Action of metformin therapy against advanced glycation, oxidative stress and inflammation in type 2 diabetes patients: 3 months follow-up study

Correlation between serum advanced glycation end-products and vascular complications in patient with type 2 diabetes

Advanced glycation end-products (AGEs) formation increases with metabolic disorders, leading to higher serum AGE levels in patients with progressive vascular complications. Measuring AGE levels in biological samples requires multiple pre-analytical processing steps, rendering analysis of multiple samples challenging. This study evaluated the progression of diabetic complications by analyzing AGE levels using a pre-analytical processing strategy based on a fully automated solid phase-extraction system. Serum samples from patients with diabetes, with or without macrovascular complications (Mac or non-Mac) or microvascular complications (Mic or non-Mic), were processed with the established methods. Free and total AGE levels in sera were measured using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). In patients with diabetes, both free and total AGE levels were elevated in those with complications compared to those without complications. In Mac and Mic groups, free and total AGE levels and z-scores (the sum of normalized AGE levels) also increased. AGE z-scores were markedly higher than those of single AGE levels in distinguishing each complication. Our study demonstrated that the free AGE z-score, measured using a new analytical method without hydrolysis, correlated with the presence of vascular complications and may serve as a marker of disease complications.

Bone effects of metformin monotherapy and its combination with teneligliptin: A 12-week follow-up study in patients with type 2 diabetes mellitus

AIMS

The skeletal effects of metformin monotherapy and in combination with teneligliptin are not well illustrated in patients with T2DM. To address this, we conducted an observational study to evaluate the effect of these oral hypoglycemic agents on bone turnover markers.

METHODS

We recruited patients with T2DM and first-ever prescribed metformin monotherapy or metformin combined with teneligliptin from a tertiary care teaching hospital in New Delhi, North India. Both bone formation and resorption markers, IL-6 and PTD, were estimated along with glycated hemoglobin at baseline and 12 weeks.

RESULTS

In both groups, hbA1c levels decreased significantly from baseline to 12 weeks. In the metformin-treated group, β-CTX, sRANKL, IL-6, and PTD decreased significantly, and no significant changes were observed in P1NP, OC, BAP, or OPG at 12 weeks from baseline. In the metformin + teneligliptin group, BAP, β-CTX, sRANKL, IL-6, and PTD decreased significantly, and no significant changes were observed in P1NP, OC, or OPG after 12 weeks from baseline.

CONCLUSIONS

The positive bone outcome of metformin or teneligliptin was linked to bone resorption rather than bone formation and was independent of changes in HbA1c or PTD. However, these results must be confirmed with well-designed RCTs with more extended follow-up periods.

Regulation of the AGEs-induced inflammatory response in human periodontal ligament cells via the AMPK/NF-κB/ NLRP3 signaling pathway

The heightened prevalence and accelerated progression of periodontitis in individuals with diabetes is primarily attributed to inflammatory responses in human periodontal ligament cells (HPDLCs). This study is aimed at delineating the regulatory mechanism of nucleotide-binding oligomerization domain-like receptors (NLRs) in mediating inflammation incited by muramyl dipeptide (MDP) in HPDLCs, under the influence of advanced glycation end products (AGEs), metabolic by-products associated with diabetes. We performed RNA-seq in HPDLCs induced by AGEs treatment and delineated activation markers for the receptor of AGEs (RAGE). It showed that advanced glycation end products modulate inflammatory responses in HPDLCs by activating NLRP1 and NLRP3 inflammasomes, which are further regulated through the NF-κB signaling pathway. Furthermore, AGEs synergize with NOD2, NLRP1, and NLRP3 inflammasomes to augment MDP-induced inflammation significantly.

A Narrative Review of Diabetic Macroangiopathy: From Molecular Mechanism to Therapeutic Approaches

Diabetic macroangiopathy, a prevalent and severe complication of diabetes mellitus, significantly contributes to the increased morbidity and mortality rates among affected individuals. This complex disorder involves multifaceted molecular mechanisms that lead to the dysfunction and damage of large blood vessels, including atherosclerosis (AS) and peripheral arterial disease. Understanding the intricate pathways underlying the development and progression of diabetic macroangiopathy is crucial for the development of effective therapeutic interventions. This review aims to shed light on the molecular mechanism implicated in the pathogenesis of diabetic macroangiopathy. We delve into the intricate interplay of chronic inflammation, oxidative stress, endothelial dysfunction, and dysregulated angiogenesis, all of which contribute to the vascular complications observed in this disorder. By exploring the molecular mechanism involved in the disease we provide insight into potential therapeutic targets and strategies. Moreover, we discuss the current therapeutic approaches used for treating diabetic macroangiopathy, including glycemic control, lipid-lowering agents, and vascular interventions.

