How does blood glucose control with metformin influence intensive insulin protocols? Evidence for involvement of oxidative stress and inflammatory cytokines

Advanced glycation end product signaling and metabolic complications: Dietary approach

Advanced glycation end products (AGEs) are a heterogeneous collection of compounds formed during industrial processing and home cooking through a sequence of nonenzymatic glycation reactions. The modern western diet is full of heat-treated foods that contribute to AGE intake. Foods high in AGEs in the contemporary diet include processed cereal products. Due to industrialization and marketing strategies, restaurant meals are modified rather than being traditionally or conventionally cooked. Fried, grilled, baked, and boiled foods have the greatest AGE levels. Higher AGE-content foods include dry nuts, roasted walnuts, sunflower seeds, fried chicken, bacon, and beef. Animal proteins and processed plant foods contain furosine, acrylamide, heterocyclic amines, and 5-hydroxymethylfurfural. Furosine (2-furoil-methyl-lysine) is an amino acid found in cooked meat products and other processed foods. High concentrations of carboxymethyl-lysine, carboxyethyl-lysine, and methylglyoxal-O are found in heat-treated nonvegetarian foods, peanut butter, and cereal items. Increased plasma levels of AGEs, which are harmful chemicals that lead to age-related diseases and physiological aging, diabetes, and autoimmune/inflammatory rheumatic diseases such as systemic lupus erythematosus and rheumatoid arthritis. AGEs in the pathophysiology of metabolic diseases have been linked to individuals with diabetes mellitus who have peripheral nerves with high amounts of AGEs and diabetes has been linked to increased myelin glycation. Insulin resistance and hyperglycemia can impact numerous human tissues and organs, leading to long-term difficulties in a number of systems and organs, including the cardiovascular system. Plasma AGE levels are linked to all-cause mortality in individuals with diabetes who have fatal or nonfatal coronary artery disease, such as ventricular dysfunction. High levels of tissue AGEs are independently associated with cardiac systolic dysfunction in diabetic patients with heart failure compared with diabetic patients without heart failure. It is widely recognized that AGEs and oxidative stress play a key role in the cardiovascular complications of diabetes because they both influence and are impacted by oxidative stress. All chronic illnesses involve protein, lipid, or nucleic acid modifications including crosslinked and nondegradable aggregates known as AGEs. Endogenous AGE formation or dietary AGE uptake can result in additional protein modifications and stimulation of several inflammatory signaling pathways. Many of these systems, however, require additional explanation because they are not entirely obvious. This review summarizes the current evidence regarding dietary sources of AGEs and metabolism-related complications associated with AGEs.

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.

Metformin Use Is Associated with Decreased Mortality in COVID-19 Patients with Diabetes: Evidence from Retrospective Studies and Biological Mechanism

BACKGROUND AND AIMS

The coronavirus disease 2019 (COVID-19) increases hyperinflammatory state, leading to acute lung damage, hyperglycemia, vascular endothelial damage, and a higher mortality rate. Metformin is a first-line treatment for type 2 diabetes and is known to have anti-inflammatory and immunosuppressive effects. Previous studies have shown that metformin use is associated with decreased risk of mortality among patients with COVID-19; however, the results are still inconclusive. This study investigated the association between metformin and the risk of mortality among diabetes patients with COVID-19.

METHODS

Data were collected from online databases such as PubMed, EMBASE, Scopus, and Web of Science, and reference from the most relevant articles. The search and collection of relevant articles was carried out between 1 February 2020, and 20 June 2021. Two independent reviewers extracted information from selected studies. The random-effects model was used to estimate risk ratios (RRs), with a 95% confidence interval.

RESULTS

A total of 16 studies met all inclusion criteria. Diabetes patients given metformin had a significantly reduced risk of mortality (RR, 0.65; 95% CI: 0.54-0.80, p < 0.001, heterogeneity I2 = 75.88, Q = 62.20, and τ2 = 0.06, p < 0.001) compared with those who were not given metformin. Subgroup analyses showed that the beneficial effect of metformin was higher in the patients from North America (RR, 0.43; 95% CI: 0.26-0.72, p = 0.001, heterogeneity I2 = 85.57, Q = 34.65, τ2 = 0.31) than in patients from Europe (RR, 0.67; 95% CI: 0.47-0.94, p = 0.02, heterogeneity I2 = 82.69, Q = 23.11, τ2 = 0.10) and Asia (RR, 0.90; 95% CI: 0.43-1.86, p = 0.78, heterogeneity I2 = 64.12, Q = 11.15, τ2 = 0.40).

