High-dose Metformin Research Articles

Relationship between metformin use and vitaminB12 status in patients with type2 diabetes in Japan.

Aims/IntroductionMetformin therapy has been associated with vitamin B12 (VB12) deficiency, but information regarding this adverse effect in Asian populations is limited. We have now examined the relationship between metformin use and VB12 status in individuals with type 2 diabetes mellitus in Japan.Materials and MethodsThis cross‐sectional study was carried out with type 2 diabetes mellitus patients treated (Met group, n = 122) or not treated (control group, n = 63) with metformin. The primary end‐point was the difference in the serum concentration of homocysteine, a marker of VB12 activity, between the two groups. The serum concentrations of VB12, blood hemoglobin level and mean corpuscular volume were also compared between the groups. Subset analysis was carried out with individuals aged ≥70 years. The potential correlation between the daily dose or duration of metformin treatment and the other measured parameters was also examined.ResultsThe level of homocysteine, as well as the VB12 level, hemoglobin concentration and mean corpuscular volume, did not differ significantly between the control and treated with metformin groups. The level of homocysteine was positively and that of VB12 negatively correlated with the daily dose of metformin. Among elderly individuals, the hemoglobin level was significantly lower in the treated with metformin group than in the control group, although the mean corpuscular volume was similar in the two groups.ConclusionsThe risk of VB12 deficiency during metformin treatment appears to be low in Japanese type 2 diabetes mellitus patients. However, high doses of metformin might result in a moderate decrease in the circulating VB12 level, as well as in anemia in elderly individuals.

Effect of metformin on mitochondrial pathway of apoptosis and oxidative stress in cell model of nonalcoholic fatty liver disease

Objective: To investigate the effects of metformin on mitochondrial pathway of apoptosis and oxidative stress in cell model of nonalcoholic fatty liver disease. Methods: An in vitro cell model of nonalcoholic fatty liver disease was established using 0.6 mmol/L oleic acid to induce lipid accumulation in HepG2 cells. HepG2 cells were divided into control (Con) group, oleic acid (OA) group, and metformin-low (1mmol/L) and high (10mmol/L) dose group. Oil Red O stain was used to detect intracellular lipid droplet distribution. The levels of alanine aminotransferase and aspartate aminotransferase in the culture supernatant were detected by assay kits. DCFH-DA method was used to detect the reactive oxygen species of HepG2 cells. Double staining flow cytometry was used to detect the apoptosis rate of HepG2 cells. Western blot was used to detect caspase-3, B-lymphocyte lymphoma-related protein, B-cell lymphoma 2, and cytochrome c protein. One-way analysis of variance was used to compare the data between groups. Results: Oleic acid-induced HepG2 cells were significantly increased with lipid droplets. Low and high-dose metformin had reduced intracellular lipid droplets accumulation. The effect of metformin in the high-dose group was more significant than that in the low-dose group. Aspartate aminotransferase and alanine aminotransferase in HepG2 cells of OA group were significantly increased, which were (43.41 ± 7.11) U/L and (29.56 ± 4.11) U/L, respectively. The intracellular aspartate aminotransferase and alanine aminotransferase were decreased significantly after the treatment with low and high-dose metformin, which were (32.44 ± 4.08)U/L, (19.31 ± 3.03) U/L, (26.00 ± 3.11) U/L and (15.11 ± 4.11) U/L, respectively and the differences were statistically significant (P < 0.05). DCFH-DA test results showed that the fluorescence intensity of reactive oxygen species in the oleic acid group was 41.21% ± 4.23%, while the fluorescence intensity of reactive oxygen species in the low and high-dose metformin groups were reduced to 27.44% ± 3.91%, and 17.55% ± 5.11%, respectively and the differences between the groups were statistically significant (P < 0.05). The results of flow cytometry analysis showed that the cell apoptosis rate of the OA group was significantly higher than that of the Con group (12.12% ± 0.72% vs. 3.04% ± 0.57%, P < 0.05).The apoptosis rate of HepG2 cells was significantly reduced after metformin treatment at low and high doses (8.71% ± 0.71%, 5.71% ± 0.61%, P < 0.05). Western blot results showed that compared with the Con group, the expressions of B-lymphocyte lymphoma-related protein, cytochrome c, and caspase-3 were increased in the OA group, while the B-cell lymphoma 2 were decreased (P < 0.05). The expression of B-lymphocyte lymphoma-related protein, cytochrome c, and caspase-3 protein in HepG2 cells was decreased after treatment with low and high-dose metformin, while B-cell lymphoma 2 was increased (P < 0.05). Conclusion: Metformin can effectively alleviate steatosis and improve the HepG2 function in cell model of nonalcoholic fatty liver disease. The mechanism of metformin may be related to the reduction of oxidative stress injury, the regulation of protein expression related to mitochondrial apoptosis pathway and the inhibition of cell apoptosis.

