beta-cell failure in diabetes and preservation by clinical treatment

Expression of a novel dual-functional polypeptide and its pharmacological action research

AIMS

To develop a dual-functional medicine for hypoglycemic and anti-thrombus.

MAIN METHODS

The long-acting glucagon like peptide-1 (5×GLP-1) and nattokinase (NK) were cloned by SOE PCR and gained the GLP-1 and NK fusion polypeptide after transformed into E. coli. Use of mice models for the hypoglycemic and anti-thrombus activity of the fusion polypeptide. Balb/C mice were given the carrageenan by intraperitoneal injection to induce tail thrombus models. Type 2 diabetes mellitus mice model was used to research the hypoglycemic function of the fusion polypeptide.

KEY FINDINGS

Results showed that the fusion polypeptide could significantly prevent thrombus formation after oral administration. Continuous administration for 15 days, fasting blood glucose levels of the experimental group decreased to nearly normal levels.

SIGNIFICANCE

The present study investigated the expression, purification and functional activity of the rolGLP-1 and NK fusion polypeptide, which provided a foundation for further studying the detailed pharmaceutical mechanism and drug development.

CDK8 Regulates Insulin Secretion and Mediates Postnatal and Stress-Induced Expression of Neuropeptides in Pancreatic β Cells

Cyclin-dependent kinases (CDKs) contribute to vital cellular processes including cell cycle regulation. Loss of CDKs is associated with impaired insulin secretion and β cell survival; however, the function of CDK8 in β cells remains elusive. Here, we report that genetic ablation of Cdk8 improves glucose tolerance by increasing insulin secretion. We identify OSBPL3 as a CDK8-dependent phosphoprotein, which acts as a negative regulator of insulin secretion in response to glucose. We also show that embryonic gene silencing of neuropeptide Y in β cells is compromised in Cdk8-null mice, leading to continued expression into adulthood. Cdk8 ablation in β cells aggravates apoptosis and induces de novo expression of neuropeptides upon oxidative stress. Moreover, pancreatic islets exposed to stress display augmented apoptosis in the presence of these same neuropeptides. Our results reveal critical roles for CDK8 in β cell function and survival during metabolic stress that are in part mediated through de novo expression of neuropeptides.

Review of Newer Antidiabetic Agents for Diabetes Management in Kidney Transplant Recipients

OBJECTIVE

This systematic review describes the efficacy, safety, and drug interactions of dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and sodium-glucose transport protein 2 (SGLT2) inhibitors in kidney transplant recipients (KTRs).

DATA SOURCES

Articles were identified by English-language MEDLINE search, published prior to May 2020, using the terms kidney transplant, OR PTDM, OR NODAT, AND metformin, OR DPP4, OR GLP1, OR SGLT2.

STUDY SELECTION AND DATA EXTRACTION

All selected studies were included if the study population was composed of adult KTRs who were diagnosed with either impaired glucose tolerance, diabetes mellitus (DM), new-onset diabetes after transplant (NODAT), or posttransplantation diabetes mellitus (PTDM).

DATA SYNTHESIS

In KTRs, there is evidence for safety with DPP-4 inhibitors, GLP-1 RAs, and SGLT2 inhibitors. However, urinary tract infections and a slight initial decrease in renal function may limit use of SGLT2 inhibitors. As compared with the nontransplant type 2 DM population, SGLT2 inhibitors are not as efficacious in KTRs.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review provides an overview of the current literature on newer antidiabetic agents, addressing efficacy, safety, and drug interactions to help guide clinical decision-making for their use in KTRs.

CONCLUSION

Newer antidiabetic agents have been recommended by the American Diabetes Association for potential cardiovascular, renal, and hypoglycemic benefits. Particular agents, such as DPP-4 inhibitors and GLP-1 RAs may play a role in correcting PTDM-related defects. Clinicians need to take into account both patient-specific and drug-specific characteristics when initiating these agents in KTRs.

Rationale for Timely Insulin Therapy in Type 2 Diabetes Within the Framework of Individualised Treatment: 2020 Update

Type 2 diabetes is characterised by chronic hyperglycaemia and variable degrees of insulin deficiency and resistance. Hyperglycaemia and elevated fatty acids exert harmful effects on β-cell function, regeneration and apoptosis (gluco-lipotoxicity). Furthermore, chronic hyperglycaemia triggers a vicious cycle of insulin resistance, low-grade inflammation and a cascade of pro-atherogenic processes. Thus, timely near to normal glucose control is of utmost importance in the management of type 2 diabetes and prevention of micro- and macroangiopathy. The majority of patients are multimorbid and obese, with critical comorbidities such as cardiovascular disease, heart failure and chronic kidney disease. Recently published guidelines therefore recommend patient-centred risk/benefit-balanced use of oral glucose-lowering drugs or a glucagon-like peptide 1 (GLP-1) receptor agonist, or switching to insulin with glycated haemoglobin (HbA1c) out of target. This article covers the indications of early insulin treatment to prevent diabetes-related complications, particularly in subgroups with severe insulin deficit, and to achieve recovery of residual β-cell function. Furthermore, the individualised, risk/benefit-balanced, timely initiation of insulin as second and third option is analysed. Timely insulin initiation may prevent diabetes progression, reduce diabetes-related complications and has less serious adverse effects. Basal insulin is the preferred option in most clinical situations with consequences of undertreatment of chronic hyperglycaemia.

The Constitutive Lack of α7 Nicotinic Receptor Leads to Metabolic Disorders in Mouse

Objective: Type 2 diabetes (T2D) occurs by deterioration in pancreatic β-cell function and/or progressive loss of pancreatic β-cell mass under the context of insulin resistance. α7 nicotinic acetylcholine receptor (nAChR) may contribute to insulin sensitivity but its role in the pathogenesis of T2D remains undefined. We investigated whether the systemic lack of α7 nAChR was sufficient to impair glucose homeostasis. Methods: We used an α7 nAChR knock-out (α7^−/−) mouse model fed a standard chow diet. The effects of the lack of α7 nAChR on islet mass, insulin secretion, glucose and insulin tolerance, body composition, and food behaviour were assessed in vivo and ex vivo experiments. Results: Young α7^−/− mice display a chronic mild high glycemia combined with an impaired glucose tolerance and a marked deficit in β-cell mass. In addition to these metabolic disorders, old mice developed adipose tissue inflammation, elevated plasma free fatty acid concentrations and presented glycolytic muscle insulin resistance in old mice. Finally, α7^−/− mice, fed a chow diet, exhibited a late-onset excessive gain in body weight through increased fat mass associated with higher food intake. Conclusion: Our work highlights the important role of α7 nAChR in glucose homeostasis. The constitutive lack of α7 nAChR suggests a novel pathway influencing the pathogenesis of T2D.

Human Positron Emission Tomography Neuroimaging

Neuroimaging with positron emission tomography (PET) is the most powerful tool for understanding pharmacology, neurochemistry, and pathology in the living human brain. This technology combines high-resolution scanners to measure radioactivity throughout the human body with specific, targeted radioactive molecules, which allow measurements of a myriad of biological processes in vivo. While PET brain imaging has been active for almost 40 years, the pace of development for neuroimaging tools, known as radiotracers, and for quantitative analytical techniques has increased dramatically over the past decade. Accordingly, the fundamental questions that can be addressed with PET have expanded in basic neurobiology, psychiatry, neurology, and related therapeutic development. In this review, we introduce the field of human PET neuroimaging, some of its conceptual underpinnings, and motivating questions. We highlight some of the more recent advances in radiotracer development, quantitative modeling, and applications of PET to the study of the human brain.

A simple formula to correct for the effects of storage time and temperature on the insulin concentration

OBJECTIVE

To investigate the influence of storage time and temperature on plasma insulin levels and to establish a correction formula.

METHODS

Venous blood samples were taken from 20 volunteers and processed as follows: whole blood samples, centrifuged samples, and separated plasma samples were stored at 4°C or 25°C. Insulin levels were determined by direct chemiluminescence at 0, 0.5, 1, 2, 4, and 8 hours. According to the correlation between the insulin concentration ratio and storage time, correction formulas for the insulin concentration were established. To verify the test, the venous blood samples of another 33 volunteers were processed in the same way. The insulin levels of the samples were corrected after 3, 6, 12, and 24 hours and compared with the value at 0 hours to verify the feasibility of the corrected formula.

RESULTS

With the prolongation of storage time, the insulin levels of the whole blood samples at 4°C or 25°C and of the centrifuged samples at 25°C decreased gradually (P < .001), and the insulin level correction formulas were Ccorrection  = Cdetermination /0.991e-0.069 x , Ccorrection  = Cdetermination /1.048e-0.126 x , and Ccorrection  = Cdetermination /[-0.068ln(x) + 0.9242]. There was no significant difference between the corrected insulin results and the original results at any time within 12 hours (P > .05).