CONCLUSIONS

This meta-analysis shows evidence that supports the theory that the use of metformin is associated with a decreased risk of mortality among diabetes patients with COVID-19. Randomized control trials with a higher number of participants are warranted to assess the effectiveness of metformin for reducing the mortality of COVID-19 patients.

Metformin Attenuates Brain Injury by Inhibiting Inflammation and Regulating Tight Junction Proteins in Septic Rats

OBJECTIVE

Metformin has a potent inhibitory activity against inflammation and oxidative stress, which inevitably occur in sepsis-associated encephalopathy (SAE). The precise mechanisms underlying neuroprotective effects of metformin in SAE, are still unclear. In the present work, the protective effect of metformin on SAE using cecal ligation and puncture (CLP) model of sepsis, was assessed.

MATERIALS AND METHODS

In this experimental study, CLP procedure was performed in Wistar rats and 50 mg/kg metformin was administered immediately. Specific markers of sepsis severity, inflammation, blood brain barrier (BBB) dysfunction, and brain injury, were investigated. Specific assay kits and real-time polymerase chain reaction (RT-PCR) were used. Histopathological assessment was also carried out.

RESULTS

Treatment with metformin decreased murine sepsis score (MSS), lactate, platelet lymphocyte ratio (PLR), and high mobility group box (HMGB1) levels. The expression levels of claudin 3 (Cldn3) and claudin 5 (Cldn5) were increased following treatment with metformin. Metformin decreased the expression of S100b, neuron specific enolase (Nse), and glial fibrillary acidic protein (Gfap).

CONCLUSION

Our study suggests that metformin may inhibit inflammation and increase tight junction protein expressions which may improve BBB function and attenuate CLP-induced brain injury. Hence, the potential beneficial effects of metformin in sepsis, should be considered in future.

Prognostic impact of elevated lactate levels on mortality in critically ill patients with and without preadmission metformin treatment: a Danish registry-based cohort study

BACKGROUND

Lactate is a robust prognostic marker for the outcome of critically ill patients. Several small studies reported that metformin users have higher lactate levels at ICU admission without a concomitant increase in mortality. However, this has not been investigated in a larger cohort. We aimed to determine whether the association between lactate levels around ICU admission and mortality is different in metformin users compared to metformin nonusers.

METHODS

This cohort study included patients admitted to ICUs in northern Denmark between January 2010 and August 2017 with any circulating lactate measured around ICU admission, which was defined as 12 h before until 6 h after admission. The association between the mean of the lactate levels measured during this period and 30-day mortality was determined for metformin users and nonusers by modelling restricted cubic splines obtained from a Cox regression model.

RESULTS

Of 37,293 included patients, 3183 (9%) used metformin. The median (interquartile range) lactate level was 1.8 (1.2-3.2) in metformin users and 1.6 (1.0-2.7) mmol/L in metformin nonusers. Lactate levels were strongly associated with mortality for both metformin users and nonusers. However, the association of lactate with mortality was different for metformin users, with a lower mortality rate in metformin users than in nonusers when admitted with similar lactate levels. This was observed over the whole range of lactate levels, and consequently, the relation of lactate with mortality was shifted rightwards for metformin users.

CONCLUSION

In this large observational cohort of critically ill patients, early lactate levels were strongly associated with mortality. Irrespective of the degree of hyperlactataemia, similar lactate levels were associated with a lower mortality rate in metformin users compared with metformin nonusers. Therefore, lactate levels around ICU admission should be interpreted according to metformin use.

