Role of Glucagon and Its Receptor in the Pathogenesis of Diabetes

Where are we now? Biased signalling of Class B G protein-coupled receptor-targeted therapeutics

Class B G protein-coupled receptors (GPCRs) are a subfamily of 15 peptide hormone receptors with diverse roles in physiological functions and disease pathogenesis. Over the past decade, several novel therapeutics targeting these receptors have been approved for conditions like migraine, diabetes, and obesity, many of which are ground-breaking and first-in-class. Most of these therapeutics are agonist analogues with modified endogenous peptide sequences to enhance receptor activation or stability. Several small molecule and monoclonal antibody antagonists have also been approved or are in late-stage development. Differences in the sequence and structure of these therapeutic ligands lead to distinct signalling profiles, including biased behaviour or inhibition of specific pathways. Understanding this biased pharmacology offers unique development opportunities for improving therapeutic efficacy and reducing adverse effects. This review summarises current knowledge on the ligand bias of approved class B GPCR drugs, highlights strategies to refine and exploit their pharmacological profiles, and discusses key considerations related to receptor structure, localisation, and regulation for developing new therapies.

Baseline glucagon impacts glucose-lowering effects of acarbose but not metformin: A sub-analysis of MARCH study

BACKGROUND

The impact of glucagon on glucose-lowering therapies remains unclear. This study evaluated the effect of baseline glucagon levels on acarbose and metformin efficacy in newly diagnosed type 2 diabetes.

METHODS

A sub-analysis of the MARCH trial was conducted, involving 493 patients randomly assigned to receive either acarbose (300 mg/day) or metformin (1500 mg/day) for 48 weeks. Participants were grouped into low, medium, and high glucagon based on baseline tertiles. The primary outcome was changes in glycated hemoglobin A1c (HbA1c) at 24 and 48 weeks.

RESULTS

Significant reductions in HbA1c were observed in both acarbose and metformin groups at 24 and 48 weeks. In the acarbose group, higher baseline glucagon levels correlated with greater HbA1c reductions at 24 weeks (-1.32 % for high and -1.27 % for medium vs. -0.87 % for low; both P < 0.05) and at 48 weeks (-1.23 % for high and -1.30 % for medium vs. -0.79 % for low; both P < 0.05), while metformin showed consistent glucose-lowering effects across all glucagon subgroups.

CONCLUSION

Higher baseline glucagon significantly enhanced the glucose-lowering efficacy of acarbose but not metformin, suggesting glucagon could guide personalized diabetes treatment.

GC-MS profiling and computational analysis of Balanites aegyptiaca phytoconstituents for antidiabetic activity: insights from network pharmacology and molecular docking

This study investigates the antidiabetic potential of the extracts and subsequent phytochemicals of Balanites aegyptiaca (BA). The approaches used were GC-MS for phytochemical characterization, network pharmacology for target identification, in vitro studies, and computational techniques for the antidiabetic activity. Network pharmacology revealed genes-associated disease targets, i.e., IL-6, PPARα, GCG, and GCK, and their signaling pathways that were modulated by the identified phytocompounds. In vitro assays demonstrated substantial antioxidant activity of n-hexane and ethyl acetate extracts and were found to be comparable to ascorbic acid. The anti-inflammatory potential using the egg albumin method was found to be best for n-hexane extract in comparison to aspirin. The in vitro antidiabetic activity using α-amylase inhibition method was most pronounced in the methanol extract and was found to be comparable to acarbose. Molecular docking and molecular dynamics simulations (100 ns) identified stable interactions between BA-derived compounds and target proteins. In silico pharmacokinetic investigations revealed that the heptadecanoic acid and ragaglitazar exhibited the LD50 of 900 and 1600 mg/kg, vouching for the substantial safety. Molecular dynamics simulations confirmed the greater stability of protein-ligand complexes and also inferred about the possible ligand-protein interactions. The BA phytocompounds inherit huge potential in the management of diabetes, with promising antioxidant, anti-inflammatory, and antidiabetic effects.