Examining the clinical relevance of metformin as an antioxidant intervention

In physiological concentrations, reactive oxygen species play a vital role in regulating cell signaling and gene expression. Nevertheless, oxidative stress is implicated in the pathogenesis of numerous diseases and can inflict damage on diverse cell types and tissues. Thus, understanding the factors that mitigate the deleterious effects of oxidative stress is imperative for identifying new therapeutic targets. In light of the absence of direct treatment recommendations for reducing oxidative stress, there is a continuing need for fundamental research that utilizes innovative therapeutic approaches. Metformin, known for its multifaceted beneficial properties, is acknowledged for its ability to counteract the adverse effects of increased oxidative stress at both molecular and cellular levels. In this review, we delve into recent insights regarding metformin's antioxidant attributes, aiming to expand its clinical applicability. Our review proposes that metformin holds promise as a potential adjunctive therapy for various diseases, given its modulation of oxidative stress characteristics and regulation of diverse metabolic pathways. These pathways include lipid metabolism, hormone synthesis, and immunological responses, all of which may experience dysregulation in disease states, contributing to increased oxidative stress. Furthermore, our review introduces potential novel metformin-based interventions that may merit consideration in future research. Nevertheless, the necessity for clinical trials involving this drug remains imperative, as they are essential for establishing therapeutic dosages and addressing challenges associated with dose-dependent effects.

Communal interaction of glycation and gut microbes in diabetes mellitus, Alzheimer's disease, and Parkinson's disease pathogenesis

Diabetes and its complications, Alzheimer's disease (AD), and Parkinson's disease (PD) are increasing gradually, reflecting a global threat vis-à-vis expressing the essentiality of a substantial paradigm shift in research and remedial actions. Protein glycation is influenced by several factors, like time, temperature, pH, metal ions, and the half-life of the protein. Surprisingly, most proteins associated with metabolic and neurodegenerative disorders are generally long-lived and hence susceptible to glycation. Remarkably, proteins linked with diabetes, AD, and PD share this characteristic. This modulates protein's structure, aggregation tendency, and toxicity, highlighting renovated attention. Gut microbes and microbial metabolites marked their importance in human health and diseases. Though many scientific shreds of evidence are proposed for possible change and dysbiosis in gut flora in these diseases, very little is known about the mechanisms. Screening and unfolding their functionality in metabolic and neurodegenerative disorders is essential in hunting the gut treasure. Therefore, it is imperative to evaluate the role of glycation as a common link in diabetes and neurodegenerative diseases, which helps to clarify if modulation of nonenzymatic glycation may act as a beneficial therapeutic strategy and gut microbes/metabolites may answer some of the crucial questions. This review briefly emphasizes the common functional attributes of glycation and gut microbes, the possible linkages, and discusses current treatment options and therapeutic challenges.

Changes in Oxidative Stress and Intestinal Permeability during Pregnancy in Women with Gestational Diabetes Mellitus Treated with Metformin or Insulin and Healthy Controls: A Randomized Controlled Trial

Both oxidative stress and intestinal permeability are increased in hyperglycemic situations and have been shown to be reduced by metformin in type 2 diabetes mellitus (T2DM) patients. The aim of this study was to elucidate the effect of metformin on oxidative stress and intestinal permeability in women with gestational diabetes mellitus (GDM) treated with metformin compared to those treated with insulin and healthy controls. A total of 120 women were included from August 2016 to February 2022: 41 received metformin (MET group), 38 received insulin (INS group), and 41 were healthy controls. Baseline and antenatal visits were carried out at 25.4 ± 4.8 and 36.1 ± 0.8 weeks of pregnancy, respectively. Advanced oxidation protein products (AOPPs), total antioxidant capacity (TAC), and zonulin levels were measured at every visit. Zonulin levels from baseline to prepartum visit increased significantly in both healthy controls (0.6 ± 0.9 to 1.2 ± 1.7 ng/mL, p = 0.004) and the INS group (0.4 ± 0.3 to 0.6 ± 0.5 ng/mL, p = 0.034) but did not significantly change in the MET group (0.4 ± 0.4 to 0.5 ± 0.4 ng/mL, p = 0.202). However, TAC and AOPP levels significantly increased in women with GDM, both in the INS and MET groups but not in the healthy controls. In conclusion, in our population, metformin has been shown to avoid an increase in intestinal permeability but failed to avoid an increase in oxidative stress related to hyperglycemia.

Role of Oxidative Stress in Tuberculosis Meningitis Infection in Diabetics

Tuberculosis meningitis (TBM) is a result of the invasion of the meninges with the bacilli of Mycobacterium tuberculosis (Mtb), leading to inflammation of the meninges around the brain or spinal cord. Oxidative stress occurs when the body's cells become overwhelmed with free radicals, particularly reactive oxygen species (ROS). ROS plays a significant role in the pathogenesis of TBM due to their toxic nature, resulting in impairment of the body's ability to fight off infection. ROS damages the endothelial cells and impairs the defense mechanisms of the blood-brain barrier (BBB), which contributes to CNS susceptibility to the bacteria causing TBM. Diabetes mellitus (DM) is a common condition that is characterized by the impairment of the hormone insulin, which is responsible for modulating blood glucose levels. The increased availability of glucose in individuals with diabetes results in increased cellular activity and metabolism, leading to heightened ROS production and, in turn, increased susceptibility to TBM. In this review, we summarize our current understanding of oxidative stress and its role in both TBM and DM. We further discuss how increased oxidative stress in DM can contribute to the likelihood of developing TBM and potential therapeutic approaches that may be of therapeutic value.

Anti-diabetic combination therapy with pioglitazone or glimepiride added to metformin on the AGE-RAGE axis: a randomized prospective study

Introduction

The ratio between advanced glycation end products (AGEs) and soluble form of receptor (s-RAGE) has been proposed as a risk marker for renal and cardiovascular diseases. The aim of this study was to evaluate in the diabetes condition the influence of two different oral anti-diabetic treatments on the AGE/s-RAGE ratio, during a 5-year observation period.

