Diabetes and beta cell function: from mechanisms to evaluation and clinical implications

Current Position of Gliclazide and Sulfonylureas in the Contemporary Treatment Paradigm for Type 2 Diabetes: A Scoping Review

The increasing burden of type 2 diabetes (T2D), in relation to alarming rise in the prevalence; challenges in the diagnosis, prevention, and treatment; as well as the substantial impact of disease on longevity and quality of life, is a major concern in healthcare worldwide. Sulfonylureas (SUs) have been a cornerstone of T2D pharmacotherapy for over 60 years as oral antidiabetic drugs (OADs), while the newer generation SUs, such as gliclazide modified release (MR), are known to be associated with low risk of hypoglycemia in addition to the cardiovascular neutrality. This scoping review aimed to specifically address the current position of gliclazide MR among other SUs in the contemporary treatment paradigm for T2D and to provide a practical guidance document to assist clinicians in using gliclazide MR in real-life clinical practice. The main topics addressed in this paper include the role of early and sustained glycemic control and use of SUs in T2D management, the properties of gliclazide MR in relation to its effectiveness and safety, the use of gliclazide therapy in special populations, and the place of SUs as a class and gliclazide MR specifically in the current T2D treatment algorithm.

Alternative therapeutic strategies in diabetes management

Diabetes is a heterogeneous metabolic disease characterized by elevated blood glucose levels resulting from the destruction or malfunction of pancreatic β cells, insulin resistance in peripheral tissues, or both, and results in a non-sufficient production of insulin. To adjust blood glucose levels, diabetic patients need exogenous insulin administration together with medical nutrition therapy and physical activity. With the aim of improving insulin availability in diabetic patients as well as ameliorating diabetes comorbidities, different strategies have been investigated. The first approaches included enhancing endogenous β cell activity or transplanting new islets. The protocol for this kind of intervention has recently been optimized, leading to standardized procedures. It is indicated for diabetic patients with severe hypoglycemia, complicated by impaired hypoglycemia awareness or exacerbated glycemic lability. Transplantation has been associated with improvement in all comorbidities associated with diabetes, quality of life, and survival. However, different trials are ongoing to further improve the beneficial effects of transplantation. Furthermore, to overcome some limitations associated with the availability of islets/pancreas, alternative therapeutic strategies are under evaluation, such as the use of mesenchymal stem cells (MSCs) or induced pluripotent stem cells for transplantation. The cotransplantation of MSCs with islets has been successful, thus providing protection against proinflammatory cytokines and hypoxia through different mechanisms, including exosome release. The use of induced pluripotent stem cells is recent and requires further investigation. The advantages of MSC implantation have also included the improvement of diabetes-related comorbidities, such as wound healing. Despite the number of advantages of the direct injection of MSCs, new strategies involving biomaterials and scaffolds have been developed to improve the efficacy of mesenchymal cell delivery with promising results. In conclusion, this paper offered an overview of new alternative strategies for diabetes management while highlighting some limitations that will need to be overcome by future approaches.

Probing benzenesulfonamide-thiazolidinone hybrids as multitarget directed ligands for efficient control of type 2 diabetes mellitus through targeting the enzymes: α-glucosidase and carbonic anhydrase II

Diabetes mellitus is a chronic metabolic disorder characterized by improper expression/function of a number of key enzymes that can be regarded as targets for anti-diabetic drug design. Herein, we report the design, synthesis, and biological assessment of two series of thiazolidinone-based sulfonamides 4a-l and 5a-c as multitarget directed ligands (MTDLs) with potential anti-diabetic activity through targeting the enzymes: α-glucosidase and human carbonic anhydrase (hCA) II. The synthesized sulfonamides were evaluated for their inhibitory activity against α-glucosidase where most of the compounds showed good to potent activities. Compounds 4d and 4e showed potent inhibitory activities (IC50 = 0.440 and 0.3456 μM), comparable with that of the positive control (acarbose; IC50 = 0.420 μM). All the synthesized derivatives were also tested for their inhibitory activities against hCA I, II, IX, and XII. They exhibited different levels of inhibition against these isoforms. Compound 4d outstood as the most potent one against hCA II with Ki equals to 7.0 nM, more potent than the reference standard (acetazolamide; Ki = 12.0 nM). In silico studies for the most active compounds within the active sites of α-glucosidase and hCA II revealed good binding modes that can explain their biological activities. MM-GBSA refinements and molecular dynamic simulations were performed on the top-ranking docking pose of the most potent compound 4d to confirm the formation of stable complex with both targets. Compound 4d was screened for its in vivo antihyperglycemic efficacy by using the oral glucose tolerance test. Compound 4d decreased blood glucose level to 217 mg/dl, better than the standard acarbose (234 mg/dl). Hence, this revealed its synergistic mode of action on post prandial hyperglycemia and hepatic gluconeogenesis. Thus, these benzenesulfonamide thiazolidinone hybrids could be considered as promising multi-target candidates for the treatment of type II diabetes mellitus.

The effect of turmeric and black pepper powder incorporated in breakfast on postprandial glycemia, appetite, palatability, and gastrointestinal well-being in normal-weight adults

Culinary herbs and spices are primarily known as flavor enhancers, research suggests that black pepper (Piper nigrum) and turmeric (Curcuma longa) have now been proven to prevent many non-communicable chronic diseases such as diabetes. Bioactive components of black pepper and turmeric ameliorate glucose metabolism and appetite regulation. The present research was designed to investigate the impact of turmeric and black pepper on blood glycemia, gastrointestinal well-being, appetite, and palatability. In a randomized crossover study, four iso-caloric experimental meals each having 50 g of available carbohydrates were subjected to healthy human participants (N = 20). Turmeric and black pepper were incorporated in the breakfast meal, 1 g black pepper (BP), 1 g turmeric (TR), and combination of the (BP + TR) was added in the breakfast. Standard questionnaires were used to evaluate palatability, subjective appetite, and gastrointestinal well-being. Blood glycemia, subjective gastrointestinal well-being, and appetite were measured at 0, 30, 60, 120, and 180 min. Experimental meals BP and BP + TR resulted in lower blood glycemia (p < .05) significantly compared to control meal. A decrease in perceived eating ability and hunger, and an increase in satiety after BP + TR and BP meal was observed. No significant changes were observed after consuming test meals on gastrointestinal well-being. Compared to control and BP + TR meals, BP and TR meals had considerably lower palatability. Results showed that compared to the control intake of starchy meals supplemented with black pepper and turmeric reduced postprandial glycemia, hunger, and perceived eating ability without affecting gastrointestinal well-being.

Rat Model of Type 2 Diabetes Mellitus Recapitulates Human Disease in the Anterior Segment of the Eye

Changes in the anterior segment of the eye due to type 2 diabetes mellitus (T2DM) are not well-characterized, in part due to the lack of a reliable animal model. This study evaluates changes in the anterior segment, including crystalline lens health, corneal endothelial cell density, aqueous humor metabolites, and ciliary body vasculature, in a rat model of T2DM compared with human eyes. Male Sprague-Dawley rats were fed a high-fat diet (45% fat) or normal diet, and rats fed the high-fat diet were injected with streptozotocin i.p. to generate a model of T2DM. Cataract formation and corneal endothelial cell density were assessed using microscopic analysis. Diabetes-related rat aqueous humor alterations were assessed using metabolomics screening. Transmission electron microscopy was used to assess qualitative ultrastructural changes ciliary process microvessels at the site of aqueous formation in the eyes of diabetic rats and humans. Eyes from the diabetic rats demonstrated cataracts, lower corneal endothelial cell densities, altered aqueous metabolites, and ciliary body ultrastructural changes, including vascular endothelial cell activation, pericyte degeneration, perivascular edema, and basement membrane reduplication. These findings recapitulated diabetic changes in human eyes. These results support the use of this model for studying ocular manifestations of T2DM and support a hypothesis postulating blood-aqueous barrier breakdown and vascular leakage at the ciliary body as a mechanism for diabetic anterior segment pathology.

Therapeutic approaches for Type 1 Diabetes: Promising cell-based approaches to achieve ultimate success

Type 1 Diabetes mellitus (T1DM) is a chronic metabolic disorder characterized by pancreatic β-cells destruction. Despite substantial advances in T1DM treatment, lifelong exogenous insulin administration is the mainstay of treatments, and constant control of glucose levels is still a challenge. Endogenous insulin production by replacing insulin-producing cells is an alternative, but the lack of suitable donors is accounted as one of the main obstacles to its widespread application. The research and trials overview demonstrates that endogenous production of insulin has started to go beyond the deceased-derived to stem cells-derived insulin-producing cells. Several protocols have been developed over the past couple of years for generating insulin-producing cells (IPCs) from various stem cell types and reprogramming fully differentiated cells. A straightforward and quick method for achieving this goal is to investigate and apply the β-cell specific transcription factors as a direct strategy for IPCs generation. In this review, we emphasize the significance of transcription factors in IPCs development from different non-beta cell sources, and pertinent research underlies the marked progress in the methods for generating insulin-producing cells and application for Type 1 Diabetes treatment.