EVALUATION OF THE POSSIBLE PROTECTIVE EFFECT OF METFORMIN IN CISPLATIN - INDUCED NEPHROTOXICITY IN ADULT MALE ALBINO RATS

Backgrounds: Clinical use of cisplatin is limited by its nephrotoxicity as cisplatin -induced oxidative stress which leads ultimately to kidney dysfunction. Objective: Evaluation of the nephron-protective effect of metformin against nephrotoxicity induced by cisplatin in adult albino rats. Materials and Methods: Sixty adult male albino rats were divided randomly into 6 equal groups: Group I (control group) was injected with 1 ml isotonic saline solution intraperitoneally (I.P). Group 2 was injected with single dose of cisplatin I.P 3.5mg/kg. Group 3 was injected with single dose of cisplatin I.P 7.5 mg/kg. Group 4 was given an oral dose of metformin (350 mg/kg /day for 10 days). Group 5 was given 100 mg kg/day metformin for 3 days before cisplatin injection I.P at a dose of 7.5 mg/kg on day four, and metformin continued for 7days after. Group 6 was given 350 mg kg/day metformin for 3 days before cisplatin injection I.P at a dose of 7.5 mg/kg on day four, and metformin continued for 7days after. Body weight of each rat was recorded on day 1, 4, 7 and 10 and average weight for each group was calculated. At the end of specified duration (10 days), rats were sacrificed and both kidneys were excised, processed and stained with Hematoxylin and Eosin for histopathological study and with Periodic Acid-Schiff (PAS) and Mallory’s stain stains for histochemical study. Results: Rats injected with high dose of cisplatin (7.5 mg/kg) showed more loss of average body weight and higher blood urea nitrogen (BUN) and serum creatinine (Cr) levels than those rats injected with 3.5 mg/kg cisplatin. Rat group injected with high dose of cisplatin (7.5 mg/kg) and given low dose metformin (100 mg/kg/day) showed less loss of average body weight and improved renal functions than rat group given high dose of cisplatin (7.5 mg/kg) and high dose of metformin (350 mg/kg/ day). Histopathological examination with H&E and histochemical examination with PAS and Mallory stains revealed mild glomerular, tubular and interstitial changes in cisplatin low dose group compared to cisplatin high dose group which showed more renal damages. Group given metformin low dose + cisplatin high dose showed less renal damage than those given high dose of cisplatin+ high dose metformin. Conclusion: Metformin has protective effects against cisplatin -induced nephrotoxicity in adult male albino rats.

EVALUATION OF THE POSSIBLE PROTECTIVE EFFECT OF METFORMIN IN CISPLATIN - INDUCED NEPHROTOXICITY IN ADULT MALE ALBINO RATS

Backgrounds: Clinical use of cisplatin is limited by its nephrotoxicity as cisplatin -induced oxidative stress which leads ultimately to kidney dysfunction. Objective: Evaluation of the nephron-protective effect of metformin against nephrotoxicity induced by cisplatin in adult albino rats. Materials and Methods: Sixty adult male albino rats were divided randomly into 6 equal groups: Group I (control group) was injected with 1 ml isotonic saline solution intraperitoneally (I.P). Group 2 was injected with single dose of cisplatin I.P 3.5mg/kg. Group 3 was injected with single dose of cisplatin I.P 7.5 mg/kg. Group 4 was given an oral dose of metformin (350 mg/kg /day for 10 days). Group 5 was given 100 mg kg/day metformin for 3 days before cisplatin injection I.P at a dose of 7.5 mg/kg on day four, and metformin continued for 7days after. Group 6 was given 350 mg kg/day metformin for 3 days before cisplatin injection I.P at a dose of 7.5 mg/kg on day four, and metformin continued for 7days after. Body weight of each rat was recorded on day 1, 4, 7 and 10 and average weight for each group was calculated. At the end of specified duration (10 days), rats were sacrificed and both kidneys were excised, processed and stained with Hematoxylin and Eosin for histopathological study and with Periodic Acid-Schiff (PAS) and Mallory’s stain stains for histochemical study. Results: Rats injected with high dose of cisplatin (7.5 mg/kg) showed more loss of average body weight and higher blood urea nitrogen (BUN) and serum creatinine (Cr) levels than those rats injected with 3.5 mg/kg cisplatin. Rat group injected with high dose of cisplatin (7.5 mg/kg) and given low dose metformin (100 mg/kg/day) showed less loss of average body weight and improved renal functions than rat group given high dose of cisplatin (7.5 mg/kg) and high dose of metformin (350 mg/kg/ day). Histopathological examination with H&E and histochemical examination with PAS and Mallory stains revealed mild glomerular, tubular and interstitial changes in cisplatin low dose group compared to cisplatin high dose group which showed more renal damages. Group given metformin low dose + cisplatin high dose showed less renal damage than those given high dose of cisplatin+ high dose metformin. Conclusion: Metformin has protective effects against cisplatin -induced nephrotoxicity in adult male albino rats.

