An overview of metformin in the treatment of type 2 diabetes mellitus

Metformin: Past, Present, and Future

PURPOSE OF REVIEW

This review provides the most recent update of metformin, a biguanide oral antihyperglycemic drug used as a first-line treatment in type 2 diabetes mellitus.

RECENT FINDINGS

Metformin continues to dominate in the world of antidiabetics, and its use will continue to rise because of its high efficiency and easy availability. Apart from type 2 diabetes, research is exploring its potential in other conditions such as cancer, memory loss, bone disorders, immunological diseases, and aging. Metformin is the most prescribed oral antidiabetic worldwide. It has been in practical use for the last six decades and continues to be the preferred drug for newly diagnosed type 2 diabetes mellitus. It reduces glucose levels by decreasing hepatic glucose production, reducing intestinal glucose absorption, and increasing insulin sensitivity. It can be used as monotherapy or combined with other antidiabetics like sulfonylureas, DPP-4 inhibitors, SGLT-2 inhibitors, or insulin, improving its efficacy. Metformin can be used once or twice daily, depending on requirements. Prolonged usage of metformin may lead to abdominal discomfort, deficiency of Vitamin B12, or lactic acidosis. It should be used carefully in patients with renal impairment. Recent studies have explored additional benefits of metformin in polycystic ovarian disease, gestational diabetes mellitus, cognitive disorders, and immunological diseases. However, more extensive studies are needed to confirm these additional benefits.

INTERACTIONS OF METFORMIN AND OTHER MEDICATIONS IN REDUCING THE ODDS OF AGE-RELATED MACULAR DEGENERATION IN A COHORT OF PATIENTS WITH DIABETES

PURPOSE

A previous study from our group demonstrated protective effects of the use of metformin in the odds of developing age-related macular degeneration (AMD). This is a subgroup analysis in a cohort of patients with diabetes to assess the interaction of metformin and other medications in protecting diabetic patients against developing AMD.

METHODS

This is a case-control analysis using data from the Merative MarketScan Commercial and Medicare databases. Patients were 55 years and older with newly diagnosed AMD and matched to controls. We performed multivariable conditional logistic regressions, which adjusted for known risk factors of AMD and tested multiple interaction effects between metformin and 1) insulin, 2) sulfonylureas, 3) glitazones, 4) meglitinides, and 5) statins.

RESULTS

The authors identified 81,262 diabetic cases and 79,497 diabetic controls. Metformin, insulin, and sulfonylureas demonstrated independent protective effects against AMD development. Sulfonylureas in combination with metformin demonstrated further decreased odds of AMD development compared with metformin alone. The other medication group (exenatide, sitagliptin, and pramlintide) slightly increased the odds of developing AMD when taken alone, but the combination with metformin alleviated this effect.

CONCLUSION

The authors believe that their results bring them one step closer to finding an optimal effective hypoglycemic regimen that also protects against AMD development in diabetic patients.

The role and implication of autophagy in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a malignant tumor that originates from the biliary epithelial cells. It is characterized by a difficult diagnosis and limited treatment options. Autophagy is a cellular survival mechanism that maintains nutrient and energy homeostasis and eliminates intracellular pathogens. It is involved in various physiological and pathological processes, including the development of cancer. However, the role, mechanism, and potential therapeutic targets of autophagy in CCA have not been thoroughly studied. In this review, we introduce the classification, characteristics, process, and related regulatory genes of autophagy. We summarize the regulation of autophagy on the progression of CCA and collect the latest research progress on some autophagy modulators with clinical potential in CCA. In conclusion, combining autophagy modulators with immunotherapy, chemotherapy, and targeted therapy has great potential in the treatment of CCA. This combination may be a potential therapeutic target for CCA in the future.

Predictors of Metformin Side Effects in Patients with Newly Diagnosed Type 2 Diabetes Mellitus

Introduction Metformin has become the first-line agent for the treatment of type 2 diabetes mellitus (T2DM) in several international guidelines. Up to 25% of patients suffer from gastrointestinal side-effects, with approximately 5% unable to tolerate metformin at all.

Objective We aimed to study the effect of variables that may influence the development of metformin side effects and/or intolerance.

Method A prospective study was conducted from April 1, 2021 to March 30, 2022. One-hundred and forty-eight patients newly diagnosed with T2DM were enrolled in the study, and divided into two groups—those who were escalate to the maximum dose of metformin over 2 weeks (n = 43) and the other group over 4 weeks (n = 105). We studied the variables that may affect the development of side effects including age, gender, body mass index (BMI), lipid profile, glycemic level, and the use of other antidiabetic medications besides the duration of dose escalation.

Results Total number of patients who developed side effects was 59 (39.9%). Twenty-four (55.8%) and 35 (33.3%) patients were put in the rapid and slow escalation groups, respectively. Twenty-six (17.6%) patients developed diarrhea that was the most common side effect. Two (2.7%) men and ten women (13.5%) had stopped metformin due to severe side effects developed after initiation (p = 0.016). The mean BMI for the patients who discontinued metformin was 34.7 ± 4.1 kg/m2 in the rapid escalation arm and 31.6 ± 3.3 kg/m2 in the slow escalation arm (p = 0.003). The mean of fasting blood glucose for the patients who discontinued metformin in the rapid and slow escalation arms was 200.6 ± 25.6 and 173.4 ± 36.5 mg/dL, respectively (p = 0.022).

Conclusion The severity of metformin side effects is higher in women than in men, making more women to discontinue the drug. Besides, a higher fasting blood sugar and BMI are associated with a higher rate of discontinuation. A rapid dose escalation is associated with a higher frequency of side effects. Diarrhea is the commonest side effect encountered.

Anti-Obesity Effects of Metformin: A Scoping Review Evaluating the Feasibility of Brown Adipose Tissue as a Therapeutic Target

Brown adipose tissue (BAT) is increasingly recognized as the major therapeutic target to promote energy expenditure and ameliorate diverse metabolic complications. There is a general interest in understanding the pleiotropic effects of metformin against metabolic complications. Major electronic databases and search engines such as PubMed/MEDLINE, Google Scholar, and the Cochrane library were used to retrieve and critically discuss evidence reporting on the impact of metformin on regulating BAT thermogenic activity to ameliorate complications linked with obesity. The summarized evidence suggests that metformin can reduce body weight, enhance insulin sensitivity, and improve glucose metabolism by promoting BAT thermogenic activity in preclinical models of obesity. Notably, this anti-diabetic agent can affect the expression of major thermogenic transcriptional factors such as uncoupling protein 1 (UCP1), nuclear respiratory factor 1 (NRF1), and peroxisome-proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α) to improve BAT mitochondrial function and promote energy expenditure. Interestingly, vital molecular markers involved in glucose metabolism and energy regulation such as AMP-activated protein kinase (AMPK) and fibroblast growth factor 21 (FGF21) are similarly upregulated by metformin treatment in preclinical models of obesity. The current review also discusses the clinical relevance of BAT and thermogenesis as therapeutic targets. This review explored critical components including effective dosage and appropriate intervention period, consistent with the beneficial effects of metformin against obesity-associated complications.