Methods

Seventy-three patients with type 2 diabetes mellitus were randomly assigned to a drug therapy with pioglitazone or glimepiride, combined to metformin. Each subject was evaluated at baseline and after 5 years of treatment.

Results

In both groups s-RAGE levels did not significantly vary, while the levels of AGE and AGE/s-RAGE were both significantly reduced, basal compared to 5-year values. Within pioglitazone group, as well within glimepiride group, significant variations (Δ, as difference between 5 years of treatment minus basal) were observed for AGE (Δ= -21.1±13.4 µg/ml, P<0.001 for pioglitazone; Δ= -14.4±11.4 µg/ml, P<0.001 for glimepiride) and in AGE/s-RAGE (Δ= -0.037±0.022 µg/pg, P<0.001 for pioglitazone; Δ= -0.024±0.020µg/pg, P<0.001 for glimepiride), suggesting an average decrease of the parameters by more than 50% in both treatments. Pioglitazone was more effective than glimepiride in reducing AGE/s-RAGE ratio after 5 years of therapy.

Conclusion

These data can help to explain the benefits of oral anti-diabetic therapy in relation to the reduction of cardiovascular risk, as suggested by variations in AGE/s-RAGE ratio as biochemical marker of endothelial function; in particular, treatment with pioglitazone seems to offer greater long-term benefit on AGE-RAGE axis.

Insights into the Role of Plasmatic and Exosomal microRNAs in Oxidative Stress-Related Metabolic Diseases

A common denominator of metabolic diseases, including type 2 diabetes Mellitus, dyslipidemia, and atherosclerosis, are elevated oxidative stress and chronic inflammation. These complex, multi-factorial diseases are caused by the detrimental interaction between the individual genetic background and multiple environmental stimuli. The cells, including the endothelial ones, acquire a preactivated phenotype and metabolic memory, exhibiting increased oxidative stress, inflammatory gene expression, endothelial vascular activation, and prothrombotic events, leading to vascular complications. There are different pathways involved in the pathogenesis of metabolic diseases, and increased knowledge suggests a role of the activation of the NF-kB pathway and NLRP3 inflammasome as key mediators of metabolic inflammation. Epigenetic-wide associated studies provide new insight into the role of microRNAs in the phenomenon of metabolic memory and the development consequences of vessel damage. In this review, we will focus on the microRNAs related to the control of anti-oxidative enzymes, as well as microRNAs related to the control of mitochondrial functions and inflammation. The objective is the search for new therapeutic targets to improve the functioning of mitochondria and reduce oxidative stress and inflammation, despite the acquired metabolic memory.

Potential inhibitory effect of fish, maize, and whey protein hydrolysates on advanced glycation end-products (AGEs)

Advanced glycation end-products (AGEs) are produced in the final stage of the Maillard reaction. AGEs formation may be inhibited by natural hydrolysates derived from plant or animal sources. The present study aimed to investigate the antiglycation potential of fish, maize, and whey protein hydrolysates. It was carried out in four model systems, Bovine serum albumin (BSA)-Glucose, BSA-Fructose, BSA-Sorbitol, and BSA-HFCS (high fructose corn syrup), by evaluation of fluorescent intensity of AGEs after seven days of reaction at 37°C. The results showed that the highest inhibitory effect belonged to 0.16% of FPH (fish protein hydrolysate, percent inhibition ~99.0%), whereas maize protein hydrolysate (MPH) had lower antiglycation activity in comparison with FPH. Among all hydrolysates, whey protein hydrolysate with the lowest degree of hydrolysis showed the weakest inhibitory activity. Overall, our results indicated that the investigated hydrolysates, particularly FPH, have promising antiglycation potential and can be recommended for the production of functional foods.

Unveiling new secrets in Parkinson's disease: The glycatome

We are witnessing a considerable increase in the incidence of Parkinson's disease (PD), which may be due to the general ageing of the population. While there is a plethora of therapeutic strategies for this disease, they still fail to arrest disease progression as they do not target and prevent the neurodegenerative process. The identification of disease-causing mutations allowed researchers to better dissect the underlying causes of this disease, highlighting, for example, the pathogenic role of alpha-synuclein. However, most PD cases are sporadic, which is making it hard to unveil the major causative mechanisms of this disease. In the recent years, epidemiological evidence suggest that type-2 diabetes mellitus (T2DM) individuals have higher risk and worst outcomes of PD, allowing to raise the hypothesis that some dysregulated processes in T2DM may contribute or even trigger the neurodegenerative process in PD. One major consequence of T2DM is the unprogrammed reaction between sugars, increased in T2DM, and proteins, a reaction named glycation. Pre-clinical reports show that alpha-synuclein is a target of glycation, and glycation potentiates its pathogenicity which contributes for the neurodegenerative process. Moreover, it triggers, anticipates, or aggravates several PD-like motor and non-motor complications. A given profile of proteins are differently glycated in diseased conditions, altering the brain proteome and leading to brain dysfunction and neurodegeneration. Herein we coin the term Glycatome as the profile of glycated proteins. In this review we report on the mechanisms underlying the association between T2DM and PD, with particular focus on the impact of protein glycation.