Pentraxin-3 as a Biomarker in Diabetes Mellitus: Insights into Inflammation, Vascular Complications, and Modulation by Antidiabetic Medications

Diabetes mellitus (DM) is a multifactorial metabolic disorder associated with systemic inflammation and vascular complications. Pentraxin-3 (PTX3) has emerged as a key biomarker of inflammation and endothelial dysfunction in DM. We aimed to examine the role of PTX3 in DM and assesses the impact of pharmacological interventions on its expression. The review included studies analyzing PTX3 modulation by antidiabetic therapies, such as sodium-glucose cotransporter-2 inhibitors (SGLT-2i), glucagon-like peptide-1 agonists (GLP-1a), and dipeptidyl peptidase-4 inhibitors (DPP-4i), as well as the effects of lifestyle interventions. Clinical and experimental studies demonstrated a strong correlation between PTX3 levels and DM progression. Elevated PTX3 levels were associated with diabetic complications, including nephropathy, retinopathy, and cardiovascular diseases. Antidiabetic drugs showed differential effects on PTX3 expression, with GLP-1a and DPP-4i significantly reducing PTX3 levels, while SGLT-2i displayed a paradoxical increase. Lifestyle interventions, including dietary modifications and weight loss, yielded inconsistent effects, suggesting genetic and metabolic factors influence PTX3 regulation. While pharmacological therapies, particularly GLP-1a and DPP-4i, demonstrate anti-inflammatory effects, further research is needed to standardize PTX3 measurement and explore its potential as a therapeutic target. Personalized treatment strategies incorporating genetic profiling may optimize inflammation control and disease management in DM patients.

GPCR drug discovery: new agents, targets and indications

G protein-coupled receptors (GPCRs) form one of the largest drug target families, reflecting their involvement in numerous pathophysiological processes. In this Review, we analyse drug discovery trends for the GPCR superfamily, covering compounds, targets and indications that have reached regulatory approval or that are being investigated in clinical trials. We find that there are 516 approved drugs targeting GPCRs, making up 36% of all approved drugs. These drugs act on 121 GPCR targets, one-third of all non-sensory GPCRs. Furthermore, 337 agents targeting 133 GPCRs, including 30 novel targets, are being investigated in clinical trials. Notably, 165 of these agents are approved drugs being tested for additional indications and novel agents are increasingly allosteric modulators and biologics. Remarkably, diabetes and obesity drugs targeting GPCRs had sales of nearly US $30 billion in 2023 and the numbers of clinical trials for GPCR modulators in the metabolic diseases, oncology and immunology areas are increasing strongly. Finally, we highlight the potential of untapped target-disease associations and pathway-biased signalling. Overall, this Review provides an up-to-date reference for the drugged and potentially druggable GPCRome to inform future GPCR drug discovery and development.

Pancreatic endocrine and exocrine signaling and crosstalk in physiological and pathological status

The pancreas, an organ with dual functions, regulates blood glucose levels through the endocrine system by secreting hormones such as insulin and glucagon. It also aids digestion through the exocrine system by secreting digestive enzymes. Complex interactions and signaling mechanisms between the endocrine and exocrine functions of the pancreas play a crucial role in maintaining metabolic homeostasis and overall health. Compelling evidence indicates direct and indirect crosstalk between the endocrine and exocrine parts, influencing the development of diseases affecting both. From a developmental perspective, the exocrine and endocrine parts share the same origin-the "tip-trunk" domain. In certain circumstances, pancreatic exocrine cells may transdifferentiate into endocrine-like cells, such as insulin-secreting cells. Additionally, several pancreatic diseases, including pancreatic cancer, pancreatitis, and diabetes, exhibit potential relevance to both endocrine and exocrine functions. Endocrine cells may communicate with exocrine cells directly through cytokines or indirectly by regulating the immune microenvironment. This crosstalk affects the onset and progression of these diseases. This review summarizes the history and milestones of findings related to the exocrine and endocrine pancreas, their embryonic development, phenotypic transformations, signaling roles in health and disease, the endocrine-exocrine crosstalk from the perspective of diseases, and potential therapeutic targets. Elucidating the regulatory mechanisms of pancreatic endocrine and exocrine signaling and provide novel insights for the understanding and treatment of diseases.

Changes in immunofluorescence staining during islet regeneration in a cystic fibrosis-related diabetes (CFRD) ferret model

BACKGROUND

Knockout (KO) ferrets with the cystic fibrosis transmembrane conductance regulator (CFTR) exhibit distinct phases of dysglycemia and pancreatic remodeling prior to cystic fibrosis-related diabetes (CFRD) development. Following normoglycemia during the first month of life (Phase l), hyperglycemia occurs during the subsequent 2 months (Phase Il) with decreased islet mass, followed by a period of near normoglycemia (Phase Ill) in which the islets regenerate. We aimed to characterize islet hormone expression patterns across these Phases.

