Beta-cell Function Research Articles

Inhibition of de novo ceramide synthesis by sirtuin-1 improves beta-cell function and glucose metabolism in type 2 diabetes.

Obesity and type 2 diabetes (T2D) are major risk factors for cardiovascular (CV) diseases. Dysregulated pro-apoptotic ceramide synthesis reduces β-cell insulin secretion, thereby promoting hyperglycaemic states that may manifest as T2D. Pro-apoptotic ceramides modulate insulin sensitivity and glucose tolerance while being linked to poor CV outcomes. Sirtuin-1 (SIRT1) is a NAD + -dependent deacetylase that protects against pancreatic β-cell dysfunction; however, systemic levels are decreased in obese-T2D mice and may promote pro-apoptotic ceramide synthesis and hyperglycaemia. Herein, we aimed to assess the effects of restoring circulating SIRT1 levels to prevent metabolic imbalance in obese and diabetic mice. Circulating SIRT1 levels were reduced in obese-diabetic mice (db/db) as compared to age-matched non-diabetic db/+ controls. Restoration of SIRT1 plasma levels with recombinant murine SIRT1 for 4 weeks prevented body weight gain and improved glucose tolerance, insulin sensitivity, and vascular function in mice models of obesity and T2D. Untargeted lipidomics revealed that SIRT1 restored insulin secretory function of β-cells by reducing synthesis and accumulation of pro-apoptotic ceramides. Molecular mechanisms involved direct binding to and deacetylation of Toll-like receptor 4 (TLR4) by SIRT1 in β-cells, thereby decreasing the rate-limiting enzymes of sphingolipid synthesis SPTLC1/2 via AKT/NF-κB. Among patients with T2D, those with high baseline plasma levels of SIRT1 prior to metabolic surgery displayed restored β-cell function (HOMA2-β) and were more likely to have T2D remission during follow-up. Acetylation of TLR4 promotes β-cell dysfunction via ceramide synthesis in T2D, which is blunted by systemic SIRT1 replenishment. Hence, restoration of systemic SIRT1 may provide a novel therapeutic strategy to counteract toxic ceramide synthesis and mitigate CV complications of T2D.

The efficiency of stem cell differentiation into functional beta cells for treating insulin-requiring diabetes: Recent advances and current challenges.

In recent years, the potential of stem cells (SCs) to differentiate into various types of cells, including β-cells, has led to a significant boost in development. The efficiency of this differentiation process and the functionality of the cells post-transplantation are crucial factors for the success of stem cell therapy in diabetes. Herein, this article reviews the current advances and challenges faced by stem cell differentiation into functional β-cells for diabetes treatment. In vitro, researchers have sought to enhance the differentiation efficiency of functional β-cells by mimicking the normal pancreatic development process, using gene manipulation, pharmacological and culture conditions stimulation, three-dimensional (3D) and organoid culture, or sorting for functional β-cells based on mature islet cell markers. Furthermore, in vivo studies have also looked at suitable transplantation sites, the enhancement of the transplantation microenvironment, immune modulation, and vascular function reconstruction to improve the survival rate of functional β-cells, thereby enhancing the treatment of diabetes. Despite these advancements, developing stem cells to produce functional β-cells for efficacious diabetes treatment is a continuous research endeavor requiring significant multidisciplinary collaboration, for the stem-cell-derived beta cells to evolve into an effective cellular therapy.

Adenosine kinase inhibits β-cell proliferation by upregulating DNA methyltransferase 3A expression.

To investigate the effects of adenosine kinase (ADK), a key enzyme in determining intracellular adenosine levels, on β cells, and their underlying mechanism. Genetic animal models and transgenic immortalized cells were applied to study the effect of ADK on islet beta-cell proliferation and function. The beta-cell mass and response to glucose were measured in vivo using mice with beta-cell-specific ADK overexpression, and in vitro using ADK-overexpressed immortalized beta-cell. The expression of ADK in human islets at high abundance, especially in β cells, was decreased during the process of β-cell proliferation. Additionally, a transgenic mouse model (ADKtg/tg /Mip-Cre) was generated wherein the mouse Insulin1 gene promoter specifically overexpressed ADK in pancreatic β cells. The ADKtg/tg /Mip-Cre model exhibited impaired glucose tolerance, decreased fasting plasma insulin, loss of β-cell mass, and inhibited β-cell proliferation. Proteomic analysis revealed that ADK overexpression inhibited the expression of several proteins that promote cell proliferation and insulin secretion. Upregulating ADK in the β-cell line inhibited the expression of β-cell related regulatory molecules, including FoxO1, Appl1, Pxn, Pdx-1, Creb and Slc16a3. Subsequent in vitro experiments indicated that the inhibition of β-cell proliferation and the decreased expression of Pdx-1, Creb and Slc16a3 were rescued by DNA methyltransferase 3A (DNMT3A) knockdown in β cells. In this study, we found that the overexpression of ADK decreased the expression of several genes that regulate β cells, resulting in the inhibition of β-cell proliferation and dysfunction by upregulating the expression of DNMT3A.