Metformin suppresses SARS-CoV-2 in cell culture

Comorbidities such as diabetes worsen COVID-19 severity and recovery. Metformin, a first-line medication for type 2 diabetes, has antiviral properties and certain studies have also indicated its prognostic potential in COVID-19. Here, we report that metformin significantly inhibits SARS-CoV-2 growth in cell culture models. First, a steady increase in AMPK phosphorylation was detected as infection progressed, suggesting its important role during viral infection. Activation of AMPK in Calu3 and Caco2 cell lines using metformin revealed that metformin suppresses SARS-CoV-2 infectious titers up to 99%, in both naïve as well as infected cells. IC50 values from dose-variation studies in infected cells were found to be 0.4 and 1.43 mM in Calu3 and Caco2 cells, respectively. Role of AMPK in metformin's antiviral suppression was further confirmed using other pharmacological compounds, AICAR and Compound C. Collectively, our study demonstrates that metformin is effective in limiting the replication of SARS-CoV-2 in cell culture and thus possibly could offer double benefits as diabetic COVID-19 patients by lowering both blood glucose levels and viral load.

The ameliorating effects of metformin on disarrangement ongoing in gastrocnemius muscle of sarcopenic and obese sarcopenic mice

Sarcopenia and obese sarcopenia are increasingly prevalent chronic diseases with multifactorial pathogenesis, and no approved therapeutic drug to date. In the established sarcopenic mice models, muscle weakness, ectopic lipid deposition, and inflammatory responses in both serum and gastrocnemius muscle were observed, which were even deteriorated in obese sarcopenic models. With metformin intervention for 5 months, metformin exhibited benefits and restoring effects on gastrocnemius muscle of sarcopenic mice, but less effective on that of obese sarcopenic mice, as reflected in the increased percentage of muscle mass and enlarged fiber cross-sectional area, enhanced grip strength and exercise capacities, as well as the ameliorated ectopic lipid deposition and partially restored level of TNF-α, IL-1β, IL-6, MCP-1 and IL-1α, which may be via the activation of phospho-AMPKα (Thr172). The significant up-regulated mRNA and protein level of lipolysis related proteins like hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) may contribute to the ameliorated ectopic lipid deposition with metformin intervention. The uptake of free fatty acid may be also inhibited in obese sarcopenic mice with metformin administration, as reflected in down-regulated mRNA and protein level of fatty acid transporter CD36. Furthermore, NF-κB signaling pathway was involved in the anti-inflammatory effect of metformin. These findings suggest that metformin treatment may be conducive to the prevention of age-related sarcopenia by regulating lipid metabolism in skeletal muscle, i.e. enhanced lipolysis and attenuated hyper-inflammatory responses, which may be AMPK-dependent processes. Moreover, high-fat diet would aggravate the damage to ageing in skeletal muscles and reduced their reactivity to metformin.

The Mechanism of Action of Biguanides: New Answers to a Complex Question

Biguanides are a family of antidiabetic drugs with documented anticancer properties in preclinical and clinical settings. Despite intensive investigation, how they exert their therapeutic effects is still debated. Many studies support the hypothesis that biguanides inhibit mitochondrial complex I, inducing energy stress and activating compensatory responses mediated by energy sensors. However, a major concern related to this “complex” model is that the therapeutic concentrations of biguanides found in the blood and tissues are much lower than the doses required to inhibit complex I, suggesting the involvement of additional mechanisms. This comprehensive review illustrates the current knowledge of pharmacokinetics, receptors, sensors, intracellular alterations, and the mechanism of action of biguanides in diabetes and cancer. The conditions of usage and variables affecting the response to these drugs, the effect on the immune system and microbiota, as well as the results from the most relevant clinical trials in cancer are also discussed.

Expression of Caspase-3 in Circulating Innate Lymphoid Cells Subtypes Is Altered by Treatment with Metformin and Fluvastatin in High-Fat Diet Fed C57BL/6 Mice

The current study aimed to determine the expression levels of caspase-3 in circulating innate lymphoid cell subtypes (ILCs) in a high-fat diet (HFD)-induced prediabetes mouse model. Another critical point was to assess the therapeutic effects of metformin and fluvastatin in modulating caspase-3 activation in ILCs within these HFD-fed mice. Prominent results showed that mice exposed to HFD for 14 weeks displayed impaired glucose tolerance that was accompanied by elevated levels of low-density lipoprotein cholesterol (LDL-c) and altered haematological profile as characterised by significantly increased concentrations of red blood cell count, white cell count and lymphocytes when compared to those fed a low-fat diet (LFD). Moreover, the expression of caspase-3 in ILC1 and ILC3 was significantly increased in the HFD groups in comparison to the LFD-fed group. Notably, six-week treatment with metformin and fluvastatin reduced the caspase-3 activation in ILC subtypes. The reduced caspase-3 activation in ILC1 was inversely associated with HDL-c levels following metformin treatment. Interestingly, the reduced caspase-3 activation in ILC3 was associated with lower total cholesterol following fluvastatin treatment in these HFD-fed mice. However, there were no differences in activation of caspase-3 on ILC2 or any association between caspase-3 activation and changes in body weight or fasting blood glucose. Thus, while HFD-feeding clearly modulates ILCs, potentially leading to pro-apoptotic mechanisms, metformin and fluvastatin may play a major role in protecting against such metabolic disturbances.

Metformin Inhibits Na+/H+ Exchanger NHE3 Resulting in Intestinal Water Loss

Glycemic control is the key to the management of type 2 diabetes. Metformin is an effective, widely used drug for controlling plasma glucose levels in diabetes, but it is often the culprit of gastrointestinal adverse effects such as abdominal pain, nausea, indigestion, vomiting, and diarrhea. Diarrhea is a complex disease and altered intestinal transport of electrolytes and fluid is a common cause of diarrhea. Na+/H+ exchanger 3 (NHE3, SLC9A3) is the major Na+ absorptive mechanism in the intestine and our previous study has demonstrated that decreased NHE3 contributes to diarrhea associated with type 1 diabetes. The goal of this study is to investigate whether metformin regulates NHE3 and inhibition of NHE3 contributes to metformin-induced diarrhea. We first determined whether metformin alters intestinal water loss, the hallmark of diarrhea, in type 2 diabetic db/db mice. We found that metformin decreased intestinal water absorption mediated by NHE3. Metformin increased fecal water content although mice did not develop watery diarrhea. To determine the mechanism of metformin-mediated regulation of NHE3, we used intestinal epithelial cells. Metformin inhibited NHE3 activity and the effect of metformin on NHE3 was mimicked by a 5'-AMP-activated protein kinase (AMPK) activator and blocked by pharmacological inhibition of AMPK. Metformin increased phosphorylation and ubiquitination of NHE3, resulting in retrieval of NHE3 from the plasma membrane. Previous studies have demonstrated the role of neural precursor cell expressed, developmentally down-regulated 4-2 (Nedd4-2) in regulation of human NHE3. Silencing of Nedd4-2 mitigated NHE3 inhibition and ubiquitination by metformin. Our findings suggest that metformin-induced diarrhea in type 2 diabetes is in part caused by reduced Na+ and water absorption that is associated with NHE3 inhibition, probably by AMPK.