Metformin Protects Renal Function in Type 2 Diabetic Nephropathy: Regulation of Insulin Signaling in the Rat Model

The present study was aimed to investigate the protective role of metformin in type 2 diabetic nephropathic rats and elucidate regulation of unwanted insulin signaling in the kidney as the underlying mechanism. Diabetes mellitus was established in male Sprague Dawley rats by a single intraperitoneal injection of 40 mg/kg streptozotocin. A sustained level of blood glucose over 16.7 mM was defined as type 2 diabetes mellitus in this study. Rats were randomly classified into the normal group, diabetes mellitus group, diabetes mellitus plus low-dose and high-dose metformin groups (100 and 200 mg/kg orally). Rats received treatment for 12 weeks after which all rats were sacrificed and kidney samples were collected. The samples were dissected and prepared for the observation of structural changes of renal glomerular podocytes between the groups microscopically. The expressions of IRS-1, Akt, nephrin, desmin, phosphatidylinositol-3-hydroxy kinase (PI3K)-p85 and extra cellular matrix were probed by western blot. Compared to the control group, the downregulated nephrin and elevated levels of desmin and collagen IV in the kidney were significantly reversed by metformin treatment. Furthermore, metformin recovered the atypical activities of insulin/PI3K-Akt signaling to the normal ranges. Metformin evidently reduced the renal damage in diabetic rats, which could be due to modulating lipid metabolism and insulin resistance.

Effect of High-Dose Metformin on the Metabolic Parameters and Functional State of the Liver of Agouti Mice with Melanocortin Obesity

Effect of High-Dose Metformin on the Metabolic Parameters and Functional State of the Liver of Agouti Mice with Melanocortin Obesity

Metformin and Risk of Alzheimer's Disease Among Community-Dwelling People With Diabetes: A National Case-Control Study.

Type 2 diabetes has been linked with an increased risk of Alzheimer's disease (AD). Studies on the association between metformin use and AD have reported conflicting results. To investigate whether metformin use modifies the association between diabetes and incident, clinically verified AD. Nested case-control study. All community-dwelling people in Finland. Cases were all community-dwelling Finns with AD diagnosed from 2005 to 2011 and with diabetes diagnosed ≥ 3 years before AD (n = 9862). Cases were matched with up to 2 control persons by age, sex, and diabetes duration (n = 19 550). Cumulative metformin exposure was determined from reimbursed dispensings over a 10- to 16-year period. Adjusted odds ratios (aORs) were calculated using conditional logistic regression to estimate associations, with adjustment for potential confounders. A total of 7225 (73.3%) cases and 14528 (74.3%) controls received metformin at least once. Metformin use (ever use) was not associated with incident AD (aOR 0.99; 95% confidence interval [CI], 0.94-1.05). The adjusted odds of AD were lower among people dispensed metformin for ≥ 10 years (aOR 0.85; 95% CI, 0.76-0.95), those dispensed cumulative defined daily doses (DDDs) of < 1825-3650 (aOR 0.91; 95% CI, 0.84-0.98) and > 3650 DDDs (aOR 0.77; 95% CI, 0.67-0.88), and among persons dispensed an average of 2 g metformin daily (aOR 0.89; 95% CI, 0.82-0.96). In this large national sample we found no evidence that metformin use increases the risk of AD. Conversely, long-term and high-dose metformin use was associated with a lower risk of incident AD in older people with diabetes.

Comparing the individual effects of metformin and rosiglitazone and their combination in obese women with polycystic ovary syndrome: a randomized controlled trial