Gender Specific Effects of Nr4a1 in Obese Mice

A central aspect of type 2 diabetes disease progression is impaired functional β-cell mass. The hyperglycemic and hyperlipidemic environment present in type 2 diabetes corresponds with impaired beta cell function. The orphan nuclear receptor Nr4a1 is critical for fuel utilization in various tissues, however little is known regarding its function in the β-cell. Nr4a1 expression is decreased in the β-cell of rodent models of type 2 diabetes, as well as in primary human islets from type 2 diabetics. Here we demonstrate sex specific effects of β-cell specific Nr4a1 deletion under high fat chow feeding. While female and male βNr4a1−/− mice were no different than wild type controls when fed a standard chow diet, a clear sex dependent difference is observed when fed a high fat diet. While high fat fed male βNr4a1−/− have improved fasting and non-fasting blood glucose levels and no change in glucose tolerance, high fat fed female βNr4a1−/− mice have impaired glucose tolerance as early as one month after beginning high fat feeding. We also found that βNr4a1−/− female mice have decreased β-cell mass and decreased expression in known targets of Nr4a1 regulation including Eno1 and SDHβ. Our data suggest that Nr4a1 is critical for maintenance of beta cell function, and that loss of Nr4a1 under conditions of obesity and overnutrition in females results in impaired beta cell compensation and function. NIH R15DK124835-01A1. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Obesity to Type 2 Diabetes Mellitus: Importance of Longitudinal Characterization of the Progressive Phases as Identified in Rhesus Monkeys Maintained Under Constant Diet and Environmental Conditions

The complex physiological mechanisms that underlie the links between obesity and T2DM involve “adiposity-induced” alterations in beta cell function —not yet mechanistically understood. Clearly the changes in beta cell function are greatly increased during the progression of obesity, --not reduced!! AND multiorgan insulin resistance whose mechanisms are unknown (although likely reduced by weight loss). Rhesus monkeys have shown these and have provided an amazing look at the Phases that lead to T2DM. We have previously summarized, in a table of 49 variables, the many ways that the nonhuman primate rhesus monkey offers exciting opportunities for insight into these extraordinary conditions compared to the human with T2DM. The Importance of longitudinal characterization, with a number of measurements that are regularly and periodically carried out to assess longitudinally some of the pathophysiological processes that develop spontaneously and naturally in these monkeys as they progress from normal, lean, young animals to obese animals with or without various physiological disturbances undergo the aging process. Usually these disturbances develop at varying rates in different monkeys and include hypertension, hyperlipidemia, hyperinsulinemia, hyperglycemia, impaired glucose tolerance, insulin resistance, peripheral neuropathy, impaired renal clearance, and cardiovascular disease—in short, the entire syndrome that becomes manifest in aged and diabetic humans. The longitudinal studies depend specifically on regular assessment of each animal and determination of the rate at which that animal is or is not progressing in the development of pathophysiological disturbances. Identification of phases allows one to estimate where a given monkey is in regard to the progression to overt diabetes. Application to humans will greatly increase our predictive ability to understand the mechanisms underlying both obesity and T2DM. NIA NO1AG3 1012. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Interplay Between the American Diabetes Association's ABC Targets for Diabetes, Insulin Resistance Indices, and Dyslipidemia in Indian Type 2 Diabetes Patients.