Chronic Embryo-Larval Exposure of Fathead Minnows to the Pharmaceutical Drug Metformin: Survival, Growth, and Microbiome Responses

Metformin is a glucose-lowering drug commonly found in municipal wastewater effluents (MWWEs). The present study investigated the chronic effects of metformin in early-life stages of the fathead minnow (Pimephales promelas). Endpoints assessed were growth, survival, and deformities. The larval gut microbiome was also examined using 16 S ribosomal RNA gene amplicon sequencing to determine microbial community composition and alpha and beta diversity. Eggs and larvae were exposed to metformin measured concentrations (mean [standard deviation]) of 0.020 (0.017) μg/L (for controls) and 3.44 (0.23), 33.6 (1.6), and 269 (11) μg/L in a daily static-renewal setup, with 20 embryos per beaker. The low and middle metformin exposure concentrations represent river and MWWE concentrations of metformin. To detect small changes in growth, we used 18 replicate beakers for controls and 9 replicates for each metformin treatment. Over the 21-d exposure (5 d as embryos and 16 d posthatch [dph]), metformin did not affect survival or growth of larval fish. Hatch success, time to hatch, deformities in hatched fry, and survival were similar across all treatments. Growth (wet wt, length, and condition factor) assessed at 9 and 16 dph was also unaffected by metformin. Assessment of the microbiome showed that the larvae microbiome was dominant in Proteobacteria and Firmicutes, with small increases in Proteobacteria and decreases in Firmicutes with increasing exposure to metformin. No treatment effects were found for microbiome diversity measures. Control fish euthanized with the anesthetic tricaine methane sulfonate had decreased alpha diversity compared to those sampled by spinal severance. This experiment demonstrates that metformin at environmentally relevant concentrations (3.44 and 33.6 μg/L) and at 10 times MWWE concentrations (269 µg/L) does not adversely affect larval growth or gut microbiome in this ubiquitous freshwater fish species. Environ Toxicol Chem 2022;41:635-647. © 2021 Her Majesty the Queen in Right of Canada. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Natural and Synthetic Agents Targeting Reactive Carbonyl Species against Metabolic Syndrome

Reactive carbonyl species (RCS) may originate from the oxidation of unsaturated fatty acids and sugar in conditions of pathology. They are known to have high reactivity towards DNA as well as nucleophilic sites of proteins, resulting in cellular dysfunction. It has been considered that various pathological conditions are associated with an increased level of RCS and their reaction products. Thus, regulating the levels of RCS may be associated with the mitigation of various metabolic and neurodegenerative disorders. In order to perform a comprehensive review, various literature databases, including MEDLINE, EMBASE, along with Google Scholar, were utilized to obtain relevant articles. The voluminous review concluded that various synthetic and natural agents are available or in pipeline research that hold tremendous potential to be used as a drug of choice in the therapeutic management of metabolic syndrome, including obesity, dyslipidemia, diabetes, and diabetes-associated complications of atherosclerosis, neuropathy, and nephropathy. From the available data, it may be emphasized that various synthetic agents, such as carnosine and simvastatin, and natural agents, such as polyphenols and terpenoids, can become a drug of choice in the therapeutic management for combating metabolic syndromes that involve RCS in their pathophysiology. Since the RCS are known to regulate the biological processes, future research warrants detailed investigations to decipher the precise mechanism.

Evaluation of Dose-Dependent Obesity and Diabetes-Related Complications of Water Chestnut (Fruit of Trapa japonica) Extracts in Type II Obese Diabetic Mice Induced by 45% Kcal High-Fat Diet

Background and Objectives: The currently used pharmacological agents for metabolic disorders such as type II diabetes have several limitations and adverse effects; thus, there is a need for alternative therapeutic drugs and health functional foods. Materials and Methods: This study investigated the pharmacological effects of water chestnut (fruit of Trapa japonica) extracts (WC: 50–200 mg/kg) for type II diabetes using a 45% Kcal high-fat diet (HFD)-fed type II obese diabetic mice model for a period of 84 days, and the effects were compared to those of metformin (250 mg/kg). Results: Increases in body weight, serum biochemical indices such as triglycerides, low-density lipoprotein, and blood urea nitrogen, increases in antioxidant defense system enzymes such as catalase, superoxide dismutase, and glutathione, and mRNA expressions (such as AMPKα1 and AMPKα2) in the liver tissue and mRNA expressions (such as AMPKα2 mRNA, leptin, and C/EBPα) in the adipose tissue were observed in the HFD control group. The WC (50 mg/kg)-administered group showed no significant improvements in diabetic complications. However, HFD-induced obesity and diabetes-related complications such as hyperlipidemia, diabetic nephropathy, nonalcoholic fatty liver disease (NAFLD), oxidative stress, activity of antioxidant defense systems, and gene expressions were significantly and dose-dependently inhibited and/or normalized by oral administration of WC (100 mg/kg and 200 mg/kg), particularly at a dose of 100 mg/kg. Conclusions: The results of this study suggest that WC at an appropriate dose could be used to develop an effective therapeutic drug or functional food for type II diabetes and various associated complications, including NAFLD.

Research advances on how metformin improves memory impairment in "chemobrain"

Cognitive impairment caused by chemotherapy, referred to as “chemobrain,” is observed in approximately 70% of cancer survivors. However, it is not completely understood how chemotherapy induces cognitive dysfunction, and clinical treatment strategies for this problem are lacking. Metformin, used as a first-line treatment for type 2 diabetes mellitus, is reported to reduce the effects of chemobrain. Recently, several studies have examined the effect of metformin in rescuing chemobrain. This review discusses recent clinical/preclinical studies that addressed some mechanisms of chemobrain and evaluates the effect of metformin in rescuing chemobrain and its potential mechanisms of action.

Pharmaceutical and transformation products during unplanned water reuse: Insights into natural attenuation, plant uptake and human health impact under field conditions

In urban and periurban areas, agricultural soils are often irrigated with surface water containing a complex mixture of contaminants due to wastewater treatment plant (WWTP) effluent discharges. The unplanned water reuse of these resources for crop irrigation can represent a pathway for contaminant propagation and a potential health risk due to their introduction in the food chain. The aim of this study is to provide data about the magnitude of attenuation processes and plant uptake, allowing for a reliable assessment of contaminant transfer among compartments and of the human health risk derived from unplanned water reuse activities. Target compounds are 25 pharmaceuticals, including transformation products (TPs). The field site is an agricultural parcel where maize is irrigated by a gravity-fed surface system supplied by the Jarama river, a water course strongly impacted by WWTP effluents. Throughout the 3-month irrigation period, irrigation water and water infiltrating through the vadose zone were sampled. The agricultural soil was collected before and after the irrigation campaign, and maize was sampled before harvesting. All selected compounds are detected in irrigation water (up to 12,867 ng L^-1). Metformin, two metamizole TPs and valsartan occur with the highest concentrations. For most pharmaceuticals, results demonstrate a high natural attenuation during soil infiltration (>60%). However, leached concentrations of some compounds can be still at concern level (>400 ng L^-1). A persistent behavior is observed for carbamazepine, carbamazepine epoxide and sulfamethoxazole. Pharmaceutical soil contents are in the order of ng g^-1 and positively ionized compounds accumulate more effectively. Results also indicate the presence of a constant pool of drugs in soils. Only neutral and cationic pharmaceuticals are taken up in maize tissues, mainly in the roots. There is an insignificant threat to human health derived from maize consumption however, additional toxicity tests are recommended for 4AAA and acetaminophen.

