Metformin as a Tool to Target Aging

In the paper

“inhibition of mitochondrial complex 1 in the electron transport chain and reduction of endogenous production of reactive oxygen species (ROS) (Batandier et al., 2006; Bridges et al., 2014; Zheng et al., 2012)”

What the sources say

• ?Not checked — no full text of the sourcecites Batandier et al., 2006 source
• Disputed

  The Results section (“Biguanide effects on the flavin site and H2O2 production”) says metformin increases ‘native’ H2O2 production, rather than reducing it. It distinguishes that effect from a decrease in paraquat-stimulated H2O2 production. (LLM, conf=0.88)

  Checked by a reasoning model — may be wrong.

  cites Bridges et al., 2014 sourceExperimental — accuracy not yet measured
• Supported

  The Results section reports that metformin decreased ROS generation in cells exposed to high glucose. It also reports that metformin reduced the increase in retinal ROS in diabetic rats, supporting the attributed reduction in ROS production. (LLM, conf=0.92)

  cites Zheng et al., 2012 source

In the paper

“When rapamycin is administered late in life, it extends lifespan (Harrison et al., 2009; Miller et al., 2011), slows aging in a dose-dependent manner, shows differential effects by sex (Wilkinson et al., 2012), and is synergistic with metformin.”

What the sources say

• Partly supported

  The Liver degeneration Results report a dose-dependent decline in an age-related liver lesion in male mice, and the Adrenal tumors Results report a significant trend across doses. The Discussion concludes more broadly that rapamycin slows aspects of aging in mice, but does not establish that its overall effect on aging is dose-dependent. (LLM, conf=0.88)

  cites Wilkinson et al., 2012 sourceExperimental — accuracy not yet measured

In the paper

“activation of AMP-activated kinase (AMPK) (Cho et al., 2015; Duca et al., 2015; Foretz et al., 2010; Lien et al., 2014; Lu et al., 2015; Zheng et al., 2012)”

What the sources say

• Supported

  The Results passage reports that metformin induced AMPK activation in rat pituitary adenoma cells, measured by phosphorylation. This directly supports the attributed claim. (LLM, conf=0.94)

  cites Cho et al., 2015 source
• Supported

  In the passage labeled Abstract (Fig. 1f), the paper reports that intraduodenal metformin increased phosphorylated AMPK relative to total AMPK in rat duodenal mucosa. It also describes this as activation of duodenal AMPK. (LLM, conf=0.94)

  cites Duca et al., 2015 source
• Supported

  The Introduction states that metformin treatment activates AMPK and reports that this has been observed in human and rodent tissues. The Discussion further suggests that metformin indirectly stimulates AMPK by lowering ATP levels; its finding that gluconeogenesis inhibition is AMPK-independent does not contradict the activation claim. (LLM, conf=0.93)

  cites Foretz et al., 2010 source

In the paper

“Metformin favorably influences metabolic and cellular processes closely associated with the development of age-related conditions, such as inflammation (Saisho, 2015), autophagy (Song et al., 2015; Xie et al., 2011), and cellular senescence (Jadhav et al., 2013; Moiseeva et al., 2013).”

What the sources say

• ?Not checked — no full text of the sourcecites Saisho, 2015 source
• Supported

  Song et al. is cited for the autophagy portion of the sentence, not for inflammation or cellular senescence. The Results section reports increased autophagic flux after metformin treatment in hepatocytes, and the Discussion reports induced liver autophagic flux in ob/ob mice. The Discussion also notes that autophagy function can decline with age; it does not establish a benefit for age-related conditions in humans. (LLM, conf=0.92)

  cites Song et al., 2015 source
• Supported

  The Discussion reports that chronic metformin treatment enhanced cardiac autophagy in diabetic mice. Xie et al. is cited for the autophagy portion of the sentence, not for its separate claims about inflammation or cellular senescence. (LLM, conf=0.90)

  cites Xie et al., 2011 source

In the paper

“More importantly, these pathways have been evaluated in mammalian models, in which health span and lifespan have been extended by genetic manipulation or drugs (Johnson et al., 2013).”

What the sources say

• Supported

  The “mTOR in mammalian ageing and healthspan” section reports that rapamycin extends lifespan in mice and delays several age-related changes. It also reports increased lifespan after S6K1 gene knockout in female mice. The paper thus supports the claim about drug and genetic interventions in mammalian models, though the knockout lifespan benefit was sex-specific. (LLM, conf=0.90)

  cites Johnson et al., 2013 source

In the paper

“In C. elegans metformin extends lifespan by several possible mechanisms including the alteration of the microbiome, specifically by changing microbial folate and methionine metabolism (Cabreiro et al., 2013).”

