Metformin targets mitochondrial complex I to lower blood glucose levels

Effect of Metformin on Spontaneous Calcium Signaling in Cultured Astrocytes during Normoxic and Hypoxic Conditions

Astrocyte function is controlled by intracellular Ca2+ signaling. On the other hand, hypoxia influences calcium dynamics and its homeostatic range because of reduction of ATP synthesis, which inhibits ATP dependent processes. By using Ca2+ sensitive fluorescence dye, we studied how metformin changed spontaneous oscillating Ca2+ signals in soma of astrocytes in monocultures, prepared from rat brains. Mild hypoxic conditions (2% O2) applied for 24 h had no effect on astrocyte viability; however, it reduced the relative amplitude of Ca2+ signals, slowed the decay of the signals, and increased the period of spontaneous oscillations. Lower concentrations of metformin, 250 μM or 500 μM, applied before hypoxia reduced this influence by partially restoring the amplitude, fastening the decay, and reducing the period of Ca2+ signaling. In contrast, higher concentration, 1mM of metformin exaggerated the effects of hypoxia by reducing signals, slowing their decay and prolonged the period between signals. Unexpectedly, in astrocytes grown under normoxic conditions, all concentrations of metformin after one hour of application had effects similar to hypoxia for Ca2+ signaling. In conclusion, our data show that mild hypoxia reduces Ca2+signaling in astrocyte cell monocultures, and low concentrations of metformin under mild hypoxic conditions help to rescue the functioning of astrocytes by conditioning the cells to prolonged hypoxic influence.

Metformin use in prediabetes: A review of evidence and a focus on metabolic features among peri-menopausal women

The prevalence of prediabetes has more than doubled over the past two decades. Although hormones associated with the menstrual cycle may offer some protection against diabetes by enhancing insulin sensitivity and suppressing gluconeogenesis, the prevalence of diabetes among women remains high at 10.5%. Notably, among the perimenopausal population, the prevalence catches up to-and even surpasses-that of men starting from the 70-74 age group, according to the 2021 International Diabetes Federation (IDF) report. This narrative review examines the benefits and potential risks of metformin across diverse populations, with a particular emphasis on women in the perimenopausal phase. Metformin's interaction with hormonal regulation significantly influences both its therapeutic efficacy and long-term side effect profile, contributing to sex-specific differences in treatment response. Consequently, its effectiveness varies among women at different stages of menopause, potentially due to differential impacts on inflammatory markers and modulation of the hypothalamic-pituitary-ovarian (HPO) and hypothalamic-pituitary-thyroid (HPT) axes. Emerging evidence also highlights metformin's potential in managing conditions such as polycystic ovary syndrome (PCOS), breast tissue inflammation and endometrial disorders within this demographic. Given these potential and multifaceted benefits, this review highlights the need for further randomized controlled trials (RCTs) to investigate metformin's role among perimenopausal and menopausal women and to better understand how menopausal status may influence its efficacy. PLAIN LANGUAGE SUMMARY: The number of people with prediabetes has more than doubled in the last 20 years. By 2021, about 720 million people worldwide were living with this condition, and that number is expected to reach 1 billion by 2045. While hormones that fluctuate with the menstrual cycle might help protect against diabetes, the overall rate of diabetes among women is still concerning, at 10.5%. For women going through menopause, the situation is even more serious. From the age of 70 to 74, the rates of diabetes in women surpass those in men. This may be because menopause reduces levels of protective hormones like estrogen and progesterone, which help guard against type 2 diabetes (T2D). Despite this growing issue, there hasn't been much research focused on prediabetes in women going through menopause and how the changes in hormones might affect treatment guidelines. To address this lack of information, our review focused on the use of metformin for women in the perimenopausal stage with prediabetes, aiming to help prevent them from developing T2D in the future. We gathered insights from recent clinical trials to summarize the benefits and risks of metformin for various groups, particularly perimenopausal women. Our findings indicate that metformin can be effective for managing prediabetes, although opinions vary. It's currently the only diabetes medication recommended for prediabetes by the American Diabetes Association (ADA), supported by significant studies like the Diabetes Prevention Program (DPP) and the Coronary Endothelial Dysfunction Multicentre Prospective Study (CODYCE study). Metformin's effectiveness seems to increase when combined with lifestyle changes, such as diet and exercise. Some challenges exist, though, like concerns that it might only work for those at a high risk of developing T2D, potential side effects, and the availability of other options, such as lifestyle adjustments or a new medication called tirzepatide. Still, many experts argue that metformin remains valuable because it allows for early intervention, particularly when lifestyle changes alone may not be enough. We also found that metformin might work differently for men and women due to variations in hormone interactions, differing gut bacteria, and weight-related factors that can influence its effectiveness. Interestingly, metformin seems to work better for women who have not yet gone through menopause. This might be because it helps with weight loss and reduces inflammation, which are important for postmenopausal health. Moreover, metformin has shown promise in addressing other health issues that postmenopausal women may face, such as inflammation in breast tissue, certain types of cancer, endometrial problems (as an alternative to hormone therapy), and polycystic ovarian syndrome (PCOS). In conclusion, our review stresses the importance of creating specific guidelines for managing prediabetes (e.g., metformin therapy) in the perimenopausal population. Understanding how sex hormones interact with blood sugar control is crucial for developing effective treatments tailored to women at different stages of menopause.