Metforminin tek başına veya valproik asit ile beraber farelerde pentilentetrazol ile indüklenen nöbetler üzerine koruyucu etkisi

Amaç: Bu çalışmanın amacı, metforminin pentilentetrazol (PTZ) ile indüklenen nöbet davranışı üzerindeki etkilerini ve nöronal hasar üzerindeki nöroprotektif etkisini araştırmaktır. Gereç ve Yöntemler: 35-38 g ağırlığındaki otuz beş (35) Erkek BALB-c Albino fare rastgele beş gruba ayrıldı. Kontrol grubu, PTZ; PTZ enjekte edildi, VPA (200 mg / kg i.p.), Metformin (200 mg / kg i.p.) ve VPA + Metformin. Pentilentetrazol (PTZ) (60 mg / kg, i.p.), nöbetleri indüklemek için ilaç enjeksiyonundan 30 dakika sonra enjekte edildi ve nöbet aşamaları ve davranışsal skorlama değerlendirildi. İşlem tamamlandıktan sonra beyin dokuları çıkarıldı ve biyokimyasal ve histopatolojik prosedürlerle analiz edildi. Hipokampal Cornu Ammonis (CA) 1, CA2, CA3 ve DG (dentat girus) bölgeleri histopatolojik olarak değerlendirildi ve oksidatif stres belirteçleri (toplam antioksidan durum (TAS), toplam oksidan durum (TOS) ölçüldü. Bulgular: PTZ grubuyla karşılaştırıldığında, Metformin tek başına FMJ başlangıç süresini etkilemedi, ancak VPA ve Metformin kombinasyonu FMJ başlangıç süresini anlamlı derecede artırdığı gözlendi (p

Renal gluconeogenesis in insulin resistance: A culprit for hyperglycemia in diabetes

Renal gluconeogenesis is one of the major pathways for endogenous glucose production. Impairment in this process may contribute to hyperglycemia in cases with insulin resistance and diabetes. We reviewed pertinent studies to elucidate the role of renal gluconeogenesis regulation in insulin resistance and diabetes. A consensus on the suppressive effect of insulin on kidney gluconeogenesis has started to build up. Insulin-resistant models exhibit reduced insulin receptor (IR) expression and/or post-receptor signaling in their kidney tissue. Reduced IR expression or post-receptor signaling can cause impairment in insulin’s action on kidneys, which may increase renal gluconeogenesis in the state of insulin resistance. It is now established that the kidney contributes up to 20% of all glucose production via gluconeogenesis in the post-absorptive phase. However, the rate of renal glucose release excessively increases in diabetes. The rise in renal glucose release in diabetes may contribute to fasting hyperglycemia and increased postprandial glucose levels. Enhanced glucose release by the kidneys and renal expression of the gluconeogenic-enzyme in diabetic rodents and humans further point towards the significance of renal gluconeogenesis. Overall, the available literature suggests that impairment in renal gluconeogenesis in an insulin-resistant state may contribute to hyperglycemia in type 2 diabetes.

Lipophagy: A New Perspective of Natural Products in Type 2 Diabetes Mellitus Treatment

Autophagy has been reported to involve in the pathogenesis of type 2 diabetes mellitus (T2DM), which protects the insulin target tissues and pancreatic β-cells. However, autophagy is inhibited when the cells are lipid overload. That, in turn, increases the accumulation of fat. Lipotoxicity caused by excessive lipid accumulation contributes to pathogenesis of T2DM. Therefore, it is undeniable to break the vicious circles between lipid excess and autophagy deficiency. Lipophagy, a selective form of autophagy, is characterized by selective breakdown of lipid droplets (LDs). The nutritional status of cells contributes to the way of autophagy (selective or non-selective), while selective autophagy helps to accurately remove excess substances. It seems that lipophagy could be an effective means to decrease abnormal lipid accumulation that leads to insulin resistance and β-cell impairment by removing ectopic LDs. Based on this process, many natural compounds have been reported to decrease lipid accumulation in tissues through autophagy-lysosomal pathway, which gradually highlights the significance of lipophagy. In this review, we focus on the mechanisms that lipophagy improves T2DM and natural products that are applied to induce lipophagy. It is also suggested that natural herbs with rich contents of natural products inducing lipophagy would be potential candidates for alleviating T2DM.

Application of elastin-like biopolymer-conjugated C-peptide hydrogel for systemic long-term delivery against diabetic aortic dysfunction

Due to their short half-lives, repeated administration of anti-hyperglycemic drugs can cause pain, discomfort, tissue damage, and infection in diabetic patients. Therefore, there is a need to develop long-term drug delivery systems to treat diabetes and its complications. C-peptide can prevent diabetic complications, including diabetic vasculopathy, but its clinical application is limited by its short half-life. Here, we developed K9-C-peptide (human C-peptide conjugated to an elastin-like biopolymer) and investigated its long-term influence on hyperglycemia-induced vascular dysfunction using an aortic endothelium model in diabetic mice. Using pharmacokinetics and in vivo imaging, we found that subcutaneously injected K9-C-peptide formed a hydrogel depot that slowly released human C-peptide into the blood circulation for 19 days. Administration of K9-C-peptide, human C-peptide, or K8 polypeptide had no effect on body weight or blood glucose levels. The slow release of C-peptide from K9-C-peptide hydrogels provided prolonged prevention of oxidative stress, inflammatory responses, and endothelial apoptosis in a hyperglycemia-induced vascular dysfunction model using the diabetic mouse aorta. Subcutaneous administration of unbound human C-peptide and K8 polypeptide were used as negative controls and had no effects. These results suggest that K9-C-peptide is suitable for the long-term delivery of human C-peptide for treating vascular dysfunction in diabetic patients.

Development and characterization of metformin hydrochloride- and glyburide-containing orally disintegrating tablets

Diabetes is characterized by chronic hyperglycemia. Although metformin hydrochloride (MHCl)- and glyburide (GLB)-containing conventional tablets are available in the market and used to treat diabetes, orally disintegrating tablets (ODTs) containing the combination of these drugs are not commercially available. Therefore, the aim of this study was to prepare ODTs containing MHCl and GLB by direct-compression (DC-ODTs) and freeze-drying (FD-ODTs) methods. Physical properties of the powder mixture of DC-ODT formulation were determined (Angle of repose: 37.18 ± 1.27°; compressibility index: 20.31 ± 1.06%; Hausner ratio: 1.25 ± 0.03). Its moisture content was 0.3 ± 0.09%. The hardness values and the disintegration times for DC-ODTs and FD-ODTs were 221.60 ± 40.82 and 66.54 ± 2.68 N, and 80 and 30 s, respectively. Friability values were 0.24% for DC-ODTs and 0.38% for FD-ODTs. In uniformity-of-mass for single-dose-preparations test, the average weight was 684.38 ± 1.97 mg for DC-ODTs and 342.93 ± 2.4 mg for FD-ODTs, with less than 5% deviation for all 20 tablets. Water-absorption ratio for DC-ODTs was 1.30 ± 0.05. More than 90% of MHCl and GLB were dissolved within 5 min in both DC-ODTs and FD-ODTs. Although Caco-2 permeability of MHCl was influenced by the ODTs, GLB permeability was not. These results indicated that MHCl- and GLB-containing ODTs may be used as promising formulations for the treatment of diabetes.