What the sources say

• Supported

  The Introduction states that metformin’s lifespan-extending effects in C. elegans are mediated by cocultured E. coli, in which it inhibits folate and methionine metabolism. The Discussion adds that the lifespan effect depends on the bacterial strain; the citing sentence presents this as one possible mechanism, not a universal effect. (LLM, conf=0.94)

  cites Cabreiro et al., 2013 source

In the paper

“Studies have demonstrated that genetic pathways modulate healthy lifespan in diverse species across great evolutionary distance and established that aging-related pathways constitute a target for intervention (Barzilai et al., 2012; Longo et al., 2015).”

What the sources say

• Supported

  The section on attenuated mTOR signaling describes a highly conserved pathway whose genetic inhibition extends lifespan in yeast, nematodes and fruit flies. The section on exceptional human survival links FOXO3A to longevity and healthy aging, supporting the cross-species paraphrase. Page numbers are not available in our copy. (LLM, conf=0.88)

  cites Barzilai et al., 2012 source
• Supported

  In “Inhibitors of the TOR pathway,” the paper links mTOR signaling to lifespan and healthspan in several model species and reports that genetic or pharmacological reduction extends lifespan in yeast, worms, flies, and mice. It also identifies mTOR signaling as a candidate for targeted intervention. (LLM, conf=0.90)

  cites Longo et al., 2015 source

In the paper

“inhibition of mitochondrial complex 1 in the electron transport chain and reduction of endogenous production of reactive oxygen species (ROS) (Batandier et al., 2006; Bridges et al., 2014; Zheng et al., 2012)”

What the sources say

• ?Not checked — no full text of the sourcecites Batandier et al., 2006 source
• Supported

  The Results section (‘Metformin and related compounds inhibit catalysis by isolated complex I’) reports that metformin inhibits complex I catalysis, although weakly and reversibly. This supports the attributed claim about complex I inhibition; the claim does not attribute the sentence’s separate ROS-reduction point to this source alone. (LLM, conf=0.94)

  cites Bridges et al., 2014 source
• Partly supported

  The Results section reports that metformin decreased ROS generation in retinal endothelial cells under high-glucose stress. The Discussion links this effect to the SIRT1/LKB1/AMPK pathway, but the paper does not say that metformin inhibits mitochondrial complex I of the electron transport chain. No page number is available in our copy. (LLM, conf=0.86)

  cites Zheng et al., 2012 sourceExperimental — accuracy not yet measured

In the paper

“A more recent study (Martin-Montalvo et al., 2013) demonstrated that metformin increased lifespan by 4%–6% in different mouse breeds.”

What the sources say

• Partly supported

  The Results (‘Metformin increases healthspan and longevity of mice’) report mean lifespan extensions of 5.83% in C57BL/6 mice and 4.15% in B6C3F1 mice at the 0.1% dose. The B6C3F1 result was not statistically significant, so saying the study ‘demonstrated’ an increase in both strains overstates the evidence. (LLM, conf=0.86)

  cites Martin-Montalvo et al., 2013 sourceExperimental — accuracy not yet measured

In the paper

“Studies have demonstrated that genetic pathways modulate healthy lifespan in diverse species across great evolutionary distance and established that aging-related pathways constitute a target for intervention (Barzilai et al., 2012; Longo et al., 2015).”

What the sources say

• Supported

  The Conclusions and Future Directions section identifies metabolic signaling pathways as potential therapeutic targets for delaying aging and reports that rapamycin can extend mammalian life span. The section on attenuated mTOR signaling also describes genetic and pharmacological interventions in that aging-related pathway that extend life span in model organisms. (LLM, conf=0.93)

  cites Barzilai et al., 2012 source
• Supported

  The ‘Inhibitors of the TOR pathway’ section reports lifespan extension through genetic or pharmacological intervention in yeast, worms, flies, and mice, and identifies mTOR signaling as a target. The Conclusions likewise identify aging-related pathways and interventions to target them. Page numbers were not provided in our copy. (LLM, conf=0.93)

  cites Longo et al., 2015 source

In the paper

“When rapamycin is administered late in life, it extends lifespan (Harrison et al., 2009; Miller et al., 2011), slows aging in a dose-dependent manner, shows differential effects by sex (Wilkinson et al., 2012), and is synergistic with metformin.”

