Decreased expression of hepatic glucokinase in type 2 diabetes

The neglected PCK1/glucagon (inter)action in nutrient homeostasis beyond gluconeogenesis: Disease pathogenesis and treatment

BACKGROUND

Glucagon plays a central role in hepatic adaptation during fasting, with the upregulation of hepatic phosphoenolpyruvate carboxykinase 1 (PCK1) traditionally associated with increased gluconeogenesis. However, recent experimental models and clinical studies have challenged this view, suggesting a more complex interplay between PCK1 and glucagon, which extends beyond gluconeogenesis and has broader implications for metabolic regulation in health and disease.

SCOPE OF REVIEW

This review provides a comprehensive overview of the current evidence on the multifaceted roles of PCK1 in glucagon-dependent hepatic adaptation during fasting, which is crucial for maintaining systemic homeostasis not only of glucose, but also of lipids and amino acids. We explore the relationship between PCK1 deficiency and glucagon resistance in metabolic disorders, including inherited PCK1 deficiency and metabolic dysfunction-associated steatotic liver disease (MASLD), and compare findings from experimental animal models with whole-body or tissue-specific ablation of PCK1 or the glucagon receptor. We propose new research platforms to advance the therapeutic potential of targeting PCK1 in metabolic diseases.

MAJOR CONCLUSIONS

We propose that hepatic PCK1 deficiency might be an acquired metabolic disorder linking alterations in lipid metabolism with impaired glucagon signaling. Our findings highlight interesting links between glycerol, PCK1 deficiency, elevated plasma alanine levels and glucagon resistance. We conclude that the roles of PCK1 and glucagon in metabolic regulation are more complex than previously assumed. In this (un)expected scenario, hepatic PCK1 deficiency and glucagon resistance appear to exert limited control over glycemia, but have broader metabolic effects related to lipid and amino acid dysregulation. Given the shift in glucagon research from receptor inhibition to activation, we propose that a similar paradigm shift is needed in the study of hepatic PCK1. Understanding PCK1 expression and activity in the glucagon-dependent hepatic adaptation to fasting might provide new perspectives and therapeutic opportunities for metabolic diseases.

Modern Challenges in Type 2 Diabetes: Balancing New Medications with Multifactorial Care

Type 2 diabetes mellitus (T2DM) is a prevalent chronic metabolic disorder characterized by insulin resistance and progressive beta cell dysfunction, presenting substantial global health and economic challenges. This review explores recent advancements in diabetes management, emphasizing novel pharmacological therapies and their physiological mechanisms. We highlight the transformative impact of Sodium-Glucose Cotransporter 2 inhibitor (SGLT2i) and Glucagon-Like Peptide 1 Receptor Agonist (GLP-1RA), which target specific physiological pathways to enhance glucose regulation and metabolic health. A key focus of this review is tirzepatide, a dual agonist of the glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptors. Tirzepatide illustrates how integrating innovative mechanisms with established physiological pathways can significantly improve glycemic control and support weight management. Additionally, we explore emerging treatments such as glimins and glucokinase activators (GKAs), which offer novel strategies for enhancing insulin secretion and reducing glucose production. We also address future perspectives in diabetes management, including the potential of retatrutide as a triple receptor agonist and evolving guidelines advocating for a comprehensive, multifactorial approach to care. This approach integrates pharmacological advancements with essential lifestyle modifications-such as dietary changes, physical activity, and smoking cessation-to optimize patient outcomes. By focusing on the physiological mechanisms of these new therapies, this review underscores their role in enhancing T2DM management and highlights the importance of personalized care plans to address the complexities of the disease. This holistic perspective aims to improve patient quality of life and long-term health outcomes.

The role of adipose tissue dysfunction in hepatic insulin resistance and T2D

The root cause of type 2 diabetes (T2D) is insulin resistance (IR), defined by the failure of cells to respond to circulating insulin to maintain lipid and glucose homeostasis. While the causes of whole-body insulin resistance are multifactorial, a major contributing factor is dysregulation of liver and adipose tissue function. Adipose dysfunction, particularly adipose tissue-IR (adipo-IR), plays a crucial role in the development of hepatic insulin resistance and the progression of metabolic dysfunction-associated steatotic liver disease (MASLD) in the context of T2D. In this review, we will focus on molecular mechanisms of hepatic insulin resistance and its association with adipose tissue function. A deeper understanding of the pathophysiological mechanisms of the transition from a healthy state to insulin resistance, impaired glucose tolerance, and T2D may enable us to prevent and intervene in the progression to T2D.

Research into how carvacrol and metformin affect several human proteins in a hyperglycemic condition: A comparative study in silico and in vitro

Carvacrol (CV) is an organic compound found in the essential oils of many aromatic herbs. It is nearly unfeasible to analyze all the current human proteins for a query ligand using in vitro and in vivo methods. This study aimed to clarify whether CV possesses an anti-diabetic feature via Docking-based inverse docking and molecular dynamic (MD) simulation and in vitro characterization against a set of novel human protein targets. Herein, the best poses of CV docking simulations according to binding energy ranged from -7.9 to -3.5 (kcal/mol). After pathway analysis of the protein list through GeneMANIA and WebGestalt, eight interacting proteins (DPP4, FBP1, GCK, HSD11β1, INSR, PYGL, PPARA, and PPARG) with CV were determined, and these proteins exhibited stable structures during the MD process with CV. In vitro application, statistically significant results were achieved only in combined doses with CV or metformin. Considering all these findings, PPARG and INSR, among these target proteins of CV, are FDA-approved targets for treating diabetes. Therefore, CV may be on its way to becoming a promising therapeutic compound for treating Diabetes Mellitus (DM). Our outcomes expose formerly unexplored potential target human proteins, whose association with diabetic disorders might guide new potential treatments for DM.

Novel Therapeutics for Type 2 Diabetes Mellitus-A Look at the Past Decade and a Glimpse into the Future

Cardiovascular disease (CVD) and kidney disease are the main causes of morbidity and mortality in type 2 diabetes mellitus (T2DM). Globally, the incidence of T2DM continues to rise. A substantial increase in the burden of CVD and renal disease, alongside the socioeconomic implications, would be anticipated. Adopting a purely glucose-centric approach focusing only on glycemic targets is no longer adequate to mitigate the cardiovascular risks in T2DM. In the past decade, significant advancement has been achieved in expanding the pharmaceutical options for T2DM, with novel agents such as the sodium-glucose cotransporter type 2 (SGLT2) inhibitors and glucagon-like peptide receptor agonists (GLP-1 RAs) demonstrating robust evidence in cardiorenal protection. Combinatorial approaches comprising multiple pharmacotherapies combined in a single agent are an emerging and promising way to not only enhance patient adherence and improve glycemic control but also to achieve the potential synergistic effects for greater cardiorenal protection. In this review, we provide an update on the novel antidiabetic agents in the past decade, with an appraisal of the mechanisms contributing to cardiorenal protection. Additionally, we offer a glimpse into the landscape of T2DM management in the near future by providing a comprehensive summary of upcoming agents in early-phase trials.

Clinical investigation of glucokinase activators for the restoration of glucose homeostasis in diabetes

As a sensor, glucokinase (GK) controls glucose homeostasis, which progressively declines in patients with diabetes. GK maintains the equilibrium of glucose levels and regulates the homeostatic system set points. Endocrine and hepatic cells can both respond to glucose cooperatively when GK is activated. GK has been under study as a therapeutic target for decades due to the possibility that cellular GK expression and function can be recovered, hence restoring glucose homeostasis in patients with type 2 diabetes. Five therapeutic compounds targeting GK are being investigated globally at the moment. They all have distinctive molecular structures and have been clinically shown to have strong antihyperglycemia effects. The mechanics, classification, and clinical development of GK activators are illustrated in this review. With the recent approval and marketing of the first GK activator (GKA), dorzagliatin, GKA's critical role in treating glucose homeostasis disorder and its long-term benefits in diabetes will eventually become clear.