CONCLUSIONS

The insulin levels of the whole blood samples at 4°C or 25°C and of the plasma samples at 25°C gradually decreased with storage time. The effect of storage time on the insulin level can be reduced with the correction formulas.

Identification of potential markers for type 2 diabetes mellitus via bioinformatics analysis

Type 2 diabetes mellitus (T2DM) is a multifactorial and multigenetic disease, and its pathogenesis is complex and largely unknown. In the present study, microarray data (GSE201966) of β-cell enriched tissue obtained by laser capture microdissection were downloaded, including 10 control and 10 type 2 diabetic subjects. A comprehensive bioinformatics analysis of microarray data in the context of protein-protein interaction (PPI) networks was employed, combined with subcellular location information to mine the potential candidate genes for T2DM and provide further insight on the possible mechanisms involved. First, differential analysis screened 108 differentially expressed genes. Then, 83 candidate genes were identified in the layered network in the context of PPI via network analysis, which were either directly or indirectly linked to T2DM. Of those genes obtained through literature retrieval analysis, 27 of 83 were involved with the development of T2DM; however, the rest of the 56 genes need to be verified by experiments. The functional analysis of candidate genes involved in a number of biological activities, demonstrated that 46 upregulated candidate genes were involved in ‘inflammatory response’ and ‘lipid metabolic process’, and 37 downregulated candidate genes were involved in ‘positive regulation of cell death’ and ‘positive regulation of cell proliferation’. These candidate genes were also involved in different signaling pathways associated with ‘PI3K/Akt signaling pathway’, ‘Rap1 signaling pathway’, ‘Ras signaling pathway’ and ‘MAPK signaling pathway’, which are highly associated with the development of T2DM. Furthermore, a microRNA (miR)-target gene regulatory network and a transcription factor-target gene regulatory network were constructed based on miRNet and NetworkAnalyst databases, respectively. Notably, hsa-miR-192-5p, hsa-miR-124-5p and hsa-miR-335-5p appeared to be involved in T2DM by potentially regulating the expression of various candidate genes, including procollagen C-endopeptidase enhancer 2, connective tissue growth factor and family with sequence similarity 105, member A, protein phosphatase 1 regulatory inhibitor subunit 1 A and C-C motif chemokine receptor 4. Smad5 and Bcl6, as transcription factors, are regulated by ankyrin repeat domain 23 and transmembrane protein 37, respectively, which might also be used in the molecular diagnosis and targeted therapy of T2DM. Taken together, the results of the present study may offer insight for future genomic-based individualized treatment of T2DM and help determine the underlying molecular mechanisms that lead to T2DM.

Randomized 52-week Phase 2 Trial of Albiglutide Versus Placebo in Adult Patients With Newly Diagnosed Type 1 Diabetes

CONTEXT

GLP-1 receptor agonists are an established therapy in patients with type 2 diabetes; however, their role in type 1 diabetes remains to be determined.

OBJECTIVE

Determine efficacy and safety of once-weekly albiglutide 30 mg (up-titration to 50 mg at week 6) versus placebo together with insulin in patients with new-onset type 1 diabetes and residual insulin production.

DESIGN

52-week, randomized, phase 2 study (NCT02284009).

METHODS

A prespecified Bayesian approach, incorporating placebo data from a prior study, allowed for 3:1 (albiglutide:placebo) randomization. The primary endpoint was 52-week change from baseline in mixed meal tolerance test (MMTT) stimulated 2-h plasma C-peptide area under the curve (AUC). Secondary endpoints included metabolic measures and pharmacokinetics of albiglutide.

RESULTS

12/17 (70.6%, placebo) and 40/50 (80.0%, albiglutide) patients completed the study. Within our study, mean (standard deviation) change from baseline to week 52 in MMTT-stimulated 2-h plasma C-peptide AUC was -0.16 nmol/L (0.366) with placebo and -0.13 nmol/L (0.244) with albiglutide. For the primary Bayesian analysis (including prior study data) the posterior treatment difference (95% credible interval) was estimated at 0.12 nmol/L (0-0.24); the probability of a difference ≥0.2 nmol/L between treatments was low (0.097). A transient significant difference in maximum C-peptide was seen at week 28. Otherwise, no significant secondary endpoint differences were noted. On-therapy adverse events were reported in 82.0% (albiglutide) and 76.5% (placebo) of patients.

CONCLUSION

In newly diagnosed patients with type 1 diabetes, albiglutide 30 to 50 mg weekly for 1 year had no appreciable effect on preserving residual β-cell function versus placebo.

Impact of acute-phase insulin secretion on glycemic variability in insulin-treated patients with type 2 diabetes

AIMS

The association between β-cell function and glycemic variability remains to be clarified in insulin-treated patients with type 2 diabetes. Therefore, the study sought to examine the association of various indices of β-cell function with glycemic variability in Chinese insulin-treated patients with type 2 diabetes.

METHODS

Glycemic variability was assessed by the coefficient of variation (CV) of glucose levels with the use of continuous glucose monitoring (CGM). Basal β-cell function was evaluated by fasting C-peptide (FCP) and the homeostasis model assessment 2 for β-cell function (HOMA2-%β). Postload β-cell function was measured by 2-hour C-peptide (2hCP) and the acute C-peptide response (ACPR) to arginine.

RESULTS

When a cutoff value of CV ≥ 36% was used to define unstable glucose, the multivariable-adjusted odds ratios for labile glycemic control were 0.34 (95% CI 0.18-0.64) for each 1 ng/mL increase in ACPR, 0.47 (95% CI 0.27-0.81) for each 1 ng/mL increase in FCP, 0.77 (95% CI 0.61-0.97) for each 1 ng/mL increase in 2hCP, and 1.00 (95% CI 0.98-1.01) for each 1% increase in HOMA2-%β. When we further adjusted for 2hCP and HOMA2-%β in the ACPR and FCP analyses, and adjusted for ACPR or FCP in the 2hCP analyses, only ACPR but not FCP or 2hPC remained to be a significant and inverse predictor for labile glycemic control.

CONCLUSIONS

ACPR evaluated by the arginine stimulation test may be superior to other commonly used β-cell function parameters to reflect glycemic fluctuation in insulin-treated patients with type 2 diabetes.

Clinical outcomes of basal insulin and oral antidiabetic agents as an add-on to dual therapy in patients with type 2 diabetes mellitus

While basal insulin remains the most effective antidiabetic agent and substantially reduces the risk of hypoglycemia, few studies have examined the comparative effect of basal insulin in the real-world setting. This study aimed to assess the outcomes of adding basal insulin compared with thiazolidinediones (TZDs) or dipeptidyl peptidase-4 inhibitors (DPP-4is) as a third antidiabetic agent in patients with type 2 diabetes mellitus (T2DM). A retrospective cohort study involving T2DM was conducted with health administrative data in Taiwan. Patients starting a third antidiabetic agent after receiving a metformin-containing dual combination were identified. The study endpoints included composite major adverse cardiovascular events (MACEs), all-cause mortality, and hypoglycemia. Propensity score matching and Cox modeling were used for analysis. After matching, the basal insulin and TZD groups contained 6,101 and 11,823 patients, respectively, and the basal insulin and DPP-4i groups contained 6,051 and 11,900 patients, respectively. TZDs and DPP-4is were both associated with similar risks of MACEs and hypoglycemia but a lower risk of all-cause mortality than basal insulin (TZDs: HR 0.55, 95% CI 0.38-0.81; DPP-4is: HR 0.56, 95% CI 0.39-0.82). Further studies are needed to elucidate the findings of increased all-cause mortality risk in patients receiving basal insulin, especially those with advanced diabetes.

Far-infrared radiation prevents decline in β-cell mass and function in diabetic mice via the mitochondria-mediated Sirtuin1 pathway

Insulin deficiency in type 2 diabetes mellitus (DM) involves a decline in both pancreatic β-cell mass and function. Enhancing β-cell preservation represents an important therapeutic strategy to treat type 2 DM. Far-infrared (FIR) radiation has been found to induce promyelocytic leukemia zinc finger protein (PLZF) activation to protect the vascular endothelium in diabetic mice. The influence of FIR on β-cell preservation is unknown. Our previous study reveals that the biologically effective wavelength of FIR is 8-10 μm. In the present study, we investigated the biological effects of FIR (8-10 μm) on both survival and insulin secretion function of β-cells. FIR reduced pancreatic islets loss and increased insulin secretion in nicotinamide-streptozotocin-induced DM mice, but only promoted insulin secretion in DM PLZF^-/- mice. FIR-upregulated PLZF to induce an anti-apoptotic effect in a β cell line RIN-m5f. FIR also upregulated mitochondrial function and the ratio of NAD⁺/NADH, and then induced Sirtuin1 (Sirt1) expression. The mitochondria Complex I inhibitor rotenone blocked FIR-induced PLZF and Sirt1. The Sirt1 inhibitor EX527 and Sirt1 siRNA inhibited FIR-induced PLZF and insulin respectively. Sirt1 upregulation also increased Ca_V1.2 expression and calcium influx that promotes insulin secretion in β-cells. In summary, FIR-enhanced mitochondrial function prevents β-cell apoptosis and enhances insulin secretion in DM mice through the Sirt1 pathway.