To compare the effects of metformin, rosiglitazone, and their combination in obese polycystic ovary syndrome (PCOS) patients with insulin resistance. Prospective randomized controlled trail. Tertiary teaching hospital. Obese Chinese women (body mass index [BMI] ≥25 kg/m2) with insulin resistance who fulfilled the Rotterdam criteria of PCOS. In group 1, 68 patients administered metformin (1,500 mg/day); in group 2, 67 patients administered rosiglitazone (4mg/day); in group 3, 69 patients administered metformin (1,000 mg/day) and rosiglitazone (4 mg/day) for 6 months, all with the same diet and regular exercise lifestyle recommendation. Average menstrual interval, anthropometric measurements, androgen-related parameters, and metabolic features of insulin, carbohydrates, and lipids, with intention-to-treat analysis. The baseline parameters showed no statistically significant differences. After the 6-month treatment, most participants showed an improved menstrual pattern. There were statistically significant decreases in acne scores, weight, BMI, waist circumference, waist-to-hip ratio, and serum testosterone. The metabolic indexes of insulin, carbohydrates, and lipids were improved obviously compared with the baseline in each group. Among the three groups, the patients administered 1,500 mg/day metformin experienced greater reductions in weight. However, the rosiglitazone users (alone or combined with metformin) showed a more notable decline in total cholesterol and triglyceride levels. Considering the benefits of metformin on weight loss, high-dose metformin (1,500 mg/day) along with lifestyle modification should be recommended for obese, insulin-resistant women with PCOS. Rosiglitazone alone or combined with low-dosage metformin plus lifestyle modification should be considered for the women with abnormal lipid profiles. ChiCTR-TRC-13003642 (Chinese Clinical Trial Registry).

Safety and efficacy of vildagliptin: 52-week post-marketing surveillance of Japanese patients with type 2 diabetes in combination with other oral antidiabetics and insulin

ABSTRACT Background: Vildagliptin is a dipeptidyl peptidase-4 inhibitor that reduces glycemia in patients with type 2 diabetes mellitus (T2DM). When approved in 2013, data on vildagliptin combined with >750 mg/day metformin in Japanese patients were limited. There is a need to confirm the safety and efficacy of vildagliptin in combination with oral antidiabetic drugs (OADs). Research design and methods: This 52-week post-marketing surveillance (PMS) observational study in Japanese T2DM patients evaluated the safety and efficacy of vildagliptin in combination with OADs including high-dose metformin or insulin but excluding combination with sulfonylureas alone. Results: During this survey of 3006 Japanese T2DM patients, 13.61% of patients experienced adverse events (AEs) and 2.20% reported a serious AE (SAE). The frequency of AEs/SAEs was similar when in combination with biguanides (12.93%/1.46%), metformin ≥1000 mg/day (12.92%/1.22%), metformin <1000 mg/day (12.62%/1.54%), thiazolidine derivatives (16.71%/2.86%), α-glucosidase inhibitors (13.18%/1.90%), rapid-acting insulin secretagogues (glinides) (20.41%/5.71%), or insulin (15.87%/2.47%). The mean ± SD changes from baseline at endpoint in glycated hemoglobin and fasting blood glucose were −0.76 ± 1.27% and −23.3 ± 57.3 mg/dL, respectively, and these changes were consistent, regardless of concomitant OAD. Conclusions: Long-term vildagliptin combination therapy is safe and effective in Japanese T2DM patients in real-world settings.

Association between Metformin and a Lower Risk of Age-Related Macular Degeneration in Patients with Type 2 Diabetes.

Purpose This population-based, retrospective cohort study was to investigate whether metformin is associated with a lower risk of subsequent age-related macular degeneration (AMD) in patients with type 2 diabetes. Methods Using the Taiwan National Health Insurance Research Database from 2001 to 2013, 68205 subjects with type 2 diabetes were enrolled in the study cohort. Among them, 45524 were metformin users and 22681 were nonusers. The metformin and nonmetformin groups were followed until the end of 2013. Cox regression analyses were used to estimate hazard ratios (HRs) for AMD development associated with metformin use. Confounders included for adjustment were age, sex, and comorbidities (hypertension, hyperlipidemia, coronary artery disease, obesity, diabetic retinopathy, chronic kidney disease, and insulin treatment). Furthermore, propensity score (PS) matching method was used to choose the matched sample, and PS-adjusted Cox regression was performed. Finally, how HRs changed according to metformin treatment duration and dose was also evaluated in the metformin group. Results After adjusting for confounders, the metformin group had a significantly lower risk of AMD (adjusted HR = 0.54; 95% confidence interval [CI], 0.50–0.58). In the PS-matched sample, the significance remained (adjusted HR = 0.57; 95% CI, 0.52–0.63). In the metformin group, the adjusted HRs for the second (1.5–4 years) and third (≥4 years) tertiles of metformin treatment duration were 0.52 and 0.14, respectively, compared with the first tertile (<1.5 years). We also found significant trends of lower HRs (all p-value for trend <0.05) with increasing total and average doses. Conclusions Among patients with type 2 diabetes, those who use metformin are at a significantly lower risk of developing AMD relative to individuals who do not use metformin. Also, the trend of a significantly lower AMD risk was found with a higher dose of metformin.