Should Glucokinase be Given a Chance in Diabetes Therapeutics? A Clinical-Pharmacological Review of Dorzagliatin and Lessons Learned So Far

Despite advances in the management of type 2 diabetes mellitus (T2DM), one-third of patients with diabetes do not achieve the desired glycemic goal. Considering this inadequacy, many agents that activate glucokinase have been investigated over the last two decades but were withdrawn before submission for marketing permission. Dorzagliatin is the first glucokinase activator that has been granted approval for T2DM, only in China. As overstimulation of glucokinase is linked with pathophysiological disturbances such as fatty liver and cardiovascular issues and a loss of therapeutic efficacy with time. This review aims to highlight the benefits of glucokinase activators vis-à-vis the risks associated with chronic enzymatic activation. We discuss the multisystem disturbances expected with chronic activation of the enzyme, the lessons learned with glucokinase activators of the past, the major efficacy and safety findings with dorzagliatin and its pharmacological properties, and the status of other glucokinase activators in the pipeline. The approval of dorzagliatin in China was based on the SEED and the DAWN trials, the major pivotal phase III trials that enrolled patients with T2DM with a mean glycosylated hemoglobin of 8.3-8.4%, and a mean age of 53-54.5 years from multiple sites in China. Patients with uncontrolled diabetes, cardiac diseases, organ dysfunction, and a history of severe hypoglycemia were excluded. Both trials had a randomized double-blind placebo-controlled phase of 24 weeks followed by an open-label phase of 28 weeks with dorzagliatin. Drug-naïve patients with T2DM with a disease duration of 11.7 months were enrolled in the SEED trial while the DAWN trial involved patients with T2DM with a mean duration of 71.5 months and receiving background metformin therapy. Compared with placebo, the decline in glycosylated hemoglobin at 24 weeks was more with dorzagliatin with an estimated treatment difference of - 0.57% in the SEED trial and - 0.66% in the DAWN trial. The desired glycosylated hemoglobin (< 7%) was also attained at more than two times higher rates with dorzagliatin. The glycemic improvement was sustained in the SEED trial but decreased over 52 weeks in the DAWN trial. Hyperlipidemia was observed in 12-14% of patients taking dorzagliatin versus 9-11% of patients receiving a placebo. Additional adverse effects noticed over 52 weeks with dorzagliatin included an elevation in liver enzymes, hyperuricemia, hyperlacticacidemia, renal dysfunction, and cardiovascular disturbances. Considering the statistically significant improvement in glycosylated hemoglobin with dorzagliatin in patients with T2DM, the drug may be given a chance in treatment-naïve patients with a shorter disease history. However, with the waning therapeutic efficacy witnessed in patients with long-standing diabetes, which was also one of the potential concerns with previously tested molecules, extended studies involving patients with chronic and uncontrolled diabetes are needed to comment upon the long-term therapeutic performance of dorzagliatin. Likewise, evidence needs to be generated from other countries, patients with organ dysfunction, a history of severe hypoglycemia, cardiac diseases, and elderly patients before extending the use of dorzagliatin. Apart from monitoring lipid profiles, long-term safety studies of dorzagliatin should involve the assessment of serum uric acid, lactate, renal function, liver function, and cardiovascular parameters.

Efficacy and safety of dorzagliatin, a novel glucokinase activators, in the treatment of T2DM: A meta-analysis of randomized controlled trials

OBJECT

To evaluate the efficacy and safety of dorzagliatin for the treatment of type 2 diabetes (T2DM).

METHODS

Seven databases were systematically searched, spanning the interval from 2016 to August 2023. Randomized controlled trials (RCTS) comparing dorzagliatin with placebo for the treatment of T2DM were applicable for containing this study. The relevant data were extracted, and a meta-analysis was implemented using RevMan 5.4 software.

RESULTS

A total of 3 studies involving 1332 patients were included. We use glycated hemoglobin (HbA1c) levels as the major indicator of efficacy, FBG, 2h postprandial blood glucose, Homa-β and Homa-IR to be Secondary outcome measures. Compared with placebo group, dorzagliatin significantly reduced blood glucose levels as well as enhanced insulin resistance. In terms of safety, no serious adverse events occurred. However, lipid-related indicators, especially triglycerides levels, and the incidence of hypoglycemia were higher in patients in the dorzagliatin group compared with those in the control group, but the increase from baseline was mild.

CONCLUSIONS

Dorzagliatin exerted favorable effects in hypoglycemic control, effectively reduced the HbA1c, FBG, and 2h postprandial blood glucose levels in T2DM patients, stimulated the secretion of insulin during the initial phase, and exerted a consistent hypoglycemic effect. However, the incidence of adverse events such as elevated blood lipids and cardiovascular risk warrants further investigations through long-term clinical trials.

Improvement of early-phase insulin secretion is an independent factor for achieving glycaemic control: A pooled analysis of SEED and DAWN study

AIM

To investigate the effect of improving early phase insulin secretion function for glycaemic control in patients with type 2 diabetes mellitus treated with a new class of antidiabetic drug dorzagliatin.

MATERIALS AND METHODS

Early insulin secretion function was studied in 726 participants of which 414 were treated with dorzagliatin in the SEED and DAWN study. The early insulinogenic index (IGI30min ) and disposition index (DI) were used to assess early-phase insulin secretion function in this study. Logistic regression analysis was performed to verify the importance of IGI30min and DI indices for achieving effective glycaemic control.

RESULTS

The reduction in HbA1c has a significant correlation with the improvement of IGI30min for patients that received 24 weeks of dorzagliatin treatment (p < .001), and this correlation was not observed in the placebo group (p = .364). In the dorzagliatin treatment group, the responders showed significant improvements in homeostasis model assessment 2-β, IGI30min and DI compared with the non-responders. Logistic regression analysis revealed that the odds ratio (OR) for achieving glycaemic control was 1.28 (95% CI 1.14-1.43) for baseline IGI30min , and 1.24 (95% CI 1.14-1.35) for the 24-week incremental IGI30min from baseline. The OR for baseline DI and 24-week changes in DI from baseline were 1.39 (95% CI 1.2-1.6) and 1.30 (95% CI 1.19-1.43) respectively. The timing of insulin secretion analysis showed the significant contribution of early-phase insulin secretion, rather than late-phase insulin secretion, to postprandial glucose control with the OR for the incremental IGI30min and IGI2h to postprandial glucose control were 1.3 (95% CI 1.19-1.42) and 1 (95% CI 1-1.01) respectively.

CONCLUSIONS

Restoring the impaired early-phase insulin secretion function in patients with type 2 diabetes mellitus is a critical factor for improving the glycaemic control by dorzagliatin treatment.

Nano-Stevia reduces the liver injury caused by streptozotocin (STZ)-induced diabetes in rats by targeting PEPCK/GCK genes, INSR pathway and apoptosis

Objectives

Extensive application of stevia in the treatment of type 2 diabetes mellitus (DM) has been proven by a large number of previous studies. We prepared stevia loaded in nanoniosomes (nanostevia) to improve its bioavailability, functionality, and stability and explore its protective effects and underlying mechanisms in the liver of STZ-induced diabetic rats.

Methods

Single-dose intraperitoneal injection of STZ (50 mg/kg body weight) was used to establish diabetic model. The mRNA levels of PEPCK and GCK genes and the protein level of INSR were evaluated by Real time-PCR and Western blot assays, respectively. TUNEL assay was used to detect apoptotic cell death in the liver tissue.

Results

Diabetic rats exhibited significantly reduced levels of INSR (*** P < 0.001) as well as elevated levels of PEPCK (*** P < 0.001). Both stevia and nano-stevia were capable of increasing levels of GCK and INSR and reducing levels of PEPCK (## P < 0.01 and ### P < 0.001, respectively). In addition, significantly increased number of apoptotic cell death was seen in the liver tissue of diabetic rats (*** P < 0.001) which was markedly mitigated by treatment with both Stevia and nano-Stevia (#P < 0.05 and ## P < 0.01, respectively).

Conclusion

Both stevia and nano-stevia demonstrates potent anti-apoptotic activity in the liver tissue of diabetic rats by targeting PEPCK/GCK genes and INSR pathway. These finding show that nano-stevia has more potential to reduce the liver injury caused by STZ-induced diabetes in rats and hence can be considered a valid agent and alternative therapy for attenuating complications of type 2 DM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01278-2.

Modulation of glucose metabolism-related genes in diabetic rats treated with herbal synthetic anti-diabetic compound (α-HSA): insights from transcriptomic profiling

OBJECTIVES

Eugenia jambolana is a medicinal plant traditionally used for treating diabetes. The bioactive compound FIIc, which is derived from the fruit pulp of E. jambolana, has been identified and purified as α-HSA. Previous studies have demonstrated that administration of α-HSA for 6 weeks improved glycemic index and dyslipidemia in rats with T2D. This study investigated the molecular mechanism underlying the potential therapeutic effects of α-HSA in experimentally induced diabetic rats.

METHODS

Male Wistar rats were divided into four groups: diabetic control, diabetic treated with FIIc, diabetic treated with α-HSA, and diabetic treated with glibenclamide. Over a 6-week experimental period, transcriptomic analysis was conducted on liver, skeletal, and pancreatic tissue samples collected from the rats.

RESULTS

The study findings revealed significant upregulation of genes associated with glucose metabolism and insulin signaling in the groups treated with FIIc and α-HSA, compared to the diabetic control group. Moreover, pro-inflammatory genes were downregulated in these treatment groups. These results indicate that α-HSA has the potential to modulate key metabolic pathways, improve glucose homeostasis, enhance insulin sensitivity, and alleviate inflammation.

CONCLUSIONS

This study provides compelling scientific evidence supporting the potential of α-HSA as a therapeutic agent for diabetes treatment. The observed upregulation of genes related to glucose metabolism and insulin signaling, along with the downregulation of pro-inflammatory genes, aligns with the pharmacological activity of α-HSA in controlling glucose homeostasis and improving insulin sensitivity. These findings suggest that α-HSA holds promise as a novel therapeutic approach for managing diabetes and its associated complications.