Serum complement C3 and islet β-cell function in patients with type 2 diabetes: A 4.6-year prospective follow-up study

PURPOSE

Serum complement C3 has been shown to contribute to the incidence of type 2 diabetes (T2D), but how serum complement C3 affects islet β-cell function throughout the course of T2D is unclear. This study explored whether serum complement C3 is independently associated with changes in islet β-cell function over time in patients with T2D.

METHODS

Serum complement C3 was measured, and endogenous β-cell function was evaluated by area under the C-peptide curve (AUC_cp) during an oral glucose tolerance test (OGTT) in 411 patients with T2D at baseline from 2011 to 2015. Next, 347 of those patients with available data were pooled for a final follow-up analysis from 2014 to 2018. Changes in islet β-cell function at follow-up were evaluated by AUC_cp percentage changes (ΔAUC_cp%). In addition, other possible clinical risks for diabetes were also examined.

RESULTS

The 347 patients included in the analysis had a diabetes duration of 4.84 ± 3.63 years at baseline. Baseline serum complement C3 (baseline C3) levels were positively correlated with baseline natural logarithm of AUC_cp (lnAUC_cp) (n = 347, r = 0.288, p < 0.001), and baseline C3 was independently associated with baseline lnAUC_cp (β = 0.17, t = 3.52, p < 0.001) after adjustment for baseline glycemic status and other clinical confounders by multivariate liner regression analysis. Compared with the baseline values, complement C3 changes (ΔC3) and ΔAUC_cp% was -0.15 ± 0.28 mg/ml and -17.2 ± 18.4%, respectively, at a follow-up visit 4.57 ± 0.78 years later. Moreover, ΔC3 was positively correlated with ΔAUC_cp% (n = 347, r = 0.302, p < 0.001). Furthermore, each 0.1 mg/ml increase in ΔC3 was associated with a higher ΔAUC_cp% (1.41% [95% CI, 0.82-2.00%]) after adjusting for changes in glycemic status and other clinical confounders at follow-up.

CONCLUSIONS

In addition to serum complement C3 being independently associated with islet β-cell function at baseline, its changes were also independently associated with changes in islet β-cell function over time in patients with T2D.

Practical application of short-term intensive insulin therapy based on the concept of "treat to target" to reduce hypoglycaemia in routine clinical site

The aim is to devise a new short-term intensive insulin therapy (N-SIIT) based on the concept of "treat to target" to avoid hypoglycaemia and was applied it to various diabetic state. We determined dosage of 1 basal and 3 bolus "treat" insulin based on "target" blood glucose level and changed each insulin dose by small units (2 units) every day for 2 weeks. We evaluated the effects of N-SIIT in 74 subjects with type 2 diabetes (male 45, female 29, 64.9 ± 16.6 years old, HbA1c 10.4 ± 2.6%). Glargine U300 ("treat") and morning blood glucose level ("target") was significantly correlated with increasing insulin dose and decreasing blood glucose level in day 1-7, indicating that insulin amount was determined by target blood glucose level and lowered next target blood glucose level. Remission rates were 67.3% (Hypoglycaemia rate 5.6 %) in N-SIIT and 47.3% (Hypoglycaemia rate 38.1%) in conventional SIIT. Required amount of insulin would be automatically determined, depending on each patient pathophysiology and life style. This method is pretty simple, flexible and cheap, and provides information about the dynamic pathophysiological alteration of insulin resistance and glucotoxicity from the profile of blood glucose levels and insulin shot.

Combination use of liraglutide and insulin to Japanese patients with multiple insulin injection: efficacy and cost

OBJECTIVES

The introduction of liraglutide in the treatment of patients with type 2 diabetes already taking insulin is still subject to discussion in terms of timing and benefits. Gradually intensive insulin therapy is hastily prescribed. Switching from multiple insulin injection (MII) to insulin and liraglutide is evaluated in this study.

METHODOLOGY

We studied 92 patients with type 2 diabetes previously under MII, C-peptide ≥ 1.5 ng/ml, divided into a group with reasonable glycemic control [RC: HbA1c < 8% (64 mmol/mol)] and another with a poor control [PC: HbA1c ≥ 8%, (64 mmol/mol)] after introduction of liraglutide and insulin therapy.

RESULTS

Except for HbA1c, there were no statistical differences between RC and PC groups. Basal insulin doses were adjusted to achieve the fasting plasma glucose of 90-120 mg/dl. HbA1c was significantly improved in both groups, from 9.6% ± 1.6 (81 mmol/mol) and 7.0% ± 0.6 (53 mmol/mol) to 8.0% ± 1.5 (64 mmol/mol) and 6.8 ± 0.5% (51 mmol/mol). Reduction of body weight was significant only in RC (from 70 ± 16 kg to 68 ± 16 kg, p < 0.01). All patients from RC group and 58% of PC group reached HbA1c < 8% without hypoglycemia.

CONCLUSION

This observation persuades us to propose the liraglutide and insulin combination to patients with C-peptide ≥ 1.5 ng/ml, regardless of the HbA1c.

Synergistic Association of Carcinoembryonic Antigen and Carbohydrate Antigen 19-9 on the Risk of Abnormal Glucose Regulation

PURPOSE

Carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are tumor-associated antigens. An increased serum level of CEA and CA19-9 separately has been reported in diabetes. In this study, we examined the composite effect of elevated serum levels of both CEA and CA19-9 on subjects with type 2 diabetes and prediabetes.

PATIENTS AND METHODS

A total of 3568 adults who attended a health examination were enrolled into this cross-sectional study. Subjects were grouped into four groups according to the median serum CEA and CA19-9 levels.

RESULTS

Subjects with high CEA and high CA19-9 levels had the highest proportions of diabetes (43.9%) and prediabetes (33.04%). There was a statistically significant trend in the proportion of diabetes across the four groups (P < 0.001). Multivariable logistic regression analysis revealed higher risks of type 2 diabetes in subjects with high CEA and low CA19-9 levels (odds ratio [OR] = 2.10, 95% confidence interval [CI]: 1.39-3.18, P < 0.001) and in those with high CA19-9 and low CEA levels (OR = 2.18, 95% CI: 1.42-3.34, P < 0.001) than in those with low CEA and low CA19-9 levels; among these four groups, the highest risk of type 2 diabetes was observed in subjects with high CEA and high CA19-9 levels (OR = 2.65, 95% CI: 1.81-3.88, P < 0.001). The risk of prediabetes was significantly higher only in subjects with high CEA and high CA19-9 levels compared to those with low CEA and low CA19-9 levels (OR = 1.32, 95% CI: 1.08-1.61, P = 0.006).

CONCLUSION

CEA and CA19-9 had a synergistic ability to increase the risk of type 2 diabetes and prediabetes.

Andrographolide promotes pancreatic duct cells differentiation into insulin-producing cells by targeting PDX-1

Regeneration of β-cells by differentiation of pancreatic progenitor cells has the potential to fundamentally solve the problems of the loss of β-cell function and mass during disease progression in both type 1 or 2 diabetes. Therefore, discovery of novel differentiation inducers to promote islet regeneration is of great significance. Pancreatic and duodenal homeobox1 (PDX-1) is a key transcription factor that promotes the development and maturation of pancreatic β-cells. To screen potential novel small molecules for enhancing differentiation of PNAC-1 cells, a human pancreatic ductal cell lines into insulin-producing cells (IPCs), we developed a high-throughput screening method through fusing the PDX-1 promoter region with a luciferase reporter gene. We screened and identified that andrographolide named C1037 stimulates PDX-1 expression in both mRNA and protein level and significantly promotes PANC-1 cells differentiation into IPCs as compared with that of control cells. The therapeutic effect of C037 in Streptozotocin induced diabetic mouse model through differentiation of pancreatic ductal cells into insulin positive islets was also observed. Our study provides a novel method to screen compounds regulating the differentiation of pancreatic progenitor cells having the potential of enhancing islet regeneration for diabetes therapy.