Modulatory Effect of Lifestyle-Related, Environmental and Genetic Factors on Paraoxonase-1 Activity: A Review

Paraoxonase-1 (PON1) is a calcium-dependent, HDL-bound serum hydrolase active toward a wide variety of substrates. PON1 displays three types of activities, among which lactonase, paraoxonase, arylesterase and phosphotriesterase can be distinguished. Not only is this enzyme a major organophosphate compound detoxifier, but it is also an important constituent of the cellular antioxidant system and has anti-inflammatory and antiatherogenic functions. The concentration and activity of PON1 is highly variable among individuals, and these differences can be both of genetic origin and be a subject of epigenetic regulation. Owing to the fact that, in recent decades, the exposure of humans to an increasing number of different xenobiotics has been continuously rising, the issues concerning the role and activity of PON1 shall be reconsidered with particular attention to growing pharmaceuticals intake, dietary habits and environmental awareness. In the following manuscript, the current state of knowledge concerning the influence of certain modifiable and unmodifiable factors, including smoking, alcohol intake, gender, age and genotype variation on PON1 activity, along with pathways through which these could interfere with the enzyme's protective functions, is presented and discussed. Since exposure to certain xenobiotics plays a key role in PON1 activity, the influence of organophosphates, heavy metals and several pharmaceutical agents is also specified.

Metformin mitigates amyloid β1-40-induced cognitive decline via attenuation of oxidative/nitrosative stress and neuroinflammation

Metformin is an antidiabetic medicine widely used for management of type 2 diabetes with neuroprotective effects and promising potential to attenuate cognitive impairment. The efficacy of metformin in attenuation of Alzheimer's disease (AD) pathology has not been well-documented. Thus, this study was designed to assess protective effect of metformin against Aβ_1-40-instigared cognitive impairment. After intra-CA1 microinjection of aggregated Aβ_1-40, rats received oral metformin (50 and/or 200 mg/kg/day) for two weeks. Cognition function was analyzed in various behavioral tasks besides measurement of hippocampal oxidative stress, apoptosis, and inflammation along with H&E staining and 3-nitrotyrosine (3-NT) immunohistochemistry. Obtained data showed significant improvement of discrimination score in novel object recognition test, higher alternation score in Y maze, greater latency in passive avoidance task, and lower working and reference memory errors in radial arm maze in metformin-treated Aβ-injured group. Moreover, metformin treatment attenuated hippocampal levels of nitrite, MDA, protein carbonyl, ROS, TNFα, GFAP, DNA fragmentation intensity, caspase 3 activity, AChE activity, and increased SOD activity and level of IL-10 as an anti-inflammatory factor. In addition, metformin treatment was associated with lower CA1 neuronal loss and it also decreased intensity of 3-NT immunoreactivity as an indicator of nitrosative stress. Taken together, obtained findings showed neuroprotective and anti-dementia property of metformin in male rats and this may have potential benefit in attenuation of cognitive decline and related complications in patients with neurodegenerative disorders such as AD besides diabetes mellitus.

Concentrations of N6-Carboxymethyllysine (CML), N6-Carboxyethyllysine (CEL), and Soluble Receptor for Advanced Glycation End-Products (sRAGE) Are Increased in Psoriatic Patients

Psoriasis is a chronic, recurrent, and often severe skin disease which is frequently associated with metabolic disorders and increased risk of cardiovascular complications. One of the postulated links is an intensified process of advanced protein glycation and/or glycoxidation. Therefore, the aim of the study was to assess concentrations of N⁶-carboxymethyllysine (CML), N⁶-carboxyethyllysine (CEL), and soluble form of receptor for advanced glycation end-products (sRAGE) in psoriasis patients at different phases of the disease activity, in comparison to healthy individuals. The study material consisted of sera from psoriasis patients in active phase, in the remission phase, and healthy controls. Concentrations of CML, CEL, and sRAGE were determined using ELISA technique. In the patients with psoriasis (in both phases of the disease), concentrations of CML, CEL and sRAGE were significantly higher than in healthy individuals but they did not correlate with psoriasis area severity index (PASI) values. The remission of the disease was followed by a significant decrease in CML, CEL, and sRAGE concentrations when compared to active patients; however, these concentrations were still significantly higher than in the controls. Our data suggest that psoriasis is accompanied by an intense glycoxidation process and that high sRAGE levels seem to reflect permanent RAGE overstimulation.

Trimester-Specific Serum Fructosamine in Association with Abdominal Adiposity, Insulin Resistance, and Inflammation in Healthy Pregnant Individuals

This study aimed to (1) characterize the variations in serum fructosamine across trimesters and according to pre-pregnancy BMI (ppBMI), and (2) examine associations between fructosamine and adiposity/metabolic markers (ppBMI, first-trimester adiposity, leptin, glucose homeostasis, and inflammation measurements) during pregnancy. Serum fructosamine, albumin, fasting glucose and insulin, leptin, adiponectin, interleukin-6 (IL-6), and C-reactive protein (CRP) concentrations were measured at each trimester. In the first trimester, subcutaneous (SAT) and visceral (VAT) adipose tissue thicknesses were estimated by ultrasound. In the 101 healthy pregnant individuals included (age: 32.2 ± 3.5 y.o.; ppBMI: 25.5 ± 5.5 kg/m2), fructosamine concentrations decreased during pregnancy whereas albumin-corrected fructosamine concentrations increased (p < 0.0001 for both). Notably, fructosamine concentrations were inversely associated with ppBMI, first-trimester SAT, VAT, and leptin (r = −0.55, r = −0.61, r = −0.48, r = −0.47, respectively; p < 0.0001 for all), first-trimester fasting insulin and HOMA-IR (r = −0.46, r = −0.46; p < 0.0001 for both), and first-trimester IL-6 (r = −0.38, p < 0.01). However, once corrected for albumin, most of the correlations lost strength. Once adjusted for ppBMI, fructosamine concentrations were positively associated with third-trimester fasting glucose and CRP (r = 0.24, r = 0.27; p < 0.05 for both). In conclusion, serum fructosamine is inversely associated with adiposity before and during pregnancy, with markers of glucose homeostasis and inflammation, but the latter associations are partially influenced by albumin concentrations and ppBMI.