What the sources say

• Supported

  The Abstract reports that rapamycin fed beginning at 600 days of age extended median and maximal lifespan in male and female genetically heterogeneous mice. This supports the late-life lifespan claim; the evidence is specific to mice. (LLM, conf=0.93)

  cites Harrison et al., 2009 source
• Supported

  The Abstract and Results report that male and female mice given rapamycin from 20 months of age lived longer than controls. The Discussion likewise states that treatment initiated at 20 months significantly increased lifespan at all three test sites. The finding concerns mice, not humans. (LLM, conf=0.93)

  cites Miller et al., 2011 source

In the paper

“inhibition of mTOR (Kickstein et al., 2010; Nair et al., 2014; Pérez-Revuelta et al., 2014)”

What the sources say

• Supported

  The Results section states that metformin inhibits mTORC1 signaling and reports dose-dependent reductions in phosphorylation of two mTORC1-related targets. The Discussion cautions that these results do not establish mTOR inhibition as the primary mechanism of its effects on tau, but the citing claim does not make that stronger assertion. (LLM, conf=0.90)

  cites Kickstein et al., 2010 source
• Supported

  In “Metformin and Sp Down-regulation Inhibit mTOR Signaling,” the paper reports that metformin inhibited mTOR phosphorylation and states that it blocks mTOR signaling in pancreatic cancer cells. The later discussion likewise concludes that metformin inhibits mTOR signaling. The claim does not specify a broader population or a direct molecular mechanism. (LLM, conf=0.94)

  cites Nair et al., 2014 source
• Supported

  The Results section reports that metformin treatment reduced p-RPS6 levels in SH-SY5Y cells, consistent with inhibition of mTOR signaling. The Discussion also states that metformin triggered mTOR inhibition in HeLa cells. Page numbers are not provided in our copy. (LLM, conf=0.93)

  cites Pérez-Revuelta et al., 2014 source

In the paper

“and the CAMERA trial (Preiss et al., 2014) showed no effect of metformin (18 months) on carotid intimal medial thickness.”

What the sources say

• Supported

  The Abstract states that carotid intima-media thickness progression did not differ significantly between the metformin and placebo groups over 18 months (p=0.29). The Interpretation likewise says carotid intima-media thickness did not improve with metformin in the CAMERA study. (LLM, conf=0.94)

  cites Preiss et al., 2014 source

In the paper

“Smith et al. (2010) did not demonstrate increased lifespan in metformin-treated rats, although the high dose used (~15 times the dose used in humans) may have been toxic.”

What the sources say

• Supported

  The Abstract reports that metformin supplementation did not significantly increase lifespan at any measured quantile, overall, or at maximum lifespan compared with controls. The Survival section likewise reports no significant lifespan extension in the metformin groups. (LLM, conf=0.94)

  cites Smith et al. (2010) source

In the paper

“Several epidemiologic studies have shown that metformin use is associated with reduced cancer incidence and mortality (Landman et al., 2010; Lee et al., 2011; Libby et al., 2009; Monami et al., 2011; Tseng, 2012).”

What the sources say

• Supported

  The Results (Cancer mortality) report lower cancer mortality among metformin users, and the Conclusions describe the association after prospective follow-up. The paper also reports earlier studies finding lower cancer risk among metformin users, supporting the incidence part of this jointly cited background statement. (LLM, conf=0.90)

  cites Landman et al., 2010 source
• Supported

  The Abstract Results report lower cancer incidence among metformin users in this Taiwanese cohort. The Background also describes earlier epidemiologic evidence for reduced incidence and, indirectly, reduced cancer mortality; the paper does not itself measure mortality. (LLM, conf=0.87)

  cites Lee et al., 2011 source
• Supported

  The Conclusions report fewer cancer diagnoses among metformin users than comparators and state that metformin users had reduced overall and cancer-related mortality. This observational study supports the association attributed to it; it does not establish causation. (LLM, conf=0.93)

  cites Libby et al., 2009 source

In the paper

“A large observational study of metformin-treated T2DM patients reported lower rates of dementia than in those treated with other diabetes medications (Cheng et al., 2014).”