Background The increasing incidence of type 2 diabetes (T2D) in India underscores the pressing need for effective management strategies. Meeting the American Diabetes Association (ADA) ABC targets for diabetes (glycated hemoglobin (HbA1c), blood pressure, and serum low-density lipoprotein cholesterol (LDL-C)) is crucial for effectively managing T2D, as it reflects the optimal control of key metabolic parameters. Insulin resistance (IR) and impaired beta cell function (BCF) have been found to have a significant impact on glycemic control, lipid metabolism, and hypertension, contributing to the complex cardiovascular risk profile of patients with T2D. This study aimed to explore the association between ABC targets for diabetes, IR, BCF, and dyslipidemia in a cross-sectional cohort of T2D patients. Methods This retrospective study examined data from 681 T2D patients with comorbid hypertension and dyslipidemia. The patients were part of a one-year online lifestyle intervention program for diabetes management at the Freedom from Diabetes Clinic in Pune, India, between January 2021 and December 2022. Baseline data (at the time of enrollment in the program) on medical history and anthropometric and biochemical parameters were retrospectively extracted from medical records and used to assess ABC targets and other clinical parameters. The ABC targets for diabetes include three goals: an HbA1c level of less than 7.0%, a blood pressure level of less than 140/90 mmHg, and an LDL-C level of less than 100 mg/dL. Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), Homeostatic Model Assessment of Beta Cell Function (HOMA-B), and Quantitative Insulin Sensitivity Check Index (QUICKI) were calculated using standard formulas. Results Cross-sectional analysis at baseline showed that 152 (22.3%) participants met all three ABC targets, 306 (45.0%) and 183 (26.8%) participants met two or one targets, respectively, and 40 (5.9%) did not meet any of the ABC targets. Participants meeting all three targets showed significantly lower IR, higher sensitivity (HOMA-IR, median 2.1; QUICKI, median 0.34), higher BCF (HOMA-B, median 62.9), and healthier lipid profiles (mg/dL) (total cholesterol, median 126; triglycerides, median 114; and non-high-density lipoprotein (HDL), median 84) than those who did not meet any of the ABC targets (HOMA-IR, median 3.4; QUICKI, median 0.31; HOMA-B, median 31.7; total cholesterol, median 221; triglycerides, median 187; and non-HDL, median 182) (p < 0.01). A significant association was observed between lower BMI (< 25 kg/m2), lower IR (HOMA-IR <2.5), and meeting all three ABC targets (p < 0.01). No significant association was observed between the duration of diabetes and ABC target status (p > 0.1). Lower IR was identified as a predictor of achievement of all three ABC targets (p < 0.01). Conclusion This study highlights the significance of meeting ABC targets for diabetes in relation to not only a better lipid profile but also lower IR and higher BCF. These preliminary findings provide novel insights into the interplay between IR, BCF, dyslipidemia, and meeting ABC targets in an Indian T2D population. These findings highlight the need for effective diabetes management strategies and improved patient outcomes, considering factors such as BMI and IR indices.

Mechanisms of PAK1-Induced Skeletal Muscle Myokines in Improving Islet β-Cell Function

The critical role of skeletal muscle in regulating metabolic homeostasis is well-acknowledged. The p21-activated kinase (PAK1), a prominent signaling molecule in skeletal muscle, has garnered attention for its potential modulatory role in glucose and mitochondrial metabolism. By applying conditioned media derived from PAK1-enriched L6 Glut4 myc myotubes or myoblasts to INS-1 832/13 clonal β-cells, we confirmed that a muscle-derived circulating factor(s) could enhance β-cell function. Furthermore, our mass spectrometry analysis in the conditioned media (CM) collected from PAK1 enriched L6.GLUT4myc myotubes revealed elevated levels of one protein in particular, hepatocyte growth factor activator (HGFAC), which is categorized as a secreted myokine. HGFAC is secreted into the circulation, where, upon activation, it can act in a paracrine or endocrine fashion to proteolytically cleave and activate HGF. It has been reported that HGF has a vital role in islet β-cell mass and function and HNFα, a transcription factor that is expressed in pancreatic β-cells regulates β-cell mass or function by modulating HGFAC expression. Thus, we hypothesize that PAK1-enriched skeletal muscle releases HGFAC into the serum-free conditioned medium and the medium carrying HGFAC when applied to islet β-cells enhances insulin secretion. Elevated levels of HGFAC protein were detected in the cells and their associated CM from PAK1-enriched skeletal myotubes, as compared with that of GFP-transduced control myotubes, using sandwich ELISA to quantify HGFAC. Notably, these cells were incubated in a serum-free medium, a means to eliminate serum factors that might impact HGFAC levels or detection capacity. Given this, we tested the effect of this serum-free CM collected from PAK1-enriched L6.GLUT4myc myotubes application to species-matched (rat) clonal β-cells functional capacity. Indeed, CM from PAK1-enriched myotubes significantly enhanced glucose-stimulated insulin secretion (GSIS), as compared that of the control CM. The presence of elevated HGFAC levels in PAK1-enriched cells, and the beneficial impact of this HGFAC-enriched CM upon beta cell function, reveals a new mechanism by which PAK1-enrichment in skeletal muscle imparts improved overall whole-body glucose homeostasis. further hints at a possible intricate relationship between muscle-pancreas crosstalk in the regulation of islet β-cell insulin secretion. Future investigations into possible autocrine functions of PAK1-enriched skeletal muscle are underway. This research was funded by the National Institutes of Health to D.C.T. (DK067912, DK112917, and DK102233), and an American Heart Association Postdoctoral fellowship to R.B. (#905770). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of Including Lean Red Meat in a Plant-Based Dietary Pattern on Biomarkers of Cardiometabolic Disease Risk