Toxicity of Metformin and Hypoglycemic Therapies

Metformin along with other antidiabetic medications provide benefit to patients in the treatment of type 2 diabetes mellitus, but caution is advised in certain scenarios to avoid toxicity in kidney disease. Renal dosing, monitoring of kidney function, and evaluating the risk of developing serious side effects are warranted with some agents. The available literature with regard to incidence of adverse events and toxicity of hypoglycemic therapies is reviewed.

Metformin and LW6 impairs pancreatic cancer cells and reduces nuclear localization of YAP1

The poor survival rate of pancreatic cancer is still a major challenge for the clinicians and their patients. In this study, we evaluated the efficacy of metformin, an inhibitor of oxidative phosphorylation, in combination with LW6, which impairs malate dehydrogenase 2 activities, in treating pancreatic cancer cells. We observed that this combinational therapy significantly reduced cell proliferation, migration, and significantly induced cell death when compared to cells treated by each monotherapy or Sham. In addition, we found that the combination of metformin and LW6 increased the phosphorylation of yes-associated protein 1 at serine 127 and attenuated the nuclear localization of this transcription factor. This combinatorial treatment also decreased the level of cellular yes-associated protein 1. This suggests that metformin in combination with LW6 impairs pancreatic cancer cells and reduces nuclear localization of yes-associated protein 1.

Ishige okamurae Extract Ameliorates the Hyperglycemia and Body Weight Gain of db/db Mice through Regulation of the PI3K/Akt Pathway and Thermogenic Factors by FGF21

Type 2 diabetes mellitus and related metabolic disorders, such as dyslipidemia, present increasing challenges to health worldwide, as a result of urbanization, the increasing prevalence of obesity, poor lifestyle, and other stress-related factors. Ishige okamurae extract (IOE) is known to be effective at lowering blood glucose and ameliorating metabolic disease. However, detailed mechanisms for these effects have yet to be elucidated. Here, we show that IOE ameliorates substrate (IRS)/ phosphatidylinositol 3-kinase (PI3K)/Akt pathway and increasing glucose transporter 4 (GLUT4) expression in skeletal muscle and white adipose tissue (WAT). We also demonstrate that IOE increases the expression of fibroblast growth factor (FGF)21, a regulator of glucose and energy metabolism in muscle and WAT. In addition, IOE administration increased peroxisome proliferator-activated receptor γ coactivator 1α expression, which regulates expression of the key thermogenic molecule uncoupling protein 1 in WAT. Thus, the effects of IOE to ameliorate hyperglycemia and adiposity may be mediated through FGF21 activating insulin signaling and increasing the expression of GLUT4 and pro-thermogenic factors.

Bioequivalence of Ertugliflozin/Metformin Fixed-Dose Combination Tablets and Coadministration of Respective Strengths of Individual Components

A fixed‐dose combination (FDC) of ertugliflozin, a selective sodium‐glucose cotransporter 2 inhibitor, and immediate‐release metformin is approved for the treatment of type 2 diabetes mellitus in the United States and European Union. Four open‐label, randomized, 2‐period, single‐dose, crossover studies were conducted under fasted conditions in healthy subjects to demonstrate bioequivalence of the ertugliflozin/metformin FDC tablets and coadministration of the individual components at respective strengths. In each study, 32 or 34 subjects received an ertugliflozin/metformin FDC tablet (2.5 mg/500 mg, 7.5 mg/850 mg, or 7.5 mg/1000 mg) and the respective doses of individual components (ertugliflozin with US‐ or EU‐sourced metformin [Glucophage]). Plasma samples for ertugliflozin and metformin concentrations were collected for 72 hours in each period. For both ertugliflozin and metformin, the 90% confidence intervals for the adjusted geometric mean ratio (FDC : coadministration) for area under the plasma concentration–time profile from time zero extrapolated to infinity and maximum observed plasma concentration were within acceptance criteria for bioequivalence. The majority of adverse events were mild in intensity. The studies demonstrated that each strength of FDC tablet is bioequivalent to respective doses of coadministered individual components, supporting that safety and efficacy can be bridged to the individual components used in phase 3 studies evaluating ertugliflozin in combination with metformin.

Hepatoprotective activity of metformin: A new mission for an old drug?

Metformin, as a dimethyl biguanide prescribed as the first-line medication for treatment of type 2 diabetes mellitus, is one of the most frequently used drugs, worldwide. However, the beneficial effects of metformin are not limited to insulin sensitizing and blood glucose lowering effects as recent clinical trials deciphered lower cancer risk in metformin users. In addition, metformin protected the liver against chemical or viral hepatotoxicants through various mechanisms including activation of AMPK via inhibition of mitochondrial complex I, inhibition of mitogen activated protein kinase (MAPK) and inhibition of Smads phosphorylation. Clinical trials are under way to assess possible additive effects of metformin when co-administered along with the standard regimen for hepatocellular carcinoma (HCC) treatment. This review outlines the molecular mechanisms behind protective activity of metformin against different liver diseases.

Characterization of changes in HbA1c in patients with and without secondary failure after metformin treatments by a population pharmacodynamic analysis using mixture models

The objective of the present study was to develop a population pharmacodynamic (PPD) model to describe the glycated hemoglobin (HbA1c)-lowering effects of metformin in type 2 diabetes mellitus patients with and without secondary failure and to characterize changes in HbA1c levels in the two subpopulations using a mixture model. Information on patients was collected retrospectively from electronic medical records. In this study, the mixture model was used to characterize the bimodal effects of metformin. A PPD analysis was performed using NONMEM 7.3.0. A physiological indirect response model, based on 829 HbA1c levels of 69 patients, described the time course for the HbA1c-lowering effects of metformin. Evidence for the different effectiveness of metformin subpopulations was provided using the mixture model. In the final PPD model, the inhibition effect was constant over a study duration in a patient subpopulation without secondary failure. In contrast, the inhibition effect decreased as a function of time after start of metformin treatment in a subpopulation with secondary failure. These results indicated that HbA1c improvements appeared to deteriorate over time in patients with secondary failure. In a PPD analysis of metformin, it was possible to assign patients with secondary failure using the mixture model.