Comparison of beta-cell function between Hong Kong Chinese with young-onset type 2 diabetes and late-onset type 2 diabetes

AIMS

We compared beta-cell function in Chinese with type 2 diabetes diagnosed at age < 40 years (young-onset diabetes, YOD) and ≥ 40 years (late-onset diabetes, LOD).

METHODS

In this cross-sectional study, we selected participants from two cohorts of people with type 2 diabetes recruited in 1996-2012 (n = 4,376) and 2020-2021 (n = 794). Multivariable linear regression models were applied to compare homeostasis model assessment of beta-cell function (HOMA2-%B) and fasting plasma C-peptide across diabetes duration at enrolment between YOD and LOD.

RESULTS

The YOD group (n = 1,876, mean [SD] age: 39.9 [7.5] years, median [IQR] diabetes duration: 6 [2-12] years) was more likely to have family history of diabetes (61.6 % vs 43.6 %), obesity (41.9 % vs 26.8 %), dyslipidaemia (61.7 % vs 54.4 %), and worse glycaemic control (mean HbA1c 7.7 % vs 7.4 %) than those with LOD (n = 3,294, age: 60.8 [10.6] years, diabetes duration: 5 [1-10] years). When compared to people with LOD, HOMA2-%B and fasting plasma C-peptide were lower in the YOD group, consistently among those with BMI < 27.5 kg/m2 and HOMA2-IR ≤ 1.6 (median value), adjusted for year at enrolment, sex, diabetes duration, family history of diabetes, HbA1c, weight and lipid indices (p < 0.01). Cross-sectionally, the slopes of decline in HOMA2-%B by diabetes duration were greater in YOD than LOD among individuals with BMI < 27.5 kg/m2 (p-interaction = 0.015).

CONCLUSIONS

Chinese with YOD had accelerated loss of beta-cell function than those with LOD especially in non-obese individuals.

Vascular endothelial growth factor B regulates insulin secretion in β cells of type 2 diabetes mellitus mice via PLCγ and the IP3R‑evoked Ca2+/CaMK2 signaling pathway

Vascular endothelial growth factor B (VEGFB) plays a crucial role in glucolipid metabolism and is highly associated with type 2 diabetes mellitus (T2DM). The role of VEGFB in the insulin secretion of β cells remains unverified. Thus, the present study aimed to discuss the effect of VEGFB on regulating insulin secretion in T2DM development, and its underlying mechanism. A high‑fat diet and streptozocin (STZ) were used for inducing T2DM in mice model, and VEGFB gene in islet cells of T2DM mice was knocked out by CRISPR Cas9 and overexpressed by adeno‑Associated Virus (AAV) injection. The effect of VEGFB and its underlying mechanism was assessed by light microscopy, electron microscopy and fluorescence confocal microscopy, enzyme‑linked immunosorbent assay, mass spectrometer and western blot analysis. The decrement of insulin secretion in islet β cell of T2DM mice were aggravated and blood glucose remained at a high level after VEGFB knockout (KO). However, glucose tolerance and insulin sensitivity of T2DM mice were improved after the AAV‑VEGFB186 injection. VEGFB KO or overexpression can inhibit or activate PLCγ/IP3R in a VEGFR1‑dependent manner. Then, the change of PLCγ/IP3R caused by VEGFB/VEGFR1 will alter the expression of key factors on the Ca2+/CaMK2 signaling pathway such as PPP3CA. Moreover, VEGFB can cause altered insulin secretion by changing the calcium concentration in β cells of T2DM mice. These findings indicated that VEGFB activated the Ca2+/CaMK2 pathway via VEGFR1‑PLCγ and IP3R pathway to regulate insulin secretion, which provides new insight into the regulatory mechanism of abnormal insulin secretion in T2DM.

Development and Validation of a Risk Prediction Model for Ketosis-Prone Type 2 Diabetes Mellitus Among Patients Newly Diagnosed with Type 2 Diabetes Mellitus in China

Background

We established a nomogram for ketosis-prone type 2 diabetes mellitus (KP-T2DM) in the Chinese adult population in order to identify high-risk groups early and intervene in the disease progression in a timely manner.

Methods

We reviewed the medical records of 924 adults with newly diagnosed T2DM from January 2018 to June 2021. All patients were randomly divided into the training and validation sets at a ratio of 7:3. The least absolute shrinkage and selection operator regression analysis method was used to screen the predictors of the training set, and the multivariable logistic regression analysis was used to establish the nomogram prediction model. We verified the prediction model using the receiver operating characteristic (ROC) curve, judged the model's goodness-of-fit using the Hosmer-Lemeshow goodness-of-fit test, and predicted the risk of ketosis using the decision curve analysis.

Results

A total of 21 variables were analyzed, and four predictors-hemoglobin A1C, 2-hour postprandial blood glucose, 2-hour postprandial C-peptide, and age-were established. The area under the ROC curve for the training and validation sets were 0.8172 and 0.8084, respectively. The Hosmer-Lemeshow test showed that the prediction model and validation set have a high degree of fit. The decision curve analysis curve showed that the nomogram had better clinical applicability when the threshold probability of the patients was 0.03-0.79.

Conclusion

The nomogram based on hemoglobin A1C, 2-hour postprandial blood glucose, 2-hour postprandial C-peptide, and age has good performance and can serve as a favorable tool for clinicians to predict KP-T2DM.

GDF15 Mediates the Effect of Skeletal Muscle Contraction on Glucose-Stimulated Insulin Secretion

Exercise is a first-line treatment for type 2 diabetes and preserves β-cell function by hitherto unknown mechanisms. We postulated that proteins from contracting skeletal muscle may act as cellular signals to regulate pancreatic β-cell function. We used electric pulse stimulation (EPS) to induce contraction in C2C12 myotubes and found that treatment of β-cells with EPS-conditioned medium enhanced glucose-stimulated insulin secretion (GSIS). Transcriptomics and subsequent targeted validation revealed growth differentiation factor 15 (GDF15) as a central component of the skeletal muscle secretome. Exposure to recombinant GDF15 enhanced GSIS in cells, islets, and mice. GDF15 enhanced GSIS by upregulating the insulin secretion pathway in β-cells, which was abrogated in the presence of a GDF15 neutralizing antibody. The effect of GDF15 on GSIS was also observed in islets from GFRAL-deficient mice. Circulating GDF15 was incrementally elevated in patients with pre- and type 2 diabetes and positively associated with C-peptide in humans with overweight or obesity. Six weeks of high-intensity exercise training increased circulating GDF15 concentrations, which positively correlated with improvements in β-cell function in patients with type 2 diabetes. Taken together, GDF15 can function as a contraction-induced protein that enhances GSIS through activating the canonical signaling pathway in a GFRAL-independent manner.

ARTICLE HIGHLIGHTS

Exercise improves glucose-stimulated insulin secretion through direct interorgan communication. Contracting skeletal muscle releases growth differentiation factor 15 (GDF15), which is required to synergistically enhance glucose-stimulated insulin secretion. GDF15 enhances glucose-stimulated insulin secretion by activating the canonical insulin release pathway. Increased levels of circulating GDF15 after exercise training are related to improvements in β-cell function in patients with type 2 diabetes.

Regeneration of Pancreatic Beta Cells by Modulation of Molecular Targets Using Plant-Derived Compounds: Pharmacological Mechanisms and Clinical Potential

Type 2 diabetes (T2D) is characterized by pancreatic beta-cell dysfunction, increased cell death and loss of beta-cell mass despite chronic treatment. Consequently, there has been growing interest in developing beta cell-centered therapies. Beta-cell regeneration is mediated by augmented beta-cell proliferation, transdifferentiation of other islet cell types to functional beta-like cells or the reprograming of beta-cell progenitors into fully differentiated beta cells. This mediation is orchestrated by beta-cell differentiation transcription factors and the regulation of the cell cycle machinery. This review investigates the beta-cell regenerative potential of antidiabetic plant extracts and phytochemicals. Various preclinical studies, including in vitro, in vivo and ex vivo studies, are highlighted. Further, the potential regenerative mechanisms and the intra and extracellular mediators that are of significance are discussed. Also, the potential of phytochemicals to translate into regenerative therapies for T2D patients is highlighted, and some suggestions regarding future perspectives are made.