The objective of this study was to examine the acute effects of dietary patterns, varying in red meat quantity, on clinical biomarkers of cardiometabolic disease risk in women with overweight. We hypothesized that there would be no differences in markers of acute inflammation, glycemic control or expression of miRNAs associated with metabolic disease risks detected after consumption of a diet containing 2 servings of lean red meat/day compared to a diet void of lean red meat. Secondary analyses were performed using plasma samples collected within a randomized, crossover design study in 17 women (mean ± SEM, age: 33±1y; BMI: 27.8±0.1kg/m2) who consumed a plant-based diet containing either 0 or 2 servings of red meat/d for 1 wk/pattern. A 3-wk washout period occurred between patterns. Participants were provided with eucaloric, isonitrogenous plant-based diets containing 3 daily meals (28% of daily calories/meal) and an evening snack (16% of daily calories) that differed only in protein source. The protein sources in the plant-based diet without red meat (MEATLESS) were 100% plant-based, whereas the plant-based diet with red meat (RED MEAT) replaced a portion of plant protein with 2 servings/d of lean beef. Fasting blood samples were collected at the end of each dietary pattern for the assessment of plasma glucose, insulin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), adiponectin, and branch chain amino acids (BCAA) via colorimetric (glucose), enzyme-linked immunoassays, and high-performance liquid chromatography (BCAA). Homeostatic Model Assessment (HOMA) was used to evaluate insulin resistance (IR) and sensitivity (%S) and beta cell function (%B). Paired sample t-tests were utilized to compare the main effect of protein source (RED MEAT vs. MEATLESS) on fasting plasma biomarkers of cardiometabolic disease risk. p&lt;0.05 was considered significant. Additional ongoing analyses include querying expression of a microRNA (miRNA) panel associated with metabolic disease risks via qPCR. No differences in plasma fasting glucose (76.67±2.08 vs. 76.48±1.98mg/dL); insulin (45.89±5.47 vs. 46.31±5.49pmol/L); IL-6 (1.18±0.27 vs. 1.13±0.30pg/mL); TNF-α (4.11±0.30 vs. 4.13±0.24pg/mL); CRP (0.37±0.07 vs. 0.41±0.09mg/dL); adiponectin (10.53±1.52 vs. 10.35±1.36ug/mL); or BCAA (118.49±9.09 vs. 121.94±9.39mg/mL) concentrations or differences in HOMA -IR (1.46±0.18 vs. 1.47±0.19), -%S (115.83±11.92 vs. 117.67±14.38), or -%B (135.64±11.30 vs. 137.56±10.41) were detected when comparing RED MEAT vs. MEATLESS dietary patterns. The consumption of as much as 2 servings of lean red meat/d does not negatively influence inflammatory or metabolic signals related to cardiometabolic disease risk. These findings suggest that lean red meat can serve as a nutrient-dense protein source within a healthy dietary pattern. The Beef Checkoff; not offcial Army/DoD policy. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparison of an oral mixed meal plus arginine and intravenous glucose, GLP-1 plus arginine to unmask residual islet function in longstanding type 1 diabetes.

Residual beta cells are present in most patients with longstanding type 1 diabetes but it is unknown whether these beta cells react normally to different stimuli. Moreover a defect in proinsulin conversion and abnormal alpha cell response are also part of the islet dysfunction. A three-phase [euglycemia, hyperglycemia, and hyperglycemia + glucagon-like peptide 1 (GLP-1)] clamp was performed in patients with longstanding type 1 diabetes. Intravenous arginine boluses were administered at the end of each phase. On another day, a mixed meal stimulation test with a subsequent intravenous arginine bolus was performed. C-peptide was detectable in a subgroup of subjects at baseline (2/15) or only after stimulation (3/15). When detectable, C-peptide increased 2.9-fold [95% CI: 1.2-7.1] during the hyperglycemia phase and 14.1-fold [95% CI: 3.1-65.2] during the hyperglycemia + GLP-1 phase, and 22.3-fold [95% CI: 5.6-89.1] during hyperglycemia + GLP-1 + arginine phase when compared with baseline. The same subset of patients with a C-peptide response were identified during the mixed meal stimulation test as during the clamp. There was an inhibition of glucagon secretion (0.72-fold, [95% CI: 0.63-0.84]) during the glucose clamp irrespective of the presence of detectable beta cell function. Proinsulin was only present in a subset of subjects with detectable C-peptide (3/15) and proinsulin mimicked the C-peptide response to the different stimuli when detectable. Residual beta cells in longstanding type 1 diabetes respond adequately to different stimuli and could be of clinical benefit.NEW & NOTEWORTHY If beta cell function is detectable, the beta cells react relatively normal to the different stimuli except for the first phase response to intravenous glucose. An oral mixed meal followed by an intravenous arginine bolus can identify residual beta cell function/mass as well as the more commonly used glucose potentiated arginine-induced insulin secretion during a hyperglycemic clamp.