Investigation of the Role of a Supplementation with Taurine on the Effects of Hypoglycemic-Hypotensive Therapy Against Diabetes-Induced Nephrotoxicity in Rats

This study has examined the role of supplementing a treatment of diabetic rats with captopril (CAP), metformin (MET) or CAP-MET with the antioxidant amino acid taurine (TAU) on biochemical indices of diabetes-induced metabolic changes, oxidative stress and nephropathy. To this end, groups of 6 male Sprague-Dawley rats (250-375 g) were made diabetic with a single, 60 mg/kg, intraperitoneal dose of streptozotocin (STZ) in 10 mM citrate buffer pH 4.5 and, after 14 days, treated daily for up to 42 days with either a single oral dose of CAP (0.15 mM/kg), MET (2.4 mM/kg) or TAU (2.4 mM/kg), or with a binary or tertiary combination of these agents. Rats receiving only 10 mM citrate buffer pH 4.5 or only STZ served as negative and positive controls, respectively. All rats were sacrificed by decapitation on day 57 and their blood and kidneys collected. In addition, a 24 h urine sample was collected starting on day 56. Compared to normal rats, untreated diabetic ones exhibited frank hyperglycemia (+313%), hypoinsulinemia (-76%) and elevation of the glycated hemoglobin value (HbA1c, +207%). Also they showed increased plasma levels of Na+ (+35%), K+ (+56%), creatinine (+232%), urea nitrogen (+158%), total protein (-53%) and transforming growth factor-β1 (TGF-β1, 12.4-fold) values. These changes were accompanied by increases in the renal levels of malondialdehyde (MDA, +42%), by decreases in the renal glutathione redox state (-71%), and activities of catalase (-70%), glutathione peroxidase (-71%) and superoxide dismutase (-85%), and by moderate decreases of the urine Na+ (-33%) and K+ (-39%) values. Following monotherapy, MET generally showed a greater attenuating effect than CAP or TAU on the changes in circulating glucose, insulin and HbA1c levels, urine total protein, and renal SOD activity; and CAP appeared more potent than TAU and MET, in that order, in antagonizing the changes in plasma creatinine and urea nitrogen levels. On the other hand, TAU generally provided a greater protection against changes in glutathione redox state and in CAT and GPx activities, with other actions falling in potency between those of CAP and MET. Adding TAU to a treatment with CAP, but not to one with MET, led to an increase in protective action relative to a treatment with drug alone. On the other hand, the actions of CAP-MET, which were about equipotent with those of MET, became enhanced in the presence of TAU, particularly against the changes of the glutathione redox state and activities of antioxidant enzymes. In short, the present results suggest that the addition of TAU to a treatment of diabetes with CAP or CAP-MET, and sometimes to one with MET, will lead to a gain in protective potency against changes in indices of glucose metabolism and of renal functional impairment and oxidative stress.

A preclinical overview of metformin for the treatment of type 2 diabetes

Type 2 diabetes (T2D) is the most common type of diabetes mellitus and is mainly characterized by insulin resistance, β-cell dysfunction, and elevated hepatic glucose output. Metformin is a first-line antihyperglycemic agent that works mainly by regulating hepatic glucose production and peripheral insulin sensitivity. Metformin has been clinically applied for more than half a century, although the underlying pharmacological mechanisms remain elusive. This current review mainly focused on the development history of metformin and related preclinical studies on structural modification, pharmacological mechanisms for treatment of T2D, toxicology, pharmacokinetics, and pharmaceutics. The pharmacological function of metformin in lowering hyperglycemia suggests that multi-targeting could be an effective strategy for the discovery of new anti-diabetic drugs. A number of discoveries have revealed the pharmacologic mechanisms of metformin; however, precise mechanisms remain unclear. Deeper investigations on the biological features of metformin are expected to provide more rational applications and indications of this evergreen anti-T2D agent, which will in turn help to better understand the complicated pathogenesis of T2D.

Phenformin inhibits cell proliferation and induces cell apoptosis and autophagy in cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive malignant tumor and the prognosis of patients with advanced stage disease remains poor. Therefore, the identification of novel treatment agents for CCA is required. In the present study, the biological effects of the diabetes therapeutic agent, phenformin, in CCA cell lines was investigated. Cell Counting Kit‑8 cell viability, cellular clone formation and subcutaneous tumor formation assays were performed, which revealed that phenformin inhibited CCA cell proliferation and growth both in vitro and in vivo. In addition, phenformin induced CCA cell apoptosis and autophagy. Phenformin partly activated the liver kinase B1 (LKB1)/5' AMP‑activated protein kinase signaling pathway to exert its biological effects on CCA cell lines, as demonstrated by knockdown of LKB1, which reversed these effects. In conclusion, the present study demonstrated the biological effects of phenformin in CCA and suggested that phenformin may be a potential novel agent for CCA treatment.

Metformin: clinical use in type 2 diabetes

Metformin is one of the most popular oral glucose-lowering medications, widely considered to be the optimal initial therapy for patients with type 2 diabetes mellitus. Interestingly, there still remains controversy regarding the drug's precise mechanism of action, which is thought to involve a reduction in hepatic glucose production. It is now recommended as first-line treatment in various guidelines, including that of the EASD and ADA. Its favoured status lies in its efficacy, low cost, weight neutrality and good safety profile. Other benefits have also been described, including improvements in certain lipids, inflammatory markers, and a reduction in cardiovascular events, apparently independent from the drug's glucose-lowering effect. Data have emerged questioning the previous reluctance to use this agent in those with mild to moderate chronic kidney disease. Regulations guiding its use in patients with stable, modest renal dysfunction have, as a result, become more lenient in recent years. With no long-term studies comparing it against newer glucose-lowering drugs, some of which have more robust evidence for cardioprotection, metformin's established role as 'foundation therapy' in type 2 diabetes may justifiably be challenged.

METFORMIN: NONGLYCEMIC EFFECTS AND POTENTIAL NOVEL INDICATIONS

OBJECTIVE

Metformin is the most commonly prescribed drug for the treatment of type 2 diabetes because of its apparent robust effects in reducing cardiovascular risk. This review examines the current literature regarding the nonglycemic effects and potential novel indications for metformin.

METHODS

Review of the literature, with a focus on metformin use in Stage 3 chronic kidney disease (CKD-3) and heart failure (HF).

RESULTS

The United Kingdom Prospective Diabetes Study suggests that metformin reduces the risk of myocardial infarction, and more recent retrospective studies have shown an association between metformin use and a reduction in stroke, atrial fibrillation and all-cause mortality. The mechanism(s) explaining these putative benefits are not clear but may involve decreased energy intake (with attendant weight loss), improvement in lipids, and lowering of blood pressure; a literature review suggests that metformin lowers blood pressure when it is elevated, but not when it is normal. Metformin appears to be safe when given to patients with CKD-3. In addition, there is evidence that individuals with CKD-3, who are at increased cardiovascular risk, stand to benefit from metformin therapy. Lactic acidosis is an extremely remote and probably avoidable risk; measurement of plasma metformin levels and more frequent monitoring of renal function may be useful in selected patients with CKD-3 who are treated with metformin. Finally, there is evidence that metformin is safe in patients with HF; metformin therapy is associated with a reduction in newly incident HF and in HF mortality.

CONCLUSION

Metformin has a dominant position in the treatment of type 2 diabetes that is deserved due to its favorable and robust effects on cardiovascular risk.

ABBREVIATIONS

AMP = adenosine monophosphate BP = blood pressure CKD = chronic kidney disease CKD-3 = Stage 3 CKD eGFR = estimated glomerular filtration rate HDL = high-density lipoprotein HF = heart failure MAP = mean arterial pressure mVO2 = myocardial oxygen consumption T2DM = type 2 diabetes mellitus UKPDS = United Kingdom Prospective Diabetes Study.