Diabetes remission in drug-naïve patients with type 2 diabetes after dorzagliatin treatment: A prospective cohort study

AIM

To investigate the post-treatment effect of dorzagliatin in drug-naïve patients with type 2 diabetes (T2D) regarding the achievement of stable glycaemic control and drug-free diabetes remission.

MATERIALS AND METHODS

Patients who completed dorzagliatin treatment in the SEED trial and achieved stable glycaemic control were enrolled in this 52-week study without any antidiabetic medication. The primary endpoint was the diabetes remission probability at week 52 using the Kaplan-Meier method. The potential factors that contribute to stable glycaemic control and diabetes remission based on the characteristics of patients before and after treatment with dorzagliatin were analysed. A post hoc sensitivity analysis of diabetes remission probability using the American Diabetes Association (ADA) definition was conducted.

RESULTS

The Kaplan-Meier remission probability was 65.2% (95% CI: 52.0%, 75.6%) at week 52. Based on the ADA definition, the remission probability was 52.0% (95% CI: 31.2%, 69.2%) at week 12. The significant improvements in the insulin secretion index ΔC30/ΔG30 (41.46 ± 77.68, P = .0238), disposition index (1.22 ± 1.65, P = .0030), and steady-state variables of HOMA2-β (11.49 ± 14.58, P < .0001) and HOMA2-IR (-0.16 ± 0.36, P = .0130) during the SEED trial were important factors in achieving drug-free remission. A significant improvement in time in range (TIR), a measure of glucose homeostasis, in the SEED trial from 60% to more than 80% (estimated treatment difference, 23.8%; 95% CI: 7.3%, 40.2%; P = .0084) was observed.

CONCLUSIONS

In drug-naïve patients with T2D, dorzagliatin treatment leads to stable glycaemic control and drug-free diabetes remission. Improvements in β-cell function and TIR in these patients are important contributors to diabetes remission.

Glucokinase and glucokinase activator

Glucokinase (GK) plays a pivotal role in glucose homeostasis as the glucose sensor in the pancreas and liver. Loss of function of GK results in hyperglycemia, and gain of function causes congenital hyperinsulinemic hypoglycemia. We speculate that the progressive loss of GK at both messenger RNA (mRNA) and protein levels in the islets and liver would be the key mechanism for Type 2 diabetes (T2D) pathogenesis. The development of GK activator (GKA) as an anti-diabetic drug has been endeavored for several decades. The failure of the early development of GKAs is due to the limitation of understanding the mode of GKA action. The success of dorzagliatin in the treatment of T2D has brought new hope for GK in setting a good model for repairing the underlying defects in the pancreatic islets and liver of T2D patients.

The 15-hydroxyprostaglandin dehydrogenase inhibitor SW033291 ameliorates abnormal hepatic glucose metabolism through PGE2-EP4 receptor-AKT signaling in a type 2 diabetes mellitus mouse model

Type 2 diabetes mellitus (T2DM) is associated with high rates of morbidity and mortality worldwide. Prostaglandin E₂ (PGE₂) is a lipid signaling molecule that can ameliorate the symptoms of some metabolic diseases, including T2DM, and improve tissue repair and regeneration. Although SW033291 can increase PGE₂ levels through its action as a small molecule inhibitor of the PGE₂-degrading enzyme 15-hydroxyprostaglandin dehydrogenase, its effects on T2DM remain unclear. In the present study, we evaluated whether SW033291 treatment exerts a protective effect against T2DM and explored the underlying mechanisms. A T2DM mouse model was established using a high-fat diet combined with streptozotocin treatment. Palmitic acid-treated LO2 cells were used as an insulin-resistant cell model. SW033291 treatment reduced body weight and fasting blood glucose levels as well as serum triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels in vivo. In addition to ameliorating glucose and insulin tolerance, SW033291 treatment reversed the T2DM-induced decrease in glycogen synthesis and increase in gluconeogenesis in the liver. Furthermore, SW033291 administration increased hepatic glycogen synthase kinase 3 beta (GSK3β) phosphorylation levels to promote glycogen synthesis. SW033291 treatment also inhibited gluconeogenesis by upregulating AKT serine/threonine kinase (AKT) and forkhead box O1 (FOXO1) phosphorylation and reducing glucose-6-phosphatase and phosphoenolpyruvate carboxykinase 1 expression in the livers of T2DM model mice. Additionally, SW033291 treatment improved abnormal hepatic glucose metabolism through the PGE₂-EP4 receptor-AKT-GSK3β/FOXO1 signaling pathway in vitro. These results suggest a novel role of SW033291 in improving T2DM and support its potential as a novel therapeutic agent.

β-Cell glucokinase expression was increased in type 2 diabetes subjects with better glycemic control

BACKGROUND

Type 2 diabetes (T2D) is characterized by a progressive deterioration of β-cell function with a continuous decline in insulin secretion. Glucokinase (GCK) facilitates the rate-limiting step of glycolysis in pancreatic β-cells, to acquire the proper glucose-stimulated insulin secretion. Multiple glucokinase activators (GKAs) have been developed and clinically tested. However, the dynamic change of human pancreatic GCK expression during T2D progression has not been investigated.

METHODS

We evaluated GCK expression by measuring the average immunoreactivity of GCK in insulin+ or glucagon+ cells from pancreatic sections of 11 nondiabetic subjects (ND), 10 subjects with impaired fasting glucose (IFG), 9 with well-controlled T2D (wT2D), and 5 individuals with poorly controlled T2D (uT2D). We also assessed the relationship between GCK expression and adaptive unfolded protein response (UPR) in human diabetic β-cells.

RESULTS

We did not detect changes of GCK expression in IFG islets. However, we found β-cell GCK levels were significantly increased in T2D with adequate glucose control (wT2D) but not in T2D with poor glucose control (uT2D). Furthermore, there was a strong positive correlation between GCK expression and adaptive UPR (spliced X-box binding protein 1 [XBP1s] and activating transcription factor 4 [ATF4]), as well as functional maturity marker (urocortin-3 [UCN3]) in human diabetic β-cells.

CONCLUSIONS

Our study demonstrates that inductions of GCK enhanced adaptive UPR and UCN3 in human β-cells, which might be an adaptive mechanism during T2D progression. This finding provides a rationale for exploring novel molecules that activate β-cell GCK and thereby improve pharmacological treatment of T2D.

Patulin Alters Insulin Signaling and Metabolic Flexibility in HepG2 and HEK293 Cells

Non-communicable diseases (NCDs) have risen rapidly worldwide, sparking interest in causative agents and pathways. Patulin (PAT), a xenobiotic found in fruit products contaminated by molds, is postulated to be diabetogenic in animals, but little is known about these effects in humans. This study examined the effects of PAT on the insulin signaling pathway and the pyruvate dehydrogenase complex (PDH). HEK293 and HepG2 cells were exposed to normal (5 mM) or high (25 mM) glucose levels, insulin (1.7 nM) and PAT (0.2 μM; 2.0 μM) for 24 h. The qPCR determined gene expression of key enzymes involved in carbohydrate metabolism while Western blotting assessed the effects of PAT on the insulin signaling pathway and Pyruvate Dehydrogenase (PDH) axis. Under hyperglycemic conditions, PAT stimulated glucose production pathways, caused defects in the insulin signaling pathway and impaired PDH activity. These trends under hyperglycemic conditions remained consistent in the presence of insulin. These findings are of importance, given that PAT is ingested with fruit and fruit products. Results suggest PAT exposure may be an initiating event in insulin resistance, alluding to an etiological role in the pathogenesis of type 2 diabetes and disorders of metabolism. This highlights the importance of both diet and food quality in addressing the causes of NCDs.

A phase I open-label clinical trial to study drug-drug interactions of Dorzagliatin and Sitagliptin in patients with type 2 diabetes and obesity

This is a phase 1, open-label, single-sequence, multiple-dose, single-center trial conducted in the US (NCT03790839), to evaluate the clinical pharmacokinetics, safety and pharmacodynamics of dorzagliatin co-administered with sitagliptin in patients with T2D and obesity. The trial has completed. 15 patients with T2D and obesity were recruited and treated with sitagliptin 100 mg QD on Day 1-5, followed by a combination of sitagliptin 100 mg QD with dorzagliatin 75 mg BID at second stage on Day 6-10 and the third stage of dorzagliatin 75 mg BID alone on Day 11-15. Primary outcomes include pharmacokinetic geometric mean ratio (GMR), safety and tolerability. Secondary outcomes include the incremental area under the curve for 4 hours post oral glucose tolerance test (iAUC) of pharmacodynamic biomarkers and glucose sensitivity. GMR for AUC_0-24h and C_max were 92.63 (90% CI, 85.61, 100.22) and 98.14 (90% CI, 83.73, 115.03) in combination/sitagliptin, and 100.34 (90% CI, 96.08, 104.79) and 102.34 (90% CI, 86.92, 120.50) in combination/dorzagliatin, respectively. Combination treatment did not increase the adverse events and well-tolerated in T2D patients. Lack of clinically meaningful pharmacokinetic interactions between dorzagliatin and sitagliptin, and an improvement of glycemic control under combination potentially support their co-administration for diabetes management.