Characteristics and Biological Properties of Imeglimin Hydrochlo ride, A Novel Antidiabetic Agent: A Systematic Review.

WHO indicates that diabetes will become the 7th leading reason for death by 2030. The physiopathology of dysfunctioning is associated with obesity, weight gain and predominantly insulin resistance in insulin-sensitive cells and continuous deterioration of pancreatic beta cell function..Imeglimin is an investigational novel oral anti-diabetic drug. The motive of the review is to comprehensively explore the chemistry, biological and analytical analysis of the Imeglimin hydrochloride. To enhance the understanding, a systematic review was conducted by forming a database of relevant existing studies from electronic resources like Web of Science, ScienceDirect and PubMed. The methodology is reflected in the PRISMA design. The drug was approved in the year 2021 for therapeutic purposes in Japan. It is the novel and first approved drug for this type of Anti-diabetic treatment. It is a small molecular drug whose molecular weight is 191.6 grams per mole utilized for oral administration. Imeglimin is thought to have both activities, as the amount of glucose is dependent on insulin secretory impact and insulin sensitivity is increased. Therapeutic, pharmacological, and analytical considerations for the novel drug Imeglimin hydrochloride are discussed in this review.

Adaptations to maternal WSD-feeding and metformin use on fetal islets from non-human primate offspring

Given the current increased prevalence of diabetes in pregnancy, the potential relative risks and benefits of oral glycemic agents on the developing offspring should be evaluated and considered. Metformin (Met) is a common oral glycemic agent prescribed in pregnancy that is not metabolized, but is renally excreted and actively transported across the placenta. Thus, the developing fetus is exposed to near equivalent maternal adult doses with subsequent risk of adverse consequences. Using a non-human primate model of maternal overnutrition, our group previously demonstrated that developmental exposure to a Western-style diet (WSD) results in an inappropriate increase in glucose-stimulated insulin secretion and changes in expression of several ion channels involved in insulin secretion in islets from juvenile offspring. Given that maternal overnutrition results in an excess energy supply to the developing fetus while Met inhibits mitochondrial respiration, we hypothesize that maternal WSD-feeding and Met will result in maladaptive beta-cell function in the fetus. Static insulin secretion assays on islets from chow (CD) and WSD +/- Met-exposed offspring show no differences in glucose-stimulated insulin secretion. Nevertheless, islets from a mWSD+Met-exposed fetus showed lower oxygen consumption and extracellular acidification rate relative to mWSD+placebo fetal islets, suggesting that maternal diet influences fetal programming and adaptation to Met in fetal islets. Therefore, we predict that the metabolic response to intrauterine Met exposure differs depending on the maternal diet. Elucidation of the mechanisms mediating adaptations to maternal diet and Met exposure during development may provide insight on interventions to avoid beta-cell failure in the offspring as they age. All nonhuman primate studies were supported in part by the Oregon National Primate Research Center grant P51 OD011092 from the National Institutes of Health/Offce of the Director. D.T.C. was supported by the Vanderbilt University Training Program in Molecular Endocrinology (5T32 DK563-30) and a predoctoral fellowship from the NIH/NIDDK (1F31 DK135164).T.A.D., C.E.M., K.M.A., J.E.F., P.K., and M.G. were supported by NIH/NIDDK Grants R24 DK090964 and R01 DK128187. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Moving from Insulin Substitution to the Treatment of the Underlying Autoimmune Disease in Type 1 Diabetes.

Currently, a paradigm change occurs in type 1 diabetes from insulin substitution to the treatment of the underlying autoimmune disease. Teplizumab, a humanized monoclonal anti-CD3 antibody, is the first FDA-approved disease-modifying treatment of preclinical stage 2 diabetes. Research of drugs like golimumab, a monoclonal antibody specific for TNF alpha, baricitinib, a tyrosine kinase inhibitor, or frexalimab, a monoclonal antibody against the CD40 ligand, is still ongoing. Repurposing drugs that have been used in other indications like the calcium channel blocker verapamil, antithymocyte globulin (ATG), an antibody preparation used in solid organ transplantation, glucagon-like peptide-1 agonists utilized in type 2 diabetes and obesity, or the antiviral drugs pleconaril and ribavirin have shown positive effects in preserving beta-cell function. While new therapies to halt autoimmunity and restore beta cells in stages one to three are being developed, replacing beta-cell function via inducible pluripotent stem cells have shown glucose control and insulin independence in long-standing type 1 diabetes, albeit with concomitant immunosuppression. Multicenter multinational initiatives developing a clinical trial network like INNODIA or a research platform with the goal of stopping type 1 diabetes in its early stages like EDENT1FI will be instrumental to study these new strategies.