The pathological characters of islets aging in old rhesus monkeys

The loss of β cell mass and function in aged population plays a critical role in the prevalence of Type 2 diabetes. However, the causal relations between aging and age-related pancreatic islets degeneration still have not been fully elucidated. Rhesus monkey is one of the most ideal nonhuman primate animal models of a wide range of human diseases, including diabetes and aging-related diseases. In the present study, we observed the overall physiological function, glycolipid metabolism and islet function of middle-age and elderly rhesus monkeys, and compared their gene expression profiles by transcriptome sequencing of isolated islets. Through these analyses, we are aimed to evaluate the pathological characters of islets of old rhesus monkeys in the process of aging, and to provide some tips for the prevention and treatment of diabetes in the elderly population. The results suggested that there was no significant physiological disorder in monkeys of approximately 20 years old, except the glucose metabolism was mildly disturbed. In pancreas tissues and isolated islets of elderly monkeys, we found that the islets sizes were distinctly decreased, and the insulin secretion was compromised. Notably, the islets fibrosis and proportion of insulin/glucagon co-expressing cells increased significantly. Moreover, the β cell identity markers, transcription factors PDX1 and Nkx6.1 were losing with advancing age. Analysis of the RNA sequencing of isolated islets showed the genes related to type 1 diabetes and β cell function changed markedly. In conclusion, we found that in the elderly monkeys around 20 years old, the decreased islets size and compromised insulin secretion may contribute to the disturbed glucose metabolism, and the loss of β cell identity markers is a typical molecular change of islet senescence.

The evaluation of early stage oxidative status in streptozotocin induced diabetes in rats

Early-stage diabetes can be defined as the stages before absolute insulin deficiency in patients. In this study, the early stage oxidative effect of streptozotocin(STZ) induced diabetes mellitus was evaluated. 28 male adult Sprague-Dawley rats were divided into four groups; control group and 7th, 14th, 21st days diabetic groups. Diabetic groups received single 65 mg/kg STZ injection intraperitoneally. Rats were decapitated at 7th, 14th and 21st days, liver tissues were taken. Nitric oxide(NO), malondialdehyde(MDA) levels and catalase, arginase activities were measured. MDA and NO levels were increased (respectively p < .001 and p < .01), mainly 14 and 21 days after STZ administration; moreover, while liver catalase activity was progressively decreased (p < .001), oppositely arginase was increased in the same time period (p < .01). Results show that MDA and nitric oxide together with catalase and arginase switch at an early stage of diabetes and they may contribute to subsequent complications related to diabetes via increased oxidative damage.

Oral fat tolerance testing identifies abnormal pancreatic β-cell function and insulin resistance in individuals with normal glucose tolerance

AIMS/INTRODUCTION

Insulin sensitivity and β-cell function are affected by lipid metabolism disorders, even before the onset of type 2 diabetes. People are in the postprandial state most of the time. Therefore, identifying postprandial hyperlipemia is important. This study aimed to assess patients with abnormalities in lipid metabolism, but with normal glucose tolerance, using oral fat tolerance testing (OFTT) to identify defects in insulin sensitivity and β-cell function.

MATERIALS AND METHODS

We included 248 volunteers with normal glucose tolerance who underwent OFTT. They were divided into three groups in accordance with their fasting and 4-h postprandial triglyceride (TG) concentrations. Their lipid concentrations during OFTT were compared. The disposition index (DI) was applied to estimate β-cell function, and the Matsuda insulin sensitivity index (ISI_M ) was used to assess insulin sensitivity. We used multiple linear regression analysis to estimate the relationships of fasting and postprandial TG concentrations with β-cell function and insulin sensitivity .

RESULTS

The changes in TG concentrations during OFTT were more marked than those in low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol or total cholesterol concentrations. As lipid metabolism deteriorated, the ISI_M and the DI gradually decreased. Multiple linear regression analysis showed that fasting and 4-h postprandial TG concentrations affected LnISI_M and LnDI.

CONCLUSIONS

In individuals with normal glucose tolerance, β-cell function and insulin sensitivity gradually decrease with a deterioration in the lipid profile. Not only fasting TG, but also postprandial TG concentrations are independent risk factors for impaired β-cell function and insulin resistance.

Trypanosoma brucei brucei Induced Hypoglycaemia Depletes Hepatic Glycogen and Altered Hepatic Hexokinase and Glucokinase Activities in Infected Mice

PURPOSE

Little progress has been made in understanding the effect of Trypanosoma brucei brucei infection that was allowed to run its course without treatment on human and animal carbohydrate metabolism even though most of the symptoms associated with the disease can be clearly linked with interference with host energy generation. The present study therefore assessed the course of untreated Trypanosoma brucei brucei infection on hepatic glycogen, hepatic hexokinase and glucokinase activities.

METHODS

Mice were grouped into two: control and infected group. Trypanosomiasis was induced by intraperitoneal inoculation of 1 × 10⁴ parasites/mice in 0.3 ml of phosphate saline glucose. The infection was allowed to run its course until the first mortality was recorded with all the mice showing chronic symptoms of the second stage of the disease before the research was terminated. Blood and liver samples were collected from the mice in each group for the assessment of hepatic glycogen and total protein, hepatic hexokinase and glucokinase activities, liver biomarkers, blood glucose and protein with packed cell volume.

RESULTS

The infection resulted in decrease in blood glucose, hepatic glycogen, liver protein, PCV, hepatic hexokinase and glucokinase activities, but increase in serum total protein and liver biomarkers.

CONCLUSION

Trypanosomiasis negatively affects hepatic integrity, resulting in the depletion of hepatic glycogen content and suppression of both hepatic hexokinase and glucokinase activities. The suppression of hepatic hexokinase and glucokinase activities suggested that trypanosomiasis affected the oxidation of glucose and host energy generation via glycolysis. This probably denied the host of the needed energy which is likely the reason for early death in untreated African trypanosomiasis.

An Overview of the Evidence and Mechanism of Drug-Herb Interactions Between Propolis and Pharmaceutical Drugs

With the growing interest in the medicinal use of propolis, numerous studies have reported significant interactions between propolis extract and pharmaceutical drugs which may result in great clinical benefits or risks. The present study aims to review the drug-herb interactions of the full-spectrum propolis extract and main pharmaceutical drugs from the pharmacodynamic and pharmacokinetic aspects and elucidate the underlying pharmacological mechanisms. A literature search was conducted between June 2021 and February 2022 in Google Scholar, PubMed, MEDLINE, and EMBASE databases to include English studies from years 2000 to 2022 that evaluated the interaction of full-spectrum propolis extract and standard pharmaceutical drugs/cytochromes P450s. Studies that looked into geopropolis, propolis fractions, and isolated compounds, or interaction of propolis with foods, bioactive molecules, or receptors other than standard pharmaceutical drugs were excluded. From a pharmacodynamic perspective, propolis extract exhibited positive or synergistic interaction with several chemotherapeutic drugs by enhancing antitumor activity, sensitizing the chemoresistance cell lines, and attenuating multi-organ toxicity. The molecular mechanisms were associated with upregulating the apoptotic signal and immunomodulatory activity and attenuating oxidative damage. Propolis extract also enhanced the anti-bacterial and antifungal activities of many antimicrobial drugs against sensitive and resistant organisms, with an effect against the gram-positive bacteria stronger than that of the gram-negative bacteria. The synergistic action was related to strengthened action on interfering cell wall integrity and protein synthesis. The strong antioxidant activity of propolis also strengthened the therapeutic effect of metformin in attenuating hyperglycemia and pancreatic damage, as well as mitigating oxidative stress in the liver, kidney, and testis. In addition, propolis showed a potential capacity to enhance short-term and long-term memory function together with donepezil and improve motor function with levodopa and parasite killing activity with praziquantel. Pharmacokinetic studies showed inhibitory activities of propolis extracts on several CYP450 enzymes in vitro and in vivo. However, the effects on those CYP450 were deemed insignificant in humans, which may be attributed to the low bioavailability of the contributing bioactive compounds when administered in the body. The enhanced bioactivities of propolis and main pharmaceutical drugs support using propolis in integrative medicine in anti-cancer, anti-microbial, antidiabetic, and neurological disorders, with a low risk of altered pharmacokinetic activities.

Elucidating the metabolic characteristics of pancreatic β-cells from patients with type 2 diabetes (T2D) using a genome-scale metabolic modeling

Diabetes is a global health problem caused primarily by the inability of pancreatic β-cells to secrete adequate insulin. Despite extensive research, the identity of factors contributing to the dysregulated metabolism-secretion coupling in the β-cells remains elusive. The present study attempts to capture some of these factors responsible for the impaired β-cell metabolism-secretion coupling that contributes to diabetes pathogenesis. The metabolic-flux profiles of pancreatic β-cells were predicted using genome-scale metabolic modeling for ten diabetic patients and ten control subjects. Analysis of these flux states shows reduction in the mitochondrial fatty acid oxidation and mitochondrial oxidative phosphorylation pathways, that leads to decreased insulin secretion in diabetes. We also observed elevated reactive oxygen species (ROS) generation through peroxisomal fatty acid β-oxidation. In addition, cellular antioxidant defense systems were found to be attenuated in diabetes. Our analysis also uncovered the possible changes in the plasma metabolites in diabetes due to the β-cells failure. These efforts subsequently led to the identification of seven metabolites associated with cardiovascular disease (CVD) pathogenesis, thus establishing its link as a secondary complication of diabetes.