A multicentre, randomized, double-blind, parallel, active- and placebo-controlled Phase 3 clinical study of the glucokinase activator PB-201 in treatment-naive patients with type 2 diabetes mellitus: A study protocol

AIM

To report the rationale for using PB-201, a partial glucokinase activator (GKA), for a Phase 3 study (NCT05102149) assessing its efficacy and safety in a Chinese population and to describe the design of this GKA Phase 3 trial, the first to involve both an active control and a placebo control arm.

MATERIALS AND METHODS

This is an ongoing, multicentre, randomized, double-blind, three-arm placebo and active control study to be carried out among 672 Chinese treatment-naive participants with type 2 diabetes mellitus (T2DM) to assess the efficacy and safety of PB-201 for approximately 60 weeks, including a screening period and a safety follow-up period.

RESULTS

The primary objective of this study was to monitor change in glycated haemoglobin levels with PB-201 in treatment-naive T2DM participants from baseline to 24 weeks in comparison with vildagliptin and placebo. The key secondary objective was to assess the efficacy and safety of PB-201 following treatment for a time period of 52 weeks.

CONCLUSION

This pivotal study will offer critical information regarding the efficacy and safety of PB-201 in Chinese treatment-naive T2DM participants that would help to establish robust evidence for the benefit-risk evaluation of this drug.

"Ficus johannis Boiss. leaves ethanolic extract ameliorate streptozotocin-induced diabetes in rats by upregulating the expressions of GCK, GLUT4, and IGF and downregulating G6P"

The leaves of Ficus johannis Boiss (F. johannis), commonly known as Fig tree, Anjir, and Teen, are used by the folk medicinal practitioners in Iran for controlling hyperglycemia in diabetic patients. This study investigated the pharmacological basis for antidiabetic effect of the ethanolic extract of F. johannis leaves using in vitro and in vivo experimental models. Qualitative screening of phytochemicals, estimation of total phenolic and flavonoid contents, and in vitro antioxidant and α-amylase inhibition assays were performed. Moreover, the High-performance liquid chromatography (HPLC) quantification, acute toxicity, glucose tolerance, and in vivo antidiabetic effect along with the evaluation of gene expressions involved in diabetes mellitus were carried out. Significant quantities of phenolic (71.208 ± 2.89 mgg^-1 GAE) and flavonoid (26.38 ± 3.53 mgg^-1 QE) were present. Inhibitory concentration (IC₅₀) of the plant extract exhibited an excellent in vitro antioxidant (IC₅₀ = 33.81 µg/mL) and α-amylase (IC₅₀ = 12.18 µg/mL) inhibitory potential. The HPLC analysis confirmed the gallic acid (257.79 mgg^-1) as main constituent of the extract followed by kaempferol (22.86 mgg^-1), myricetin (0.16 mgg^-1), and quercetin (3.22 mgg^-1). Ethanolic extract displayed glucose tolerance in normo-glycemic rats. Streptozotocin-induced hyperglycemia declined dose dependently in the extract treated rats with improvement in lipid profile and liver and renal function biomarkers. The F. johannis-treated groups showed an increase in mRNA expressions of glucose transporter 4 (GLUT-4), glucokinase, insulin growth like factor 1 and peroxisomal proliferator activating receptor gamma in pancreas. However, the Glucose-6-phosphatase was downregulated. Present study suggests that the ethanolic extract of F. johannis leaves demonstrates a good anti-diabetic profile by improving insulin sensitivity, GLUT-4 translocation, and carbohydrate metabolism while inhibiting lipogenesis.

Dorzagliatin, a Dual-Acting Glucokinase Activator, Increases Insulin Secretion and Glucose Sensitivity in Glucokinase Maturity-Onset Diabetes of the Young and Recent-Onset Type 2 Diabetes

Glucokinase (GK, gene symbol GCK) maturity-onset diabetes of the young (MODY) is caused by heterozygous inactivating mutations in GK and impaired glucose sensing. We investigated effects of dorzagliatin, a novel allosteric GK activator, on insulin secretion rates (ISRs) and β-cell glucose sensitivity (βCGS) in GCK-MODY and recent-onset type 2 diabetes. In a double-blind, randomized, crossover study, 8 participants with GCK-MODY and 10 participants with type 2 diabetes underwent 2-h 12 mmol/L hyperglycemic clamps following a single oral dose of dorzagliatin 75 mg or matched placebo. Effects of dorzagliatin on wild-type and mutant GK enzyme activity were investigated using an NADP+-coupled assay with glucose-6-phosphate dehydrogenase in vitro. In GCK-MODY, dorzagliatin significantly increased absolute and incremental second-phase ISRs versus placebo but not the acute insulin response. Dorzagliatin improved βCGS in GCK-MODY with an upward and leftward shift in ISR-glucose response. Dorzagliatin increased basal ISRs in type 2 diabetes, with smaller changes in second-phase ISRs versus GCK-MODY. In vitro, dorzagliatin directly reduced the glucose half saturation concentration of wild-type GK and selected GK mutants to varying degrees. Dorzagliatin directly restored enzyme activity of select GK mutants and enhanced wild-type GK activity, thereby correcting the primary defect of glucose sensing in GCK-MODY.

Anthocyanins: Potential Therapeutic Approaches towards Obesity and Diabetes Mellitus Type 2

Overweight and obesity are present in about three-quarters of the adult population in Mexico. The inflammatory mechanisms subjacent to visceral white adipose tissue are accountable for the initiation and development of cardiometabolic alterations, including type 2 diabetes. Lifestyle changes are pillars within its therapeutics and, thus, current dietary modifications should include not only hypocaloric prescriptions with balanced macronutrient intake, preferably by increasing the amount of whole grains, fruits, vegetables, nuts and legumes, but in concomitance, bioactive substances, such as anthocyanins, have been correlated with lower incidence of this disease.

AMPK inhibits liver gluconeogenesis: fact or fiction?

Is there a role for AMPK in the control of hepatic gluconeogenesis and could targeting AMPK in liver be a viable strategy for treating type 2 diabetes? These are frequently asked questions this review tries to answer. After describing properties of AMPK and different small-molecule AMPK activators, we briefly review the various mechanisms for controlling hepatic glucose production, mainly via gluconeogenesis. The different experimental and genetic models that have been used to draw conclusions about the role of AMPK in the control of liver gluconeogenesis are critically discussed. The effects of several anti-diabetic drugs, particularly metformin, on hepatic gluconeogenesis are also considered. We conclude that the main effect of AMPK activation pertinent to the control of hepatic gluconeogenesis is to antagonize glucagon signalling in the short-term and, in the long-term, to improve insulin sensitivity by reducing hepatic lipid content.

A systematic analysis of anti-diabetic medicinal plants from cells to clinical trials

Background

Diabetes is one of the fastest-growing health emergencies of the 21st century, placing a severe economic burden on many countries. Current management approaches have improved diabetic care, but several limitations still exist, such as decreased efficacy, adverse effects, and the high cost of treatment, particularly for developing nations. There is, therefore, a need for more cost-effective therapies for diabetes management. The evidence-based application of phytochemicals from plants in the management of diseases is gaining traction.

Methodology

Various plants and plant parts have been investigated as antidiabetic agents. This review sought to collate and discuss published data on the cellular and molecular effects of medicinal plants and phytochemicals on insulin signaling pathways to better understand the current trend in using plant products in the management of diabetes. Furthermore, we explored available information on medicinal plants that consistently produced hypoglycemic effects from isolated cells to animal studies and clinical trials.

Results

There is substantial literature describing the effects of a range of plant extracts on insulin action and insulin signaling, revealing a depth in knowledge of molecular detail. Our exploration also reveals effective antidiabetic actions in animal studies, and clear translational potential evidenced by clinical trials.

Conclusion

We suggest that this area of research should be further exploited in the search for novel therapeutics for diabetes.

Effect of quercetin and Abelmoschus esculentus (L.) Moench on lipids metabolism and blood glucose through AMPK-α in diabetic rats (HFD/STZ)

Phosphoenolpyruvate carboxykinase (PEPCK) is a key enzyme in the glyconeogenesis pathway. The AMP-activated protein kinase alpha (AMPK-α) pathway regulates PEPCK, which itself is activated by the AMP/ATP ratio and liver kinase B1 (KB1). The Abelmoschus esculentus (L.) Moench (okra) plant contains a large amount of quercetin that can function as an agonist or an antagonist. The aim of this study was to examine the effects of quercetin flavonoid and A. esculentus extract on the level of AMPK-α expression and associated metabolic pathways. The findings demonstrate that metformin, quercetin, and okra extract may significantly raise AMPK-α levels while significantly lowering PEPCK and hormone-sensitive lipase (HSL) levels, in addition to improving glucose and lipid profiles. By stimulating KB1, these substances increased AMPK-α activation. Additionally, AMPK-α activation improved insulin resistance and Glucose transporter type 4 (GLUT4) gene expression levels. Since AMPK-α maintains energy balance and its activity has not been reported to be inhibited so far, it could be a potent therapeutic target. PRACTICAL APPLICATIONS: The development of effective AMPK-α agonists and antagonists holds promise for the treatment of metabolic disorders like diabetes. Dietary polyphenols are a valuable source for developing new drugs. However, due to the lack of understanding of the underlying mechanisms of their effect on cells, their use in the treatment of diabetes is controversial. In addition to chemicals that have medicinal benefits, chemists are searching for less harmful substances. Using plants containing bioactive chemicals for this purpose can be a good alternative to chemical drugs.