METHODS

Immunofluorescence staining per islet area was performed to characterize islet hormone expression patterns in age matched CFTR KO and wild type (WT) ferrets, focusing on the first three phases.

RESULTS

In Phase I, insulin staining intensity was higher in CF (p < 0.01) than WT but decreased in Phase III (p < 0.0001). Glucagon was lower in CF during Phases I and increased in Phase III, while proinsulin decreased (p < 0.0001) Phases II and III. CF sections showed lower proinsulin-to-insulin ratio in Phase I (p < 0.01) and in Phase III (p < 0.05) compared to WT. Conversely, glucagon-to-insulin ratio was lower in CF in Phase I (p < 0.0001) but increased in Phase III (p < 0.0001). Mender's coefficient overlap showed higher overlap of insulin over proinsulin in CF sections in Phase II (p < 0.001) and Phase III (p < 0.0001) compared to WT. Mender's coefficient rate was higher in CF sections during Phase II (p < 0.001).

CONCLUSION

CF ferret islets revealed significant immunofluorescent staining changes compared to WT during various phases of disease, providing insights into CRFD pathophysiology.

Captopril inhibits the overproduction of proopiomelanocortin and adrenocorticotropic hormone in the pituitary gland of male diabetic mice in close relationship with an increase in glucocorticoid receptor expression

Prior investigation shows that diabetic patients present hypothalamus-pituitary-adrenal (HPA) axis hyperactivity related to impaired negative feedback. This study investigates the effect of Captopril on the overproduction of adrenocorticotropic hormone (ACTH) and its precursor proopiomelanocortin (POMC) in the pituitary gland of male diabetic mice. Diabetes was induced by intravenous injection of alloxan into fasted Swiss-webster mice, and the animals were treated with Captopril for 14 consecutive days, starting 7 days post-diabetes induction. Plasma corticosterone levels were evaluated by ELISA, while pituitary gland expressions of angiotensin-II type 1 receptor (AT1), angiotensin-II type 2 receptor (AT2), ACTH, Bax, Bcl-2, KI-67, POMC, and glucocorticoid receptor (GR) were evaluated using immunohistochemistry or Western blot. Diabetic mice showed pituitary gland overexpression of AT1, without altering AT2 levels, which were sensitive to Captopril treatment. Furthermore, diabetic mice presented hypercortisolism, along with an increase in the number of corticotroph cells, POMC and ACTH expression, and number of proliferative cells, and a decrease of GR expression in the pituitary gland. In addition, treatment with Captopril reduced systemic corticosterone levels, corticotroph and proliferative cell numbers, and Bcl-2, POMC, and ACTH expression in the pituitary gland of diabetic mice, besides increasing the expression of Bax and GR. In conclusion, these findings show that Captopril is a promising therapy for treating complications associated with HPA axis hyperactivity in diabetic patients, in a mechanism probably related to the downregulation of POMC production in the pituitary gland and subsequent reduction of systemic corticosterone levels.

Interruption of glucagon signaling augments islet non-alpha cell proliferation in SLC7A2- and mTOR-dependent manners

OBJECTIVE

Dysregulated glucagon secretion and inadequate functional beta cell mass are hallmark features of diabetes. While glucagon receptor (GCGR) antagonism ameliorates hyperglycemia and elicits beta cell regeneration in pre-clinical models of diabetes, it also promotes alpha and delta cell hyperplasia. We sought to investigate the mechanism by which loss of glucagon action impacts pancreatic islet non-alpha cells, and the relevance of these observations in a human islet context.

METHODS

We used zebrafish, rodents, and transplanted human islets comprising six different models of interrupted glucagon signaling to examine their impact on delta and beta cell proliferation and mass. We also used models with global deficiency of the cationic amino acid transporter, SLC7A2, and mTORC1 inhibition via rapamycin, to determine whether amino acid-dependent nutrient sensing was required for islet non-alpha cell growth.

RESULTS

Inhibition of glucagon signaling stimulated delta cell proliferation in mouse and transplanted human islets, and in mouse islets. This was rapamycin-sensitive and required SLC7A2. Likewise, gcgr deficiency augmented beta cell proliferation via SLC7A2- and mTORC1-dependent mechanisms in zebrafish and promoted cell cycle engagement in rodent beta cells but was insufficient to drive a significant increase in beta cell mass in mice.

