exenatide- and 25 placebo-treated participants, 23 (92.0%) and 20 (80.0%) completed 24 weeks of treatment, respectively. At baseline, the mean participant age was 52 years, 61% were female, the mean body weight was 104.6 kg, and 73.5% of participants had prediabetes (impaired fasting glucose or impaired glucose tolerance). After 24 weeks, for dapagliflozin/exenatide versus placebo: the difference in body weight change was -4.13 kg (95% confidence interval -6.44, -1.81; P < .001), which was mostly attributable to adipose tissue reduction without lean tissue change; 36.0% versus 4.2% of participants achieved ≥5% body weight loss, respectively; and prediabetes was less frequent with active treatment (34.8% vs 85.0%, respectively; P < .01). The difference in SBP change for dapagliflozin/exenatide versus placebo was -6.7 mm Hg. As expected, nausea and injection-site reactions were more frequent with dapagliflozin/exenatide than with placebo. Only two and three participants, respectively, discontinued because of adverse events.

CONCLUSIONS

Compared with placebo, dapagliflozin/exenatide dual therapy reduced body weight, frequency of prediabetes and SBP over 24 weeks and was well tolerated in obese adults without diabetes.

Rationale, Design, and Baseline Characteristics of Beijing Prediabetes Reversion Program: A Randomized Controlled Clinical Trial to Evaluate the Efficacy of Lifestyle Intervention and/or Pioglitazone in Reversion to Normal Glucose Tolerance in Prediabetes

Background. Patients with prediabetes are at high risk for diabetes and cardiovascular disease (CVD). No study has explored whether intervention could revert prediabetes to normal glycemic status as the primary outcome. Beijing Prediabetes Reversion Program (BPRP) would evaluate whether intensive lifestyle modification and/or pioglitazone could revert prediabetic state to normoglycemia and improve the risk factors of CVD as well. Methods. BPRP is a randomized, multicenter, 2 × 2 factorial design study. Participants diagnosed as prediabetes were randomized into four groups (conventional/intensive lifestyle intervention and 30 mg pioglitazone/placebo) with a three-year follow-up. The primary endpoint was conversion into normal glucose tolerance. The trial would recruit 2000 participants (500 in each arm). Results. Between March 2007 and March 2011, 1945 participants were randomized. At baseline, the individuals were 53 ± 10 years old, with median BMI 26.0 (23.9, 28.2) kg/m² and HbA1c 5.8 (5.6, 6.1)%. 85% of the participants had IGT and 15% had IFG. Parameters relevant to glucose, lipids, blood pressure, lifestyle, and other metabolic markers were similar between conventional and intensive lifestyle intervention group at baseline. Conclusion. BPRP was the first study to determine if lifestyle modification and/or pioglitazone could revert prediabetic state to normoglycemia in Chinese population. Major baseline parameters were balanced between two lifestyle intervention groups. This trial is registered with www.chictr.org.cn: ChiCTR-PRC-06000005.

Pioglitazone is equally effective for diabetes prevention in older versus younger adults with impaired glucose tolerance

To determine the efficacy of pioglitazone to prevent type 2 diabetes in older compared to younger adults with pre-diabetes. Six hundred two participants with impaired glucose tolerance (IGT) were randomized in double blind fashion to placebo or pioglitazone for diabetes prevention in the ACT NOW study (NEJM 364:1104-1115, 2011). Cox proportional hazard regression was used to compare time to development of diabetes over a mean of 2 years between older (≥61 years) and younger participants. We compared effects of pioglitazone versus placebo on metabolic profiles, inflammatory markers, adipokines, β cell function (disposition index), insulin sensitivity (Matsuda index), and body composition by ANOVA. Diabetes incidence was reduced by 85 % in older and 69 % in younger subjects (p = 0.41). β cell function (disposition index) increased by 35.0 % in the older and 26.7 % in younger subjects (p = 0.83). Insulin sensitivity (Matsuda index) increased by 3.07 (5.2-fold) in older and by 2.54 (3.8-fold) in younger participants (p = 0.58). Pioglitazone more effectively increased adiponectin in older versus younger subjects (22.9 ± 3.2 μg/mL [2.7-fold] vs. 12.7 ± 1.4 μg/mL [2.2-fold], respectively; p = 0.04). Younger subjects tended to have a greater increase in whole body fat mass compared to older subjects (3.6 vs. 3.1 kg; p = 0.061). Younger and older subjects had similar decreases in bone mineral density (0.018 ± 0.0071 vs. 0.0138 ± 0.021 g/cm2). Younger and older pre-diabetic adults taking pioglitazone had similar reductions in conversion to diabetes and older adults had similar or greater improvements in metabolic risk factors, demonstrating that pioglitazone is useful in preventing diabetes in older adults.