Zishen Pill alleviates diabetes in Db/db mice via activation of PI3K/AKT pathway in the liver

Background

The rising global incidence of type 2 diabetes mellitus (T2DM) highlights a need for new therapies. The Zishen Pill (ZSP) is a traditional Chinese herbal decoction that has previously shown hypoglycemic effects in C57BL/KsJ-db/db mice, although the therapeutic mechanism remains unknown. This study aims to explore the underlying mechanisms of ZSP’s hypoglycemic effects using db/db mice.

Methods

Db/db mice were divided into two groups: model group and ZSP group, while wt/wt mice were used as a normal control. ZSP was given to mice by gavage for 40 days. During treatment, blood glucose level and body weight were monitored continuously. Oral glucose tolerance test (OGTT) was performed at day 35. Blood and tissue samples were collected at the end of treatment for further analyses. Mice liver samples were analyzed with mRNA transcriptomics using functional annotation and pathway enrichment to identify potential mechanisms that were then explored with qPCR and Western Blot techniques.

Results

ZSP treatment significantly reduced weight gain and glycemic severity in db/db mice. ZSP also partially restored the glucose homeostasis in db/db mice and increased the hepatic glycogen content. Transcriptomic analyses showed ZSP increased expression of genes involved in glycolysis including Hk2, Hk3, Gck and Pfkb1, and decreased expression of G6pase. Additionally, the gene and protein expression of phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway, and Csf1 and Flt3 mRNA expression were significantly upregulated in ZSP group.

Conclusion

ZSP treatment reduced the severity of diabetic symptoms in db/db mice. ZSP increased expression of genes associated with glycogen synthesis and glycolysis, and decreased gluconeogenesis via the enhancement of the PI3K/AKT signaling in the liver.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00683-8.

Decoding Diabetes Biomarkers and Related Molecular Mechanisms by Using Machine Learning, Text Mining, and Gene Expression Analysis

The molecular basis of diabetes mellitus is yet to be fully elucidated. We aimed to identify the most frequently reported and differential expressed genes (DEGs) in diabetes by using bioinformatics approaches. Text mining was used to screen 40,225 article abstracts from diabetes literature. These studies highlighted 5939 diabetes-related genes spread across 22 human chromosomes, with 112 genes mentioned in more than 50 studies. Among these genes, HNF4A, PPARA, VEGFA, TCF7L2, HLA-DRB1, PPARG, NOS3, KCNJ11, PRKAA2, and HNF1A were mentioned in more than 200 articles. These genes are correlated with the regulation of glycogen and polysaccharide, adipogenesis, AGE/RAGE, and macrophage differentiation. Three datasets (44 patients and 57 controls) were subjected to gene expression analysis. The analysis revealed 135 significant DEGs, of which CEACAM6, ENPP4, HDAC5, HPCAL1, PARVG, STYXL1, VPS28, ZBTB33, ZFP37 and CCDC58 were the top 10 DEGs. These genes were enriched in aerobic respiration, T-cell antigen receptor pathway, tricarboxylic acid metabolic process, vitamin D receptor pathway, toll-like receptor signaling, and endoplasmic reticulum (ER) unfolded protein response. The results of text mining and gene expression analyses used as attribute values for machine learning (ML) analysis. The decision tree, extra-tree regressor and random forest algorithms were used in ML analysis to identify unique markers that could be used as diabetes diagnosis tools. These algorithms produced prediction models with accuracy ranges from 0.6364 to 0.88 and overall confidence interval (CI) of 95%. There were 39 biomarkers that could distinguish diabetic and non-diabetic patients, 12 of which were repeated multiple times. The majority of these genes are associated with stress response, signalling regulation, locomotion, cell motility, growth, and muscle adaptation. Machine learning algorithms highlighted the use of the HLA-DQB1 gene as a biomarker for diabetes early detection. Our data mining and gene expression analysis have provided useful information about potential biomarkers in diabetes.

Genetic and Pharmacological Inhibition of GCN2 Ameliorates Hyperglycemia and Insulin Resistance in Type 2 Diabetic Mice

It is well recognized that there is a strong and complex association between nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D). We previously demonstrated that genetic knockout or pharmacological inhibition of general control nondepressible kinase 2 (GCN2), a well-known amino acid sensor, alleviated hepatic steatosis and insulin resistance in obese mice. However, whether GCN2 affects the development of T2D remains unclear. After a high-fat diet (HFD) plus low-dose streptozotocin (STZ) treatments, Gcn2−/− mice developed less hyperglycemia, insulin resistance, hepatic steatosis, and oxidative stress than wild-type (WT) mice. Inhibition of GCN2 by intraperitoneal injection of 3 mg/kg GCN2iB (a specific inhibitor of GCN2) every other day for 6 weeks also ameliorated hyperglycemia, insulin resistance, hepatic steatosis, and oxidative stress in HFD/STZ- and leptin receptor deletion (db/db)-induced T2D mice. Moreover, depletion of hepatic GCN2 in db/db mice by tail vein injection of an AAV8-shGcn2 vector resulted in similar improvement in those metabolic disorders. The protective mechanism of GCN2 inhibition in T2D mice was associated with regulation of the glucose metabolic pathway, repression of lipogenesis genes, and activation of the Nrf2 pathway. Together, our data provide evidence that strategies to inhibit hepatic GCN2 activity may be novel approaches for T2D therapy.

Type 2 Diabetes Mellitus (T2DM) and Carbohydrate Metabolism in Relation to T2DM from Endocrinology, Neurophysiology, Molecular Biology, and Biochemistry Perspectives

Type 2 diabetes mellitus (T2DM) is a severe disease caused by metabolic disorders, particularly carbohydrate metabolism disorders. The disease is a fatal global trouble characterised by high prevalence rates, causing death, blindness, kidney failure, myocardial infarction, amputation of lower limps, and stroke. Biochemical metabolic pathways like glycolysis, gluconeogenesis, glycogenesis, and glycogenolysis are critical pathways that regulate blood glucose levels with the glucokinase (GK) enzyme playing a central role in glucose homeostasis. Any factor that perturbs the aforementioned biochemical pathways is detrimental. Endocrinological, neurophysiological, and molecular biological pathways that are linked to carbohydrate metabolism should be studied, grasped, and manipulated in order to alleviate T2DM global chaos. The challenge, howbeit, is that, since the body is an integration of systems that complement one another, studying one “isolated” system is not very useful. This paper serves to discuss endocrinology, neurophysiology, and molecular biology pathways that are involved in carbohydrate metabolism in relation to T2DM.

Hepatic Transcriptome Analysis Provides New Insight into the Lipid-Reducing Effect of Dietary Taurine in High-Fat Fed Groupers (Epinephelus coioides)

A transcriptome analysis was conducted to provide the first detailed overview of dietary taurine intervention on liver lipid accumulation caused by high-fat in groupers. After an eight-week feeding, the fish fed 15% fat diet (High-fat diet) had higher liver lipid contents vs. fish fed 10% fat diet (Control diet). 15% fat diet with 1% taurine (Taurine diet) improved weight gain and feed utilization, and decreased hepatosomatic index and liver lipid contents vs. the High-fat diet. In the comparison of the Control vs. High-fat groups, a total of 160 differentially expressed genes (DEGs) were identified, of which up- and down-regulated genes were 72 and 88, respectively. There were 49 identified DEGs with 26 and 23 of up- and down-regulated in the comparison to High-fat vs. Taurine. Several key genes, such as cysteine dioxygenase (CDO1), ADP-ribosylation factor 1/2 (ARF1_2), sodium/potassium-transporting ATPase subunit alpha (ATP1A), carnitine/acylcarnitine translocase (CACT), and calcium/calmodulin-dependent protein kinase II (CAMK) were obtained by enrichment for the above DEGs. These genes were enriched in taurine and hypotaurine metabolism, bile secretion, insulin secretion, phospholipase D signaling pathway, and thermogenesis pathways, respectively. The present study will also provide a new insight into the nutritional physiological function of taurine in farmed fish.