Serum Metrnl Level is Correlated with Insulin Resistance, But Not with β-Cell Function in Type 2 Diabetics

Background

Metrnl is a novel identified adipomyokine which might have therapeutic potential for metabolic and inflammatory diseases, including type 2 diabetes mellitus. We aimed to explore the associations of circulating Metrnl level with β-cell function and insulin resistance (IR) and further explore the possible correlation between Metrnl and another adipomyokine named irisin in patients diagnosed type 2 diabetes.

Material/Methods

Our study recruited 59 participants with type 2 diabetes and 30 normal glucose tolerance (NGT) participants. We used enzyme-linked immunosorbent assay (ELISA) to measure serum levels of Metrnl and irisin. The associations of Metrnl level with indexes of β-cell function and IR and irisin level were analyzed by multiple linear regression analysis or spearman correlation analysis.

Results

Compared with NGT participants, serum Metrnl level was elevated in participants with type 2 diabetes: 210.30 pg/mL (range 105.94–323.91 pg/mL) versus 132.02 pg/mL (range 104.93–195.92 pg/mL). Metrnl level did not show significant correlation with β-cell function-related indicators, but positively correlated with HOMA2-IR and negatively correlated with HOMA2-%S after controlling multiple covariates in participants with type 2 diabetes. Metrnl level was also not associated with obesity-related indicators (body mass index, waist circumference, body fat percentage, and visceral adipose tissue area) in the type 2 diabetes group. In addition, the correlation between Metrnl and irisin level was also not present (r=−0.159, P=0.229) in type 2 diabetes group.

Conclusions

Serum Metrnl level was associated with IR, but not with β-cell function in participants with diagnosed type 2 diabetes.

Can Antidiabetic Drugs Improve Male Reproductive (Dys)Function Associated with Diabetes?

The alarming increase in the number of diabetic patients worldwide raises concerns regarding the impact of the disease on global health, not to mention on social and economic aspects. Furthermore, the association of this complex metabolic disorder with male reproductive impairment is worrying, mainly due to the increasing chances that young individuals, at the apex of their reproductive window, could be affected by the disease, further contributing to the disturbing decline in male fertility worldwide. The cornerstone of diabetes management is glycemic control, proven to be effective in avoiding, minimizing or preventing the appearance or development of disease-related complications. Nonetheless, the possible impact of these therapeutic interventions on male reproductive function is essentially unexplored. To address this issue, we have made a critical assessment of the literature on the effects of several antidiabetic drugs on male reproductive function. While the crucial role of insulin is clear, as shown by the recovery of reproductive impairments in insulin-deficient individuals after treatment, the same clearly does not apply to other antidiabetic strategies. In fact, there is an abundance of controversial reports, possibly related to the various study designs, experimental models and compounds used, which include biguanides, sulfonylureas, meglitinides, thiazolidinediones/glitazones, bile acid sequestrants, amylin mimetics, as well as sodiumglucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide 1 (GLP1), α-glucosidase inhibitors and dipeptidyl peptidase 4 (DPP4) inhibitors. These aspects constitute the focus of the current review.

Silicon dioxide nanoparticles induce insulin resistance through endoplasmic reticulum stress and generation of reactive oxygen species

Background

Silicon dioxide nanoparticles (SiO₂ NPs) are one of the most widely utilized NPs in various food sectors. However, the potential endocrine toxicity of SiO₂ NPs has not been characterized.

Results

In the present study, mice were orally administered a series of doses of SiO₂ NPs. All doses of SiO₂ NPs were absorbed into the blood, liver, and pancreas of the mice. Administration of 100 mg/kg bw (body weight) of SiO₂ NPs significantly increased blood glucose levels in mice. However, the same dose of SiO₂ fine-particles (FPs) did not result in altered blood glucose. Whole-genome analysis showed that SiO₂ NPs affected the expression of genes associated with reactive oxygen species (ROS) production and endoplasmic reticulum (ER) stress. In addition, we showed that SiO₂ NPs activated xenobiotic metabolism, resulting in ER stress. Endoplasmic reticulum stress resulted in increased ROS production, which activated the NF-κB pathway leading to expression of inflammatory cytokines. Increased inflammatory cytokine expression resulted in serine phosphorylation of IRS1, which induced insulin resistance (IR). Furthermore these inflammatory cytokines activated the MAPK pathway, which further promoted the serine phosphorylation of IRS1. Insulin resistance resulted in elevated blood glucose. The ER stress inhibitor 4-phenylbutyric acid (4-PBA) inhibited SiO₂ NP-induced ROS production. The ROS scavenger N-acetylcysteine (NAC) did not affect SiO₂ NP-induced ER stress, but inhibited SiO₂ NP-induced activation of the NF-κB and MAPK pathways, expression of inflammatory cytokines, SiO₂ NP-induced serine phosphorylation of IRS1, and SiO2 NP-induced elevations of blood glucose.

Conclusion

Silicon dioxide NPs induced IR through ER stress and generation of ROS, but SiO₂ FPs did not. Therefore, lifelong exposure of humans to SiO₂ NPs may result in detrimental effects on blood glucose. The results of this study strongly suggested that non-nanoformed SiO₂ should be used as food additives.

Fetal androgen signaling defects affect pancreatic β-cell mass and function, leading to glucose intolerance in high-fat diet-fed male rats

We previously demonstrated that androgen signaling expands pancreatic β-cell mass in the sexual maturation period (Am J Physiol Endocrinol Metab 314: E274-E286, 2018). The aim of this study was to elucidate whether fetal androgen signaling plays important roles in β-cell mass development and β-cell function in adulthood, defects of which are associated with type 2 diabetes mellitus. In the pancreas of male fetuses, androgen receptor (AR) was strongly expressed in the cytoplasm and at the cell membrane of Nkx6.1-positive β-cell precursor cells but was markedly reduced in insulin-positive β-cells. Administration of the anti-androgen flutamide to pregnant dams during late gestation reduced β-cell mass and Ki67-positive proliferating β-cells at birth in a male-specific manner without affecting body weight. The decrease of β-cell mass in flutamide-exposed male rats was not recovered when rats were fed a standard diet, whereas it was fully recovered when rats were fed a high-fat diet (HFD), at 6 and 12 wk of age. Flutamide exposure in utero led to the development of glucose intolerance in male rats due to a decrease in insulin secretion when fed HFD but not standard diet. Insulin sensitivity did not differ between the two groups irrespective of diet. These results indicated that the action of fetal androgen contributed to β-cell mass expansion in a sex-specific manner at birth and to the development of glucose intolerance by decreasing the secretion of insulin in HFD-fed male rats. Our data demonstrated the involvement of fetal androgen signaling in hypothesized sex differences in the developmental origins of health and disease by affecting pancreatic β-cell function.

Insulin Resistance in Healthy U.S. Adults: Findings from the National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

Insulin is fundamental in two conditions that are epidemic in the United States and globally: obesity and type II diabetes. Given insulin's established mechanistic involvement in energy balance and glucose tolerance, we examined its relationship to common health-related endpoints in a large population-based sample.

METHODS

The National Health and Nutrition Examination Survey is a cross-sectional study that uses a complex multistage probability design to obtain a representative sample of the United States population. Adult participants were included from 8 successive 2-year data waves (1999-2014), including 9,224 normal individuals, 7,699 prediabetic, and 3,413 diabetic subjects. The homeostatic model for insulin resistance (HOMA-IR) was available for 20,336 participants and its relationship with demographic, anthropometric, and clinical data was analyzed. We examined the relationship of HOMA-IR to 8 groups of outcome variables: general health, anthropometric/metabolic [waist size, body mass index (BMI)], cardiovascular (blood pressure), lipid [triglycerides, high-density lipoprotein (HDL)], hepatic [alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT)], hematologic [white blood cells (WBC), hemoglobin (Hgb), platelets], inflammatory (C-reactive protein), and nutritional (vitamins D and C, serum folate, and pyridoxine) variables.

RESULTS

HOMA-IR was generally strongly, monotonically, and highly significantly associated with adjusted outcomes in normal subjects, although clinical laboratory values were generally within normal bounds across insulin quartiles. In the normal subset, the odds ratio and 95% confidence interval for a quartile change in HOMA-IR for obesity (BMI > 30) was 3.62 (3.30-3.97), and for the highest quintile for the triglyceride/HDL the ratio was 2.00 (1.77-2.26), for GGT it was 1.40 (1.24-1.58), and for WBC it was 1.28 (1.16-1.40). The relationship of HOMA-IR to the various outcomes was broadly similar to that observed in prediabetics and diabetics with a few exceptions.

CONCLUSIONS

HOMA-IR levels in a large sample of normal individuals are associated with poorer general health and adverse changes across a wide range of markers. A similar pattern of alterations is observed in prediabetic and diabetic samples.