CONCLUSIONS

Our findings demonstrate that interruption of glucagon signaling augments islet non-alpha cell proliferation in zebrafish, rodents, and transplanted human islets in a manner requiring SLC7A2 and mTORC1 activation. An increase in delta cell mass may be leveraged for future beta cell regeneration therapies relying upon delta cell reprogramming.

Stapled peptides as potential therapeutics for diabetes and other metabolic diseases

The field of peptide drug research has experienced notable progress, with stapled peptides featuring stabilized α-helical conformation, emerging as a promising field. These peptides offer enhanced stability, cellular permeability, and binding affinity and exhibit potential in the treatment of diabetes and metabolic disorders. Stapled peptides, through the disruption of protein-protein interactions, present varied functionalities encompassing agonism, antagonism, and dual-agonism. This comprehensive review offers insight into the technology of peptide stapling and targeting of crucial molecular pathways associated with glucose metabolism, insulin secretion, and food intake. Additionally, we address the challenges in developing stapled peptides, including concerns pertaining to structural stability, peptide helicity, isomer mixture, and potential side effects.

Research advances in understanding crosstalk between organs and pancreatic β-cell dysfunction

Obesity has increased dramatically worldwide. Being overweight or obese can lead to various conditions, including dyslipidaemia, hypertension, glucose intolerance and metabolic syndrome (MetS), which may further lead to type 2 diabetes mellitus (T2DM). Previous studies have identified a link between β-cell dysfunction and the severity of MetS, with multiple organs and tissues affected. Identifying the associations between pancreatic β-cell dysfunction and organs is critical. Research has focused on the interaction between the liver, gut and pancreatic β-cells. However, the mechanisms and related core targets are still not perfectly elucidated. The aims of this review were to summarize the mechanisms of β-cell dysfunction and to explore the potential pathogenic pathways and targets that connect the liver, gut, adipose tissue, muscle, and brain to pancreatic β-cell dysfunction.

Insights into the structure and activation mechanism of some class B1 GPCR family members

In humans, 15 genes encode the class B1 family of GPCRs, which are polypeptide hormone receptors characterized by having a large N-terminal extracellular domain (ECD) and receive signals from outside the cell to activate cellular response. For example, the insulinotropic polypeptide (GIP) stimulates the glucose-dependent insulinotropic polypeptide receptor (GIPR), while the glucagon receptor (GCGR) responds to glucagon by increasing blood glucose levels and promoting the breakdown of liver glycogen to induce the production of insulin. The glucagon-like peptides 1 and 2 (GLP-1 and GLP-2) elicit a response from glucagon-like peptide receptor types 1 and 2 (GLP1R and GLP2R), respectively. Since these receptors are implicated in the pathogenesis of diabetes, studying their activation is crucial for the development of effective therapies for the condition. With more structural information being revealed by experimental methods such as X-ray crystallography, cryo-EM, and NMR, the activation mechanism of class B1 GPCRs becomes unraveled. The available crystal and cryo-EM structures reveal that class B1 GPCRs follow a two-step model for peptide binding and receptor activation. The regions close to the C-termini of hormones interact with the N-terminal ECD of the receptor while the regions close to the N-terminus of the peptide interact with the TM domain and transmit signals. This review highlights the structural details of class B1 GPCRs and their conformational changes following activation. The roles of MD simulation in characterizing those conformational changes are briefly discussed, providing insights into the potential structural exploration for future ligand designs.

Non-functional alpha-cell hyperplasia with glucagon-producing NET: a case report

Introduction

Alpha-cell hyperplasia (ACH) is a rare pancreatic endocrine condition. Three types of ACH have been described: functional or nonglucagonoma hyperglucagonemic glucagonoma syndrome, reactive or secondary to defective glucagon signaling, and non-functional. Few cases of ACH with concomitant pancreatic neuroendocrine tumors (pNETs) have been reported and its etiology remains poorly understood. A case report of non-functional ACH with glucagon-producing NET is herein presented.