The Relationship between the Lipid Accumulation Product and Beta-cell Function in Korean Adults with or without Type 2 Diabetes Mellitus: The 2015 Korea National Health and Nutrition Examination Survey

AIMS

This study was conducted to assess the relationship between the lipid accumulation product index (LAP) and the homeostasis model assessment for insulin resistance (HOMA-IR) and beta-cell function (HOMA-B) in Korean adults with or without type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

The study was carried out using data from the 2015 Korean National Health and Nutrition Examination Survey (KNHANES) and included 4,922 adults aged 20 or older.

RESULTS

There were several key findings. First, in overall population, after adjusting for related variables, HOMA-IR (p < .001) and HOMA-B (p < .001) level were positively associated with quartiles of LAP. Second, in non-T2DM group, HOMA-IR (p < .001) and HOMA-B level (p < .001) were positively associated with quartiles of LAP. Third, in T2DM group, HOMA-IR (p < .001) level was positively associated with the quartiles of LAP, but HOMA-B (p = .153) level was not significant. In addition, HOMA-B level was increased with an increasing metabolic syndrome component in non-T2DM (p < .001) but not in T2DM (p = .267).

CONCLUSIONS

LAP was positively associated with both HOMA-IR and HOMA-B in non-diabetic Korean adults. However, LAP was positively associated with HOMA-IR in Korean adults with T2DM, while the association with HOMA-B was not significant.

Early Initiation of Intermittently Scanned Continuous Glucose Monitoring in a Pediatric Population With Type 1 Diabetes: A Real World Study

BACKGROUND

Use of Continuous Glucose Monitoring (CGM) systems early in the course of diabetes has the potential to help glycemic management and to improve quality of life (QoL). No previous research has examined these outcomes in children-adolescents with type 1 diabetes (T1D) who use intermittently scanned CGM (isCGM) starting within the first month after diagnosis.

AIM

To evaluate the impact of isCGM early after T1D diagnosis, on metabolic control and QoL, comparing a group who started the use of the device within one month from the onset with another one who started at least one year later.

SUBJECTS AND METHODS

Patients who used isCGM within 1 month from T1D diagnosis were enrolled in group A; those who didn't have the device during the first year were considered as control group (group B). HbA1c and total daily insulin were evaluated at 3 (T1), 6 (T2) and 12 (T3) months post-baseline (T0, diabetes onset), QoL after 1 year. In group A, isCGM glucose metrics were also recorded.

RESULTS

85 patients were enrolled in group A and 67 patients in group B. In group A isCGM was well accepted during follow up: no patient dropped out; percentage of time with active sensor was in mean > 87%; number of scans/day remained stable. QoL was higher in group A than in group B both in children-adolescents (p<0.0001) and in parents (p 0.003). Group A presented lower HbA1c during the first year after diagnosis (p<0.001), and this data correlated with glucose management indicator (GMI), time in range (TIR) and mean glucose. The honeymoon period lasted more in group A than in B (p 0.028). Furthermore, the mean hypoglycemia duration decreased during follow-up (p 0.001) in group A.

CONCLUSIONS

Early use of isCGM, starting within the first month after diagnosis, improves metabolic control and QoL in pediatric patients with T1D.

Botanical Interventions to Improve Glucose Control and Options for Diabetes Therapy

Diabetes mellitus is a major public health problem worldwide. This endocrine disease is clustered into distinct subtypes based on the route of development, with the most common forms associated with either autoimmunity (T1DM) or obesity (T2DM). A shared hallmark of both major forms of diabetes is a reduction in function (insulin secretion) or mass (cell number) of the pancreatic islet beta-cell. Diminutions in both mass and function are often present. A wide assortment of plants have been used historically to reduce the pathological features associated with diabetes. In this review, we provide an organized viewpoint focused around the phytochemicals and herbal extracts investigated using various preclinical and clinical study designs. In some cases, crude extracts were examined directly, and in others, purified compounds were explored for their possible therapeutic efficacy. A subset of these studies compared the botanical product with standard of care prescribed drugs. Finally, we note that botanical formulations are likely suspects for future drug discovery and refinement into class(es) of compounds that have either direct or adjuvant therapeutic benefit.

Efficacy of flavonoids on biomarkers of type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

A systematic review and meta-analysis of 28 randomized controlled trials (RCTs) to assess the efficacy of flavonoids intake on key biomarkers related to Type 2 diabetes mellitus was conducted. The mean difference (MD) with 95% confidence intervals (95% CI) was pooled using a random-effects model. Significant reduction in fasting glucose (MD: -0.22, 95% CI: -0.34 to -0.09, p = 0.0013), hemoglobin A1c (HbA1c) (MD: -0.26, 95% CI: -0.46 to -0.05, p = 0.021), homeostasis model assessment of insulin resistance (HOMA-IR) (MD: -0.40, 95% CI: -0.66 to -0.15, p = 0.0039), triglyceride (TG) (MD: -0.13, 95% CI: -0.21 to -0.05, p = 0.002), total cholesterol (TC) (MD: -0.14, 95% CI: -0.21 to -0.08, p = 0.0002), and low density lipoprotein-C (LDL-C) (MD: -0.15; 95% CI: -0.24 to -0.07, p = 0.0009) were observed in intervention group compare to placebo at the end of trial. Moreover, flavonoid intake had negative but non-significant effect on insulin (MD: -0.46), 2 h-postprandial glucose (2 h-PPG) (MD: -0.22), homeostasis model assessment of β-cell function (HOMA-β) (MD: -2.81), and insignificantly increased high-density lipoprotein-C (HDL-C) (MD: 0.03). In conclusion, flavonoid intake has modest but statistically significant benefits in glucose metabolism, insulin sensitivity, and lipid metabolism, especially for significantly lowing fasting blood glucose, HOMA-IR, HbA1c, TG, TC, and LDL-C.

Amelioration of Diabetic Nephropathy by Targeting Autophagy via Rapamycin or Fasting: Relation to Cell Apoptosis/Survival

Autophagy has been demonstrated to have a beneficial effect on diabetic nephropathy (DN). Rapamycin, an inhibitor of mTOR, was shown to stimulate β-cell autophagy. However, its effects on preventing or ameliorating DN is unclear, and its effects are worth studying. As fasting is now an attractive protective strategy, we aim to compare its effect to rapamycin effects on pancreatic and renal cells. Twenty-eight adult male Wistar Albino rats were randomly divided into four groups, using streptozotocin (STZ) to induce diabetes mellitus (DM). Autophagy was induced by two ways; rapamycin or fasting. The extent of autophagy and apoptosis were investigated by measuring the level of LC3B and p53 proteins, respectively, in pancreatic and kidney tissues using Western blotting (WB) technique and imaging the renal cells under transmission electron microscope. The efflux transporter P-glycoprotein was quantified by WB as well. Rapamycin-induced autophagy occurred concurrently with apoptosis. On the other hand, fasting supported P-glycoprotein recovery and renal cell survival together with disabling β-cells apoptosis. In conclusion, this study provides a potential link between rapamycin or fasting for the cross-regulation of apoptosis and autophagy in the setting of cell stress as DN. Unlike rapamycin, fasting enhanced the active expression of ABCB1 efflux protein, providing insights on the potential ameliorative effects of fasting in DN that require further elucidation.

Effect of brown seaweed on plasma glucose in healthy, at-risk, and type 2 diabetic individuals: systematic review and meta-analysis

Context

Sustained hyperglycemia triggers chronic disease, including type 2 diabetes. A considerable volume of research has explored the effects of brown seaweed on plasma glucose control, but equivocal findings have been reported.

Objective

A systematic review and meta-analysis was conducted to assess the evidence from human randomized controlled trials (RCTs) on the effects of brown seaweed on plasma glucose in healthy, at-risk, and individuals with type 2 diabetes.

Data Sources

MEDLINE/PubMed, EMBASE, and the Cochrane Library were searched for reports published between 2000 and 2020.

Data Extraction

Population, intervention, comparator, outcome, and study design data were extracted.

Data Analysis

Eighteen RCTs met our inclusion criteria. The reported results varied across and between populations. Meta-analyses showed a significant effect, favoring the intervention group for both fasting (mean difference –4.6 [95% CI –7.88, –1.33]) and postprandial (mean difference –7.1 [95% CI –7.4, –6.9]) plasma glucose.

Conclusion

Brown seaweed and its extracts show potential for preventing and managing hyperglycemia. Our meta-analysis confirms that brown seaweed positively affects plasma glucose homeostasis, with particularly promising postprandial plasma glucose effects. However, further research is needed because no high-quality RCT was identified. Species-specific and dose–response research is also required.

Systematic Review Registration

PROSPERO registration no. CRD42020187849.