Advanced Glycation End Products: Potential Mechanism and Therapeutic Target in Cardiovascular Complications under Diabetes

The occurrence and development of cardiovascular complications are predominantly responsible for the increased morbidity and mortality observed in patients with diabetes. Oxidative stress under hyperglycemia is currently considered the initial link to diabetic cardiovascular complications and a key node for the prevention and treatment of diabetes-related fatal cardiovascular events. Numerous studies have indicated that the common upstream pathway in the context of oxidative stress in the cardiovascular system under diabetic conditions is the interaction of advanced glycation end products (AGEs) with their receptors (RAGEs). Therefore, a further understanding of the relationship between oxidative stress and AGEs is of great significance for the prevention and treatment of cardiovascular complications in patients with diabetes. In this review, we will briefly summarize the recent research advances in diabetes with an emphasis on oxidative stress and its association with AGEs in diabetic cardiovascular complications.

A Review on The Protective Effects of Metformin in Sepsis-Induced Organ Failure

Despite advances in sepsis management, it remains a major intensive-care-unit (ICU) concern. From new prospective, positive effects of metformin, such as anti-oxidant and anti-inflammatory properties are considered potentially beneficial properties for management of septic patients. This article reviewed the potential ameliorative effects of metformin in sepsis-induced organ failure. Information were retrieved from PubMed, Scopus, Embase, and Google Scholar. Multi-organ damage, oxidative stress, inflammatory cytokine stimulation, and altered circulation are hallmarks of sepsis. Metformin exerts its effect via adenosine monophosphate-activated protein kinase (AMPK) activation. It improves sepsis-induced organ failure by inhibiting the production of reactive oxygen species (ROS) and pro-inflammatory cytokines, preventing the activation of transcription factors related to inflammation, decreasing neutrophil accumulation/infiltration, and also maintaining mitochondrial membrane potential. Studies reported the safety of metformin therapeutic doses, with no evidence of lactic acidosis, in septic patients.

Altered superoxide dismutase-1 activity and intercellular adhesion molecule 1 (ICAM-1) levels in patients with type 2 diabetes mellitus

Inflammation and oxidative stress are linked to type 2 diabetes mellitus (T2DM). In this work, we analyzed patients' blood markers of antioxidant capacity, oxidative stress and inflammation in individuals with T2DM, in pre-diabetes state (pre-DM) and controls without diabetes. Patients were divided into three groups, according to glycated hemoglobin A1c (HbA1c): <7%, 7-9%, and >9%. Superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities, total thiols, nitric oxide (•NO), tumor necrosis factor alpha (TNF-α) and intercellular adhesion molecule 1 (ICAM-1) levels of the individuals were measured. Plasma SOD activity was higher in T2DM subjects compared to the controls. While total thiols levels were lower in T2DM groups when compared to pre-DM, the values remained unchanged when compared to controls. ICAM-1 levels of T2DM groups were lower than in controls, while GPx activity, •NO, and TNF-α levels were similar among all groups. A positive correlation was found between SOD and HbA1c levels. Concluding, individuals with T2DM present altered SOD activity, total thiols, and ICAM-1 levels, which might contribute to further complications. There is a positive correlation between SOD activity and HbA1c levels. No apparent correlation exists between total thiols and ICAM-1 levels and with any other of the parameters evaluated in this study.

Effect of Preadmission Metformin Use on Clinical Outcome of Acute Respiratory Distress Syndrome among Critically Ill Patients with Diabetes

BACKGROUND

Acute respiratory distress syndrome (ARDS) is related to high mortality and morbidity. There are no proven therapeutic measures however, to improve the clinical course of ARDS, except using low tidal volume ventilation. Metformin is known to have pleiotropic effects including anti-inflammatory activity. We hypothesized that pre-admission metformin might alter the progress of ARDS among intensive care unit (ICU) patients with diabetes mellitus (DM).

METHODS

We performed a retrospective cohort study from January 1, 2005, to April 30, 2005 of patients who were admitted to the medical ICU at Seoul National University Hospital because of ARDS, and reviewed ARDS patients with DM. Metformin use was defined as prescribed within 3-month pre-admission.

RESULTS

Of 558 patients diagnosed with ARDS, 128 (23.3%) patients had diabetes and 33 patients were treated with metformin monotherapy or in combination with other antidiabetic medications. Demographic characteristics, cause of ARDS, and comorbid conditions (except chronic kidney disease) were not different between metformin users and nonusers. Several severity indexes of ARDS were similar in both groups. The 30-day mortality was 42.42% in metformin users and 55.32% in metformin nonusers. On multivariable regression analysis, use of metformin was not significantly related to a reduced 30-day mortality (adjusted β-coefficient, -0.19; 95% confidence interval, -1.76 to 1.39; p=0.816). Propensity score-matched analyses showed similar results.