Case report

A 72-year-old male was referred to our institution for a 2 cm single pNET incidentally found during imaging for acute cholecystitis. The patient's past medical history included type 2 diabetes (T2D) diagnosed 12 years earlier, for which he was prescribed metformin, dapagliflozin, and semaglutide. The pNET was clinically and biochemically non-functioning, apart from mildly elevated glucagon 217 pg/ml (<209), and 68Ga-SSTR PET/CT positive uptake was only found at the pancreatic tail (SUVmax 11.45). The patient underwent a caudal pancreatectomy and the post-operative 68Ga-SSTR PET/CT was negative. A multifocal well-differentiated NET G1, pT1N0M0R0 (mf) strongly staining for glucagon on a background neuroendocrine alpha-cell hyperplasia with some degree of acinar fibrosis was identified on pathology analysis.

Discussion and conclusion

This case reports the incidental finding of a clinically non-functioning pNET in a patient with T2D and elevated glucagon levels, unexpectedly diagnosed as glucagon-producing NET and ACH. A high level of suspicion was required to conduct the glucagon immunostaining, which is not part of the pathology routine for a clinically non-functioning pNET, and was key for the diagnosis that otherwise would have been missed. This case highlights the need to consider the diagnosis of glucagon-producing pNET on an ACH background even in the absence of glucagonoma syndrome.

Interruption of glucagon signaling augments islet non-alpha cell proliferation in SLC7A2- and mTOR-dependent manners

Objective

Dysregulated glucagon secretion and inadequate functional beta cell mass are hallmark features of diabetes. While glucagon receptor (GCGR) antagonism ameliorates hyperglycemia and elicits beta cell regeneration in pre-clinical models of diabetes, it also promotes alpha and delta cell hyperplasia. We sought to investigate the mechanism by which loss of glucagon action impacts pancreatic islet non-alpha cells, and the relevance of these observations in a human islet context.

Methods

We used zebrafish, rodents, and transplanted human islets comprising six different models of interrupted glucagon signaling to examine their impact on delta and beta cell proliferation and mass. We also used models with global deficiency of the cationic amino acid transporter, SLC7A2, and mTORC1 inhibition via rapamycin, to determine whether amino acid-dependent nutrient sensing was required for islet non-alpha cell growth.

Results

Inhibition of glucagon signaling stimulated delta cell proliferation in mouse and transplanted human islets, and in mouse islets. This was rapamycin-sensitive and required SLC7A2. Likewise, gcgr deficiency augmented beta cell proliferation via SLC7A2- and mTORC1-dependent mechanisms in zebrafish and promoted cell cycle engagement in rodent beta cells but was insufficient to drive a significant increase in beta cell mass in mice.

Conclusion

Our findings demonstrate that interruption of glucagon signaling augments islet non-alpha cell proliferation in zebrafish, rodents, and transplanted human islets in a manner requiring SLC7A2 and mTORC1 activation. An increase in delta cell mass may be leveraged for future beta cell regeneration therapies relying upon delta cell reprogramming.

Receptors and Signaling Pathways Controlling Beta-Cell Function and Survival as Targets for Anti-Diabetic Therapeutic Strategies

Preserving the function and survival of pancreatic beta-cells, in order to achieve long-term glycemic control and prevent complications, is an essential feature for an innovative drug to have clinical value in the treatment of diabetes. Innovative research is developing therapeutic strategies to prevent pathogenic mechanisms and protect beta-cells from the deleterious effects of inflammation and/or chronic hyperglycemia over time. A better understanding of receptors and signaling pathways, and of how they interact with each other in beta-cells, remains crucial and is a prerequisite for any strategy to develop therapeutic tools aimed at modulating beta-cell function and/or mass. Here, we present a comprehensive review of our knowledge on membrane and intracellular receptors and signaling pathways as targets of interest to protect beta-cells from dysfunction and apoptotic death, which opens or could open the way to the development of innovative therapies for diabetes.

Stilbenoids from fenugreek seeds alleviate insulin resistance by regulating the PI3K/AKT/mTOR signaling pathway in a type 2 diabetes zebrafish model

Insulin resistance (IR) is the main cause of type 2 diabetes mellitus (T2DM). The specific targets and underlying mechanisms responsible for the ameliorative effects of the stilbenoid compounds found in fenugreek seeds for ameliorating IR require further study. Here, we were predicted by using the network pharmacology prediction, molecular docking and molecular dynamics simulation approach the targets in common and the potential mechanismsof three stilbenoid compounds (rhaponticin, desoxyrhaponticin, and rhapontigenin) in relation to T2DM and IR. The results showed that the compounds may improve IR through the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway. Molecular docking studies revealed that they exhibit high binding affinity with the structural domains of peroxisome proliferator-activated receptor gamma (PPARG), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), PI3K, and AKT. These results suggest that PPARG and GAPDH may be the potential targets for these three compounds in the treatment of T2DM.Subsequently, experiments using the zebrafish T2DM model showed that the stilbenoid compounds had varying degrees of efficacy in improving IR through the PI3K/AKT/mTOR signaling pathway, and rhaponticin had the most promising effects. The findings implicate a potential mechanism of action for the three stilbenoid compounds in enhancing insulin resistance (IR) through modulation of the PI3K/AKT/mTOR pathway.