Human Pancreatic β Cell Regenerative Therapy: Exploring the Role of Chicoric Acid as a Phytochemical Candidate

Diabetes is a global health issue, impacting life expectancy and productivity. Pathogenesis of diabetes mellitus involves decreased functional beta cells, making beta cell replacement and regeneration a crucial area of research. However, current methods like whole pancreas transplant or stem cell-derived beta cells have limitations for diabetic patients. Exploring pharmacological approaches to stimulate regeneration of residual beta cells is valuable, as many diabetic patients retain some beta cells. Finding drugs that target and regenerate these cells effectively is a challenge, with no approved options available currently. Nature provides several therapeutic agents, and chicoric acid (CA) found in medicinal plants like Cichorium intybus, and shows potential for beta cell regeneration. Cichorium intybus possesses antioxidants, phenolics, and flavonoids, aiding its antidiabetic activity by targeting hyperglycemia, oxidative stress, inflammation, and hyperlipidemia. CA's multifaceted effects on glucose homeostasis are attributed to its involvement in various interconnected processes and pathways. This comprehensive review explores the molecular-level mechanisms through which chicoric acid facilitates beta cell regeneration, insulin release, and glucose uptake. The findings suggest that chicoric acid holds promise as a phytochemical agent for diabetes prevention and treatment. Its natural origin, antidiabetic properties, and multi-dimensional effects make it a potential candidate. Hence, further research to fully elucidate the efficacy and safety of chicoric acid for β cell regeneration as an antidiabetic agent is essential. In summary, this extensive review at the molecular level, concludes that chicoric acid is a phytochemical with great antidiabetic potential and may be indicated both as a preventive and therapeutic agent.

Single-cell transcriptomics reveals a role for pancreatic duct cells as potential mediators of inflammation in diabetes mellitus.

Inflammation of the pancreas contributes to the development of diabetes mellitus. Although it is well-accepted that local inflammation leads to a progressive loss of functional beta cell mass that eventually causes the onset of the disease, the development of islet inflammation remains unclear. Here, we used single-cell RNA sequencing to explore the cell type-specific molecular response of primary human pancreatic cells exposed to an inflammatory environment. We identified a duct subpopulation presenting a unique proinflammatory signature among all pancreatic cell types. Overall, the findings of this study point towards a role for duct cells in the propagation of islet inflammation, and in immune cell recruitment and activation, which are key steps in the pathophysiology of diabetes mellitus.

Pancreatic beta-cell mass and function and therapeutic implications of using antidiabetic medications in type 2 diabetes.

Nowadays, the focus of diabetes treatment has switched from lowering the glucose level to preserving glycemic homeostasis and slowing the disease progression. The main pathophysiology of both type 1 diabetes and long-standing type 2 diabetes is pancreatic β-cell mass loss and dysfunction. According to recent research, human pancreatic β-cells possess the ability to proliferate in response to elevated insulin demands. It has been demonstrated that in insulin-resistant conditions in humans, such as obesity or pregnancy, the β-cell mass increases. This ability could be helpful in developing novel treatment approaches to restore a functional β-cell mass. Treatment strategies aimed at boosting β-cell function and mass may be a useful tool for managing diabetes mellitus and stopping its progression. This review outlines the processes of β-cell failure and detail the many β-cell abnormalities that manifest in people with diabetes mellitus. We also go over standard techniques for determining the mass and function of β-cells. Lastly, we provide the therapeutic implications of utilizing antidiabetic drugs in controlling the mass and function of pancreatic β-cells.

Correlation between TCF7L2 gene expression and certain biochemical parameters in type 2 diabetes mellitus

ObjectivesThe transcription factor 7-like 2 gene (TCF7L2) is associated with a predisposition to type 2 diabetes mellitus (T2DM) in different ethnic populations. This article investigated the relationship between TCF7L2 gene expression and several biochemical indexes among different age categories of T2DM in a sample of the Iraqi population. MethodsOne hundred and fifty blood samples were collected from three groups: young T2DM (10–35 years), old T2DM (40–80 years), and healthy control (10–65 years) groups. Both sexes were enrolled. qPCR was performed to explore the expression of the TCF7L2 gene. Biochemical tests were performed to assess hemoglobin A1C (HbA1c), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels. The body mass index (BMI) was calculated. The results were statistically analyzed. ResultsPatients with T2DM had higher BMI, TG, and LDL, and lower HDL than the control group. There was a strong positive correlation between hemoglobin A1C (HbA1c) and BMI, TG, and LDL and a negative correlation between HbA1c and HDL. Expression of the TCF7L2 gene showed a significant difference between old and young patients by 1.68 and 0.207 fold, respectively. These results showed that old patients had higher gene expression than young patients. ConclusionTCF7L2 gene expression was affected by age, with higher expression in old T2DM patients. This may influence beta cell functions and insulin secretion.