CONCLUSION

Pre-admission metformin use was not associated with reduced 30-day mortality among ARDS patients with DM in our medical ICU.

Metformin is not associated with lactic acidosis in patients with diabetes undergoing coronary artery bypass graft surgery: a case control study

BACKGROUND

Metformin associated lactic acidosis (MALA) is a rare but lethal complication. There is no consensus regarding when to stop and resume metformin in patients who undergo coronary artery bypass grafting (CABG). This study aimed to determine if uninterrupted metformin administration in patients with diabetes undergoing CABG increases the risk of lactic acidosis.

METHODS

Over a span of 12 months (2015-2016), 127 patients with type 2 diabetes underwent isolated CABG. Of those, 41 patients (32%) continued taking metformin and 86 patients (68%) took other antidiabetic agents. Patients taking metformin took the drug until the day of surgery and resumed taking it 3 h after extubation.

RESULTS

There were no differences in clinical outcomes or complications between groups. Serial measurement of cardiac, liver, and kidney biomarkers were similar between groups. The mean peak lactic acid level was significantly higher in the non-metformin users (5.4 ± 2.6 vs. 7.4 ± 4.1 mmol/l; P = 0.001). Multivariable logistic regression analysis identified the need for vasopressor administration as an independent predictor of lactic acidosis (odds ratio: 7.3, 95% confidence interval: 2.5-20.6; P < 0.001).

CONCLUSION

In the absence of risk factors associated with persistent lactic acidosis, such as shock or acute kidney or liver injury, continued peri-operative metformin administration was not associated with the occurrence of lactic acidosis in patients undergoing CABG. Elevated lactic acid levels seem to be directly related to tissue anoxia caused by escalating vasopressor support after surgery.

Dysglycemia and Glucose Control During Sepsis

Sepsis predisposes to disordered metabolism and dysglycemia; the latter is a broad term that includes hyperglycemia, hypoglycemia, and glycemic variability. Dysglycemia is a marker of illness severity. Large randomized controlled trials have provided considerable insight into the optimal blood glucose targets for critically ill patients with sepsis. However, it may be that the pathophysiologic consequences of dysglycemia are dynamic throughout the course of a septic insult and also altered by premorbid glycemia. This review highlights the relevance of hyperglycemia, hypoglycemia, and glycemic variability in patients with sepsis with an emphasis on a rational approach to management.

Preadmission metformin use and mortality among intensive care patients with diabetes: a cohort study

Introduction

Metformin has anti-inflammatory and anti-thrombotic effects that may improve the outcome of critical illness, but clinical data are limited. We examined the impact of preadmission metformin use on mortality among intensive care unit (ICU) patients with type 2 diabetes.

Methods

We conducted this population-based cohort study among all persons admitted to the 17 ICUs in Northern Denmark (population approximately 1.8 million). We focused on all patients with type 2 diabetes who were admitted to the ICUs between January 2005 and December 2011. Through individual-level linkage of population-based medical databases, type 2 diabetes was identified using a previously validated algorithm including hospital diagnoses, filled prescriptions for anti-diabetic drugs, and elevated HbA1c levels. Metformin use was identified by filled prescriptions within 90 days before admission. Covariates included surgery, preadmission morbidity, diabetes duration, and concurrent drug use. We computed 30-day mortality and hazard ratios (HRs) of death using Cox regression adjusted for covariates, both overall and after propensity score matching.

Results

We included 7,404 adult type 2 diabetes patients, representing 14.0% of 52,964 adult patients admitted to the ICUs. Among type 2 diabetes patients, 1,073 (14.5%) filled a prescription for metformin as monotherapy within 90 days before admission and 1,335 (18.0%) received metformin in combination with other anti-diabetic drugs. Thirty-day mortality was 17.6% among metformin monotherapy users, 17.9% among metformin combination therapy users, and 25.0% among metformin non-users. The adjusted HRs were 0.80 (95% confidence interval (CI): 0.69, 0.94) for metformin monotherapy users and 0.83 (95% CI: 0.71, 0.95) for metformin combination therapy users, compared to non-users. Propensity-score-matched analyses yielded the same results. The association was evident across most subgroups of medical and surgical ICU patients, but most pronounced in elderly patients and in patients with well-controlled diabetes. Former metformin use was not associated with decreased mortality.