Antidiabetic and neuroprotective effects of a novel repaglinide analog

Repaglinide (RPG) is an oral insulin secretagogue used in the treatment of diabetes. In this study, a new RPG analog was synthesized. Its antidiabetic and neuroprotective effects on dorsal root ganglions (DRG) in streptozotocin (STZ)-induced diabetic rats were examined compared to RPG. To assess the effects of 2-methoxy-4-(2-((3-methyl-1-(2-(piperidin-1-yl)phenyl)butyl)amino)-2-oxoethoxy)benzoic acid (OXR), the impact of OXR on oxidative stress biomarkers, motor function, and the expression of the glutamate dehydrogenase 1 (GLUD1), SLC2A2/glucose transporter 2 (GLUT2), and glucokinase (GCK) genes in STZ-induced diabetic rats were assessed. DRGs were examined histologically using hemotoxylin and eosin staining. Molecular docking was used to investigate the interactions between OXR and the binding site of RPG, the ATP-sensitive potassium (KATP) channel. Following 5 weeks of treatment, OXR significantly increased the level of total antioxidant power, decreased reactive oxygen species, and lipid peroxidation in the DRGs of diabetic rats. OXR restored STZ-induced pathophysiological damages in DRG tissues. Administration of OXR improved motor function of rats with diabetic neuropathy. Administration of 0.5 mg/kg OXR reduced blood glucose while promoting insulin, mainly through upregulation of messenger RNA expression of GLUD1, GLUT2, and GCK in the pancreas. Molecular docking revealed a favorable binding mode of OXR to the KATP channel. In conclusion, OXR has neuroprotective effects in diabetic rats by lowering oxidative stress, lowering blood glucose, and stimulating insulin secretion. We report that 0.5 mg/kg OXR administration was the most effective concentration of the compound in this study. OXR may be a promising target for further research on neuroprotective antidiabetic molecules.

Dorzagliatin in drug-naïve patients with type 2 diabetes: a randomized, double-blind, placebo-controlled phase 3 trial

Improving glucose sensitivity remains an unmet medical need in treating type 2 diabetes (T2D). Dorzagliatin is a dual-acting, orally bioavailable glucokinase activator that enhances glucokinase activity in a glucose-dependent manner, improves glucose-stimulated insulin secretion and demonstrates effects on glycemic control in patients with T2D. We report the findings of a randomized, double-blind, placebo-controlled phase 3 clinical trial to evaluate the efficacy and safety of dorzagliatin in patients with T2D. Eligible drug-naïve patients with T2D (n = 463) were randomly assigned to the dorzagliatin or placebo group at a ratio of 2:1 for 24 weeks of double-blind treatment, followed by 28 weeks of open-label treatment with dorzagliatin for all patients. The primary efficacy endpoint was the change in glycated hemoglobin from baseline to week 24. Safety was assessed throughout the trial. At week 24, the least-squares mean change in glycated hemoglobin from baseline (95% confidence interval) was -1.07% (-1.19%, -0.95%) in the dorzagliatin group and -0.50% (-0.68%, -0.32%) in the placebo group (estimated treatment difference, -0.57%; 95% confidence interval: -0.79%, -0.36%; P < 0.001). The incidence of adverse events was similar between the two groups. There were no severe hypoglycemia events or drug-related serious adverse events in the dorzagliatin group. In summary, dorzagliatin improved glycemic control in drug-naïve patients with T2D and showed a good tolerability and safety profile.

Dorzagliatin add-on therapy to metformin in patients with type 2 diabetes: a randomized, double-blind, placebo-controlled phase 3 trial

Metformin, the first-line therapy for type 2 diabetes (T2D), decreases hepatic glucose production and reduces fasting plasma glucose levels. Dorzagliatin, a dual-acting orally bioavailable glucokinase activator targeting both the pancreas and liver glucokinase, decreases postprandial glucose in patients with T2D. In this randomized, double-blind, placebo-controlled phase 3 trial, the efficacy and safety of dorzagliatin as an add-on therapy to metformin were assessed in patients with T2D who had inadequate glycemic control using metformin alone. Eligible patients with T2D (n = 767) were randomly assigned to receive dorzagliatin or placebo (1:1 ratio) as an add-on to metformin (1,500 mg per day) for 24 weeks of double-blind treatment, followed by 28 weeks of open-label treatment with dorzagliatin for all patients. The primary efficacy endpoint was the change in glycated hemoglobin (HbA1c) levels from baseline to week 24, and safety was assessed throughout the trial. At week 24, the least-squares mean change from baseline in HbA1c (95% confidence interval (CI)) was -1.02% (-1.11, -0.93) in the dorzagliatin group and -0.36% (-0.45, -0.26) in the placebo group (estimated treatment difference, -0.66%; 95% CI: -0.79, -0.53; P < 0.0001). The incidence of adverse events was similar between groups. There were no severe hypoglycemia events or drug-related serious adverse events in the dorzagliatin and metformin combined therapy group. In patients with T2D who experienced inadequate glycemic control with metformin alone, dorzagliatin resulted in effective glycemic control with good tolerability and safety profile ( NCT03141073 ).

Dendrocalamus latiflorus and its component rutin exhibit glucose-lowering activities by inhibiting hepatic glucose production via AKT activation

The potential medicinal value of Ma bamboo (Dendrocalamus latiflorus), one of the most popular and economically important bamboo species in China, has been underestimated. In the present study, we found that D. latiflorus leaf extract (DLE) reduced fasting blood glucose levels, body weight, and low-density lipoprotein cholesterol with low liver toxicity in db/db mice. In addition, gene expression profiling was performed and pathway enrichment analysis showed that DLE affected metabolic pathways. Importantly, DLE activated the AKT signaling pathway and reduced glucose production by downregulating glucose-6-phosphatase (G6PC) and phosphoenolpyruvate carboxykinase 1 (PCK1) expression. Moreover, network pharmacology analysis identified rutin as an active component in DLE through targeting insulin growth factor 1 receptor (IGF1R), an upstream signaling transducer of AKT. Due to its hypoglycemic effects and low toxicity, DLE may be considered an adjuvant treatment option for type 2 diabetes patients.

Optimized 3D Culture of Hepatic Cells for Liver Organoid Metabolic Assays

The liver is among the principal organs for glucose homeostasis and metabolism. Studies of liver metabolism are limited by the inability to expand primary hepatocytes in vitro while maintaining their metabolic functions. Human hepatic three-dimensional (3D) organoids have been established using defined factors, yet hepatic organoids from adult donors showed impaired expansion. We examined conditions to facilitate the expansion of adult donor-derived hepatic organoids (HepAOs) and HepG2 cells in organoid cultures (HepGOs) using combinations of growth factors and small molecules. The expansion dynamics, gluconeogenic and HNF4α expression, and albumin secretion are assessed. The conditions tested allow the generation of HepAOs and HepGOs in 3D cultures. Nevertheless, gluconeogenic gene expression varies greatly between conditions. The organoid expansion rates are limited when including the TGFβ inhibitor A8301, while are relatively higher with Forskolin (FSK) and Oncostatin M (OSM). Notably, expanded HepGOs grown in the optimized condition maintain detectable gluconeogenic expression in a spatiotemporal distribution at 8 weeks. We present optimized conditions by limiting A8301 and incorporating FSK and OSM to allow the expansion of HepAOs from adult donors and HepGOs with gluconeogenic competence. These models increase the repertoire of human hepatic cellular tools available for use in liver metabolic assays.

Multi-Omics Comparison of the Spontaneous Diabetes Mellitus and Diet-Induced Prediabetic Macaque Models

The prevalence of diabetes mellitus has been increasing for decades worldwide. To develop safe and potent therapeutics, animal models contribute a lot to the studies of the mechanisms underlying its pathogenesis. Dietary induction using is a well-accepted protocol in generating insulin resistance and diabetes models. In the present study, we reported the multi-omics profiling of the liver and sera from both peripheral blood and hepatic portal vein blood from Macaca fascicularis that spontaneously developed Type-2 diabetes mellitus with a chow diet (sDM). The other two groups of the monkeys fed with chow diet and high-fat high-sugar (HFHS) diet, respectively, were included for comparison. Analyses of various omics datasets revealed the alterations of high consistency. Between the sDM and HFHS monkeys, both the similar and unique alterations in the lipid metabolism have been demonstrated from metabolomic, transcriptomic, and proteomic data repeatedly. The comparison of the proteome and transcriptome confirmed the involvement of fatty acid binding protein 4 (FABP4) in the diet-induced pathogenesis of diabetes in macaques. Furthermore, the commonly changed genes between spontaneous diabetes and HFHS diet-induced prediabetes suggested that the alterations in the intra- and extracellular structural proteins and cell migration in the liver might mediate the HFHS diet induction of diabetes mellitus.

The efficacy and safety of glucokinase activators for the treatment of type-2 diabetes mellitus: A meta-analysis

BACKGROUND

Glucokinase activators (GKAs) are a novel family of glucose-lowering agents used for the treatment of type-2 diabetes mellitus. Treatment with different GKAs has been shown to reduce blood glucose levels in these patients. We compared the efficacy/safety of GKAs in patients with type-2 diabetes mellitus through a meta-analysis.