IMPACT

Clinically, checking insulin levels may be helpful to identify patients that merit further observation and are candidates for early interventions.

Exenatide regulates pancreatic islet integrity and insulin sensitivity in the nonhuman primate baboon Papio hamadryas

The glucagon-like peptide-1 receptor agonist exenatide improves glycemic control by several and not completely understood mechanisms. Herein, we examined the effects of chronic intravenous exenatide infusion on insulin sensitivity, β cell and α cell function and relative volumes, and islet cell apoptosis and replication in nondiabetic nonhuman primates (baboons). At baseline, baboons received a 2-step hyperglycemic clamp followed by an l-arginine bolus (HC/A). After HC/A, baboons underwent a partial pancreatectomy (tail removal) and received a continuous exenatide (n = 12) or saline (n = 12) infusion for 13 weeks. At the end of treatment, HC/A was repeated, and the remnant pancreas (head-body) was harvested. Insulin sensitivity increased dramatically after exenatide treatment and was accompanied by a decrease in insulin and C-peptide secretion, while the insulin secretion/insulin resistance (disposition) index increased by about 2-fold. β, α, and δ cell relative volumes in exenatide-treated baboons were significantly increased compared with saline-treated controls, primarily as the result of increased islet cell replication. Features of cellular stress and secretory dysfunction were present in islets of saline-treated baboons and absent in islets of exenatide-treated baboons. In conclusion, chronic administration of exenatide exerts proliferative and cytoprotective effects on β, α, and δ cells and produces a robust increase in insulin sensitivity in nonhuman primates.

Centaurium erythraea extract improves survival and functionality of pancreatic beta-cells in diabetes through multiple routes of action

ETHNOPHARMACOLOGICAL RELEVANCE

Centaurium erythraea Rafn (CE) is used as a traditional medicinal plant in Serbia to treat different ailments due to its antidiabetic, antipyretic, antiflatulent and detoxification effects.

AIM OF THE STUDY

Elucidation of the mechanisms that underlie the antioxidant and pro-survival effects of the CE extract (CEE) in beta-cells and pancreatic islets from streptozotocin (STZ)-treated diabetic rats.

MATERIAL AND METHODS

Diabetes was induced in rats by multiple applications of low doses of STZ (40 mg/kg intraperitoneally (i.p.), for five consecutive days). CEE (100 mg/kg) was administered orally, in the pre-treated group for two weeks before diabetes induction, during the treatments with STZ and for four weeks after diabetes onset, and in the post-treatment group for four weeks after diabetes induction. The impact of CEE on diabetic islets was estimated by histological and immunohistochemical examination of the pancreas. Molecular mechanisms of the effects of CEE were also analyzed in insulinoma Rin-5F cells treated with STZ (12 mM) and CEE (0.25 mg/mL). Oxidative stress was evaluated by assessing the levels of DNA damage, lipid peroxidation, protein S-glutathionylation and enzymatic activities and expression of CAT, MnSOD, CuZnSOD, GPx and GR in beta-cells. The presence and activities of the redox-sensitive and islet-enriched regulatory proteins were also analyzed.

RESULTS

Treatment with CEE ameliorated the insulin level and glycemic control in STZ-induced diabetic rats by improving the structural and functional properties of pancreatic islets through multiple routes of action. The disturbance of islet morphology and islet cell contents in diabetes was reduced by the CEE treatment and was associated with a protective effect of CEE on the levels of insulin, GLUT-2 and p-Akt in diabetic islets. The antioxidant effect of CEE on STZ-treated beta-cells was displayed as reduced DNA damage, lipid peroxidation, protein S-glutathionylation and alleviation of STZ-induced disruption in MnSOD, CuZnSOD and CAT enzyme activities. The oxidative stress-induced disturbance of the transcriptional regulation of CAT, MnSOD, CuZnSOD, GPx and GR enzymes in beta-cells was improved after the CEE treatment, and was observed as readjustment of the presence and activities of redox-sensitive NFκB-p65, FOXO3A, Sp1 and Nrf-2 transcription factors. The observed CEE-mediated induction of proliferative and pro-survival pathways and insulin expression/secretion after STZ-induced oxidative stress in beta-cells could be partially attributed to a fine-tuned modulation of the activities of pro-survival Akt, ERK and p38 kinases and islet-enriched Pdx-1 and MafA regulatory factors.

CONCLUSIONS

The results of this study provide evidence that CEE improves the structural and functional properties of pancreatic beta-cells by correcting the endogenous antioxidant regulatory mechanisms and by promoting proliferative and pro-survival pathways in beta-cells.

Molecular mechanisms underlying zinc oxide nanoparticle induced insulin resistance in mice

Zinc oxide nanoparticles (ZnO NPs) represent an important class of commercially applied materials. Recently, adverse effects of ZnO NPs were found in humans and animals following ingestion, although the effects on endocrine system disease remain unclear. In this study, ZnO NPs were orally administered to mice, and at doses of 25 mg/kg bw (body weight) ZnO NPs and above, plasma glucose increased significantly. The genome-wide effects of ZnO NPs were then investigated using RNA-sequencing technology. In the cluster analysis, the most significantly enriched Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways concerned membranes and their close association with endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) generation. Biochemical and gene and protein expression analyses revealed that ZnO NPs activated a xenobiotic biodegradation response and increased the expression of cytochrome P450 (CYP) enzymes in mice livers, leading to ER stress. The ER stress increased ROS generation. The high levels of ROS activated the MAPK and NF-κB pathways and induced an inflammation response, resulting in the phosphorylation of insulin receptor substrate 1. Thus, the insulin resistance that developed was the primary mechanism for the increase in the plasma glucose of mice treated orally with ZnO NPs.

Dimeric NGF Mimetic Attenuates Hyperglycaemia and DNA Damage in Mice with Streptozotocin-Induced Early-Stage Diabetes

BACKGROUND

NGF deficiency is one of the reasons for reduced β-cells survival in diabetes. Our previous experiments revealed the ability of low-weight NGF mimetic, GK-2, to reduce hyperglycaemia in a model of advanced diabetes. The increase in DNA damage in advanced diabetes was repeatedly reported, while there were no data about DNA damage in the initial diabetes.

AIM

The study aimed to establish whether DNA damage occurs in initial diabetes and whether GK-2 is able to overcome the damage.

METHODS

The early-stage diabetes was modelled in Balb/c mice by streptozotocin (STZ) (130 mg/kg, i.p.). GK-2 was administered at a dose of 0.5 mg/kg, i.p., subchronically. The evaluation of DNA damage was performed using the alkaline comet assay; the percentage of DNA in the tail (%TDNA) and the percentage of the atypical DNA comets ("ghost cells") were determined.

RESULTS

STZ at this subthreshold dose produced a slight increase in glycemia and MDA. Meanwhile, pronounced DNA damage was observed, concerning mostly the percentage of "ghost cells" in the pancreas, the liver and kidneys. GK-2 attenuated the degree of hyperglycaemia and reduced the % of "ghost cells" and %TDNA in all the organs examined; this effect continued after discontinuation of the therapy.

CONCLUSION

Early-stage diabetes is accompanied by DNA damage, manifested by the increase of "ghost cells" percentage. The severity of these changes significantly exceeds the degree of hyperglycaemia and MDA accumulation. GK-2 exerts an antihyperglycaemic effect and attenuates the degree of DNA damage. Our results indicate that the comet assay is a highly informative method for search of antidiabetic medicines.

Pharmacokinetics and Pharmacodynamics of Insulin Tregopil in Relation to Premeal Dosing Time, Between Meal Interval, and Meal Composition in Patients With Type 2 Diabetes Mellitus

We evaluated the pharmacokinetics and pharmacodynamics of oral insulin tregopil in relation to premeal dosing time, between‐meal interval, and meal composition type in type 2 diabetes mellitus patients in a randomized, placebo‐controlled, crossover study consisting of 3 sequential cohorts. In Cohort 1, insulin tregopil administered 10 to 20 minutes before a meal resulted in optimal postmeal exposure and demonstrated better postprandial glucose‐lowering effect (glucose area under concentration‐time curve [AUC]) compared to the 30‐minute group. In Cohort 2, insulin tregopil pharmacokinetic exposure (plasma AUC) showed a progressive increase through 4, 5, and 6 hours of between‐meal interval. The 6‐hour between‐meal interval resulted in better absorption of insulin tregopil in comparison to 4‐ and 5‐hour intervals. However, no significant differences were observed in pharmacodynamic parameters except for higher glucose AUC_0‐180min in the insulin tregopil 4‐hour group during the afternoon meal as compared to the morning meal. In Cohort 3, a high‐fiber meal had the least impact on insulin tregopil absorption and resulted in the highest reduction in plasma glucose levels in the afternoon. A high‐fat meal reduced insulin tregopil absorption in the afternoon meal; however, pharmacodynamic response was not diminished significantly. Insulin tregopil has a rapid onset of action of approximately 10 minutes and, when administered 10 to 20 minutes before a meal, demonstrated up to 13% to 18% reduction in blood glucose levels compared to baseline. A 5‐hour between‐meal interval minimizes the impact of a meal on absorption of subsequent (afternoon) insulin tregopil dose, and the pharmacodynamic response of insulin tregopil is not altered by meal composition. Insulin tregopil was well tolerated in patients with type 2 diabetes mellitus.