Metformin use in women with polycystic ovary syndrome (PCOS): Opportunities, benefits, and clinical challenges

Metformin, a synthetic biguanide, is widely used to manage type 2 diabetes, and is commonly prescribed in polycystic ovary syndrome (PCOS) to address insulin resistance and associated metabolic and reproductive disturbances. PCOS is characterised by hormonal imbalances such as hyperandrogenism and anovulation, metabolic abnormalities including insulin resistance and increased cardiometabolic risk, and higher rates of pregnancy complications. However, the role of metformin in the multifaceted nature of PCOS remains debated. This review synthesises the mechanisms of action of metformin and its effects on metabolic, hormonal, reproductive, and pregnancy-related outcomes in PCOS. In non-pregnant women, metformin improves insulin resistance, menstrual regularity, and androgen levels, particularly in those with obesity or insulin resistance, and may enhance fertility when combined with other treatments. However, it is not effective as a first-line therapy for weight loss, ovulation induction, or treatment of clinical hyperandrogenic features, including hirsutism or acne. In pregnancy, metformin may reduce early pregnancy loss, miscarriage, and preterm birth, though findings for gestational diabetes and preeclampsia are inconsistent. Evidence is limited by study heterogeneity, varying diagnostic criteria, and the use of aggregate data in meta-analyses, all of which make interpretation challenging. Future research should prioritise well-powered clinical trials, individual patient data meta-analyses, and longer-term follow-up studies, particularly in pregnancy, to better define the populations most likely to benefit from metformin use across the PCOS spectrum. PLAIN LANGUAGE SUMMARY: Polycystic ovary syndrome (PCOS) is a common condition that affects up to 1 in 10 women of reproductive age. It is characterised by irregular or absent periods, signs of elevated male hormones (high androgens or excess hair growth), and/or polycystic ovaries seen on ultrasound. These features can lead to fertility problems, acne, psychological distress, and an increased risk of various disorders such as depression, type 2 diabetes and heart disease. Many women with PCOS also experience challenges during pregnancy, including a higher risk of miscarriage, preterm birth, and gestational diabetes. Metformin is a medication most often used to manage diabetes. In women with PCOS, it can help improve how the body responds to insulin, which may also reduce male hormone levels, improve menstrual cycles, and support fertility. This review examines the role of metformin in treating PCOS-both before and during pregnancy-by summarising key findings from the available evidence. In women who are not pregnant, metformin can help improve insulin resistance, hormone levels, and menstrual regularity, particularly among those who are overweight or have signs of insulin resistance. However, metformin alone is not a first-choice treatment for weight loss, ovulation problems, or symptoms such as acne and unwanted hair growth. When combined with other treatments, such as hormone therapy or fertility medications, it may offer additional benefits. During pregnancy, metformin is considered safe for use in women with PCOS and may lower the risk of early pregnancy loss and preterm birth. However, its effects on preventing gestational diabetes or high blood pressure are less clear, with mixed results across studies. Some research suggests that babies exposed to metformin in the womb may have slightly larger head sizes or a higher risk of being overweight in early childhood, but the long-term health effects remain unknown. Overall, metformin can be a helpful part of treatment for some women with PCOS, especially those with insulin resistance or certain pregnancy risks. Still, it is not a one-size-fits-all solution. More high-quality research is needed to better understand which women benefit most and to assess any long-term effects on children exposed to metformin during pregnancy.