Vitamin B12 deficiency and diabetic neuropathy in patients taking metformin: a cross-sectional study.

ObjectiveVitamin B12 deficiency resulting from metformin use has been demonstrated in multiple studies. In this study, we aimed to evaluate the prevalence of vitamin B12 deficiency in patients with chronic metformin use and the relationship between vitamin B12 deficiency and diabetic neuropathy.MethodsA cross-sectional study was conducted with 162 patients. Vitamin B12 levels were measured by chemiluminescence immunoassay. Diabetic neuropathy was evaluated by patient record, nerve conduction and Michigan test for the diagnosis of diabetic neuropathy. Additional data, including demographic characteristics were collected. A linear regression model was used to evaluate variables that correlated with vitamin B12 levels and diabetic neuropathy.ResultsLow vitamin B12 levels were found in 7.3% (95% CI: 4.0–12%) of patients. In those with diabetic neuropathy, altered (low and borderline) vitamin B12 level was 64% (95% CI: 47–78%) compared to 17% (95% CI: 10–26%) in patients without diabetic neuropathy (coefficient: −110.8; CI 95%: −165.8, −59.7). Those taking a higher metformin dose had lower levels of vitamin B12 (coefficient: −0.061; CI 95%: −0.09, −0.024). In addition, female patients had higher levels of vitamin B12 compared to men (coefficient: 49.1; CI 95%: 2.3–95).ConclusionsVitamin B12 deficiency is highly prevalent, especially in patients with diabetic neuropathy. In this study an inverse correlation was found between diabetic neuropathy and the plasma level of vitamin B12. Higher doses of metformin and male sex were factors related to lower levels of vitamin B12.

The preventive effect of metformin on progression of benign prostate hyperplasia: A nationwide population-based cohort study in Korea.

Metformin, a first-line treatment for type 2 diabetes mellitus (T2DM), has recently been recognized for its pleotropic anti-proliferative, anti-cancer, and anti-aging effects. Contrary to the studies characterizing metformin effects in prostate cancer, little is known about these effects in BPH progression. With the Sample Cohort DB data during 2007 and 2017 from the Health Insurance Review and Assessment Service (HIRA) in South Korea, we investigated the preventative effect of metformin on BPH progression. The study population consisted of 211,648 BPH naïve patients that were diagnosed with BPH in 2009 and a follow-up occurrence of prostatectomy until 2017 that was defined as progression of BPH. These patients were divided into three treatment groups: without T2DM, T2DM without metformin, and T2DM with metformin. The hazard ratio in the T2DM with metformin group was 0.86 for prostatectomy compared to the group without T2DM (CI = 0.77–0.96, P value = 0.007) after adjusting for confounding factors such as age, comorbidity, residential area, level of hospital, and category of BPH medications. The T2DM with high-dose metformin group had a significantly lower risk of prostatectomy with hazard ratio of 0.76 (CI = 0.62–0.92, P value = 0.005) in stratified analysis. Our results suggest that metformin may improve BPH progression based on the reduced risk of prostatectomy, although T2DM effects on BPH were unclear. Future observational studies and prospective trials are needed to confirm the effects of metformin on BPH progression.

Acute Exercise Intervention Combined with Metformin’s Influences on Glucose Homeostasis in T2D Mice

PURPOSE: The aim of our investigation was to determine the effects of different ways of acute exercise intervention combined with high dose of metformin on glucose homeostasis and its relative molecular mechanisms in type 2 diabetic mice. METHODS: 4-week high fat diet (HFD) and one-time Streptozocin (100mg/kg) intraperitoneal injection were used for building T2D mice. 24 mice were divided into normal control (NC), normal acute resistance training (NCR) and normal acute endurance training (NCE) group, all n=8, fed in normal chow. Finally 48 mice were developing T2D and divided into diabetic control (DC), diabetic acute resistance training (DCR), diabetic acute endurance training (DCE), high dose of metformin (200mg/kg) control (HMC), metformin combined with acute resistance training (HMR) and metformin combined with acute endurance continuous training (HME) group, all n=8. RESULTS: The two ways also enhanced blood glucose and lipid metabolism in T2D mice. Compared to HMC group, hepatic G6Pase mRNA expression in HMR and HME group was significantly escalated and hepatic FBP1 mRNA expression of both groups were significantly declined. Compared to HMC group, hepatic GLUT2 and Gck mRNA expression in HMR and HME group showed opposite trends, one was down and the other was up. Compared to HMC group, hepatic PEPCK mRNA expression in HMR group mice was notably raised and hepatic AMPKα2, PGC-1α and CREB mRNA expression in HMR and HME group mice were notably increased and only hepatic AMPKα1 mRNA expression in HMR group was significantly increased. CONCLUSIONS: Acute resistance training (ART) and acute endurance training (AET) combined with metformin can effectively improve glucose homeostasis in T2D mice. And the two ways can improve blood glucose and lipid metabolism in T2D mice. ART combined with metformin was better to improve glucose homeostasis and inhibit hepatic gluconeogenesis relative mRNA expression in T2D mice probably via the signaling pathway of AMPKα-PGC-1α-CREB.