Tyrosine nitration of glucagon impairs its function: Extending the role of heme in T2D pathogenesis

New studies raise the possibility that the higher glucagon (GCG) level present in type 2 diabetes (T2D) is a compensatory mechanism to enhance β-cell function, rather than induce dysregulated glucose homeostasis, due to an important role for GCG that acts directly within the pancreas on insulin secretion by intra-islet GCG signaling. However, in states of poorly controlled T2D, pancreatic α cell mass increases (overproduced GCG) in response to insufficient insulin secretion, indicating decreased local GCG activity. The reason for this decrease is not clear. Recent evidence has uncovered a new role of heme in cellular signal transduction, and its mechanism involves reversible binding of heme to proteins. Considering that protein tyrosine nitration in diabetic islets increases and glucose-stimulated insulin secretion (GSIS) decreases, we speculated that heme modulates GSIS by transient interaction with GCG and catalyzing its tyrosine nitration, and the tyrosine nitration may impair GCG activity, leading to loss of intra-islet GCG signaling and markedly impaired insulin secretion. Data presented here elucidate a novel role for heme in disrupting local GCG signaling in diabetes. Heme bound to GCG and induced GCG tyrosine nitration. Two tyrosine residues in GCG were both sensitive to the nitrating species. Further, GCG was also demonstrated to be a preferred target peptide for tyrosine nitration by co-incubation with BSA. Tyrosine nitration impaired GCG stimulated cAMP-dependent signaling in islet β cells and decreased insulin release. Our results provided a new role of heme for impaired GSIS in the pathological process of diabetes.

From classical dualistic antagonism to hormone synergy: potential of overlapping action of glucagon, insulin and GLP-1 for the treatment of diabesity

The increasing prevalence of 'diabesity', a combination of type 2 diabetes and obesity, poses a significant global health challenge. Unhealthy lifestyle factors, including poor diet, sedentary behaviour, and high stress levels, combined with genetic and epigenetic factors, contribute to the diabesity epidemic. Diabesity leads to various significant complications such as cardiovascular diseases, stroke, and certain cancers. Incretin-based therapies, such as GLP-1 receptor agonists and dual hormone therapies, have shown promising results in improving glycaemic control and inducing weight loss. However, these therapies also come with certain disadvantages, including potential withdrawal effects. This review aims to provide insights into the cross-interactions of insulin, glucagon, and GLP-1, revealing the complex hormonal dynamics during fasting and postprandial states, impacting glucose homeostasis, energy expenditure, and other metabolic functions. Understanding these hormonal interactions may offer novel hypotheses in the development of 'anti-diabesity' treatment strategies. The article also explores the question of the antagonism of insulin and glucagon, providing insights into the potential synergy and hormonal overlaps between these hormones.

Insulin:Glucagon Bipolar Axis in Obesity With a Glimpse Into Its Association With Insulin Resistance in Different Glucose Tolerance States

BACKGROUND

Dysregulation of insulin and glucagon secretion alters the normal insulin:glucagon ratio (IGR) in type 2 diabetes mellitus, obesity, and metabolic syndrome. This study explores the scope of construing the role of these two diametrically opposing hormones on the glucose level not just in obesity but in different glucose tolerance states by looking at the hormone levels and at the insulin glucagon bipolar axis itself.

MATERIALS AND METHODS

This is an analytical cross-sectional study of 60 healthy adults consisting of an equal number of adults who are lean and adults who are obese. It was conducted at North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences (NEIGRIHMS), located in Shillong City, Meghalaya, India. Fasting glucose, insulin, glucagon, and lipids were estimated. Postprandial estimation of glucose was done two hours after oral administration of 75 grams of glucose solution.