Mixed-Lineage Leukaemia Gene Regulates Glucose-Sensitive Gene Expression and Insulin Secretion in Pancreatic Beta Cells.

The escalating prevalence of diabetes mellitus underscores the need for a comprehensive understanding of pancreatic beta cell function. Interest in glucose effectiveness has prompted the exploration of novel regulatory factors. The myeloid/lymphoid or mixed-lineage leukaemia gene (MLL) is widely recognised for its role in leukemogenesis and nuclear regulatory mechanisms through its histone methyltransferase activity in active chromatin. However, its function within pancreatic endocrine tissues remains elusive. Herein, we unveil a novel role of MLL in glucose metabolism and insulin secretion. MLL knockdown in βHC-9 pancreatic beta cells diminished insulin secretion in response to glucose loading, paralleled by the downregulation of the glucose-sensitive genes SLC2a1 and SLC2a2. Similar observations were made in MLL heterozygous knockout mice (MLL+/-), which exhibited impaired glucose tolerance and reduced insulin secretion without morphological anomalies in pancreatic endocrine cells. The reduction in insulin secretion was independent of changes in beta cell mass or insulin granule morphology, suggesting the regulatory role of MLL in glucose-sensitive gene expression. The current results suggest that MLL interacts with circadian-related complexes to modulate the expression of glucose transporter genes, thereby regulating glucose sensing and insulin secretion. Our findings shed light on insulin secretion control, providing potential avenues for therapeutics against diabetes.

Clinical and Laboratory Characteristics of MODY Cases, Genetic Mutation Spectrum and Phenotype-genotype Relationship

Maturity onset diabetes of the young (MODY) occurs due to mutations in genes involved in pancreatic beta cell function and insulin secretion, has heterogeneous clinical and laboratory features, and account for 1-5% of all diabetes cases. The prevalence and distribution of MODY subtypes vary between countries. The aim of this study was to evaluate the clinical and laboratory characteristics, mutation distribution, and phenotype-genotype relationship in a large case series of pediatric Turkish patients genetically diagnosed with MODY. MODY cases from 14 different pediatric endocrinology departments were included. Diagnosis, treatment, follow-up data, and results of genetic analysis were evaluated. A total of 224 patients were included, of whom 101 (45%) were female, and the mean age at diagnosis was 9.4±4.1 years. Gene variant distribution was: 146 (65%) GCK; 43 (19%) HNF1A; 8 (3.6%) HNF4A, 8 (3.6%) KLF11 and 7 (3.1%) HNF1B. The remaining 12 variants were: PDX (n=1), NEUROD1 (n=3), CEL (n=1), INS (n=3), ABCC8 (n= 3) and KJNC11 (n=1). Of the cases, 197 (87.9%) were diagnosed with incidental hyperglycemia, 16 with ketosis (7%) and 7 (3%) with diabetic ketoacidosis (DKA), while 30% presented with classical symptoms of diabetes. Two-hundred (89%) had a family history of diabetes. Anti-GAD antibody was detected in 13 cases, anti-islet antibody in eight and anti-insulin antibody in four. Obesity was present in 16. Distribution of therapy was: 158 (71%) diet only; 23 (11%) intensive insulin treatment; 17 (7.6%) sulfonylureas; 10 (4.5%) metformin; and 6 (2.7%) insulin and oral anti-diabetic treatment. This was the largest genetically diagnosed series from Turkey. The most common gene variants were GCK and HNF1A with much lower proportions for other MODY types. Hyperglycemia was the most common presenting symptom while 11% of patients had diabetes-associated autoantibodies and 7% were obese. The majority of patients received dietary management only.

Effect of Immunotherapy on C-peptide Levels in Patients With Type I Diabetes Mellitus: A Systematic Review of Randomized Controlled Trials.