Evaluation of the association between urinary cadmium levels below threshold limits and the risk of diabetes mellitus: a dose-response meta-analysis

As cadmium levels are increasing in the environment, the adverse effects of cadmium exposure specifically associated with chronic diseases are receiving increasing attention. Several population-based studies have been conducted on the association between cadmium and diabetes mellitus (DM) but have reported controversial results. Here, we aimed to evaluate the association between cadmium exposure and DM. In this meta-analysis, a random effects model was used because there was evidence of heterogeneity among studies. A dose-response relationship was assessed through a restricted cubic spline model with three knots. The results showed a positive association between cadmium levels in the body and DM (OR = 1.27; 95% CI, 1.07-1.52). The cadmium levels in the body were defined on the basis of combined urinary and blood cadmium. Subgroup analysis further indicated a positive association between urinary cadmium levels and DM (OR = 1.31; 95% CI, 1.02-1.69). The dose-response analysis results showed a positive association between levels of urinary cadmium above 2.43 μg/g creatinine and DM, and the risk of DM increased by 16% for each l μg/g creatinine increase in urinary cadmium levels. The results from our meta-analysis indicate that cadmium levels in the body are positively associated with DM, and urinary cadmium levels above 2.43 μg/g creatinine are associated with an increased risk of DM.

Design, synthesis and biological evaluation of novel FFA1/GPR40 agonists: New breakthrough in an old scaffold

Based on an old phenoxyacetic acid scaffold, CPU014 (compound 14) has been identified as a superior agonist by comprehensive exploration of structure-activity relationship. In vitro toxicity study suggested that CPU014 has lower risk of hepatotoxicity than TAK-875. During acute toxicity study (5-500 mg/kg), a favorable therapeutic window of CPU014 was observed by evaluation of plasma profiles and liver slices. Moreover, CPU014 promotes insulin secretion in a glucose-dependent manner, while no GLP-1 secretion has been enhanced. Other than good pharmacokinetic properties, CPU014 significantly improved glucose tolerance both in normal and diabetic models without the risk of hypoglycemia. These subversive findings provided a safer candidate CPU014, which is currently in preclinical study to assess its potential for the treatment of diabetes.

Sonodynamic therapy inhibits palmitate-induced beta cell dysfunction via PINK1/Parkin-dependent mitophagy

In type 2 diabetes mellitus (T2DM), the overload of glucose and lipids can promote oxidative stress and inflammatory responses and contribute to the failure of beta cells. However, therapies that can modulate the function of beta cells and thus prevent their failure have not been well explored. In this study, beta cell injury model was established with palmitic acid (PA) to simulate the lipotoxicity (high-fat diet) found in T2DM. Sonodynamic therapy (SDT), a novel physicochemical treatment, was applied to treat injured beta cells. We found that SDT had specific effects on mitochondria and induced transient large amount of mitochondrial reactive oxygen species (ROS) production in beta cells. SDT also improved the morphology and function of abnormal mitochondria, inhibited inflammatory response and reduced beta cell dysfunction. The improvement of mitochondria was mediated by PINK1/Parkin-dependent mitophagy. Additionally, SDT rescued the transcription of PINK1 mRNA which was blocked by PA treatment, thus providing abundant PINK1 for mitophagy. Moreover, SDT also increased insulin secretion from beta cells. The protective effects of SDT were abrogated when mitophagy was inhibited by cyclosporin A (CsA). In summary, SDT potently inhibits lipotoxicity-induced beta cell failure via PINK1/Parkin-dependent mitophagy, providing theoretical guidance for T2DM treatment in aspects of islet protection.

Pharmacokinetics and metabolism of GW9508 in rat by liquid chromatography/electrospray ionization tandem mass spectrometry

In this study, a simple, fast and sensitive LC/MS/MS method was developed and validated for the determination of GW9508 in rat plasma. The sample was precipitated with acetonitrile and subsequently separated on ZORBAX Eclipse XDB C₁₈ column (50 mm × 2.1 mm, 5 μm). Mobile phase was composed of 0.1% formic acid in water and acetonitrile with gradient elution, at a flow rate of 0.4 mL/min. The analyte and internal standard were quantitatively monitored with precursor-to-product transitions of m/z 348.2→183.1 and m/z 397.2→260.2, respectively. The linearity of the assay was evident in the range of 1-1000 ng/mL with correlation coefficient more than 0.998. The validation parameters were all within the acceptable limits. The validated method has been successfully applied to the pharmacokinetics study of GW9508 in rat plasma, and our results demonstrated that GW9508 showed low clearance, moderate half-life and ideal bioavailability (54.88%). Furthermore, metabolites stemmed from rat plasma, rat hepatocytes and human hepatocytes were analyzed by an LC-Q-Exactive-Orbitrap-MS assay, resulting in the identification of seven metabolites based on the accurate mass and fragment ions. Acylglucuronide conjugate (M6) was found as the most abundant metabolite in all tested matrices. The metabolic pathways were proposed as hydroxylation and glucuronidation. This study provided an overview of disposition of GW9508, which is highly instructive for better understanding the effectiveness and toxicity of this drug.

Insulin Degludec, a Novel Ultra-Long-Acting Basal Insulin versus Insulin Glargine for the Management of Type 2 Diabetes: A Systematic Review and Meta-Analysis

INTRODUCTION

The purpose of this study was to compare insulin degludec with insulin glargine in terms of efficacy and safety in patients with type 2 diabetes.

METHODS

We systematically searched PubMed, Embase, Web of Science, and Cochrane Library databases for randomized controlled trials published prior to 13 August 2018 (no language restrictions) which compared insulin degludec with insulin glargine. Our main endpoints were glycemic control, hypoglycemic event, weight gain, and serious adverse events (SAEs). We assessed pooled data using random-effects models.

RESULTS

A total of 15 studies that included 9619 patients in the insulin degludec arm of the studies and 7075 patients in the insulin glargine arm were identified and subsequently assessed. Our analysis showed that compared with insulin glargine, insulin degludec yielded an improved mean reduction in fasting plasma glucose (FPG) (weighted mean difference [WMD] - 5.20 mg/dL, 95% confidence interval [CI] - 7.34, - 3.07, P < 0.00001) and a lower ratio of participants experiencing ≥ 1 severe   hypoglycemic event (relative risk [RR] 0.68, 95% CI 0.50, 0.93, P = 0.01) and nocturnal hypoglycemia (RR 0.81, 95% CI 0.75, 0.88, P < 0.0001); however, in the insulin degludec group there was a lower ratio of participants with glycated hemoglobin (HbA1c) of ≤ 7.0%    (RR 0.92, 95% CI 0.86, 0.98, P = 0.01). There was no statistically significant difference between the two treatment groups for HbA1c reduction (WMD 0.03, 95% CI - 0.00, 0.07, P = 0.08), body weight gain (WMD 0.12, 95% CI - 0.19, 0.43, P = 0.46), and proportion of participants with SAEs (RR 0.97, 95% CI 0.92, 1.02, P = 0.20).

CONCLUSIONS

Insulin degludec and insulin glargine provide similar glycemic control, but insulin degludec also lowers the risk of hypoglycemia. Consequently, insulin degludec may be an alternative treatment for the management of patients with type 2 diabetes who are prone to hypoglycemia with insulin glargine.

Antagonistic Glucagon Receptor Antibody Promotes α-Cell Proliferation and Increases β-Cell Mass in Diabetic Mice

Under extreme conditions or by genetic modification, pancreatic α-cells can regenerate and be converted into β-cells. This regeneration holds substantial promise for cell replacement therapy in diabetic patients. The discovery of clinical therapeutic strategies to promote β-cell regeneration is crucial for translating these findings into clinical applications. In this study, we reported that treatment with REMD 2.59, a human glucagon receptor (GCGR) monoclonal antibody (mAb), lowered blood glucose without inducing hypoglycemia in normoglycemic, streptozotocin-induced type 1 diabetic (T1D) and non-obesity diabetic mice. Moreover, GCGR mAb treatment increased the plasma glucagon and active glucagon-like peptide-1 levels, induced pancreatic ductal ontogenic α-cell neogenesis, and promoted α-cell proliferation. Strikingly, the treatment also increased the β-cell mass in these two T1D models. Using α-cell lineage-tracing mice, we found that the neogenic β-cells were likely derived from α-cell conversion. Therefore, GCGR mAb-induced α- to β-cell conversion might represent a pre-clinical approach for improving diabetes therapy.