What the sources say

• Partly supported

  In Analysis Two, dementia was diagnosed in 3.8% of metformin users, compared with 5.0% of sulfonylurea users and 14.3% of thiazolidinedione users. The adjusted rate was substantially higher for thiazolidinedione users than for metformin users, but the paper found no clear difference for sulfonylurea users. Thus, the claim overgeneralizes the finding to other diabetes medications as a group. Page numbers were not supplied in the passages. (LLM, conf=0.88)

  cites Cheng et al., 2014 sourceExperimental — accuracy not yet measured

In the paper

“There is also evidence from studies performed both in vitro and in vivo of metformin’s role in attenuating tumorigenesis (Anisimov and Bartke, 2013; Karnevi et al., 2013; Liu et al., 2011; Quinn et al., 2013; Salani et al., 2012; Tosca et al., 2010).”

What the sources say

• Supported

  Section 9.1 (Mammary carcinogenesis) reports inhibition of human breast-cancer cell growth in vitro, though only at high metformin concentrations. Section 9.8 (Lung carcinogenesis) reports reduced tumor burden and prevention of carcinogen-induced lung tumorigenesis in mice. Together, these passages support the claim that in vitro and in vivo studies provide evidence of metformin attenuating tumorigenesis. (LLM, conf=0.90)

  cites Anisimov and Bartke, 2013 source
• Supported

  The Background (page not provided) reports that metformin has shown anti-tumour effects in prior studies. Its cited studies include an in vivo hamster study and a study explicitly described as finding antitumour effects both in vitro and in vivo. Karnevi et al.’s own experiments were in vitro, but the cited sentence attributes the broader evidence to several papers, not this study alone. (LLM, conf=0.88)

  cites Karnevi et al., 2013 source
• Supported

  The Results report that metformin inhibited growth of trastuzumab-resistant breast cancer cells in vitro. The paper also reports a significant decrease in mammary tumorigenesis in metformin-treated mice, citing earlier work for that in vivo finding. Together, these passages support the broad claim about evidence from both settings. (LLM, conf=0.88)

  cites Liu et al., 2011 source

In the paper

“The effects on health span indices such as time on rotarod, distance on treadmill, open field tests, cataract index, oral glucose tolerance tests, insulin tolerance, and cognitive function (Allard et al., 2016) were improved by ~30%.”

What the sources say

• Partly supported

  The Results (§3.3–3.4; page unavailable) report better rotarod performance and preservation of spatial memory in metformin-treated mice compared with high-fat-fed mice. But wheel-running distance did not differ, and §3.2 reports a 20% reduction in blood glucose only at the final oral glucose-tolerance time point, not a roughly 30% improvement across health-span indices. The paper does not report open-field, cataract-index, or insulin-tolerance results. (LLM, conf=0.90)

  cites Allard et al., 2016 sourceExperimental — accuracy not yet measured

In the paper

“Further, metformin treatment was associated with improvement in cardiovascular disease (CVD) risk factors (Goldberg et al., 2013; Haffner et al., 2005) and subclinical atherosclerosis (coronary artery calcium) in male participants (Goldberg et al., 2015).”

What the sources say

• Supported

  The Results report favorable changes in LDL and HDL lipoprotein subfractions with metformin compared with placebo. The Discussion describes these changes as mostly favorable; the claim concerns risk factors, not a demonstrated reduction in cardiovascular events. (LLM, conf=0.91)

  cites Goldberg et al., 2013 source
• Supported

  The Results report that, compared with placebo, the metformin group had significantly greater reductions in weight, insulin resistance, fasting insulin, and glucose. The Discussion also reports a modest reduction in CRP, a nontraditional cardiovascular risk factor. These findings support the general claim of improvement in risk factors among participants with impaired glucose tolerance; the copy does not provide passage page numbers. (LLM, conf=0.91)

  cites Haffner et al., 2005 source

In the paper

“SU-treated patients had lower survival than both matched non-diabetic controls and metformin-treated diabetic patients.”

What the sources say

• Supported

  The Conclusions state that patients initiated on sulfonylurea monotherapy had markedly reduced survival compared with both matched non-diabetic controls and patients receiving metformin monotherapy. The Discussion reports the same pattern, while cautioning that the comparison between treatment groups could not be adjusted for some covariates. (LLM, conf=0.95)

  cites Bannister et al., 2014 source

In the paper

“In an unpublished trial, non-diabetic subjects (n = 80) with mild cognitive impairment showed significant improvements in some cognitive domains after 12 months of metformin treatment (Luchsinger et al., 2016).”