The Molecular Mechanisms of Hypoglycemic Properties and Safety Profiles of Swietenia Macrophylla Seeds Extract: A Review

BACKGROUND: Insulin resistance (IR) is known as the root cause of type 2 diabetes; hence, it is a substantial therapeutic target. Nowadays, studies have shifted the focus to natural ingredients that have been utilized as a traditional diabetes treatment, including Swietenia macrophylla. Accumulating evidence supports the hypoglycemic activities of S. macrophylla seeds extract, although its molecular mechanisms have yet to be well-established. AIM: This review focuses on the hypoglycemic molecular mechanisms of S. macrophylla seeds extract and its safety profiles. METHODS: An extensive search of the latest literature was conducted from four main databases (PubMed, Scopus, Science Direct, and Google Scholar) using several keywords: “swietenia macrophylla, seeds, and diabetes;” “swietenia macrophylla, seeds, and oxidative stress;” “swietenia macrophylla, seeds, and inflammation;” “swietenia macrophylla, seeds, and GLUT4;” and “swietenia macrophylla, seeds, and toxicities.” RESULTS: The hypoglycemic activities occur through modulating several pathways associated with IR and T2D pathogenesis. The seeds extract of S. macrophylla modulates oxidative stress by decreasing malondialdehyde (MDA), oxidized low-density lipoprotein, and thiobarbituric acid-reactive substances while increasing antioxidant enzymes (superoxide dismutase, glutathione peroxidase, and catalase). Another propose mechanism is the modulating of the inflammatory pathway by attenuating nuclear factor kappa β, tumor necrosis factor α, inducible nitric oxide synthase, and cyclooxygenase 2. Some studies have shown that the extract can also control phosphatidylinositol-3-kinase/ Akt (PI3K/Akt) pathway by inducing glucose transporter 4, while suppressing phosphoenolpyruvate carboxykinase. Moreover, in vitro cytotoxicity and in vivo toxicity studies supported the safety profile of S. macrophylla seeds extract with the LD50 higher than 2000 mg/kg. CONCLUSION: The potential of S. macrophylla seeds as antidiabetic candidate is supported by many studies that have documented their non-toxic and hypoglycemic effects, which involve several molecular pathways.

Impaired soft and hard callus formation during fracture healing in diet-induced obese mice as revealed by 3D contrast-enhanced computed tomography imaging

The impact of diabetes mellitus on bone fracture healing is clinically relevant as the patients experience delayed fracture healing. Even though efforts have been made to understand the detrimental effects of type 2 diabetes mellitus (T2DM) on the fracture healing process, the exact mechanisms causing the pathophysiological outcomes remain unclear. The aim of this study was to assess alterations in bone fracture healing (tibial fracture surgery, intramedullary pinning) of diet-induced obese (DIO) mice, and to investigate the in vitro properties of osteochondroprogenitors derived from the diabetic micro-environment. High-resolution contrast-enhanced microfocus X-ray computed tomography (CE-CT) enabled a simultaneous 3D assessment of the amount and spatial distribution of the regenerated soft and hard tissues during fracture healing and revealed that osteogenesis as well as chondrogenesis are altered in DIO mice. Compared to age-matched lean controls, DIO mice presented a decreased bone volume fraction and increased callus volume and adiposity at day 14 post-fracture. Of note, bone turnover was found altered in DIO mice relative to controls, evidenced by decreased blood serum osteocalcin and increased serum CTX levels. The in vitro data revealed that not only the osteogenic and adipogenic differentiation of periosteum-derived cells (PDCs) were altered by hyperglycemic (HG) conditions, but also the chondrogenic differentiation. Elevated PPARγ expression in HG conditions confirmed the observed increase in differentiated adipocytes in vitro. Finally, chondrogenesis-related genes COL2 and COL10 were downregulated for PDCs treated with HG medium, confirming that chondrogenic differentiation is compromised in vitro and suggesting that this may affect callus formation and maturation during the fracture healing process in vivo. Altogether, these results provide novel insights into the alterations of long bone fracture repair and suggest a link between HG-induced dysfunctionality of osteochondroprogenitor differentiation and fracture healing impairment under T2DM conditions.

A Review of Current Trends with Type 2 Diabetes Epidemiology, Aetiology, Pathogenesis, Treatments and Future Perspectives

Type 2 diabetes (T2D), which has currently become a global pandemic, is a metabolic disease largely characterised by impaired insulin secretion and action. Significant progress has been made in understanding T2D aetiology and pathogenesis, which is discussed in this review. Extrapancreatic pathology is also summarised, which demonstrates the highly multifactorial nature of T2D. Glucagon-like peptide (GLP)-1 is an incretin hormone responsible for augmenting insulin secretion from pancreatic beta-cells during the postprandial period. Given that native GLP-1 has a very short half-life, GLP-1 mimetics with a much longer half-life have been developed, which are currently an effective treatment option for T2D by enhancing insulin secretion in patients. Interestingly, there is continual emerging evidence that these therapies alleviate some of the post-diagnosis complications of T2D. Additionally, these therapies have been shown to induce weight loss in patients, suggesting they could be an alternative to bariatric surgery, a procedure associated with numerous complications. Current GLP-1-based therapies all act as orthosteric agonists for the GLP-1 receptor (GLP-1R). Interestingly, it has emerged that GLP-1R also has allosteric binding sites and agonists have been developed for these sites to test their therapeutic potential. Recent studies have also demonstrated the potential of bi- and tri-agonists, which target multiple hormonal receptors including GLP-1R, to more effectively treat T2D. Improved understanding of T2D aetiology/pathogenesis, coupled with the further elucidation of both GLP-1 activity/targets and GLP-1R mechanisms of activation via different agonists, will likely provide better insight into the therapeutic potential of GLP-1-based therapies to treat T2D.

Combined effect of metformin and gallic acid on inflammation, antioxidant status, endoplasmic reticulum (ER) stress and glucose metabolism in fructose-fed streptozotocin-induced diabetic rats

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Metformin, gallic acid and a combination of both improved glucose metabolism and antioxidant status in diabetic rats.

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Metformin, gallic acid and a combination of both lowered levels of IL-6 and TNF-α in liver and pancreas of diabetic rats.

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Metformin, gallic acid and a combination of both decreased the expression of ATF4 in liver and pancreas of diabetic rats.

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Metformin/GA combination appeared more effective than metformin only and gallic acid only.

Over time, diabetes patients usually need combination therapy involving two or more agents, including phytonutrients to attain therapeutic targets. The purpose of this research is to elucidate the combined effect of metformin and gallic acid (GA) on glucose metabolism, inflammation as well as oxidative and endoplasmic reticulum (ER) stresses in fructose-fed diabetic rats. Thirty-five rats of Wistar strain were arbitrarily distributed into five groups, each containing seven animals as follows: normal control, diabetic control, groups administered 100 mg/kg bw metformin only, 50 mg/kg bw gallic acid only and a combination of both. Experimental animals were made diabetic by single injection of 40 mg/kg streptozotocin (intraperitoneally) subsequent to 14 days administration of 10 % fructose prior. Treatment of rats continued for 21 days following diabetes confirmation. Glucose and insulin levels as well as lipid profile were evaluated in the serum, while activities of catalase and superoxide dismutase were estimated in both liver and pancreas. In addition, levels of malondialdehyde, interleukin-6 and tumor necrosis factor-alpha, as well as expression of activating transcription factor-4 were evaluated in liver and pancreas of diabetic rats. Activities of glucose-6-phosphatase and glucokinase were also determined in liver of diabetic animals. Metformin only, GA only and combination of metformin and GA significantly improved antioxidant status and glucose homeostasis while inflammation and endoplasmic reticulum stress were significantly ameliorated in diabetic rats. Metformin/GA combination appeared to improve glucose metabolism by increasing insulin level and ameliorating the dysregulated activities of glucose metabolizing enzymes and ER stress better than either metformin only or GA only. It could be concluded that coadministration of metformin/GA produced a combined effect in ameliorating diabetes in Wistar rats and could be considered in treatment of diabetes.

β-Cell pre-mir-21 induces dysfunction and loss of cellular identity by targeting transforming growth factor beta 2 (Tgfb2) and Smad family member 2 (Smad2) mRNAs

OBJECTIVE

β-cell microRNA-21 (miR-21) is increased by islet inflammatory stress but it decreases glucose-stimulated insulin secretion (GSIS). Thus, we sought to define the effects of miR-21 on β-cell function using in vitro and in vivo systems.

METHODS

We developed a tetracycline-on system of pre-miR-21 induction in clonal β-cells and human islets, along with transgenic zebrafish and mouse models of β-cell-specific pre-miR-21 overexpression.