Vitamin B12 Deficiency Among a Sample of Type 2 Diabetic Patients on Metformin in Erbil-City

Background and objectives:Metformin is the most common oral hypoglycemic agent used as first line together with life style modification in almost all type 2 diabetes patients worldwide. The aim of the study was to determine the percentage of vitamin B12 deficiency in a sample of patients with type 2 diabetes mellitus and its association with the daily dose metformin (? 1.000 mg) and more than two years durations of treatment and anemia. Methods:A cross-sectional study was carried out on a sample of 100 adult patients with type 2 diabetes mellitus who attended the diabetic center and two General Teaching Hospitals in Erbil city during the period from the 1st of June to the end of December 2017. Vitamin B12 level, hemoglobin concentration, and other biochemical indicators of all recruited patients were obtained. Results: The mean age (+SD) of diabetic patients was 54.35 (± 9.71) years and the range was between 24 to 75 years. More than half of the patients (57%) had poor glycemic control and about one third (29%) of patients had vitamin B12 level less than 200 pg/ml. Patients with obesity, longer duration of disease and on high dose of metformin had a significantly higher level of vitamin B12 deficiency. Conclusions:vitamin B12 deficiency is common among patients with type 2 diabetes mellitus especially among those using high dose of metformin for a long time. Therefore, identifying low vitamin B12 level among diabetic patients raises the concern to the patients for the future complications and challenge for the clinicians for management.

1117-P: Metformin Increases Blood Lactic Acid in Elderly Diabetic Veterans with Stage 3 CKD

Aim: Recently, the FDA endorsed metformin (MET) use in type 2 diabetes (T2D) patients with stage 3 CKD (CKD3). However, MET safety in elderly T2D subjects with CKD3 is unknown. Methods: We studied lactic acid (LA) levels in ambulatory elderly male U.S. Veterans with stable nondiabetic CKD3 (eGFR 30-59ml/min/1.73m2) (Group 1) and diabetic CKD3 not on MET (Group 2) and on MET (Group 3) for at least 6 months. Hyperlactatemia was defined as LA &amp;gt;2mmol/L. Patients with history of HIV, advanced CHF, alcohol abuse, and liver cirrhosis were excluded. Clinical and biochemical characteristics were analyzed using ANOVA, χ2 test and Fisher’s exact tests. Results: Mean LA levels were similar at 1.3±0.3 and 1.3±0.4 mmol/L in Group 1 (N=24, age 74.9±6.4 years, BMI 29.5±4.0kg/m2) and Group 2 (N=28, age 74.4±6.2 years, BMI 32.5±5.8kg/m2), respectively; while, LA was significantly higher in Group 3 (N=40, age 71.7±5.0 years, BMI 33.9±7.5kg/m2) at 2.0±1.0mmol/L compared with Group 2 subjects (P&amp;lt;0.001). Only 1 patient in each Group 1 (4.2%) and Group 2 (3.6%) had hyperlactatemia, as compared with 17 pts in Group 3 (42.5%) (P&amp;lt;0.05). Mild lactic acidosis (LA 5.2mmol/L, bicarbonate 18meq/L, anion gap 16) resolving with MET discontinuation was diagnosed in one Group 3 subject. Average daily MET dose in Group 3 was 1325±581mg and glycemic control was equal in Groups 2 and 3 (HbA1c 7.5±1.3 vs. 7.6±1.3%). There was no difference in mean LA level or frequency of hyperlactatemia between Group 3 pts with CKD stage 3A (eGFR 45-59, MET 1394±619mg/day) and stage 3B (eGFR 30-44, MET 1000±0mg/day). No differences in age, BMI, weight, eGFR, and HbA1c were seen in Group 3 pts with and without hyperlactatemia except trend towards higher MET dose in the hyperlactatemia patients (1500±560 vs. 1196±574 mg/day, P=0.1). Conclusions: MET increases risk of hyperlactatemia in elderly men with T2D and CKD3 without clear predisposing factors while not offering explicit therapeutic advantage. We recommend using lower MET doses in elderly diabetic men with stage 3 CKD. Disclosure A.R. Gosmanov: None. E. Gosmanova: Advisory Panel; Self; Amgen Inc.