Extracellular vesicle miR-32 derived from macrophage promotes arterial calcification in mice with type 2 diabetes via inhibiting VSMC autophagy

Background

The development of diabetes vascular calcification (VC) is tightly associated with the inhibition of vascular smooth muscle cell (VSMC) autophagy. Previously, our team found that miR-32-5p (miR-32) promotes macrophage activation, and miR-32 is expressed at higher level in the plasma of patients with coronary calcification. However, whether miR-32 mediates the function of macrophages in type 2 diabetes (T2D) VC is still unclear.

Methods

Wild-type (WT) and miR-32−/− mice were used in this study. qRT-PCR and western blotting were used to analyze gene expression. Flow cytometry was used to analyze the influence of glucose concentration on macrophage polarization. Nanoparticle tracking analysis (NTA), transmission electron microscopy, and confocal microscopy were used to identify macrophage extracellular vehicles (EVs). Immunofluorescence, in situ hybridization (ISH), immunohistochemistry, and alizarin red staining were used to analyze the influence of macrophage EVs on autophagy and calcification of the aorta of miR-32−/− mice. A luciferase assay was used to analyze the effect of miR-32 on myocyte enhancer factor 2D (Mef2d) expression. Co-IP combined with mass spectrometry (MS) and transcriptome sequencing was used to analyze the signalling pathway by which Mef2d acts in VSMC autophagy.

Results

We found that high glucose conditions upregulate miR-32 expression in macrophages and their EVs. Importantly, macrophages and their EVs promote VSMC osteogenic differentiation and upregulate miR-32 expression in VSMCs. Moreover, miR-32 mimics transfection promoted osteogenic differentiation and inhibited autophagy in VSMCs. In vitro and in vivo experiments showed that Mef2d is the key target gene of miR-32 that inhibits VSMC autophagy. Furthermore, MS and transcriptome sequencing found that cGMP-PKG is an important signalling pathway by which Mef2d regulates VSMC autophagy. In addition, after T2D miR-32−/− mice were injected with macrophage EVs via the caudal vein, miR-32 was detected in aortic VSMCs of miR-32−/− mice. Moreover, autophagy was significantly inhibited, and calcification was significantly enhanced in aorta cells.

Conclusions

These results reveal that EVs are the key pathway by which macrophages promote T2D VC, and that EVs miR-32 is a key cause of autophagy inhibition in VSMCs.

Metformin use is associated with a lower risk of rotator cuff disease in patients with type 2 diabetes mellitus

AIMS

- Metformin has been mentioned to be protective against inflammation, degeneration, and oxidative stress, conditions that are associated with rotator cuff disease. To access the association between metformin use and risk of rotator cuff disease in patients with type 2 diabetes mellitus (DM).

METHODS

- This was a retrospective cohort study utilizing Taiwan National Health Insurance Research Database between January 1, 2000, and December 31, 2012 to retrieved participants. Metformin and propensity score matched never metformin users were determined at baseline (between the date of onset of DM and the index date), and followed to December 31, 2013. Propensity scores were adopted to address measurable confounders (including demographic variables, Diabetes Complications Severity Index, and relevant comorbidities and co-medication). A multivariable Cox proportional hazards regression model was applied to estimate the adjusted hazard ratios (HRs) for the risk of the first diagnosis of rotator cuff disease on the full cohort and on the propensity score matched cohort.

RESULTS

- In the propensity score matched cohort, a total of 34,964 individuals (19,416 [55.5%] men), 17,482 individuals were taking metformin, 559 [3.2%] of whom developed rotator cuff disease. Incidence of rotator cuff disease was 4.51 per 10,000 person-months in the metformin users and 5.11 in the controls. Among metformin group, the aHR (95% CI) was 0.879 (0.784-0.984) after full adjustment. The potential beneficial effect on the risk of rotator cuff disease was consistently observed across all subgroups, including sex, age, concomitant other glucose lowering drugs, and level of Diabetes Complications Severity Index (all P for interaction > 0.050).

CONCLUSION

- Metformin use was associated with a lower risk of rotator cuff disease in patients with type 2 DM.

Metformin and the heart: Update on mechanisms of cardiovascular protection with special reference to comorbid type 2 diabetes and heart failure

Metformin has been in clinical use for the management of type 2 diabetes for more than 60 years and is supported by a vast database of clinical experience: this includes evidence for cardioprotection from randomised trials and real-world studies. Recently, the position of metformin as first choice glucose-lowering agent has been supplanted to some extent by the emergence of newer classes of antidiabetic therapy, namely the sodium-glucose co-transporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists. These agents have benefitted through support from large cardiovascular outcomes trials with more modern trial designs than earlier studies conducted to assess metformin. Nevertheless, clinical research on metformin continues to further assess its many potentially advantageous effects. Here, we review the evidence for improved cardiovascular outcomes with metformin in the context of the current era of diabetes outcomes trials. Focus is directed towards the potentially cardioprotective actions of metformin in patients with type 2 diabetes and heart failure (HF), now recognised as the most common complication of diabetes.