RESULTS

β-cell miR-21 induction markedly reduced GSIS and led to reductions in transcription factors associated with β-cell identity and increased markers of dedifferentiation, which led us to hypothesize that miR-21 induces β-cell dysfunction by loss of cell identity. In silico analysis identified transforming growth factor-beta 2 (Tgfb2) and Smad family member 2 (Smad2) mRNAs as predicted miR-21 targets associated with the maintenance of β-cell identity. Tgfb2 and Smad2 were confirmed as direct miR-21 targets through RT-PCR, immunoblot, pulldown, and luciferase assays. In vivo zebrafish and mouse models exhibited glucose intolerance, decreased peak GSIS, decreased expression of β-cell identity markers, increased insulin and glucagon co-staining cells, and reduced Tgfb2 and Smad2 expression.

CONCLUSIONS

These findings implicate miR-21-mediated reduction of mRNAs specifying β-cell identity as a contributor to β-cell dysfunction by the loss of cellular differentiation.

Probiotics Contribute to Glycemic Control in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

This systematic review aimed to evaluate the effectiveness and safety of probiotics for glycemic control in adults with impaired glucose control, including prediabetes and type 2 diabetes mellitus (T2DM). We searched PubMed, Embase, and Cochrane databases, and trial registries up to February 2019. We included randomized controlled trials (RCTs) of participants with prediabetes or T2DM. Eligible trials compared probiotics versus either placebo, no intervention, or comparison probiotics, or compared synbiotics versus prebiotics. Primary outcomes were mean change in fasting blood glucose (FBG) and glycated hemoglobin (HbA1c) from baseline to short term (<12 wk) and long term (≥12 wk). We performed meta-analyses using the random-effects model. We included 28 RCTs (1947 participants). Overall, probiotics reduced FBG more than the placebo/no intervention group with a mean difference (MD) of -12.99 mg/dL (95% CI: -23.55, -2.42; P value: 0.016) over the short term; and -2.99 mg/dL (95% CI: -5.84, -0.13; P value: 0.040) over the long term. There was also some evidence for reduced HbA1c in the probiotics group at both short term (MD: -0.17; 95% CI: -0.37, 0.02; P value: 0.084) and long term (MD: -0.14; 95% CI: -0.34, 0.06; P value: 0.172), however, these did not reach statistical significance possibly because only a few trials reported HbA1c as an outcome. Subgroup analyses showed a greater reduction in HbA1c in participants not receiving insulin therapy than those receiving insulin therapy. Furthermore, the effect of probiotics on the reduction of FBG was more pronounced in participants with FBG >130 mg/dL and those not receiving insulin therapy than their counterparts. Probiotics were also effective in lowering serum cholesterol over the short and long term. In conclusion, we found that probiotics may have a glucose-lowering effect in T2DM participants. The effect appeared to be stronger in participants with poorly controlled diabetes and those not on insulin therapy. Systematic review registration: CRD42019121682.

Systemic Inflammation and COVID-19 Mortality in Patients with Major Noncommunicable Diseases: Chronic Coronary Syndromes, Diabetes and Obesity

COVID-19 is currently considered an inflammatory disease affecting the entire organism. In severe forms, an augmented inflammatory response leads to the fulminant “cytokine storm”, which may result in severe multisystemic end-organ damage. Apart from the acute inflammatory response, it seems that chronic inflammation also plays a major role in the clinical evolution of COVID-19 patients. Pre-existing inflammatory conditions, such as those associated with chronic coronary diseases, type 2 diabetes mellitus or obesity, may be associated with worse clinical outcomes in the context of COVID-19 disease. These comorbidities are reported as powerful predictors of poor outcomes and death following COVID-19 disease. Moreover, in the context of chronic coronary syndrome, the cytokine storm triggered by SARS-CoV-2 infection may favor vulnerabilization and rupture of a silent atheromatous plaque, with consequent acute coronary syndrome, leading to a sudden deterioration of the clinical condition of the patient. This review aims to present the current status of knowledge regarding the link between COVID-19 mortality, systemic inflammation and several major diseases associated with poor outcomes, such as cardiovascular diseases, diabetes and obesity.

Groucho co-repressor proteins regulate β cell development and proliferation by repressing Foxa1 in the developing mouse pancreas

Groucho-related genes (GRGs) are transcriptional co-repressors that are crucial for many developmental processes. Several essential pancreatic transcription factors are capable of interacting with GRGs; however, the in vivo role of GRG-mediated transcriptional repression in pancreas development is still not well understood. In this study, we used complex mouse genetics and transcriptomic analyses to determine that GRG3 is essential for β cell development, and in the absence of Grg3 there is compensatory upregulation of Grg4 Grg3/4 double mutant mice have severe dysregulation of the pancreas gene program with ectopic expression of canonical liver genes and Foxa1, a master regulator of the liver program. Neurod1, an essential β cell transcription factor and predicted target of Foxa1, becomes downregulated in Grg3/4 mutants, resulting in reduced β cell proliferation, hyperglycemia, and early lethality. These findings uncover novel functions of GRG-mediated repression during pancreas development.

Promoting exercise, reducing sedentarism or both for diabetes prevention: The "Seguimiento Universidad De Navarra" (SUN) cohort

BACKGROUND AND AIM

Both physical activity (PA) and sedentary behaviors have demonstrated independent associations with the development of type 2 diabetes mellitus (T2DM). However, the combination of both, has been less explored. We aimed to compare the associations of PA-only versus the simultaneous effect of PA and sedentary behaviors on T2DM in a Mediterranean cohort.

METHODS AND RESULTS

Participants (n = 19,524) initially free of T2DM from the SUN Project were followed-up for a median of 10.4 years. Analyses were conducted in 2018. PA and sedentary parameters (TV viewing time and sitting time) were assessed through a validated questionnaire. The amount of each PA was expressed in METs-h/wk. After that, a previously developed 8-item active + sedentary lifestyle score was computed. T2DM was defined according to ADA criteria. To adjust for potential confounders, Cox regression models were adjusted. Among 19,524 participants, 175 cases of new-onset T2DM were observed during follow-up. After multivariable adjustment, higher PA was strongly inversely associated with T2DM, showing highly significant differences between extreme quartiles (HR = 0.51; 95% CI 0.32-0.79 p for trend<0.001). When considering not only PA, but also the more comprehensive active + sedentary lifestyle combined score, even stronger differences were found between the lowest and the highest categories (HR = 0.40; 95%CI 0.20-0.80; p for trend<0.001).

CONCLUSION

Sedentary lifestyles, in addition to PA patterns, should be included in the assessment of T2DM risk. Promoting PA should be coupled with the avoidance of a sedentary lifestyle to lower the risk of T2DM.

Effect of eugenol treatment in hyperglycemic murine models: A meta-analysis

Diabetes is a highly prevalent health condition affecting many people worldwide. In vitro studies have described the positive effects of cloves and its major compound, eugenol, in the treatment of diabetes. However, it is unclear whether the effects of this compound are negative, neutral, or positive, on hyperglycemic animals. Therefore, a meta-analytical review was conducted to determine the magnitude of effects of eugenol on variables directly and indirectly related to diabetes. This study revealed that eugenol treatment decreased the glucose levels and the activity of carbohydrate-metabolizing enzymes, ameliorated the lipid profile, and reduced the oxidative, renal, and hepatic damages in hyperglycemic rodents. Moreover, eugenol alleviated the weight loss and restored the activity of the antioxidant defense system. Insulin levels was not affected by eugenol treatment. Also, mixed model analyses revealed that the use of purified or non-purified eugenol and the concentrations administered significantly affected the treatment outcome. In conclusion, our findings indicate that eugenol may have potential therapeutic effects in the treatment of diabetes. Furthermore, this study can direct future preclinical and clinical trials, with important implications for human health.

Non-invasive multimodal imaging of Diabetic Retinopathy: A survey on treatment methods and Nanotheranostics

Diabetes Retinopathy (DR) is one of the most prominent microvascular complications of diabetes. It is one of the pre-eminent causes for vision impairment followed by blindness among the working-age population worldwide. The de facto cause for DR remains challenging, despite several efforts made to unveil the mechanism underlying the pathology of DR. There is quite less availability of the low cost pre-emptive theranostic imaging tools in terms of in-depth resolution, due to the multiple factors involved in the etiology of DR. This review work comprehensively explores the various reports and research works on all perspectives of diabetic retinopathy (DR), and its mechanism. It also discusses various advanced non-destructive imaging modalities, current, and future treatment approaches. Further, the application of various nanoparticle-based drug delivery strategies used for the treatment of DR are also discussed. In a nutshell, the present review work bolsters the pursuit of the development of an advanced non-invasive optical imaging modal with a nano-theranostic approach for the future diagnosis and treatment of DR and its associated ocular complications.