Blood glycemia-modulating effects of melanian snail protein hydrolysates in mice with type II diabetes

Freshwater animal proteins have long been used as nutrient supplements. In this study, melanian snail (Semisulcospira libertina) protein hydrolysates (MPh) were found to exert anti-diabetic and protective effects against liver and kidney damage in mice with type II diabetes adapted to a 45% kcal high-fat diet (HFD). The hypoglycemic, hepatoprotective and nephroprotective effects of MPh were analyzed after 12 weeks of the continuous oral administration of MPh at 125, 250 and 500 mg/kg. Diabetic control mice exhibited an increase in body weight, and blood glucose and insulin levels, with a decrease in serum high-density lipoprotein (HDL) levels. In addition, an increase in the regions of steatohepatitis, hepatocyte hypertrophy, and lipid droplet deposit-related renal tubular vacuolation degenerative lesions were detected, with noticeable expansion and hyperplasia of the pancreatic islets, and an increase in glucagon- and insulin-producing cells, insulin/glucagon cell ratios in the endocrine pancreas and hepatic lipid peroxidation, as well as decreased zymogen contents. Furthermore, a deterioration of the endogenous antioxidant defense system was observed, with reduced glucose utilization related hepatic glucokinase (GK) activity and an increase in hepatic gluconeogenesis-related phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6pase) activity. However, all of these diabetic complications were significantly inhibited by oral treatment with MPh in a dose-dependent manner. In addition, the marked dose-dependent inhibition of hepatic lipid peroxidation, the depletion of the liver endogenous antioxidant defense system, and changes in hepatic glucose-regulating enzyme activities were also observed. The results of this study suggest that MPh exerts potent anti-diabetic effects, along with the amelioration of related complications in mice with type II diabetes. The overall effects of MPh at a dose of 125 mg/kg on HFD-induced diabetes and related complications were similar or more potent than those of metformin (250 mg/kg).

Metformin-like antidiabetic, cardio-protective and non-glycemic effects of naringenin: Molecular and pharmacological insights

Metformin is a widely used drug for the treatment of type 2 diabetes (T2D). Its blood glucose-lowering effects are initially due to inhibition of hepatic glucose production and increased peripheral glucose utilization. Metformin has also been shown to have several beneficial effects on cardiovascular risk factors and it is the only oral antihyperglycaemic agent thus far associated with decreased macrovascular complications in patients with diabetes. Adenosine Monophosphate Activated-Protein Kinase (AMPK) is a major cellular regulator of lipid and glucose metabolism. Recent evidence shows that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profiles, blood pressure and insulin-resistance making it a novel therapeutic target in the treatment of T2D. Naringenin a flavonoid found in high concentrations as its glycone naringin in citrus fruits, has been reported to have antioxidant, antiatherogenic, anti- dyslipidemic and anti-diabetic effects. It has been shown that naringenin exerts its anti-diabetic effects by inhibition of gluconeogenesis through upregulations of AMPK hence metformin-like effects. Naringin has further been shown to have non-glycemic affects like metformin that mitigate inflammation and cell proliferation. This review evaluates the potential of naringenin as anti-diabetic, anti-dyslipidemic anti-inflammatory and antineoplastic agent similar to metformin and proposes its further development for therapeutic use in clinical practice.

The protective potential of metformin against acetaminophen-induced hepatotoxicity in BALB/C mice

CONTEXT

Acetaminophen overdose is regarded to a common cause of acute liver failure. The hepatotoxicity leads to mitochondrial oxidative stress and subsequent necrotic hepatocellular death.

OBJECTIVE

This study examines the protective effect of metformin on acetaminophen-induced oxidative stress, inflammation and subsequent hepatotoxicity in mice.

MATERIALS AND METHODS

Male BALB/c mice were orally administered to acetaminophen (250 mg/kg/d) for a 7-day period. The mice received metformin (100 and 200 mg/kg/d, p.o.) for 21 days. To evaluate acetaminophen-induced oxidative stress, liver tissue level of malodialdehyde (MDA), end product of membrane lipid peroxidation, and activities of superoxide dismutase (SOD) and glutathione (GSH) were measured. Histological analysis and measurement of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were performed. Moreover, tissue concentrations of proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), along with, C-reactive protein (CRP) were assessed.

RESULTS

Acetaminophen caused focal hepatocyte necrosis, inflammation and fatty degeneration, as well as increased tissue levels of AST, ALT, ALP and MDA, and also decreased GSH and SOD activities. Moreover, IL-6, TNF-α and CRP levels were increased following acetaminophen hepatotoxicity. Metformin (200 mg/kg/d) significantly normalized MDA, SOD and GSH levels (p < 0.001), and exerted a hepatoprotective effect by significant decreasing ALT, AST and ALP concentrations (p < 0.001). The tissue levels of IL-6, TNF-α and CRP were markedly decreased by 21-day treatment with metformin (200 mg/kg/d) (p < 0.001).

DISCUSSION

The results suggest metformin protects hepatocytes against acute acetaminophen toxicity. Metformin is indicated to diminish oxidative stress, proinflammatory cytokines, and hepatocyte necrosis.

Metformin Use Is Associated with Improved Survival in Patients Undergoing Resection for Pancreatic Cancer

Preclinical evidence has demonstrated anti-tumorigenic effects of metformin. The effects of metformin following pancreatic cancer, however, remain undefined. We sought to assess the association between metformin use and survival using a large, nationally representative sample of patients undergoing surgery for pancreatic cancer. Patients undergoing a pancreatic resection between January 01, 2010, and December 31, 2012, were identified using the Truven Health MarketScan database. Clinical data, including history of metformin use, as well as operative details and information on long-term outcomes were collected. Multivariable Cox proportional hazards regression analysis was performed to assess the effect of metformin use on overall survival (OS). A total of 3393 patients were identified. The mean age of patients was 54.2 years (SD = 9.1 years). Roughly one half of patients were female (n = 1735, 51.1 %); 49.1 % (n = 1665) presented with a Charlson comorbidity index of 3 or greater (CCI ≥3); and 19.6 % (n = 664) had diabetes. At the time of surgery, 60.0 % (n = 2034) of patients underwent a pancreaticoduodenectomy, 35.7 % (n = 1212) a partial/distal pancreatectomy, while 4.3 % (n = 147) had a total pancreatectomy. On pathology, 1057 (31.2 %) had lymph node metastasis. Metformin use was identified in 456 patients (13.4 %) and was more commonly administered among patients without locally advanced disease (14.3 vs. 11.6 %, p = 0.038). While OS was comparable between patients within the first year of surgery (OS at 1 year 65.4 % [95 % confidence interval (CI) 63.4-67.3 %] vs. 69.2 % [95 % CI 64.2-73.4 %]), patients who received metformin demonstrated an improved OS beginning at 18 months following surgery. On multivariable analysis adjusting for patient and clinicopathologic characteristics, metformin use was independently associated with a decreased risk of mortality (hazard ratio [HR] = 0.79, 95 % CI 0.67-0.93, p = 0.005). Metformin use was associated with an improved overall survival among patients undergoing pancreatic surgery for pancreatic cancer. Further work is necessary to better understand its role in modifying cancer-specific and overall health outcomes.