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GCGR mAb induced α-cell expansion by neogenesis and cell proliferation

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GCGR mAb increased the β-cell mass in type 1 diabetic mice

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GCGR mAb might promote α- to β-cell conversion in type 1 diabetic mice

What role do fat cells play in pancreatic tissue?

Background

It is now generally accepted that obesity is a major risk factor for type 2 diabetes mellitus (T2DM). Hepatic steatosis in particular, as well as visceral and ectopic fat accumulation within tissues, is associated with the development of the disease. We recently presented the first study on isolated human pancreatic adipocytes and their interaction with islets [Gerst, F., Wagner, R., Kaiser, G., Panse, M., Heni, M., Machann, J., et al., 2017. Metabolic crosstalk between fatty pancreas and fatty liver: effects on local inflammation and insulin secretion. Diabetologia 60(11):2240–2251.]. The results indicate that the function of adipocytes depends on the overall metabolic status in humans which, in turn, differentially affects islet hormone release.

Scope of Review

This review summarizes former and recent studies on factors derived from adipocytes and their effects on insulin-secreting β-cells, with particular emphasis on the human pancreas. The adipocyte secretome is discussed with a special focus on its influence on insulin secretion, β-cell survival and apoptotic β-cell death.

Major Conclusions

Human pancreatic adipocytes store lipids and release adipokines, metabolites, and pro-inflammatory molecules in response to the overall metabolic, humoral, and neuronal status. The differentially regulated adipocyte secretome impacts on endocrine function, i.e., insulin secretion, β-cell survival and death which interferes with glycemic control. This review attempts to explain why the extent of pancreatic steatosis is associated with reduced insulin secretion in some studies but not in others.

The role of membrane excitability in pancreatic β-cell glucotoxicity

Persistent hyperglycemia is causally associated with pancreatic β-cell dysfunction and loss of pancreatic insulin. Glucose normally enhances β-cell excitability through inhibition of K_ATP channels, opening of voltage-dependent calcium channels, increased [Ca²⁺]_i, which triggers insulin secretion. Glucose-dependent excitability is lost in islets from K_ATP-knockout (K_ATP-KO) mice, in which β-cells are permanently hyperexcited, [Ca²⁺]_i, is chronically elevated and insulin is constantly secreted. Mouse models of human neonatal diabetes in which K_ATP gain-of-function mutations are expressed in β-cells (K_ATP-GOF) also lose the link between glucose metabolism and excitation-induced insulin secretion, but in this case K_ATP-GOF β-cells are chronically underexcited, with permanently low [Ca²⁺]_i and lack of glucose-dependent insulin secretion. We used K_ATP-GOF and K_ATP-KO islets to examine the role of altered-excitability in glucotoxicity. Wild-type islets showed rapid loss of insulin content when chronically incubated in high-glucose, an effect that was reversed by subsequently switching to low glucose media. In contrast, hyperexcitable K_ATP-KO islets lost insulin content in both low- and high-glucose, while underexcitable K_ATP-GOF islets maintained insulin content in both conditions. Loss of insulin content in chronic excitability was replicated by pharmacological inhibition of K_ATP by glibenclamide, The effects of hyperexcitable and underexcitable islets on glucotoxicity observed in in vivo animal models are directly opposite to the effects observed in vitro: we clearly demonstrate here that in vitro, hyperexcitability is detrimental to islets whereas underexcitability is protective.

Diabetes pharmacotherapy and effects on the musculoskeletal system

Persons with type 1 or type 2 diabetes have a significantly higher fracture risk than age-matched persons without diabetes, attributed to disease-specific deficits in the microarchitecture and material properties of bone tissue. Therefore, independent effects of diabetes drugs on skeletal integrity are vitally important. Studies of incretin-based therapies have shown divergent effects of different agents on fracture risk, including detrimental, beneficial, and neutral effects. The sulfonylurea class of drugs, owing to its hypoglycemic potential, is thought to amplify the risk of fall-related fractures, particularly in the elderly. Other agents such as the biguanides may, in fact, be osteo-anabolic. In contrast, despite similarly expected anabolic properties of insulin, data suggests that insulin pharmacotherapy itself, particularly in type 2 diabetes, may be a risk factor for fracture, negatively associated with determinants of bone quality and bone strength. Finally, sodium-dependent glucose co-transporter 2 inhibitors have been associated with an increased risk of atypical fractures in select populations, and possibly with an increase in lower extremity amputation with specific SGLT2I drugs. The role of skeletal muscle, as a potential mediator and determinant of bone quality, is also a relevant area of exploration. Currently, data regarding the impact of glucose lowering medications on diabetes-related muscle atrophy is more limited, although preclinical studies suggest that various hypoglycemic agents may have either aggravating (sulfonylureas, glinides) or repairing (thiazolidinediones, biguanides, incretins) effects on skeletal muscle atrophy, thereby influencing bone quality. Hence, the therapeutic efficacy of each hypoglycemic agent must also be evaluated in light of its impact, alone or in combination, on musculoskeletal health, when determining an individualized treatment approach. Moreover, the effect of newer medications (potentially seeking expanded clinical indication into the pediatric age range) on the growing skeleton is largely unknown. Herein, we review the available literature regarding effects of diabetes pharmacotherapy, by drug class and/or by clinical indication, on the musculoskeletal health of persons with diabetes.

Predicting and understanding the response to short-term intensive insulin therapy in people with early type 2 diabetes

OBJECTIVE

Short-term intensive insulin therapy (IIT) early in the course of type 2 diabetes acutely improves beta-cell function with long-lasting effects on glycemic control. However, conventional measures cannot determine which patients are better suited for IIT, and little is known about the molecular mechanisms determining response. Therefore, this study aimed to develop a model that could accurately predict the response to IIT and provide insight into molecular mechanisms driving such response in humans.

METHODS

Twenty-four patients with early type 2 diabetes were assessed at baseline and four weeks after IIT, consisting of basal detemir and premeal insulin aspart. Twelve individuals had a beneficial beta-cell response to IIT (responders) and 12 did not (nonresponders). Beta-cell function was assessed by multiple methods, including Insulin Secretion-Sensitivity Index-2. MicroRNAs (miRNAs) were profiled in plasma samples before and after IIT. The response to IIT was modeled using a machine learning algorithm and potential miRNA-mediated regulatory mechanisms assessed by differential expression, correlation, and functional network analyses (FNA).

RESULTS

Baseline levels of circulating miR-145-5p, miR-29c-3p, and HbA1c accurately (91.7%) predicted the response to IIT (OR = 121 [95% CI: 6.7, 2188.3]). Mechanistically, a previously described regulatory loop between miR-145-5p and miR-483-3p/5p, which controls TP53-mediated apoptosis, appears to also occur in our study population of humans with early type 2 diabetes. In addition, significant (fold change > 2, P < 0.05) longitudinal changes due to IIT in the circulating levels of miR-138-5p, miR-192-5p, miR-195-5p, miR-320b, and let-7a-5p further characterized the responder group and significantly correlated (|r| > 0.4, P < 0.05) with the changes in measures of beta-cell function and insulin sensitivity. FNA identified a network of coordinately/cooperatively regulated miRNA-targeted genes that potentially drives the IIT response through negative regulation of apoptotic processes that underlie beta cell dysfunction and concomitant positive regulation of proliferation.

CONCLUSIONS

Responses to IIT in people with early type 2 diabetes are associated with characteristic miRNA signatures. This study represents a first step to identify potential responders to IIT (a current limitation in the field) and provides important insight into the pathophysiologic determinants of the reversibility of beta-cell dysfunction. ClinicalTrial.gov identifier: NCT01270789.