Metformin maintains intrahepatic triglyceride content through increased hepatic de novo lipogenesis

OBJECTIVE

Metformin is a first-line pharmacotherapy in the treatment of type 2 diabetes, a condition closely associated with non-alcoholic fatty liver disease (NAFLD). Although metformin promotes weight loss and improves insulin sensitivity, its effect on intrahepatic triglyceride (IHTG) remains unclear. We investigated the effect of metformin on IHTG, hepatic de novo lipogenesis (DNL), and fatty acid (FA) oxidation in vivo in humans.

DESIGN AND METHODS

Metabolic investigations, using stable-isotope tracers, were performed in ten insulin-resistant, overweight/obese human participants with NAFLD who were treatment naïve before and after 12 weeks of metformin treatment. The effect of metformin on markers of s.c. adipose tissue FA metabolism and function, along with the plasma metabolome, was investigated.

RESULTS

Twelve weeks of treatment with metformin resulted in a significant reduction in body weight and improved insulin sensitivity, but IHTG content and FA oxidation remained unchanged. Metformin treatment was associated with a significant decrease in VLDL-triglyceride (TG) concentrations and a significant increase in the relative contribution of DNL-derived FAs to VLDL-TG. There were subtle and relatively few changes in s.c. adipose tissue FA metabolism and the plasma metabolome with metformin treatment.

CONCLUSIONS

We demonstrate the mechanisms of action of metformin whereby it improves insulin sensitivity and promotes weight loss, without improvement in IHTG; these observations are partly explained through increased hepatic DNL and a lack of change in FA oxidation.

Morphological and functional characterization of diabetic cardiomyopathy in db/db mice following exercise, metformin alone, or combination treatments

The aim of the study was to explore different effects of exercise, metformin alone, or exercise combined with metformin on cardiovascular morphological and functional changes in early stage of type 2 diabetes mellitus. Eight-week-old diabetic db/db mice and BKS mice were recruited and exposed to three different treatments (exercise, metformin alone, or their combination) for 8 weeks. Metformin was administered intragastrically, and aerobic exercise was performed using treadmill with 7-12 m/min, 30-40 min/day, 5 days/week. In the combination group, aerobic exercise was carried out for 30 min after intragastric administration of metformin. The results showed that all three treatments improved cardiac fibrosis and aortic lipid deposition. Exercise intervention failed to alleviate myocardial hypertrophy, but it improved the declined heart rate and diastolic blood pressure in diabetic db/db mice. In contrast, metformin caused opposite effects in these mice. The combination of exercise and metformin had additive effects on glucose intolerance and insulin sensitivity rather than on the improvement of myocardial and aortic structure. In conclusion, metformin improved changes in the morphology and structure of the heart and aorta, while exercise alone or in combination with metformin demonstrated more advantages in cardiac functional reserve through the physiological hypertrophy of myocardium in diabetic db/db mice.

A review on protective roles and potential mechanisms of metformin in diabetic patients diagnosed with COVID-19

The novel coronavirus disease 2019 (COVID-19), is currently the leading threat to public health and a huge challenge to the healthcare systems across the globe and caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Obesity, a state of chronic inflammation, and diabetes mellitus are risk factors for severe SARS-CoV-2. Metformin is one of the most commonly used antidiabetic medications that displayed immunomodulatory activity through AMP-activated protein kinase. Metformin has sex-specific immunomodulatory and cytokine-reducing activities. Therefore, this review aimed to summarize the protective roles of Metformin and its possible molecular mechanisms for use in COVID-19 patients. To include studies, publications related to Metformin and its possible molecular mechanisms for COVID-19 were searched from the databases such as Web of Science, PubMed, Medline, Elsevier, Google Scholar, and SCOPUS, via English key terms. Maintaining proper blood glucose levels using oral antidiabetic drugs like Metformin reduced the detrimental effects of COVID-19 by different possible mechanisms such as Metformin-mediated anti-inflammatory and immunomodulatory activities; effect on viral entry and ACE2 stability; inhibition of virus infection; alters virus survival and endosomal pH; mTOR inhibition; and influence on gut microbiota. Fascinatingly, in diabetic patients with COVID-19, treatment with Metformin was associated with a noticeable reduction in mortality rates and disease severity among infected patients. Metformin was comprehensively investigated for its anti-inflammatory, antiviral capabilities, immunomodulatory, and antioxidant, which would elucidate its capability to confer vascular and cardiopulmonary protection in COVID-19.