Metformin may offer no protective effect in men undergoing external beam radiation therapy for prostate cancer.

To assess whether metformin reduces radio-resistance and increases survival in men undergoing external beam radiation therapy (EBRT) for prostate cancer (PCa), and to determine its effect on hypoxia inducible factor 1-α (HIF1α). All patients treated with curative intent with EBRT for PCa at a major cancer centre between 2000 and 2007 were included in this study. The outcome measures of time to biochemical failure (BF), metastasis, PCa-specific mortality and overall survival (OS) were analysed in those taking metformin vs those not, using competing risk and Cox regression models. To determine metformin's effect on HIF1α expression and survival invitro, PC3 cells with high basal HIF1α levels were subjected to increasing doses of metformin after H2 O2 -induced oxidative stress. A total of 2055 eligible cases, including 113 who were on metformin, were identified, with a median follow-up of 95.7months. There were no differences in age, initial prostate-specific antigen level, Gleason score, T-stage, D'Amico risk class or duration of androgen deprivation therapy (ADT) between patients who were or were not on metformin. Treatment with metformin did not result in any apparent improvement in time to BF, time to metastasis detection or OS, but there was a 1.5-fold increase in PCa-specific deaths (P = 0.045) in patients on metformin and ADT when adjusted for cancer risk and comorbidities. When comparing patients on high-dose metformin (>1g/d) with those on low-dose metformin (≤1g), there was no difference in either time to metastases or time to BF. In vitro metformin at a high concentration of 100μM did not reduce HIF1α expression, nor did metformin affect the PC3 cell survival when exposed to oxidative stress (H2 O2 ). No association was found between the use of metformin and time to metastasis detection, time to BF or OS in patients undergoing radiation therapy with or without ADT for PCa. In vitro, low therapeutic concentrations of metformin had no effect on HIF1α, and this observation could explain the conflicting evidence for the effectiveness of metformin in men undergoing EBRT for PCa. Higher, more toxic doses of metformin may be required to inhibit the mammalian target of rapamycin-HIF1α pathway in this patient group.

Modulation of Electron Transport by Metformin in Cardiac Protection: Role of Complex I

RationaleModulation of mitochondrial complex I during reperfusion reduces cardiac injury following ischemia. Complex I exists in two structural states: active (A) and deactive (D) with transition from A→D during ischemia. Reperfusion reactivates D→A with reactive oxygen species (ROS) production. Metformin treatment may preserve the D form.ObjectiveWe hypothesize that maintenance of deactivation of complex I during early reperfusion will protect cardiomyocytes. The goal is to evaluate the potential of acute, high dose Metformin treatment to modulate complex I at the onset of reperfusion/reoxygenation and decrease subsequent cellular injury.MethodsH9c2 cells underwent 6 hr. simulated ischemia and 24 hr. reoxygenation with or without metformin treatment (1 mM) at the onset of reoxygenation. Cell death, ROS and thiol modification were studied. Additional experiments were performed with or without siRNA knockdown of AMPKa2 catalytic subunit.ResultsMetformin selectively inhibited complex I oxidative phosphorylation measured at reoxygenation (Metformin: 0.34±0.1 vs control: 0.59±0.05 nmolO2/min/106cells; ±SE; n=5–10; p&lt;0.05) with decreased total cell death following simulated ischemia and reoxygenation (Metformin: 8.3±0.2 vs. control: 14.4±0.6%; n=3–6; p&lt;0.05). Complex II driven oxidative phosphorylation was not reduced by metformin, supporting selectively to complex I. Apoptosis assessed by annexin‐V labeling and flow cytometry was also decreased by metformin treatment. The “burst” of ROS at reoxygenation was decreased and free thiol group content was preserved by metformin treatment at reoxygenation. Metformin decreased cell death in AMPK knockdown cells.ConclusionMetformin blockade of complex I at the onset of reoxygenation reduces cell injury. Metformin specifically inhibited complex I at reoxygenation with less oxidative injury, in line with protection against D→A reactivation of complex I. Metformin protection was AMPK independent, supporting a complex I mechanism of protection. Acute, high dose Metformin is a potentially safe translational complex I inhibitor to treat ischemia‐reperfusion injury.Support or Funding InformationThis work was supported by the Office of Research and Development, Medical Research Service Merit Review Award (2IO1BX001355‐01A2) and Department of Veterans Affairs; National Institutes of Health NIH R21AG054975‐01This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Mitochondrial Complex I Inhibition by Metformin Limits Reperfusion Injury.