What the sources say

• Partly supported

  The Results (Changes in the clinical outcomes) report significantly greater improvement with metformin after 12 months in one measure, SRT total recall; differences in other cognitive outcomes were not significant. The Methods describe 80 participants with amnestic mild cognitive impairment but allowed some people with untreated diabetes, so “non-diabetic” is inaccurate. The cited work is itself a published trial, not an unpublished one. (LLM, conf=0.92)

  cites Luchsinger et al., 2016 sourceExperimental — accuracy not yet measured

In the paper

“No definitive trials have been conducted.”

In the paper

“There is overwhelming evidence that single gene mutations in nutrient-sensing pathways, such as insulin/insulin-like growth factor (IGF) signaling (Bartke et al., 2001) or the mechanistic target of rapamycin (mTOR) signaling pathways, extend lifespan and health span in invertebrates.”

What the sources say

• Not checked yetcites Bartke et al., 2001 source

In the paper

“and extends lifespan by ~20% in a model of Huntington’s disease (Ma et al., 2007) only in males.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Ma et al., 2007

In the paper

“Metformin is a drug approved to treat diabetes but appears to target a number of aging-related mechanisms.”

In the paper

“It increases mean lifespan in female outbred mice by ~40% (Anisimov et al., 2008).”

What the sources say

• Not checked yet

  Checked before — its earlier verdict is held back until a new check runs.

  cites Anisimov et al., 2008 source

In the paper

“and reduction in DNA damage (Algire et al., 2012).”

What the sources say

• ?Not checked — no full text of the sourcecites Algire et al., 2012 source

In the paper

“In the HOME trial of insulin-treated T2DM patients, addition of metformin resulted in 40% reduction (compared with placebo) in a CVD composite after 4 years of follow-up (Kooy et al., 2009).”

What the sources say

• ?Not checked — no full text of the sourcecites Kooy et al., 2009 source

In the paper

“Mortality benefits have also been described in other observational studies and long-term follow-up of the UKPDS cohort, which showed 36% reduction in all-cause mortality in the metformin treatment group (p = 0.011) (UKPDS Group, 1998).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites UKPDS Group, 1998

In the paper

“Metformin reduced the incidence of T2DM by 31% compared to placebo over a mean follow-up of ~3 years and was effective in all age categories in preventing diabetes, defined by HbA1C level, including the ~20% who were age 60 or older at baseline (Knowler et al., 2015).”

What the sources say

• Not checked yetcites Knowler et al., 2015 source

In the paper

“an analysis from the Medicare Current Beneficiary Survey showed only a non-statistically significant survival benefit for metformin-treated patients (Tinetti et al., 2015).”

What the sources say

• Not checked yet

  Checked before — its earlier verdict is held back until a new check runs.

  cites Tinetti et al., 2015 source

In the paper

“Further, the lowest risk was seen in those with longer-term (> 6 years) metformin use (Ng et al., 2014).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Ng et al., 2014

In the paper

“Metformin reduced the incidence of T2DM by 31% compared to placebo over a mean follow-up of ~3 years and was effective in all age categories in preventing diabetes, defined by HbA1C level, including the ~20% who were age 60 or older at baseline (Knowler et al., 2015).”

What the sources say

• Not checked yetcites Knowler et al., 2015 source

In the paper

“with a recently published trial showing negative results in advanced pancreatic cancer (Kordes et al., 2015).”

What the sources say

• ?Not checked — no full text of the sourcecites Kordes et al., 2015 source

In the paper

“Mild anemia occurred in ~12% of metformin-treated participants versus ~8% in the placebo group (p = 0.04).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Diabetes Prevention Program Research Group, 2012

In the paper

“Metformin has been used with an excellent safety record for over 60 years.”

In the paper

“Further, metformin treatment was associated with improvement in cardiovascular disease (CVD) risk factors (Goldberg et al., 2013; Haffner et al., 2005) and subclinical atherosclerosis (coronary artery calcium) in male participants (Goldberg et al., 2015).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Goldberg et al., 2015

In the paper

“The dose of 1 mM is well above the comparable dose range in humans, and indeed doses higher than this increased mortality. This is also the case in mammals. When using a 10-fold increase in the dose that showed benefit in mice, mortality increased (Martin-Montalvo et al., 2013).”

What the sources say

• Not checked yetcites Martin-Montalvo et al., 2013 source