Small-molecule antagonism of the interaction of the RAGE cytoplasmic domain with DIAPH1 reduces diabetic complications in mice

The macro- and microvascular complications of type 1 and 2 diabetes lead to increased disease severity and mortality. The receptor for advanced glycation end products (RAGE) can bind AGEs and multiple proinflammatory ligands that accumulate in diabetic tissues. Preclinical studies indicate that RAGE antagonists have beneficial effects on numerous complications of diabetes. However, these antagonists target the extracellular domains of RAGE, which bind distinct RAGE ligands at diverse sites in the immunoglobulin-like variable domain and two constant domains. The cytoplasmic tail of RAGE (ctRAGE) binds to the formin, Diaphanous-1 (DIAPH1), and this interaction is important for RAGE signaling. To comprehensively capture the breadth of RAGE signaling, we developed small-molecule antagonists of ctRAGE-DIAPH1 interaction, termed RAGE229. We demonstrated that RAGE229 is effective in suppressing RAGE-DIAPH1 binding, Förster resonance energy transfer, and biological activities in cellular assays. Using solution nuclear magnetic resonance spectroscopy, we defined the molecular underpinnings of the interaction of RAGE229 with RAGE. Through in vivo experimentation, we showed that RAGE229 assuaged short- and long-term complications of diabetes in both male and female mice, without lowering blood glucose concentrations. Last, the treatment with RAGE229 reduced plasma concentrations of TNF-α, IL-6, and CCL2/JE-MCP1 in diabetic mice, in parallel with reduced pathological and functional indices of diabetes-like kidney disease. Targeting ctRAGE-DIAPH1 interaction with RAGE229 mitigated diabetic complications in rodents by attenuating inflammatory signaling.

Does Metformin Modulate Mitochondrial Dynamics and Function in Type 2 Diabetic Patients?

Metformin is an effective drug against type 2 diabetes (T2D), a pathogenesis in which mitochondrial dysfunction is one of the main players. Thus, our first aim was to describe the effect of metformin on mitochondrial function in an outpatient population with T2D. For analyzing this hypothesis, we performed a preliminary cross-sectional study complying with the STROBE requirements. We studied leukocytes from 139 healthy controls, 39 T2D patients without metformin treatment, and 81 T2D patients who had been on said treatment for at least 1 year. Leukocytes from T2D patients displayed higher total and mitochondrial reactive oxygen species levels, lower mitochondrial membrane potential, and lower oxygen consumption. Moreover, their mitochondria expressed lower mRNA and protein levels of fusion proteins mitofusin-1 (MFN1), mitofusin-2 (MFN2), and optic atrophy 1 (OPA1), and higher protein and gene expression levels of mitochondrial fission protein 1 (FIS1) and dynamin-related protein 1 (DRP-1). In addition, we observed enhanced leukocyte/endothelial interactions in T2D patients. Metformin reversed most of these effects, ameliorating mitochondrial function and dynamics, and reducing the leukocyte/endothelial interactions observed in T2D patients. These results raise the question of whether metformin tackles T2D by improving mitochondrial dysfunction and regulating mitochondrial dynamics. Furthermore, it would seem that metformin modulates the alteration of interactions between leukocytes and the endothelium, a subclinical marker of early atherosclerosis. Antioxid. Redox Signal. 35, 377-385.

Advanced glycation end products and their receptors in serum of patients with type 2 diabetes

Glycation is a non-enzymatic process involving the reaction of reducing sugars or reactive oxoaldehyde with proteins, lipids or nucleic acids, which results in the formation of advanced glycation end products (AGEs). The presented work discusses the glycation process in people with advanced stage of type 1 or type 2 diabetes. The concentration of different AGEs and their receptors for 58 serum samples was determined by ELISA and by spectrofluorimetric methods. In addition to fluorescent low molecular weight and protein-bound AGEs, we have also marked a new class of AGEs: melibiose-derived glycation product (MAGE). Our attention was also focused on the two groups of AGEs receptors: scavenger receptors (SR-A and SR-B) and RAGE. The correlation between the SR-AI scavenging receptors concentration and the fluorescence of AGEs as well as diabetes biological markers: GFR, creatinine contentration and HbA1c was demonstrated. A relationship between the concentration of AGEs and their receptors was also found in serum sample of patients treated with the metformin and aspirin. Furthermore, the concentration of SR-AI scavenger and the fluorescence of total AGEs was significantly lower in treated patients than in non treated patients. AGEs have also been found to contribute to the development of cardiovascular disease, atherosclerosis and diabetic complications, what could be deduced from the correlation of AGEs level and HDL cholesterol or uric acid level. Thus, it was confirmed that AGEs are involved in the pathomechanism of diabetes and other degenerative diseases. Nowadays, it is believed that AGEs due to the long time remaining in the body may be an important diagnostic marker. Their determination may allow monitoring the progression of the disease and the effectiveness of the therapy.

Diabetes and coronavirus (SARS-CoV-2): Molecular mechanism of Metformin intervention and the scientific basis of drug repurposing

Coronavirus Disease 2019 (COVID-19), caused by a new strain of coronavirus called Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), was declared a pandemic by WHO on March 11, 2020. Soon after its emergence in late December 2019, it was noticed that diabetic individuals were at an increased risk of COVID-19-associated complications, ICU admissions, and mortality. Maintaining proper blood glucose levels using insulin and/or other oral antidiabetic drugs (such as Metformin) reduced the detrimental effects of COVID-19. Interestingly, in diabetic COVID-19 patients, while insulin administration was associated with adverse outcomes, Metformin treatment was correlated with a significant reduction in disease severity and mortality rates among affected individuals. Metformin was extensively studied for its antioxidant, anti-inflammatory, immunomodulatory, and antiviral capabilities that would explain its ability to confer cardiopulmonary and vascular protection in COVID-19. Here, we describe the various possible molecular mechanisms that contribute to Metformin therapy's beneficial effects and lay out the scientific basis of repurposing Metformin for use in COVID-19 patients.