Transient, reversible blockade of complex I during early reperfusion after ischemia limits cardiac injury. We studied the cardioprotection of high dose of metformin in cultured cells and mouse hearts via the novel mechanism of acute downregulation of complex I. The effect of high dose of metformin on complex I activity was studied in isolated heart mitochondria and cultured H9c2 cells. Protection with metformin was evaluated in H9c2 cells at reoxygenation and at early reperfusion in isolated perfused mouse hearts and in vivo regional ischemia reperfusion. Acute, high-dose metformin treatment inhibited complex I in ischemia-damaged mitochondria and in H9c2 cells following hypoxia. Accompanying the complex I modulation, high-dose metformin at reoxygenation decreased death in H9c2 cells. Acute treatment with high-dose metformin at the end of ischemia reduced infarct size following ischemia reperfusion in vitro and in vivo, including in the AMP kinase-dead mouse. Metformin treatment during early reperfusion improved mitochondrial calcium retention capacity, indicating decreased permeability transition pore (MPTP) opening. Acute, high-dose metformin therapy decreased cardiac injury through inhibition of complex I accompanied by attenuation of MPTP opening. Moreover, in contrast to chronic metformin treatment, protection by acute, high-dose metformin is independent of AMP-activated protein kinase activation. Thus, a single, high-dose metformin treatment at reperfusion reduces cardiac injury via modulation of complex I.

Low metformin causes a more oxidized mitochondrial NADH/NAD redox state in hepatocytes and inhibits gluconeogenesis by a redox-independent mechanism

The mechanisms by which metformin (dimethylbiguanide) inhibits hepatic gluconeogenesis at concentrations relevant for type 2 diabetes therapy remain debated. Two proposed mechanisms are 1) inhibition of mitochondrial Complex 1 with consequent compromised ATP and AMP homeostasis or 2) inhibition of mitochondrial glycerophosphate dehydrogenase (mGPDH) and thereby attenuated transfer of reducing equivalents from the cytoplasm to mitochondria, resulting in a raised lactate/pyruvate ratio and redox-dependent inhibition of gluconeogenesis from reduced but not oxidized substrates. Here, we show that metformin has a biphasic effect on the mitochondrial NADH/NAD redox state in mouse hepatocytes. A low cell dose of metformin (therapeutic equivalent: <2 nmol/mg) caused a more oxidized mitochondrial NADH/NAD state and an increase in lactate/pyruvate ratio, whereas a higher metformin dose (≥5 nmol/mg) caused a more reduced mitochondrial NADH/NAD state similar to Complex 1 inhibition by rotenone. The low metformin dose inhibited gluconeogenesis from both oxidized (dihydroxyacetone) and reduced (xylitol) substrates by preferential partitioning of substrate toward glycolysis by a redox-independent mechanism that is best explained by allosteric regulation at phosphofructokinase-1 (PFK1) and/or fructose 1,6-bisphosphatase (FBP1) in association with a decrease in cell glycerol 3-phosphate, an inhibitor of PFK1, rather than by inhibition of transfer of reducing equivalents. We conclude that at a low pharmacological load, the metformin effects on the lactate/pyruvate ratio and glucose production are explained by attenuation of transmitochondrial electrogenic transport mechanisms with consequent compromised malate-aspartate shuttle and changes in allosteric effectors of PFK1 and FBP1.

Metformin use is associated with a low risk of tuberculosis among newly diagnosed diabetes mellitus patients with normal renal function: A nationwide cohort study with validated diagnostic criteria.

Human studies on the use of metformin as host-directed therapy (HDT) for tuberculosis (TB) are rare. We performed a nationwide cohort study to evaluate the effect of metformin on mitigating the risk of active TB among patients with diabetes mellitus (DM). Among newly diagnosed DM patients identified in the Taiwan National Health Insurance Research Database, metformin users, defined on the basis of >90 cumulative defined daily doses within 1 year, and propensity-score-matched metformin nonusers were selected. The primary outcome was incident TB, identified using diagnostic criteria validated by real patient data at a medical center. Independent predictors were investigated using Cox regression analysis. Similar analysis was performed in a subpopulation without a history of hypertensive nephropathy and renal replacement therapy. A total of 88,866 metformin users and 88,866 propensity-score-matched nonusers were selected. Validation results showed that the TB diagnostic criteria had a sensitivity of 99.13% and specificity of 99.90%. During follow-up, 707 metformin users and 807 nonusers developed active TB. Metformin use was independently associated with a lower risk of incident TB (hazard ratio [HR]: 0.84 [0.74–0.96]). TB risk was lower in high-dose metformin users than in low-dose users (HR: 0.83 [0.72–0.97]). The effect of metformin remained when analysis was restricted in the subpopulation without renal function impairment. Newly diagnosed diabetic patients without contraindication should receive metformin as an anti-diabetic medication, with potential additional benefit against TB.