METHODS

We searched the PubMed, Excerpt Medica Database, and Cochrane Central Register of Controlled Trials databases for articles published before December 30, 2020. We computed the weighted mean difference (WMD) and 95% confidence interval (CI) for the change from baseline to the study endpoint for GKA versus placebo treatments.

RESULTS

A total of 4 articles (5 studies) were included in the meta-analysis. GKAs were associated with reductions in glycated hemoglobin levels from baseline (WMD, -0.3%; 95% CI, -0.466% to -0.134%). No significant difference between GKA and placebo treatment was observed in the results of fasting plasma glucose levels from baseline (WMD 0.013 mmol/L; 95% CI, -0.304-0.33 mmol/L). A significantly higher change in 2-hour postprandial plasma glucose (2-h PPG) levels (WMD -2.434 mmol/L; 95% CI, -3.304 to -1.564 mmol/L) was observed following GKA than placebo treatment. GKAs were associated with a higher prevalence of causing hypoglycemic events than placebo treatment (risk difference [RD], 0.06; 95% CI 0.013-0.106). GKAs had no association with the risk of developing adverse effects (RD, 0.038; 95% CI, -0.03-0.106) and serious adverse events (RD, 0.01; 95% CI, -0.004-0.023).

CONCLUSIONS

GKAs were more effective for postprandial blood glucose control. However, these agents showed a significantly high risk of causing hypoglycemia.

PROSPERO REGISTRATION NUMBER

CRD42021220364.

Blood transcriptome profiling as potential biomarkers of suboptimal health status: potential utility of novel biomarkers for predictive, preventive, and personalized medicine strategy

The early identification of Suboptimal Health Status (SHS) creates a window opportunity for the predictive, preventive, and personalized medicine (PPPM) in chronic diseases. Previous studies have observed the alterations in several mRNA levels in SHS individuals. As a promising "omics" technology offering comprehension of genome structure and function at RNA level, transcriptome profiling can provide innovative molecular biomarkers for the predictive identification and targeted prevention of SHS. To explore the potential biomarkers, biological functions, and signalling pathways involved in SHS, an RNA sequencing (RNA-Seq)-based transcriptome analysis was firstly conducted on buffy coat samples collected from 30 participants with SHS and 30 age- and sex-matched healthy controls. Transcriptome analysis identified a total of 46 differentially expressed genes (DEGs), in which 22 transcripts were significantly increased and 24 transcripts were decreased in the SHS group. A total of 23 transcripts were selected as candidate predictive biomarkers for SHS. Gene Ontology (GO) annotations and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that several biological processes were related to SHS, such as ATP-binding cassette (ABC) transporter and neurodegeneration. Protein-protein interaction (PPI) network analysis identified 10 hub genes related to SHS, including GJA1, TWIST2, KRT1, TUBB3, AMHR2, BMP10, MT3, BMPER, NTM, and TMEM98. A transcriptome predictive model can distinguish SHS individuals from the healthy controls with a sensitivity of 83.3% (95% confidence interval (CI): 73.9-92.7%), a specificity of 90.0% (95% CI: 82.4-97.6%), and an area under the receiver operating characteristic curve of 0.938 (95% CI: 0.882-0.994). In the present study, we demonstrated that blood (buffy coat) samples appear to be a very promising and easily accessible biological material for the transcriptomic analyses focused on the objective identification of SHS by using our transcriptome predictive model. The pattern of particularly determined DEGs can be used as predictive transcriptomic biomarkers for the identification of SHS in an individual who may, subjectively, feel healthy, but at the level of subcellular mechanisms, the changes can provide early information about potential health problems in this person. Our findings also indicate the potential therapeutic targets in dealing with chronic diseases related to SHS, such as T2DM and CVD, and an early onset of neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases, as well as the findings suggest the targets for personalized interventions as promoted in PPPM.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13167-021-00238-1.

Ethnopharmacological perspectives of glucokinase activators in the treatment of diabetes mellitus

Traditional medicinal plants have wide-reaching utilisation in the treatment of diabetes especially in developing countries where medical resources are meagre. Traditionally used anti-diabetic plants act by numerous mechanisms, however, only a few of them act through activation of the glucokinase enzyme. Glucokinase is a key regulatory enzyme in glucose metabolism thereby controls glucose homeostasis and insulin secretion. The present review significantly analyses the knowledge about various plant-based glucokinase activators including numerous phytochemicals which modulate the activity and gene expression of glucokinase and would provide data support and perspective regarding future research in the discovery and development of different plant-derived glucokinase activators.

1H NMR Metabolomics and Full-Length RNA-Seq Reveal Effects of Acylated and Nonacylated Anthocyanins on Hepatic Metabolites and Gene Expression in Zucker Diabetic Fatty Rats

Anthocyanins have been reported to possess antidiabetic effects. Recent studies indicate acylated anthocyanins have better stability and antioxidative activity compared to their nonacylated counterparts. This study compared the effects of nonacylated and acylated anthocyanins on hepatic gene expression and metabolic profile in diabetic rats, using full-length transcriptomics and ¹H NMR metabolomics. Zucker diabetic fatty (ZDF) rats were fed with nonacylated anthocyanin extract from bilberries (NAAB) or acylated anthocyanin extract from purple potatoes (AAPP) at daily doses of 25 and 50 mg/kg body weight for 8 weeks. Both anthocyanin extracts restored the levels of multiple metabolites (glucose, lactate, alanine, and pyruvate) and expression of genes (G6pac, Pck1, Pklr, and Gck) involved in glycolysis and gluconeogenesis. AAPP decreased the hepatic glutamine level. NAAB regulated the expression of Mgat4a, Gstm6, and Lpl, whereas AAPP modified the expression of Mgat4a, Jun, Fos, and Egr1. This study indicated different effects of AAPP and NAAB on the hepatic transcriptomic and metabolic profiles of diabetic rats.

Glucokinase activation as antidiabetic therapy: effect of nutraceuticals and phytochemicals on glucokinase gene expression and enzymatic activity

Diabetes represents an important public health problem. Recently, new molecular targets have been identified and exploited to treat this disease. Due to its pivotal role in glucose homeostasis, glucokinase (GCK) is a promising target for the development of novel antidiabetic drugs; however, pharmacological agents that modulate GCK activity have been linked to undesirable side-effects, limiting its use. Interestingly, plants might be a valuable source of new therapeutic compounds with GCK-activating properties and presumably no adverse effects. In this review, we describe biochemical characteristics related to the physiological and pathological importance of GCK, as well as the mechanisms involved in its regulation at different molecular levels. Posteriorly, we present a compendium of findings supporting the potential use of nutraceuticals and phytochemicals in the management of diabetes through modulation of GCK expression and activity. Finally, we propose critical aspects to keep in mind when designing experiments to evaluate GCK modulation properly.

Vanillic acid mitigates the impairments in glucose metabolism in HepG2 cells through BAD-GK interaction during hyperinsulinemia

Glucokinase (GK), a key regulator of hepatic glucose metabolism in the liver and glucose sensor and mediator in the secretion of insulin in the pancreas, is not studied in detail for its therapeutic application in diabetes. Herein, we study the alteration in GK activity during hyperinsulinemia-induced insulin resistance in HepG2 cells. We also investigated the link between GK and Bcl-2-associated death receptor (BAD) during hyperinsulinemia. There are emerging demands for GK activators from natural resources, and we selected vanillic acid (VA) to evaluate its potential as GK activators during hyperinsulinemia in HepG2 cells. VA is a phenolic compound and a commonly used food additive in many food industries. We found that VA safeguarded GK inhibition during hyperinsulinemia significantly in HepG2 cells. VA also prevented the depletion of glycogen synthesis during hyperinsulinemia, which is evident from protein expression studies of phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, glycogen synthase, and glycogen synthase kinase-3β. This was associated with activation of BAD activity, which was also confirmed by Western blotting. Molecular docking revealed strong binding between GK active site and VA, supporting their strong interaction. These are the first in vitro data to indicate the beneficial properties of VA with respect to insulin resistance induced by hyperinsulinemia by GK activation. Since it is activated via BAD, the hypoglycemia associated with general GK activation is not expected here and therefore has significant implications for future therapies against diabetes.

The effects and safety of activators of glucokinase versus placebo in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

We undertook a systematic review and meta-analysis to assess the effects and safety of activators of glucokinase (GKAs) in patients with type 2 diabetes mellitus (T2DM). 11 RCTs, including 2,429 participants, are enrolled in our study. According to different doses, we divided the studies into 3 groups: low-dose group, medium-dose group and high-dose group for subgroup analysis. There were decreases of HbA1c in all dose group (WMD = -0.27, 95%CI (-0.51~ -0.03), Z = 2.17, p = 0.03; WMD = -0.37, 95%CI (-0.58~ -0.16), Z = 3.41, p = 0.0006; WMD = -0.60, 95%CI (-0.86~ -0.33), Z = 4.43, p < 0.00001). Though the total risk of hypoglycemia is absolutely low, in the high-dose group higher hypoglycemia than the placebo can be observed (RR = 0.03, 95%CI (0.00~0.06), Z = 2.27, p = 0.02). In addition, the study found that the drug was less likely to have adverse reactions such as diarrhea, headache and dizziness, nasopharyngitis and upper respiratory tract infection (RR = 0.76, 95%CI (0.36~1.60), Z = 0.73, p = 0.47; RR = 1.26, 95%CI (0.73~2.17), Z = 0.83, p = 0.41; RR = 0.71, 95%CI (0.41~1.22), Z = 1.25, p = 0.21; RR = 1.61, 95%CI (0.77~3.36), Z = 1.26, p = 0.21). It concludes that GKAs are relatively effective and safe in the treatment of patients with T2DM, but in consideration of the potential risk of hypoglycemia in the high-dose group, the low-dose and medium-dose group, in the clinical practice, can be an excellent choice.