The use of the soluble receptor for advanced glycation-end products (sRAGE) as a potential biomarker of disease risk and adverse outcomes

The soluble receptor for advanced glycation end-products (sRAGE) has been classically considered a sink for pro-inflammatory RAGE ligands and as such has been associated with protection from inflammatory stress and disease. An alternative, though not mutually exclusive view is that high levels of sRAGE in circulation reflect the overstimulation of cell surface RAGE which if persistent, lead to the amplification of pro-inflammatory processes and the exacerbation of pathological states. With these two scenarios in mind this review focuses on the potential role of sRAGE as a prospective biomarker of disease risk and adverse outcomes.

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The prognostic value of measuring sRAGE levels in blood is subjected to debate.

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Raised sRAGE levels may result from the overstimulation of cell surface RAGE.

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Raised sRAGE may reflect chronic inflammation and multimorbidity rather than a healthy state.

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sRAGE is a promising biomarker of disease risk and adverse outcomes.

Skin autofluorescence predicts cancer in subjects with type 2 diabetes

INTRODUCTION

Subjects with type 2 diabetes have an excess risk of cancer. The potential role of advanced glycation end products (AGEs) accumulated during long-term hyperglycemia in cancer development has been suggested by biological studies but clinical data are missing. AGEs can be estimated by measuring the skin autofluorescence. We searched whether the skin autofluorescence could predict new cancers in persons with type 2 diabetes.

RESEARCH DESIGN AND METHODS

From 2009 to 2015, we measured the skin autofluorescence of 413 subjects hospitalized for uncontrolled or complicated type 2 diabetes, without any history of cancer. The participants were followed for at least 1 year and the occurrences of new cancers were compared according to their initial skin autofluorescences.

RESULTS

The participants were mainly men (57.9%), with poorly controlled (HbA1c 72±14 mmol/mol or 8.7%±1.8%) and/or complicated type 2 diabetes. Their median skin autofluorescence was 2.6 (2.2-3.0) arbitrary units. Forty-five new cancer cases (10.9%) were registered during 4.8±2.3 years of follow-up: 75.6% of these subjects had skin autofluorescence higher than the median (χ²: p=0.001). By Cox regression analysis adjusted for age, gender, body mass index, history of smoking and renal parameters, skin autofluorescence >2.6 predicted a 2.57-fold higher risk of cancer (95% CI 1.28 to 5.19, p=0.008). This association remained significant after excluding the eight cancers that occurred in the 4 years after inclusion (OR 2.95, 95% CI 1.36 to 6.38, p=0.006). As a continuous variable, skin autofluorescence was also related to new cancers (OR 1.05, 95% CI 1.01 to 1.10, p=0.045).

CONCLUSIONS

Skin autofluorescence, a potential marker of glycemic memory, predicts the occurrence of cancer in subjects with type 2 diabetes. This relation provides a new clinical argument for the role of AGEs in cancer. Their estimation by measuring the skin autofluorescence may help select subjects with diabetes in cancer screening programs.

Chitosan-Stabilized Selenium Nanoparticles and Metformin Synergistically Rescue Testicular Oxidative Damage and Steroidogenesis-Related Genes Dysregulation in High-Fat Diet/Streptozotocin-Induced Diabetic Rats

BACKGROUND

this study examined the metformin (MF) and/or chitosan stabilized selenium nanoparticles (CH-SeNPs) efficacy to alleviate the male reproductive function impairment in a high-fat diet feed with low-dose streptozotocin (HFD/STZ) induced type 2 diabetes mellitus (T2DM) diabetic rat model.

METHODS

control non-diabetic, HFD/STZ diabetic, HFD/STZ+MF, HFD/STZ+CH-SeNPs, and HFD/STZ+MF+CH-SeNPs rat groups were used. After 60 days, semen evaluation, hormonal assay, enzymatic antioxidant, lipid peroxidation, testis histopathology, and the steroidogenesis-related genes mRNA expressions were assessed.

RESULTS

in the HFD/STZ diabetic rats, sperm count and motility, male sexual hormones, and testicular antioxidant enzymes were significantly reduced. However, sperm abnormalities and testicular malondialdehyde were significantly incremented. The steroidogenesis-related genes, including steroidogenic acute regulatory protein (StAr), cytochrome11A1 (CYP11A1), cytochrome17A1 (CYP17A1), and hydroxysteroid 17-beta dehydrogenase 3 (HSD17B3), and the mitochondrial biogenesis related genes, including peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGCα) and sirtuin (SIRT), were significantly downregulated in the HFD/STZ diabetic rats. However, CYP19A1mRNA expression was significantly upregulated. In contrast, MF and/or CH-SeNPs oral dosing significantly rescued the T2DM-induced sperm abnormalities, reduced sperm motility, diminished sexual hormones level, testicular oxidative damage, and steroidogenesis-related genes dysregulation. In the MF and CH-SeNP co-treated group, many of the estimated parameters differ considerably from single MF or CH-SeNPs treated groups.

CONCLUSIONS

the MF and CH-SeNPs combined treatment could efficiently limit the diabetic complications largely than monotherapeutic approach and they could be considered a hopeful treatment option in the T2DM.