Administration of Melatonin and Metformin Prevents Deleterious Effects of Circadian Disruption and Obesity in Male Rats

Circadian disruption and obesity synergize to predispose to development of type 2 diabetes mellitus (T2DM), signifying that therapeutic targeting of both circadian and metabolic dysfunctions should be considered as a potential treatment approach. To address this hypothesis, we studied rats concomitantly exposed to circadian disruption and diet-induced obesity (CDO), a rat model recently shown to recapitulate phenotypical aspects of obese T2DM (eg, circadian disruption, obesity, insulin resistance, and islet failure). CDO rats were subsequently treated daily (for 12 wk) by timed oral gavage with vehicle, melatonin (a known chronobiotic), metformin, or combination treatment of both therapeutics. Melatonin treatment alone improved circadian activity rhythms, attenuated induction of β-cell failure, and enhanced glucose tolerance. Metformin alone did not modify circadian activity but enhanced insulin sensitivity and glucose tolerance. Importantly, the combination of melatonin and metformin had synergistic actions to modify progression of metabolic dysfunction in CDO rats through improved adiposity, circadian activity, insulin sensitivity, and islet cell failure. This study suggests that management of both circadian and metabolic dysfunctions should be considered as a potential preventative and therapeutic option for treatment of obesity and T2DM.

Oral 2-oleyl glyceryl ether improves glucose tolerance in mice through the GPR119 receptor

The intestinal G protein-coupled receptor GPR119 is a novel metabolic target involving glucagon-like peptide-1 (GLP-1)-derived insulin-regulated glucose homeostasis. Endogenous and diet-derived lipids, including N-acylethanolamines and 2-monoacylglycerols (2-MAG) activate GPR119. The purpose of this work is to evaluate whether 2-oleoyl glycerol (2-OG) improves glucose tolerance through GPR119, using wild type (WT) and GPR 119 knock out (KO) mice. We here show that GPR119 is essential for 2-OG-mediated release of GLP-1 and CCK from GLUTag cells, since a GPR119 specific antagonist completely abolished the hormone release. Similarly, in isolated primary colonic crypt cultures from WT mice, GPR119 was required for 2-OG-stimulated GLP-1 release while there was no response in crypts from KO mice. In vivo, gavage with 2-oleyl glyceryl ether ((2-OG ether), a stable 2-OG analog with a potency of 5.3 µM for GPR119 with respect to cAMP formation as compared to 2.3 µM for 2-OG), significantly (P < 0.05) improved glucose clearance in WT littermates, but not in GPR119 KO mice. Finally, deletion of GPR119 in mice resulted in lower glucagon levels, whereas the levels of insulin and GIP were unchanged. In the present study we show that 2-OG stimulates GLP-1 secretion through GPR119 activation in vitro, and that fat-derived 2-MAGs are potent candidates for mediating fat-induced GLP-1 release through GPR119 in vivo. © 2016 BioFactors, 42(6):665-673, 2016.

Lacking of estradiol reduces insulin exocytosis from pancreatic β-cells and increases hepatic insulin degradation

Low levels of plasma estrogens are associated with weight-gain, android fat distribution, and a high prevalence of obesity-related comorbidities such as glucose intolerance and type II diabetes. The mechanisms underlying the association between low levels of estrogens and impaired glucose homeostasis are not completely understood. To begin to test this, we used three-month-old female C57BL/6J mice that either underwent ovariectomy (OVX) or received a sham surgery (Sham), and we characterized glucose homeostasis. In a subsequent series of experiments, OVX mice received estradiol treatment (OVX+E₂) or vehicle (OVX) for 6 consecutive days. As has been previously reported, lack of ovarian hormones resulted in dysregulated glucose homeostasis. To begin to explore the mechanisms by which this occurs, we characterized the impact of estrogens on insulin secretion and degradation in these mice. Insulin secretion and plasma insulin levels were lower in OVX mice. OVX mice had lower levels of pancreatic Syntaxin 1-A (Synt-1A) protein, which is involved in insulin extrusion from the pancreas. In the liver, OVX mice had higher levels of insulin-degrading enzyme (IDE) and this was associated with higher insulin clearance. Estradiol treatment improved glucose intolerance in OVX mice and restored insulin secretion, as well as normalized the protein content of pancreatic Synt-1A. The addition of estrogens to OVX mice reduced IDE protein to that of Sham mice. Our data suggest loss of ovarian estradiol following OVX led to impaired glucose homeostasis due to pancreatic β-cell dysfunction in the exocytosis of insulin, and upregulation of hepatic IDE protein content resulting in lower insulinemia, which was normalized by estradiol replacement.