The efficacy and safety of glucokinase activators for the treatment of type-2 diabetes mellitus: A protocol for systematic review and meta-analysis

BACKGROUND

Glucokinase activators are a novel family of glucose-lowering agents used for the treatment of type-2 diabetes mellitus (T2DM). Glucokinase activators blind to GK activate the enzyme allosterically. Treatment with different GKAs has been shown to reduce fasting and postprandial glucose in patients with type 2 diabetes. We compared the efficacy/safety of glucokinase activators in T2DM patients through a meta-analysis.

METHODS

We searched PubMed, Excerpt Medica Database, and Cochrane Central Register of Controlled Trials databases for articles published before December 30, 2020. Two independent reviewers extracted the information from article. The quality of articles were assessed by 2 independent reviewers using the 5 items of scale proposed by Jadad. We computed the weighted mean difference and 95% confidence interval (CI) for a change from baseline to the study endpoint for glucokinase activators vs placebo. Egger test and Begg test were used to assess the possible publication bias caused by the tendency of published studies to be positive.

RESULTS

The present meta-analysis will compare the efficacy and safety of glucokinase activators and placebo for the treatment of T2DM.

CONCLUSIONS

This meta-analysis will provide advanced evidence on the efficacy and safety of glucokinase activators for the treatment of T2DM.

ETHICS AND DISSEMINATION

Ethical approval and patient consent are not required because this study is a literature-based study. This systematic review and meta-analysis will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42021220364.

The in vivo digestibility study of banana flour with high content of resistant starch at different ripening stages

Resistant starch, a functional food ingredient, can improve the nutritional value of food products. In this study, the in vitro digestibility of starch from banana flour at four ripening stages was evaluated. The result showed that the resistant starch content of banana flour at ripening stage 1 was up to 81%. Furthermore, to explore the effect of resistant starch in the body, the in vivo digestibility of banana flour was investigated. The intake of banana flour at ripening stage 1 resulted in a nearly 70% decrease in the homeostasis model assessment of insulin resistance value, compared to that of the model group. By contrast, the genes related to glucokinase were upregulated by 66%, and the expression level of the insulin receptor gene was increased by more than 1.5 times that of the model group. Thus, natural banana flour has potential for controlling type 2 diabetes mellitus.

P2Y12 shRNA normalizes inflammatory dysfunctional hepatic glucokinase activity in type 2 diabetic rats

The celiac ganglion projects its postganglionic (including purinergic) fibers to the liver. P2Y12 receptor is one of the P2Y family members. We found that the expression levels of P2Y12 receptor in both celiac ganglia and liver were increased in type 2 diabetes mellitus (T2DM) rats which also displayed an enhanced activity of celiac sympathetic nerve discharge (SND). In addition, a marked decrease of hepatic glucokinase (GK) expression was accompanied by reduced hepatic glycogen synthesis in T2DM rats, whereas meanwhile the levels of NLRP3, active caspase-1, NF-κB, and interleukin-1β were elevated. All these abnormal alterations could be largely reversed after treatment of short hairpin RNA (shRNA) targeting P2Y12. Our results indicate that the silence of P2Y12 by shRNA may effectively correct the anomalous activity of celiac SND and improve the dysfunctional hepatic glucokinase by counteracting hepatocyte inflammation and likely pyroptosis due to activated NLRP3 inflammasome and caspase-1 signaling, thereby attenuating hyperglycemia in T2DM rats.

Nutritional and medical food therapies for diabetic retinopathy

Diabetic retinopathy (DR) is a form of microangiopathy. Reducing oxidative stress in the mitochondria and cell membranes decreases ischemic injury and end-organ damage to the retina. New approaches are needed, which reduce the risk and improve the outcomes of DR while complementing current therapeutic approaches. Homocysteine (Hcy) elevation and oxidative stress are potential therapeutic targets in DR. Common genetic polymorphisms such as those of methylenetetrahydrofolate reductase (MTHFR), increase Hcy and DR risk and severity. Patients with DR have high incidences of deficiencies of crucial vitamins, minerals, and related compounds, which also lead to elevation of Hcy and oxidative stress. Addressing the effects of the MTHFR polymorphism and addressing comorbid deficiencies and insufficiencies reduce the impact and severity of the disease. This approach provides safe and simple strategies that support conventional care and improve outcomes. Suboptimal vitamin co-factor availability also impairs the release of neurotrophic and neuroprotective growth factors. Collectively, this accounts for variability in presentation and response of DR to conventional therapy. Fortunately, there are straightforward recommendations for addressing these issues and supporting traditional treatment plans. We have reviewed the literature for nutritional interventions that support conventional therapies to reduce disease risk and severity. Optimal combinations of vitamins B1, B2, B6, L-methylfolate, methylcobalamin (B12), C, D, natural vitamin E complex, lutein, zeaxanthin, alpha-lipoic acid, and n-acetylcysteine are identified for protecting the retina and choroid. Certain medical foods have been successfully used as therapy for retinopathy. Recommendations based on this review and our clinical experience are developed for clinicians to use to support conventional therapy for DR. DR from both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have similar retinal findings and responses to nutritional therapies.

Unlocking the Potential of HK2 in Cancer Metabolism and Therapeutics

Glycolysis is a tightly regulated process in which several enzymes, such as Hexokinases (HKs), play crucial roles. Cancer cells are characterized by specific expression levels of several isoenzymes in different metabolic pathways and these features offer possibilities for therapeutic interventions. Overexpression of HKs (mostly of the HK2 isoform) have been consistently reported in numerous types of cancer. Moreover, deletion of HK2 has been shown to decrease cancer cell proliferation without explicit side effects in animal models, which suggests that targeting HK2 is a viable strategy for cancer therapy. HK2 inhibition causes a substantial decrease of glycolysis that affects multiple pathways of central metabolism and also destabilizes the mitochondrial outer membrane, ultimately enhancing cell death. Although glycolysis inhibition has met limited success, partly due to low selectivity for specific isoforms and excessive side effects of the reported HK inhibitors, there is ample ground for progress. The current review is focused on HK2 inhibition, envisaging the development of potent and selective anticancer agents. The information on function, expression, and activity of HKs is presented, along with their structures, known inhibitors, and reported effects of HK2 ablation/inhibition. The structural features of the different isozymes are discussed, aiming to stimulate a more rational approach to the design of selective HK2 inhibitors with appropriate drug-like properties. Particular attention is dedicated to a structural and sequence comparison of the structurally similar HK1 and HK2 isoforms, aiming to unveil differences that could be explored therapeutically. Finally, several additional catalytic- and non-catalytic roles on different pathways and diseases, recently attributed to HK2, are reviewed and their implications briefly discussed.

Lactobacillus rhamnosus Reduces Blood Glucose Level through Downregulation of Gluconeogenesis Gene Expression in Streptozotocin-Induced Diabetic Rats

Some lactic acid bacteria (LAB) are observed to be potential probiotics with functional properties such as lowering fasting blood glucose (FBG), as a promising hyperglycemia management. This study investigated the ability and mechanism of Lactobacillus rhamnosus BSL and Lactobacillus rhamnosus R23 on lowering FBG in diabetic rats induced by streptozotocin (STZ). The rats were orally administered with L. rhamnosus BSL and L. rhamnosus R23 by giving 1 mL cell suspension (10⁹ CFU/mL) daily for 30 days. The body weight (BW) was recorded once in three days, and FBG was recorded once in six days. An oral glucose tolerance test (OGTT) was measured 1 week after injection with STZ and before sacrifice. Fecal samples were collected on days 0, 15, and 30 for LAB population and identification, performed by PCR detecting 16S rRNA. Oral administration of L. rhamnosus BSL and L. rhamnosus R23 decreased FBG and improved glucose tolerance via downregulation of glucose-6-phosphatase (G6pc) expression by 0.57- and 0.60-fold change, respectively (P < 0.05). The lipid profiles, BUN, creatinine, SGOT, and SGPT were significantly (P < 0.05) different between normal and diabetic rats, but they were not significantly (P > 0.05) different among diabetic rats. Both strains were effective in increasing fecal LAB population. Molecular identification of the isolated LAB from fecal sample indicated that they were able to survive and pass through the digestive tract. These results suggested that both strains have the ability to manage blood glucose level and become a promising agent to manage hyperglycemia and diabetes.