Conclusions

Preadmission metformin use was associated with reduced 30-day mortality among medical and surgical intensive care patients with type 2 diabetes.

The predictive value of resting heart rate following osmotherapy in brain injury: back to basics

Background

The importance of resting heart rate as a prognostic factor was described in several studies. An elevated heart rate is an independent risk factor for adverse cardiovascular events and total mortality in patients with coronary artery disease, chronic heart failure, and the general population. Also heart rate is elevated in the Multi Organ Dysfunction Syndrome (MODS) and the mortality due to MODS is highly correlated with inadequate sinus tachycardia.

To evaluate the value of resting heart rate in predicting mortality in patients with traumatic brain injury along scoring systems like Acute Physiology and Chronic Health Evaluation(APACHE II), Sequential Organ Failure Assessment (SOFA) and Glasgow Coma Score (GCS).

Method

By analyzing data which was collected from an open labeled randomized clinical trial that compared the different means of osmotherapy (mannitol vs bolus or infusion hypertonic saline), heart rate, GCS, APACHE II and SOFA score were measured at baseline and daily for 7 days up to 60 days and the relationship between elevated heart rate and mortality during the first 7 days and 60th day were assessed.

Results

After adjustments for confounding factors, although there was no difference in mean heart rate between either groups of alive and expired patients, however, we have found a relative correlation between 60th day mortality rate and resting heart rate (P=0.07).

Conclusion

Heart rate can be a prognostic factor for estimating mortality rate in brain injury patients along with APACHE II and SOFA scores in patients with brain injury.

Effect of chicory seed extract on glucose tolerance test (GTT) and metabolic profile in early and late stage diabetic rats

Background and purpose of the study

The goal was to evaluate and compare the effects of aqueous extract of the seeds of chicory, Cichorium intybus L., on glucose tolerance test (GTT) and blood biochemical indices of experimentally-induced hyperglycemic rats.

Methods

Late stage and early stage of Type 2 diabetes mellitus (T2DM) were induced in rats by streptozotocin (STZ) and a combination of STZ and niacinamide (NIA/STZ), respectively. Within each group, one subgroup received daily i. p. injections of chicory extract (125 mg/kg body weight, for 28 days). Body weight and fasting blood sugar (FBS) were measured weekly. Blood was analyzed for glycosylated hemoglobin (HbA1c) and sera for alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO), triacylglycerol (TG), total cholesterol (TC), total protein, and insulin on days 10 and 28 after treatment. Intraperitoneal glucose tolerance test (IPGTT) along with insulin determination was performed on a different set of rats in which the chicory-treated groups received the extract for 10 days.

Results

During 4 weeks of treatment, chicory prevented body-weight loss and decreased FBS. ALT activities and levels of TG, TC and HbA1c decreased, and concentration of NO increased in the chicory treated groups (p < 0.05). Unlike late-stage diabetes, fasting serum insulin concentrations were higher and GTT pattern approximated to normal in chicory-treated early-stage diabetic rats.

Conclusions

Chicory appeared to have short-term (about 2 hours, as far as GTT is concerned) and long-term (28 days, in this study) effects on diabetes. Chicory may be useful as a natural dietary supplement for slowing down the pace of diabetes progress, and delaying the development of its complications.

Comparison of hypertonic saline versus normal saline on cytokine profile during CABG

Background and the purpose of the study

Blood contact with artificial surfaces of the extracorporeal circuit and ischemia-reperfusion injury in CABG with CPB, may lead to a systemic inflammatory response. Hypertonic saline have been recently investigated as a fluid in order to decrease inflammatory response and cytokines generation in patients undergo cardiac operations. Our purpose is to study the prophylactic effect of HS 5% infusion versus NS on serum IL-6 as an inflammatory & IL-10 as an anti-inflammatory biomarker in CABG patients.

Methods

The present study is a randomized double-blinded clinical trial. 40 patients undergoing CABG were randomized to receive HS 5% or NS before operation. Blood samples were obtained after receiving HS or NS, just before operation, 24 and 48 hours post-operatively. Plasma levels of IL-6 and IL-10 were measured by ELISA.