Hepatic stress associated with pathologies characterized by disturbed glucose production

The liver is an organ with many facets, including a role in energy production and metabolic balance, detoxification and extraordinary capacity of regeneration. Hepatic glucose production plays a crucial role in the maintenance of normal glucose levels in the organism i.e. between 0.7 to 1.1 g/l. The loss of this function leads to a rare genetic metabolic disease named glycogen storage disease type I (GSDI), characterized by severe hypoglycemia during short fasts. On the contrary, type 2 diabetes is characterized by chronic hyperglycemia, partly due to an overproduction of glucose by the liver. Indeed, diabetes is characterized by increased uptake/production of glucose by hepatocytes, leading to the activation of de novo lipogenesis and the development of a non-alcoholic fatty liver disease. In GSDI, the accumulation of glucose-6 phosphate, which cannot be hydrolyzed into glucose, leads to an increase of glycogen stores and the development of hepatic steatosis. Thus, in these pathologies, hepatocytes are subjected to cellular stress mainly induced by glucotoxicity and lipotoxicity. In this review, we have compared hepatic cellular stress induced in type 2 diabetes and GSDI, especially oxidative stress, autophagy deregulation, and ER-stress. In addition, both GSDI and diabetic patients are prone to the development of hepatocellular adenomas (HCA) that occur on a fatty liver in the absence of cirrhosis. These HCA can further acquire malignant traits and transform into hepatocellular carcinoma. This process of tumorigenesis highlights the importance of an optimal metabolic control in both GSDI and diabetic patients in order to prevent, or at least to restrain, tumorigenic activity during disturbed glucose metabolism pathologies.

Preserving Insulin Secretion in Diabetes by Inhibiting VDAC1 Overexpression and Surface Translocation in β Cells

Type 2 diabetes (T2D) develops after years of prediabetes during which high glucose (glucotoxicity) impairs insulin secretion. We report that the ATP-conducting mitochondrial outer membrane voltage-dependent anion channel-1 (VDAC1) is upregulated in islets from T2D and non-diabetic organ donors under glucotoxic conditions. This is caused by a glucotoxicity-induced transcriptional program, triggered during years of prediabetes with suboptimal blood glucose control. Metformin counteracts VDAC1 induction. VDAC1 overexpression causes its mistargeting to the plasma membrane of the insulin-secreting β cells with loss of the crucial metabolic coupling factor ATP. VDAC1 antibodies and inhibitors prevent ATP loss. Through direct inhibition of VDAC1 conductance, metformin, like specific VDAC1 inhibitors and antibodies, restores the impaired generation of ATP and glucose-stimulated insulin secretion in T2D islets. Treatment of db/db mice with VDAC1 inhibitor prevents hyperglycemia, and maintains normal glucose tolerance and physiological regulation of insulin secretion. Thus, β cell function is preserved by targeting the novel diabetes executer protein VDAC1.

3D-Models of Insulin-Producing β-Cells: from Primary Islet Cells to Stem Cell-Derived Islets

There is a need for physiologically relevant assay platforms to provide functionally relevant models of diabetes, to accelerate the discovery of new treatment options and boost developments in drug discovery. In this review, we compare several 3D-strategies that have been used to increase the functional relevance of ex vivo human primary pancreatic islets and developments into the generation of stem cell derived pancreatic beta-cells (β-cells). Special attention will be given to recent approaches combining the use of extracellular matrix (ECM) scaffolds with pancreatic molecular memory, which can be used to improve yield and functionality of in vitro stem cell-derived pancreatic models. The ultimate goal is to develop scalable cell-based platforms for diabetes research and drug screening. This article will critically assess key aspects related to in vitro pancreatic 3D-ECM models and highlight the most promising approaches for future research.

Grape pomace polyphenols improve insulin response to a standard meal in healthy individuals: A pilot study

BACKGROUND & AIMS

Dietary polyphenols have beneficial effects on glucose/lipid metabolism in subjects at high risk to develop type 2 diabetes; however, the underlying mechanisms are not clear. We aimed to evaluate: 1) the acute effects of the consumption of a drink rich in polyphenols from red grape pomace (RGPD) on glucose/insulin and triglyceride responses to a standard meal in healthy individuals, and, 2) the relationship between plasma levels of phenolic metabolites and metabolic parameters.

METHODS

Twelve healthy men, aged 20-40 years participated in a randomized, controlled study according to a cross-over design. After a 3-day low-polyphenol diet, all participants consumed, on two different days and separated by a one week interval, after an overnight fast, a drink rich in polyphenols (1.562 g gallic acid equivalents (GAE)) or a control drink (CD, no polyphenols), followed after 3 h by a standard meal (960 kcal, 18% protein, 30% fat, 52% CHO). Blood samples were taken at fasting, 3 h after the drink, over 5 h after the standard meal and at fasting on the next day to measure plasma concentrations of glucose, insulin, triglyceride and phenolic metabolites.

RESULTS

Glycemic and triglyceride post-meal responses were similar after both the RGPD and the control drink. In contrast, postprandial insulin incremental area (iAUC_0-5h) was 31% lower (p < 0.05), insulin secretion index was 18% lower (p < 0.016) and insulin sensitivity (S_I) index was 36% higher (p = 0.037) after the RGPD compared to CD. Among phenolic metabolites, gallic acid correlated inversely with the insulin response (r = -0.604; p = 0.032) and positively with the S_I index (r = 0.588, p = 0.037).

CONCLUSIONS

RGPD consumption acutely reduced postprandial insulin levels and improved insulin sensitivity. This effect could be likely related to the increase in gallic acid levels. This drink, added to usual diet, could contribute to increase the daily intake of polyphenols, with potential health benefits. CLINICALTRIALS.

GOV IDENTIFIER

NCT02865278.

Insulin resistance and β-cell dysfunction and the relationship with cardio-metabolic disorders among women with polycystic ovary syndrome

OBJECTIVE

To investigate both independent and combined effects of insulin resistance and β-cell dysfunction on cardio-metabolic abnormalities in polycystic ovary syndrome (PCOS).

DESIGN

A national epidemiologic survey was performed in reproductive aged females in China from October 2007 to September 2011.

METHODS

A total of 824 PCOS and 2715 non-PCOS were included. The Rotterdam Criteria were applied for PCOS diagnosis. We used the homeostasis model assessment of insulin resistance (HOMA-IR) and HOMA of β-cell function (HOMA-β) to evaluate insulin resistance and β-cell dysfunction, respectively.

RESULTS

Compared with non-PCOS, PCOS showed a higher index of HOMA-IR and HOMA-β, and a higher prevalence of obesity, central obesity, and dyslipidaemia. High HOMA-IR was independently related to a high prevalence of obesity, central obesity, dyslipidaemia, and high blood glucose in PCOS. In contrast, a low index of HOMA-β index was independently correlated with a low prevalence of obesity, and central obesity, but negatively correlated with an elevated prevalence of high blood glucose in PCOS. In addition, proportion of insulin resistance was higher than that of β-cell dysfunction in PCOS with cardio-metabolic disorders. β-cell dysfunction was negatively correlated with the prevalence of central obesity and obesity.

CONCLUSIONS

Insulin resistance and β-cell dysfunction independently affected cardio-metabolic abnormalities in PCOS, while insulin resistance was correlated with a higher prevalence of cardio-metabolic abnormalities than that of β-cell dysfunction. Moreover, β-cell dysfunction and insulin resistance showed divergent correlations with obesity in PCOS.

Different roles of insulin receptor a and b in maintaining blood glucose homeostasis in zebrafish

An inability of insulin to signal glycolysis and gluconeogenesis would largely result in type 2 diabetes. In this study, the physiological roles of zebrafish insulin receptor a and b in maintaining blood glucose homeostasis were characterized. We observed that, though blood glucose in insra-/- fish and insrb-/- fish were comparable with the control siblings at 0 h postprandium (hpp), the most evident hyperglycemia have been observed in insra-/- fish from 1 hpp to 3 hpp. A mild increase of blood glucose in insrb-/- fish has been seen only at 1.5 hpp. The down-regulated expressions of glycolytic enzymes were observed in insra-/- fish and insrb-/- fish liver and muscle, together with the significantly decreased activities or concentrations of glycolytic enzymes. These results suggest that both Insra and Insrb were critical in glycolysis. Intriguingly, the up-regulated expressions of gluconeogenic enzymes, pck1 and g6pca.1, along with the elevated enzyme activities, were observed in insra-/- fish liver at 1 hpp and 1.5 hpp. Compared with the control fish, the elevated plasma insulin and lowered phosphorylated AKT were observed in insra-/- fish and insrb-/- fish, suggesting that there is an insulin resistance in insra-/- fish and insrb-/- fish. The increased levels of both transcriptions of foxo1a and Foxo1a protein abundance in the insra-/- fish liver have been found. When insra-/- fish treated with the Foxo1 inhibitor, the postprandial blood glucose levels could be normalized, accompanied with the normalized expression levels and enzyme activities of both pck1 and g6pca.1. Therefore, Insra and Insrb demonstrate a similar role in promoting glycolysis, but Insra is involved in inhibiting gluconeogenesis via down-regulating the expression of foxo1a. Our results indicate that Insra and Insrb exhibit diversified functions in maintaining glucose homeostasis in zebrafish.