Rationale and design of Diabetes Prevention with active Vitamin D (DPVD): a randomised, double-blind, placebo-controlled study

INTRODUCTION

Recent research suggests that vitamin D deficiency may cause both bone diseases and a range of non-skeletal diseases. However, most of these data come from observational studies, and clinical trial data on the effects of vitamin D supplementation on individuals with pre-diabetes are scarce and inconsistent. The aim of the Diabetes Prevention with active Vitamin D (DPVD) study is to assess the effect of eldecalcitol, active vitamin D analogue, on the incidence of type 2 diabetes among individuals with pre-diabetes.

METHODS AND ANALYSIS

DPVD is an ongoing, prospective, multicentre, randomised, double-blind and placebo-controlled outcome study in individuals with impaired glucose tolerance. Participants, men and women aged ≥30 years, will be randomised to receive eldecalcitol or placebo. They will also be given a brief (5-10 min long) talk about appropriate calorie intake from diet and exercise at each 12-week visit. The primary end point is the cumulative incidence of type 2 diabetes. Secondary endpoint is the number of participants who achieve normoglycaemia at 48, 96 and 144 weeks. Follow-up is estimated to span 144 weeks.

ETHICS AND DISSEMINATION

All protocols and an informed consent form comply with the Ethics Guideline for Clinical Research (Japan Ministry of Health, Labour and Welfare). The study protocol has been approved by the Institutional Review Board at Kokura Medical Association and University of Occupational and Environmental Health. The study will be implemented in line with the CONSORT statement.

TRIAL REGISTRATION NUMBER

UMIN000010758; Pre-results.

Update and Next Steps for Real-World Translation of Interventions for Type 2 Diabetes Prevention: Reflections From a Diabetes Care Editors' Expert Forum

The International Diabetes Federation estimates that 415 million adults worldwide now have diabetes and 318 million have impaired glucose tolerance. These numbers are expected to increase to 642 million and 482 million, respectively, by 2040. This burgeoning pandemic places an enormous burden on countries worldwide, particularly resource-poor regions. Numerous landmark trials evaluating both intensive lifestyle modification and pharmacological interventions have persuasively demonstrated that type 2 diabetes can be prevented or its onset can be delayed in high-risk individuals with impaired glucose tolerance. However, key challenges remain, including how to scale up such approaches for widespread translation and implementation, how to select appropriately from various interventions and tailor them for different populations and settings, and how to ensure that preventive interventions yield clinically meaningful, cost-effective outcomes. In June 2015, a Diabetes Care Editors' Expert Forum convened to discuss these issues. This article, an outgrowth of the forum, begins with a summary of seminal prevention trials, followed by a discussion of considerations for selecting appropriate populations for intervention and the clinical implications of the various diagnostic criteria for prediabetes. The authors outline knowledge gaps in need of elucidation and explore a possible new avenue for securing regulatory approval of a prevention-related indication for metformin, as well as specific considerations for future pharmacological interventions to delay the onset of type 2 diabetes. They conclude with descriptions of some innovative, pragmatic translational initiatives already under way around the world.

Improvement of oral contraceptive-induced glucose dysregulation and dyslipidemia by valproic acid is independent of circulating corticosterone

CONTEXT

Cardiometabolic disorders are rapidly becoming major public health challenges. Valproic acid (VPA) is a widely prescribed anticonvulsant drug.

OBJECTIVE

We hypothesized that treatment with VPA would improve the regulation of glucose and atherogenic dyslipidemia through reduction in circulating corticosterone.

METHODS

Female Wistar rats recieved (p.o.) combined oral contraceptive (COC) containing 1.0 µg ethinylestradiol plus 5.0 µg levonorgestrel and valproic acid (VPA; 20 mg) for 8 weeks.

RESULTS

Treatment with COC led to elevated fasting blood glucose, insulin, corticosterone, triglycerides (TG), TG/HDL-cholesterol ratio, insulin resistance (IR) and impaired glucose tolerance. VPA significantly attenuated the alterations induced by COC treatment, but did not affect the corticosterone level. However, VPA treatment led to significant increases in plasma insulin, corticosterone, atherogenic lipids and impaired glucose tolerance in rats not treated with COC.

CONCLUSION

The findings in this study suggest that VPA mitigates against the development of COC-induced insulin resistance and dyslipidemia independent of elevated circulating corticosterone.