Results and major conclusion

Patients received HS had lower levels of IL-6 and higher level of IL-10 compared with NS group, however these differences were not statistically significant. Results of this study suggest that pre-treatment with small volume hypertonic saline 5% may have beneficial effects on inflammatory response following CABG operation.

Metformin as an adjunct to insulin for glycemic control in patients with type 2 diabetes after CABG surgery: a randomized double blind clinical trial

Perioperative hyperglycemia is common in patients with type 2 diabetes undergoing Coronary Artery Bypass Graft (CABG) surgery and there is a direct relation between postoperative hyperglycemia and mortality rate in these patients. The aim of the present study is to determine the efficacy of metformin on glycemic control in diabetic patients after CABG surgery. In a randomized double blind clinical trial, 100 patients with type 2 diabetes admitted in open heart ICU after CABG surgery in Mazandaran Heart Center were enrolled. They were randomly assigned to two intervention and control groups. Three hours after extubation, therapeutic antiglycemic regimens were applied in these two groups and continued for three days. Intervention group received regular insulin infusion along with two metformin 500 mg tablets per twelve hours while control group received regular insulin infusion with two placebo tablets per twelve hours. Blood glucose level and other parameters were measured and recorded in determined intervals. To analyze the data, independent T-test, paired T-test, Mann-Whitney and repeated measure ANOVA tests were employed. Mean blood glucose level was not significantly different in the two groups at the beginning of the ICU admission; however, mean glucose level in insulin-metformin group, twelve hours after the initiation of the study, was significantly lower than insulin group (p < 0.05). In addition, mean doses of potassium and insulin demand as well as mean number of episodes of hyperglycemia, hypoglycemia and glucose levels out of the accepted range were significantly lower in insulin-metformin group (p < 0.05). Alterations in mean levels of lactate, BE, pH and creatinine were not statistically significant in these two groups. It seems that adding metformin to insulin leads to a better glycemic control in type two diabetic patients undergoing CABG surgery without causing metabolic acidosis. Therefore, it might be a potential option in blood glucose control protocol in this group of patients.

Biochemical evidence on the potential role of organophosphates in hepatic glucose metabolism toward insulin resistance through inflammatory signaling and free radical pathways

Several studies show that organophosphate pesticides exert several effects on glucose homeostasis. The current study investigates the influence of subchronic exposure to malathion (MT) on hepatic gluconeogenesis in relation to acetyl cholinesterase (AChE) inhibition, oxidative stress and inflammatory response in the rat. MT was administered by gavage at doses of 25, 50 and 100 mg/kg for 32 days. Fasting hyperglycemia was seen in line with an increased activity of hepatic phosphoenolpyruvate carboxykinase, glucose 6-phosphatase and tumor necrosis factor α. In addition to the impaired glucose tolerance and inhibition of AChE in a dose-dependent manner, there were significant increases in hepatic lipid peroxidation, carbonyl groups and 8-deoxyguanosine as the biomarkers of reactive oxygen species–mediated damage to lipid, protein and DNA, respectively. Altered quality of the liver in glucose production especially gluconeogenesis could be a compensatory mechanism against MT toxicity or even result in tissue damage. MT-induced insulin resistance in the liver occurs through oxidative and inflammatory signaling pathways.

Does high-dose metformin cause lactic acidosis in type 2 diabetic patients after CABG surgery? A double blind randomized clinical trial

Metformin is a dimethyl biguanide oral anti-hyperglycemic agent. Lactic acidosis due to metformin is a fatal metabolic condition that limits its use in patients in poor clinical condition, consequently reducing the number of patients who benefit from this medication. In a double blind randomized clinical trial, we investigated 200 type 2 diabetic patients after coronary artery bypass surgery in the open heart ICU of the Mazandaran Heart Center, and randomly assigned them to equal intervention and control groups. The intervention group received regular insulin infusion along with 2 metformin 500 mg tablets every twelve hours, while the control group received only intravenous insulin with 2 placebo tablets every twelve hours. Lactate level, pH, base excess, blood glucose and serum creatinine were measured over five 12 h periods, with data averaged for each period. The primary outcome in this study was high lactate levels. Comparison between the 2 groups was made by independent Student’s t-test. To compare changes in multiple measures in each group and analysis of group interaction, a repeated measurement ANOVA test was used.