Cardioprotective role of GTS-21 by attenuating the TLR4/NF-κB pathway in streptozotocin-induced diabetic cardiomyopathy in rats

The cholinergic anti-inflammatory pathway (CAP) was investigated in a variety of inflammatory conditions and constitutes a valuable line in their treatment. In the current study, we investigated the anti-inflammatory effect of GTS-21 (GTS) as a partial selective α7 nicotinic acetylcholine receptor (α7-nAchR) agonist in diabetic cardiomyopathy model in rats. This mechanism was elaborated to study whether it could alleviate the electrocardiographic, histopathological, and molecular levels of Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB) pathway proteins. Diabetes was induced by the injection of streptozotocin (STZ) (50 mg/kg). Diabetic rats were treated with GTS (1 or 2 mg/kg/day), methyllycaconitine (MLA), a selective α7-nAchR antagonist (2 mg/kg/day) plus GTS (2 mg/kg/day), or the vehicle. All treatments were given by the intraperitoneal route. Ventricular rate and different electrocardiograph (ECG) anomalies were detected. Plasma levels of cardiac troponin T (cTnT) and creatine kinase MB (CK-MB) were measured by ELISA. Additionally, we elucidated the levels of several proteins involved in the TLR4/NF-κB pathway. Cardiac levels of TLR4 and phosphorylated protein kinase B (p-Akt) were detected by ELISA. The cardiac expression of myeloid differentiation primary response 88 (Myd88), tumor necrosis factor receptor-associated factor 6 (TRAF6), NF-κB, interleukin 1β (IL-1β), and active caspase-1 were evaluated by immunohistochemical staining. Finally, the cardiac levels of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) were determined by ELISA. Diabetic rats showed (i) ECG signs of cardiomyopathy such as significant ST segment elevations, prolonged QRS, QT intervals, and ventricular tachycardia; (ii) increased plasma levels of cTnT and CK-MB; (iii) increased expression of cardiac TLR4; (iv) elevated immunohistochemical expression of cardiac, Myd88, TRAF6, and NF-κB; (v) diminution in the cardiac expression of p-Akt; and (vi) adaptive increases in cardiac expression of TNF-α and IL-6. These effects were ameliorated in diabetic rats treated with both doses of GTS. Pretreatment with MLA did not completely reverse the ameliorative effect of GTS on cTnT, TRAF6, TNF-α, and IL-6, thereby reinforcing the presence of possible α7-nAchR-independent mechanisms. The activation of α7-nAchR with GTS offers a promising prophylactic strategy for diabetic cardiomyopathy by attenuating the TLR4/NF-κB pathway.

Notch1 Has an Important Role in β-Cell Mass Determination and Development of Diabetes

BACKGROUND

Notch signaling pathway plays an important role in regulating pancreatic endocrine and exocrine cell fate during pancreas development. Notch signaling is also expressed in adult pancreas. There are few studies on the effect of Notch on adult pancreas. Here, we investigated the role of Notch in islet mass and glucose homeostasis in adult pancreas using Notch1 antisense transgenic (NAS).

METHODS

Western blot analysis was performed for the liver of 8-week-old male NAS mice. We also conducted an intraperitoneal glucose tolerance test (IPGTT) and intraperitoneal insulin tolerance test in 8-week-old male NAS mice and male C57BL/6 mice (control). Morphologic observation of pancreatic islet and β-cell was conducted in two groups. Insulin secretion capacity in islets was measured by glucose-stimulated insulin secretion (GSIS) and perifusion.

RESULTS

NAS mice showed higher glucose levels and lower insulin secretion in IPGTT than the control mice. There was no significant difference in insulin resistance. Total islet and β-cell masses were decreased in NAS mice. The number of large islets (≥250 µm) decreased while that of small islets (<250 µm) increased. Reduced insulin secretion was observed in GSIS and perifusion. Neurogenin3, neurogenic differentiation, and MAF bZIP transcription factor A levels increased in NAS mice.

CONCLUSION

Our study provides that Notch1 inhibition decreased insulin secretion and decreased islet and β-cell masses. It is thought that Notch1 inhibition suppresses islet proliferation and induces differentiation of small islets. In conclusion, Notch signaling pathway may play an important role in β-cell mass determination and diabetes.

Type 2 diabetes subgroups and potential medication strategies in relation to effects on insulin resistance and beta-cell function: A step toward personalised diabetes treatment?

Background

Type 2 diabetes is a syndrome defined by hyperglycaemia that is the result of various degrees of pancreatic β-cell failure and reduced insulin sensitivity. Although diabetes can be caused by multiple metabolic dysfunctions, most patients are defined as having either type 1 or type 2 diabetes. Recently, Ahlqvist and colleagues proposed a new method of classifying patients with adult-onset diabetes, considering the heterogenous metabolic phenotype of the disease. This new classification system could be useful for more personalised treatment based on the underlying metabolic disruption of the disease, although to date no prospective intervention studies have generated data to support such a claim.

Scope of Review

In this review, we first provide a short overview of the phenotype and pathogenesis of type 2 diabetes and discuss the current and new classification systems. We then review the effects of different anti-diabetic medication classes on insulin sensitivity and β-cell function and discuss future treatment strategies based on the subgroups proposed by Ahlqvist et al.

Major Conclusions

The proposed novel type 2 diabetes subgroups provide an interesting concept that could lead to a better understanding of the pathophysiology of the broad group of type 2 diabetes, paving the way for personalised treatment choices based on understanding the root cause of the disease. We conclude that the novel subgroups of adult-onset diabetes would benefit from anti-diabetic medications that take into account the main pathophysiology of the disease and thereby prevent end-organ damage. However, we are only beginning to address the personalised treatment of type 2 diabetes, and studies investigating the effects of current and novel drugs in subgroups with different metabolic phenotypes are needed to develop personalised treatment of the syndrome

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Novel subgroups of type 2 diabetes provide a concept that could lead to a better understanding of its pathophysiology.

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Treatment strategies would benefit from anti-diabetic medications that influence the main pathophysiology of diabetes.

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Here, we review different anti-diabetic medications classes affecting insulin sensitivity and β-cell function.

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We suggest that future treatment strategies could benefit by taking into account subgroups provided by Ahlqvist et al.

Living Therapeutics: The Next Frontier of Precision Medicine

Modern medicine has long studied the mechanism and impact of pathogenic microbes on human hosts, but has only recently shifted attention toward the complex and vital roles that commensal and probiotic microbes play in both health and dysbiosis. Fueled by an enhanced appreciation of the human-microbe holobiont, the past decade has yielded countless insights and established many new avenues of investigation in this area. In this review, we discuss advances, limitations, and emerging frontiers for microbes as agents of health maintenance, disease prevention, and cure. We highlight the flexibility of microbial therapeutics across disease states, with special consideration for the rational engineering of microbes toward precision medicine outcomes. As the field advances, we anticipate that tools of synthetic biology will be increasingly employed to engineer functional living therapeutics with the potential to address longstanding limitations of traditional drugs.

Distinctive Metabolomics Patterns Associated With Insulin Resistance and Type 2 Diabetes Mellitus

Obesity is associated with an increased risk of insulin resistance (IR) and type 2 diabetes mellitus (T2DM) which is a multi-factorial disease associated with a dysregulated metabolism and can be prevented in pre-diabetic individuals with impaired glucose tolerance. A metabolomic approach emphasizing metabolic pathways is critical to our understanding of this heterogeneous disease. This study aimed to characterize the serum metabolomic fingerprint and multi-metabolite signatures associated with IR and T2DM. Here, we have used untargeted high-performance chemical isotope labeling (CIL) liquid chromatography-mass spectrometry (LC-MS) to identify candidate biomarkers of IR and T2DM in sera from 30 adults of normal weight, 26 obese adults, and 16 adults newly diagnosed with T2DM. Among the 3633 peak pairs detected, 62% were either identified or matched. A group of 78 metabolites were up-regulated and 111 metabolites were down-regulated comparing obese to lean group while 459 metabolites were up-regulated and 166 metabolites were down-regulated comparing T2DM to obese groups. Several metabolites were identified as IR potential biomarkers, including amino acids (Asn, Gln, and His), methionine (Met) sulfoxide, 2-methyl-3-hydroxy-5-formylpyridine-4-carboxylate, serotonin, L-2-amino-3-oxobutanoic acid, and 4,6-dihydroxyquinoline. T2DM was associated with dysregulation of 42 metabolites, including amino acids, amino acids metabolites, and dipeptides. In conclusion, these pilot data have identified IR and T2DM metabolomics panels as potential novel biomarkers of IR and identified metabolites associated with T2DM, with possible diagnostic and therapeutic applications. Further studies to confirm these associations in prospective cohorts are warranted.