RESULT

The study demonstrated a state of hyperinsulinemia and hyperglucagonemia prevailing in obesity and all sub-categories of the group of persons who are obese. The study showed a higher fasting IGR in the group consisting of adults who were obese (with a mean of 4.11) when compared with the group of adults who are lean (with a mean of 2.24). Fasting IGR was seen to increase with increasing levels of insulin resistance and increasing impairment in glucose tolerance. IGR showed a positive correlation with the homeostatic model assessment for insulin resistance (HOMA-IR) in the impaired fasting glucose (IFG) category and strongly in the impaired glucose tolerance (IGT) category.

CONCLUSION

Hyperglucagonemia in the group of adult persons who are obese indicates a decreased sensitivity of alpha cells to insulin failing insulin to adequately suppress the secretion of glucagon. The study also demonstrated a positive correlation between IGR and HOMA-IR in obesity and all glucose tolerance states of the group of adults who are obese. It is telltale that the sturdier the insulin resistance, the higher the IGR.

Insulin therapy among diabetic patients in rural communities of Sub-Saharan Africa: a perspective review

In this perspective review, we describe a brief background on the status quo of diabetes mellitus-related therapies and glycemic control among patients in rural communities in sub-Saharan Africa. The article discusses insulin therapy as well as the difficulties in obtaining insulin and oral hypoglycemic medications for diabetic patients living in sub-Saharan Africa. We wrap up our discussion with suggestions on solutions and opportunities for future research to tackle this health challenge in these impoverished communities. We conducted a literature search from PubMed and Google Scholar up until August 2023. Key words were used to generate search terms used to retrieve the required information. All types of literature with pertinent information on the current topic were included in the study. Diabetes mellitus is on the rise in sub-Saharan Africa. Several studies have reported poor glycemic control, low screening rates for diabetes mellitus, cigarette smoking, high alcohol consumption, prescription of antidiabetic therapy, and associated costs as contributors to the uptake of antidiabetic treatment. Although there is paucity of data on the extent of insulin therapy uptake and its possible modifiable contributors among the diabetic patients in the region, the anticipated increase in the number of people with diabetes on the continent makes it critical for global leaders to address the research gaps in insulin therapy among rural communities of sub-Saharan Africa, thus reducing the burden of diabetes in these populations.

An orally available compound suppresses glucagon hypersecretion and normalizes hyperglycemia in type 1 diabetes

Suppression of glucagon hypersecretion can normalize hyperglycemia during type 1 diabetes (T1D). Activating erythropoietin-producing human hepatocellular receptor type-A4 (EphA4) on α cells reduced glucagon hypersecretion from dispersed α cells and T1D islets from both human donor and mouse models. We synthesized a high-affinity small molecule agonist for the EphA4 receptor, WCDD301, which showed robust plasma and liver microsome metabolic stability in both mouse and human preparations. In islets and dispersed islet cells from nondiabetic and T1D human donors, WCDD301 reduced glucagon secretion comparable to the natural EphA4 ligand, Ephrin-A5. In diabetic NOD and streptozotocin-treated mice, once-daily oral administration of WCDD301 formulated with a time-release excipient reduced plasma glucagon and normalized blood glucose for more than 3 months. These results suggest that targeting the α cell EphA4 receptor by sustained release of WCDD301 is a promising pharmacologic pathway for normalizing hyperglycemia in patients with T1D.

Pharmacological inhibitors of β-cell dysfunction and death as therapeutics for diabetes

More than 500 million adults suffer from diabetes worldwide, and this number is constantly increasing. Diabetes causes 5 million deaths per year and huge healthcare costs per year. β-cell death is the major cause of type 1 diabetes. β-cell secretory dysfunction plays a key role in the development of type 2 diabetes. A loss of β-cell mass due to apoptotic death has also been proposed as critical for the pathogenesis of type 2 diabetes. Death of β-cells is caused by multiple factors including pro-inflammatory cytokines, chronic hyperglycemia (glucotoxicity), certain fatty acids at high concentrations (lipotoxicity), reactive oxygen species, endoplasmic reticulum stress, and islet amyloid deposits. Unfortunately, none of the currently available antidiabetic drugs favor the maintenance of endogenous β-cell functional mass, indicating an unmet medical need. Here, we comprehensively review over the last ten years the investigation and identification of molecules of pharmacological interest for protecting β-cells against dysfunction and apoptotic death which could pave the way for the development of innovative therapies for diabetes.