Type 1 diabetes mellitus is an autoimmune condition characterized by insulin deficiency resulting from loss of function of beta cells in the pancreas, leading to hyperglycemia and associated long-term systemic complications and even death. Immunotherapy demonstrates beta cell function-preserving potential; however, its impact on C-peptide levels, a definitive biomarker of beta cell function, and endogenous insulin secretion remain unclear. A systematic review of various immunotherapeutic interventions is hence needed for a comprehensive assessment of their effectiveness as well as identifying research gaps and influencing future research and clinical decisions. An extensive literature search was done in PubMed, Scopus, and Cochrane Library databases using precise keywords and filters to identify relevant studies. Three independent reviewers assessed eligibility according to predetermined eligibility criteria, and data was extracted. The Cochrane risk of bias assessment tool (RoB 2.0) was used to evaluate the quality and validity of the included studies. A senior reviewer resolved discrepancies and differences of opinion between independent reviewers. A total of 11 studies were included, with 1464 study participants. Both Phase II and III trials were included. Within the included studies, four studies assessed the anti-CD3 monoclonal antibody otelixizumab as an intervention. Another anti-CD3 monoclonal antibody, teplizumab, was assessed as an intervention in four studies, whereas two studies assessed the anti-CD20 antibody rituximab and one study assessed abatacept as its interventional drug. Otelixizumab demonstrated benefits at higher doses but was associated with adverse effects like Ebstein-Barr virus reactivation and cytomegalovirus infection, while at lower doses it failed to show a significant difference in C-peptide levels or glycosylated hemoglobin (HbA1c). Teplizumab, on the other hand, showed promise in reducing C-peptide loss and exogenous insulin requirements and was associated with adverse events such as rash, lymphopenia, urinary tract infection, and cytokine release syndrome. However, these reactions were only associated with therapy initiation, and they subsided on their own. Rituximab improved C-peptide responses, and abatacept therapy demonstrated reduced loss of C-peptide, improved C-peptide levels, and lowered HbA1c. Teplizumab, rituximab, otelixizumab, and abatacept show potential for preserving beta cell function by reducing C-peptide loss in patients with type I diabetes mellitus. However, careful monitoring of adverse reactions, particularly viral infections and cytokine release syndrome, is necessary for the safe implementation of these therapies.

The metabolome as a diagnostic for maximal aerobic capacity during exercise in type 1 diabetes

Aims/hypothesisOur aim was to characterise the in-depth metabolic response to aerobic exercise and the impact of residual pancreatic beta cell function in type 1 diabetes. We also aimed to use the metabolome to distinguish individuals with type 1 diabetes with reduced maximal aerobic capacity in exercise defined by V˙O2peak\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{V}{\ ext{O}}_{\ ext{2peak}}$$\\end{document}.MethodsThirty participants with type 1 diabetes (≥3 years duration) and 30 control participants were recruited. Groups did not differ in age or sex. After quantification of peak stimulated C-peptide, participants were categorised into those with undetectable (<3 pmol/l), low (3–200 pmol/l) or high (>200 pmol/l) residual beta cell function. Maximal aerobic capacity was assessed by V˙O2peak\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{V}{\ ext{O}}_{\ ext{2peak}}$$\\end{document} test and did not differ between control and type 1 diabetes groups. All participants completed 45 min of incline treadmill walking (60% V˙O2peak\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{V}{\ ext{O}}_{\ ext{2peak}}$$\\end{document}) with venous blood taken prior to exercise, immediately post exercise and after 60 min recovery. Serum was analysed using targeted metabolomics. Metabolomic data were analysed by multivariate statistics to define the metabolic phenotype of exercise in type 1 diabetes. Receiver operating characteristic (ROC) curves were used to identify circulating metabolomic markers of maximal aerobic capacity (V˙O2peak\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{V}{\ ext{O}}_{\ ext{2peak}}$$\\end{document}) during exercise in health and type 1 diabetes.ResultsMaximal aerobic capacity (V˙O2peak\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{V}{\ ext{O}}_{\ ext{2peak}}$$\\end{document}) inversely correlated with HbA1c in the type 1 diabetes group (r2=0.17, p=0.024). Higher resting serum tricarboxylic acid cycle metabolites malic acid (fold change 1.4, p=0.001) and lactate (fold change 1.22, p=1.23×10−5) differentiated people with type 1 diabetes. Higher serum acylcarnitines (AC) (AC C14:1, F value=12.25, p=0.001345; AC C12, F value=11.055, p=0.0018) were unique to the metabolic response to exercise in people with type 1 diabetes. C-peptide status differentially affected metabolic responses in serum ACs during exercise (AC C18:1, leverage 0.066; squared prediction error 3.07). The malic acid/pyruvate ratio in rested serum was diagnostic for maximal aerobic capacity (V˙O2peak\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{V}{\ ext{O}}_{\ ext{2peak}}$$\\end{document}) in people with type 1 diabetes (ROC curve AUC 0.867 [95% CI 0.716, 0.956]).Conclusions/interpretationThe serum metabolome distinguishes high and low maximal aerobic capacity and has diagnostic potential for facilitating personalised medicine approaches to manage aerobic exercise and fitness in type 1 diabetes.Graphical