Redox homeostasis and cell cycle activation mediate beta-cell mass expansion in aged, diabetes-prone mice under metabolic stress conditions: Role of thioredoxin-interacting protein (TXNIP)

Overnutrition contributes to insulin resistance, obesity and metabolic stress, initiating a loss of functional beta-cells and diabetes development. Whether these damaging effects are amplified in advanced age is barely investigated. Therefore, New Zealand Obese (NZO) mice, a well-established model for the investigation of human obesity-associated type 2 diabetes, were fed a metabolically challenging diet with a high-fat, carbohydrate restricted period followed by a carbohydrate intervention in young as well as advanced age. Interestingly, while young NZO mice developed massive hyperglycemia in response to carbohydrate feeding, leading to beta-cell dysfunction and cell death, aged counterparts compensated the increased insulin demand by persistent beta-cell function and beta-cell mass expansion. Beta-cell loss in young NZO islets was linked to increased expression of thioredoxin-interacting protein (TXNIP), presumably initiating an apoptosis-signaling cascade via caspase-3 activation. In contrast, islets of aged NZOs exhibited a sustained redox balance without changes in TXNIP expression, associated with higher proliferative potential by cell cycle activation. These findings support the relevance of a maintained proliferative potential and redox homeostasis for preserving islet functionality under metabolic stress, with the peculiarity that this adaptive response emerged with advanced age in diabetes-prone NZO mice.

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Differential expression of redox and cell cycle genes in young and aged islets.

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Increased TXNIP expression is associated with the induction of beta-cell apoptosis.

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Islets of aged mice maintained redox homeostasis and proliferative potential.

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Aging under diet-induced metabolic stress does not amplify beta-cell failure.

CCL4 Inhibition in Atherosclerosis: Effects on Plaque Stability, Endothelial Cell Adhesiveness, and Macrophages Activation

Atherosclerosis is an arterial inflammatory disease. The circulating level of the C-C chemokine ligand (CCL4) is increased in atherosclerotic patients. This study aimed to investigate whether CCL4 inhibition could retard the progression of atherosclerosis. In ApoE knockout mice, CCL4 antibody treatment reduced circulating interleukin-6 (IL-6) and tumor necrosis factor (TNF)-α levels and improved lipid profiles accompanied with upregulation of the liver X receptor. CCL4 inhibition reduced the atheroma areas and modified the progression of atheroma plaques, which consisted of a thicker fibrous cap with a reduced macrophage content and lower matrix metalloproteinase-2 and -9 expressions, suggesting the stabilization of atheroma plaques. Human coronary endothelial cells (HCAECs) and macrophages were stimulated with TNF-α or oxidized LDL (ox-LDL). The induced expression of E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) were attenuated by the CCL4 antibody or CCL4 si-RNA. CCL4 inhibition reduced the adhesiveness of HCAECs, which is an early sign of atherogenesis. CCL4 blockade reduced the activity of metalloproteinase-2 and -9 and the production of TNF-α and IL-6 in stimulated macrophages. The effects of CCL4 inhibition on down-regulating adhesion and inflammation proteins were obtained through the nuclear factor kappa B (NFκB) signaling pathway. The direct inhibition of CCL4 stabilized atheroma and reduced endothelial and macrophage activation. CCL4 may be a novel therapeutic target for modulating atherosclerosis.

A polysaccharide extract from the medicinal plant Maidong inhibits the IKK-NF-κB pathway and IL-1β-induced islet inflammation and increases insulin secretion

The herb dwarf lilyturf tuber (Maidong, Ophiopogonis Radix) is widely used in Chinese traditional medicine to manage diabetes and its complications. However, the role of Maidong polysaccharide extract (MPE) in pancreatic β-cell function is unclear. Here, we investigated whether MPE protects β-cell function and studied the underlying mechanisms. We treated db/db and high-fat diet (HFD)-induced obese mice with 800 or 400 mg/kg MPE or water for 4 weeks, followed by an oral glucose tolerance test. Pancreas and blood were collected for molecular analyses, and clonal MIN6 β-cells and primary islets from HFD-induced obese mice and normal chow diet-fed mice were used in additional analyses. In vivo, MPE both increased insulin secretion and reduced blood glucose in the db/db mice but increased only insulin secretion in the HFD-induced obese mice. MPE substantially increased the β-cell area in both models (3-fold and 2-fold, p < 0.01, for db/db and HFD mice, respectively). We observed reduced nuclear translocation of the p65 subunit of NF-κB in islets of MPE-treated db/db mice, coinciding with enhanced glucose-stimulated insulin secretion (GSIS). In vitro, MPE potentiated GSIS and decreased interleukin 1β (IL-1β) secretion in MIN6 β-cells. Incubation of MIN6 cells with tumor necrosis factor α (TNFα), interferon-γ, and IL-1β amplified IL-1β secretion and inhibited GSIS. These effects were partially reversed with MPE or the IκB kinase β inhibitor PS1145, coinciding with reduced activation of p65 and p-IκB in the NF-κB pathway. We conclude that MPE may have potential for therapeutic development for β-cell protection.

Bioactive Phytochemicals Isolated from Akebia quinata Enhances Glucose-Stimulated Insulin Secretion by Inducing PDX-1

Chocolate vine (Akebia quinata) is consumed as a fruit and is also used in traditional medicine. In order to identify the bioactive components of A. quinata, a phytosterol glucoside stigmasterol-3-O-β-d-glucoside (1), three triterpenoids maslinic acid (2), scutellaric acid (3), and hederagenin (4), and three triterpenoidal saponins akebia saponin PA (5), hederacoside C (6), and hederacolchiside F (7) were isolated from a 70% EtOH extract of the fruits of A. quinata (AKQU). The chemical structures of isolates 1-7 were determined by analyzing the 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data. Here, we evaluated the effects of AKQU and compounds 1-7 on insulin secretion using the INS-1 rat pancreatic β-cell line. Glucose-stimulated insulin secretion (GSIS) was evaluated in INS-1 cells using the GSIS assay. The expression levels of the proteins related to pancreatic β-cell function were detected by Western blotting. Among the isolates, stigmasterol-3-O-β-d-glucoside (1) exhibited strong GSIS activity and triggered the overexpression of pancreas/duodenum homeobox protein-1 (PDX-1), which is implicated in the regulation of pancreatic β-cell survival and function. Moreover, isolate 1 markedly induced the expression of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), insulin receptor substrate-2 (IRS-2), phosphoinositide 3-kinase (PI3K), and Akt, which regulate the transcription of PDX-1. The results of our experimental studies indicated that stigmasterol-3-O-β-d-glucoside (1) isolated from the fruits of A. quinata can potentially enhance insulin secretion, and might alleviate the reduction in GSIS during the development of T2DM.

Nitric oxide interacts with cholinoceptors to modulate insulin secretion by pancreatic β cells

Dysfunction of the pancreatic β cells leads to several chronic disorders including diabetes mellitus. Several mediators and mechanisms are known to be involved in the regulation of β cell secretory function. In this study, we propose that cytokine-induced nitric oxide (NO) production interacts with cholinergic mechanisms to modulate insulin secretion from pancreatic β cells. Using a rat insulinoma cell line INS-1, we demonstrated that β cell viability decreases significantly in the presence of SNAP (NO donor) in a concentration- and time-dependent manner. Cell viability was also found to be decreased in the presence of a combined treatment of SNAP with SMN (muscarinic receptor antagonist). We then investigated the impact of these findings on insulin secretion and found a significant reduction in glucose uptake by INS-1 cells in the presence of SNAP and SMN as compared with control. Nitric oxide synthase 3 gene expression was found to be significantly reduced in response to combined treatment with SNAP and SMN suggesting an interaction between the cholinergic and nitrergic systems. The analysis of gene and protein expression further pin-pointed the involvement of M₃ muscarinic receptors in the cholinergic pathway. Upon treatment with cytokines, reduced cell viability was observed in the presence of TNF-α and IFN-γ. A significant reduction in insulin secretion was also noted after treatment with TNF-α and IFN-γ and IL1-β. The findings of the present study have shown for the first time that the inhibition of the excitatory effects of cholinergic pathways on glucose-induced insulin secretion may cause β cell injury and dysfunction of insulin secretion in response to cytokine-induced NO production.

Factors Influencing Mitochondrial Function as a Key Mediator of Glucose-Induced Insulin Release: Highlighting Nicotinamide Nucleotide Transhydrogenase

Pancreatic β-cells recognize blood glucose changes and release insulin that is a peptide hormone responsible for stable glycemia. Diabetes, a chronic disorder of insulin insufficiency, leads to disturbed glucose homeostasis and multi-organ problems. Glucose and insulin are key markers in the follow-up and control of this disease. Mitochondrial metabolism of pancreatic beta cells is a crucial part of glucose-stimulated cascade of insulin secretion. Effective factors on β-cells mitochondrial function in production of compounds such as tricarboxylic acid intermediates, glutamate, nicotinamide adenine dinucleotide phosphate, and reactive oxygen species can have great effects on the secretion of insulin under diabetes. This review enhances our knowledge of factors influencing mitochondrial function as a key mediator of glucose-induced insulin release that accordingly will be helpful to further our understanding of the mechanisms implicated in the progressive beta cell failure that results in diabetes.