There was no significant difference between the 2 groups regarding pH, base excess, or bicarbonate intake (P>0.05). No patient showed lactic acidosis in either group. Lactate levels were 23.0 vs 23.4 in the insulin-metformin and insulin only groups when the study was started, respectively. At the end of the study, those levels were 18.7 vs 18.9, respectively. In addition, the ANOVA repeated measurement test did not show a significant difference in terms of changes in the amount of lactate level between the 2 groups during the five measurement tests of the study period (P>0.05).

High-dose metformin (1,000 mg twice daily with insulin) does not cause lactic acidosis in type 2 diabetic patients after coronary artery bypass surgery.

Hepatic mechanisms of the Walnut antidiabetic effect in mice

The present study was designed to explore the mechanism of action of walnut (the seed of Juglans regia) leaf and ridge on hepatic glucose metabolism in diabetic mice. Experimental diabetes was induced by intravenous administration of streptozotocin (60 mg/kg)and confirmed with an increase of blood glucose, 90–100% of the control, 72 hours later. Isolated extracts from walnut leaf and ridges were administered in a single effective dose of 400 mg/kg orally. Firstly, blood glucose was determined every 1 hour until 5 hours post administration of extracts. In the second experiment, the liver was surgically removed, 2 hours post treatment of diabetic animals with extracts, homogenized and used for measurement of key enzymes of glycogenolysis (glycogen phosphorylase, GP) and gluconeogenesis (phosphoenolpyruvate carboxykinase, PEPCK). Treatment by both leaf and ridge extracts decreased blood glucose and liver PEPCK activity and increased blood insulin and liver GP activity. It is concluded that walnut is able to lower blood glucose through inhibition of hepatic gluconeogenesis and secretion of pancreatic insulin.

A review of the herbal phosphodiesterase inhibitors; future perspective of new drugs

Phosphodiesterase inhibitors (PDEIs) are a class of drugs that are widely used because of their various pharmacological properties including cardiotonic, vasodilator, smooth muscle relaxant, antidepressant, antithrombotic, bronchodilator, antiinflammatory and enhancer of cognitive function. In the recent years, interest in drugs of plant origin has been progressively increased. Some pharmacologically active substances that come from plants demonstrate PDEI activity. They mainly belong to alkaloids, flavonoids, and saponins. In this review, studies on herbal PDEI were reviewed and their possible therapeutic applications were discussed. Screening plants for PDE inhibitory activity may help to develop standardized phytotherapeutic products or find new sources for new lead structures with PDEI pharmacological activity. The studies discussed in this paper are mainly in vitro and for more reasonable and conclusive results, it is required to conduct in vivo and finally human and clinical tests.

Improvement of inflammatory and toxic stress biomarkers by silymarin in a murine model of type one diabetes mellitus

Type 1 diabetes mellitus (T1DM) is characterized by an impairment of the insulin-secreting beta cells with an immunologic base. Inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and free radicals are believed to play key roles in destruction of pancreatic β cells. The present study was designed to investigate the effect of Silybum marianum seed extract (silymarin), a combination of several flavonolignans with immunomodulatory, anti-oxidant, and anti-inflammatory potential on streptozotocin (STZ)-induced T1DM in mouse. Experimental T1DM was induced in male albino mice by IV injection of multiplelow- doses of STZ for 5 days. Seventy-two male mice in separate groups received various doses of silymarin (20, 40, and 80 mg/kg) concomitant or after induction of diabetes for 21 days. Blood glucose and pancreatic biomarkers of inflammation and toxic stress (IL-1β, TNF-α, myeloperoxidase, lipid peroxidation, protein oxidation, thiol molecules, and total antioxidant capacity) were determined. Silymarin treatment reduced levels of inflammatory cytokines such as TNF-α and IL-1β and oxidative stress mediators like myeloperoxidase activity, lipid peroxidation, carbonyl and thiol content of pancreatic tissue in an almost dose dependent manner. No marked difference between the prevention of T1DM and the reversion of this disease by silymarin was found. Use of silymarin seems to be helpful in T1DM when used as pretreatment or treatment. Benefit of silymarin in human T1DM remains to be elucidated by clinical trials.