Review: Optimal dosing strategies for maximising the clinical response to metformin in type 2 diabetes

Recently revised consensus targets for glycaemic management in patients with type 2 diabetes are challenging and require optimisation of dosing strategies for oral antidiabetic therapies. The demonstration of significant cardiovascular outcome benefits in metformin-treated type 2 diabetic patients enrolled in the United Kingdom Prospective Diabetes Study has established this agent as the first line oral therapy after diet failure in newly presenting overweight people with type 2 diabetes mellitus. The antihyperglycaemic efficacy of metformin increases with increasing daily doses between 500 mg and the upper limits of the recommended daily dosage ( ≥ 2000 mg/day). Although metformin is associated with gastrointestinal side-effects in up to 20% of patients, this is not generally dose related. Transient dose reduction, slower titration and taking the dose with meals may ameliorate the problem. Risk of lactic acidosis due to metformin is negligible when this agent is prescribed correctly, and is unrelated to the plasma metformin concentration. Intensification of metformin therapy within the dose range represents a rational and practical therapeutic strategy for optimising glycaemic control in patients who are suitable for, and tolerant of, metformin treatment. The recently introduced 1000 mg metformin tablet should facilitate the use of higher doses and may help treatment compliance.

Novel Therapeutics for Diabetes: Uptake, Usage Trends, and Comparative Effectiveness

The number of available therapies for treating type 2 diabetes has grown considerably in recent years. This growth has been fueled by availability of newer medications, whose benefits and risks have not been fully established. In this study, we review and synthesize the existing literature on the uptake, efficacy, safety, and cost-effectiveness of novel antidiabetic agents. Specifically, we focus on three drug classes that were introduced in the market recently: thiazolidinediones (TZDs), dipeptidyl peptidase-4 (DPP-4) inhibitors, and glucagon-like peptide-1 (GLP-1) receptor agonists. Not surprisingly, we find that the usage trends reflect the efficacy and safety profile of these novel drugs. The use of TZDs increased initially but decreased after a black-box warning was issued for rosiglitazone in 2007 that highlighted the cardiovascular risks associated with using the drug. Conversely, DPP-4 inhibitors and GLP-1 receptor agonists gained market shares due to their efficacy in glycemic control as an add-on treatment to metformin. DPP-4 inhibitors were the most commonly prescribed agents among the three novel drug classes, likely because they are relatively less expensive, have better safety profile, are administered orally, and are weight neutral. Sitagliptin was the most preferred DPP-4 inhibitor. The level of evidence on the comparative effectiveness, safety, and cost implications of using novel antidiabetic agents remains low and further studies with long-term follow-ups are needed.

Metformin-associated lactic acidosis: Current perspectives on causes and risk

Although metformin has become a drug of choice for the treatment of type 2 diabetes mellitus, some patients may not receive it owing to the risk of lactic acidosis. Metformin, along with other drugs in the biguanide class, increases plasma lactate levels in a plasma concentration-dependent manner by inhibiting mitochondrial respiration predominantly in the liver. Elevated plasma metformin concentrations (as occur in individuals with renal impairment) and a secondary event or condition that further disrupts lactate production or clearance (e.g., cirrhosis, sepsis, or hypoperfusion), are typically necessary to cause metformin-associated lactic acidosis (MALA). As these secondary events may be unpredictable and the mortality rate for MALA approaches 50%, metformin has been contraindicated in moderate and severe renal impairment since its FDA approval in patients with normal renal function or mild renal insufficiency to minimize the potential for toxic metformin levels and MALA. However, the reported incidence of lactic acidosis in clinical practice has proved to be very low (<10 cases per 100,000 patient-years). Several groups have suggested that current renal function cutoffs for metformin are too conservative, thus depriving a substantial number of type 2 diabetes patients from the potential benefit of metformin therapy. On the other hand, the success of metformin as the first-line diabetes therapy may be a direct consequence of conservative labeling, the absence of which could have led to excess patient risk and eventual withdrawal from the market, as happened with earlier biguanide therapies. An investigational delayed-release metformin currently under development could potentially provide a treatment option for patients with renal impairment pending the results of future studies. This literature-based review provides an update on the impact of renal function and other conditions on metformin plasma levels and the risk of MALA in patients with type 2 diabetes.

Fermentation of Green Tea with 2% Aquilariae lignum Increases the Anti-Diabetic Activity of Green Tea Aqueous Extracts in the High Fat-Fed Mouse

Anti-diabetic effects on the metabolomic differences between green tea (GT) and Aquilariae lignum-fermented green tea (fGT) were investigated in the high fat-fed mouse. To prove the differences, hypoglycemic (blood glucose, insulin and glycated hemoglobin levels, pancreas weights and histopathological-immunohistochemistrical analysis of pancreas–insulin/glucagon cells), hepato- and nephron-protective (the changes in liver and kidney weight, histopathology of liver and kidney, serum aminotransferases (AST and ALT) levels, blood urea nitrogen, and serum creatinine levels), and hypolipidemic (the changes of serum total cholesterol, triglyceride, low- and high-density lipoprotein levels with fecal TC and TG contents) effects were evaluated. In addition, liver lipid peroxidation, the glutathione contents, and catalase and superoxide dismutase activities were measured according to the hepatic glucose-regulating enzyme activities of glucokinase (GK), glucose-6-phosphatase (G6pase) and phosphoenolpyruvate carboxykinase (PEPCK) for action mechanisms. As a result, fGT showed a stronger hypoglycemic, hepato- and nephron-protective, hypolipidemic, and anti-oxidant effect than GT in high fat-fed mice. In addition, fGT-treated mice exerted more favorable inhibitory activities against GK, G6pase, PERCK activities as compared to GT-treated mice. Taken together, fGT fermented with Aquilariae lignum, 1:49 (2%; g/g) has a stronger effect compared with GT. Therefore, fGT has the potential to increase bioactivity against type 2 diabetics.

Insulin Therapy of Nondiabetic Septic Patients Is Predicted by para-Tyrosine/Phenylalanine Ratio and by Hydroxyl Radical-Derived Products of Phenylalanine

Hydroxyl radical converts Phe to para-, meta-, and ortho-Tyr (p-Tyr, m-Tyr, o-Tyr), while Phe is converted enzymatically to p-Tyr in the kidney and could serve as substrate for gluconeogenesis. Pathological isoforms m- and o-Tyr are supposed to be involved in development of hormone resistances. Role of Phe and the three Tyr isoforms in influencing insulin need was examined in 25 nondiabetic septic patients. Daily insulin dose (DID) and insulin-glucose product (IGP) were calculated. Serum and urinary levels of Phe and Tyr isoforms were determined using a rpHPLC-method. Urinary m-Tyr/p-Tyr ratio was higher in patients with DID and IGP over median compared to those below median (P = 0.005 and P = 0.01, resp.). Urinary m-Tyr and m-Tyr/p-Tyr ratio showed positive correlation with DID (P = 0.009 and P = 0.023, resp.) and with IGP (P = 0.004 and P = 0.008, resp.). Serum Phe was a negative predictor, while serum p-Tyr/Phe ratio was positive predictor of both DID and IGP. Urinary m-Tyr and urinary m-Tyr/p-Tyr, o-Tyr/p-Tyr, and (m-Tyr+o-Tyr)/p-Tyr ratios were positive predictors of both DID and IGP. Phe and Tyr isoforms have a predictive role in carbohydrate metabolism of nondiabetic septic patients. Phe may serve as substrate for renal gluconeogenesis via enzymatically produced p-Tyr, while hydroxyl radical derived Phe products may interfere with insulin action.

Copper-catalyzed arylation of biguanide derivatives via C–N cross-coupling reactions

We developed an efficient copper-catalyzed cross-coupling reaction of biguanide hydrochloride derivatives with both aryl iodides and bromides under mild conditions.