Long-term effects of metformin on offspring health: A review of current evidence and future directions

Metformin is widely prescribed for the management of type 2 diabetes mellitus, polycystic ovary syndrome, and gestational diabetes mellitus in pregnancy. Its use is driven by factors including oral administration, lower patient and health system burden and cost, and benefits including lower risk of excess gestational weight gain and hypoglycemia compared with insulin. Metformin use appears safe in pregnancy; however, there remain concerns regarding long-term effects of intrauterine metformin exposure on offspring health. Randomized controlled trial follow-up studies suggest that metformin-exposed offspring may have altered postnatal growth trajectories and increased adiposity in childhood, although data are limited. Whether this is a transient adaptation or a precursor to long-term metabolic dysfunction is unclear, as data on cardiometabolic and neurodevelopmental parameters, including glucose homeostasis, lipid metabolism, and cognitive function, are sparse and inconsistent. Methodological challenges include heterogeneous study designs, high attrition rates, and inadequate control for confounding variables. Given these uncertainties, further well-powered, long-term prospective studies and individual patient data meta-analyses, harmonizing data and adjusting for confounders, are needed to clarify risks and benefits of metformin use in pregnancy. Until such data are available, clinicians must weigh the benefits and advantages of metformin use in pregnancy against the unknowns regarding potential long-term impact on offspring health. PLAIN LANGUAGE SUMMARY: Metformin is a medicine often used during pregnancy to help manage conditions such as type 2 diabetes, gestational diabetes, and polycystic ovary syndrome (PCOS). It is commonly chosen because it is taken as a tablet rather than by injection, has a lower risk of causing low blood sugar, and is generally easier and less expensive to use than insulin. Research has shown that metformin is safe for use during pregnancy in the short term. However, there are still questions about whether it has any lasting effects on children who were exposed to it before birth. This review explores this topic in detail. Some studies have found that children exposed to metformin during pregnancy may have slightly different growth patterns, such as having more body fat or being heavier in early childhood. However, these results are inconsistent and most studies show no clear differences in overall health outcomes, including in heart health, metabolism, or brain development. The results are mixed, and many studies are small or have design limitations, which makes it difficult to draw strong conclusions. At this stage, there is no clear evidence that metformin causes harm to children in the long term. However, because some studies suggest there may be effects on childhood growth and development, researchers emphasize the need for further long-term research. These future studies should follow children into adolescence and adulthood to better understand any lasting impacts. Until more is known, doctors and patients will need to carefully consider the known benefits of metformin in pregnancy alongside the current uncertainties about long-term effects on child health.

Modeling the extension of ovarian function after therapeutic targeting of the primordial follicle reserve

BACKGROUND

Women are increasingly choosing to delay childbirth, and those with low ovarian reserves indicative of primary ovarian insufficiency are at risk for sub- and infertility and also the early onset of menopause. Experimental strategies that promise to extend the duration of ovarian function in women are currently being developed. One strategy is to slow the rate of loss of existing primordial follicles (PFs), and a second is to increase, or 'boost', the number of autologous PFs in the human ovary. In both cases, the duration of ovarian function would be expected to be lengthened, and menopause would be delayed. This might be accompanied by an extended production of mature oocytes of sufficient quality to extend the fertile lifespan.

OBJECTIVE AND RATIONALE

In this work, we consider how slowing physiological ovarian aging might improve the health and well-being of patients, and summarize the current state-of-the-art of approaches being developed. We then use mathematical modeling to determine how interventions are likely to influence the duration of ovarian function quantitatively. Finally, we consider efficacy benchmarks that should be achieved so that individuals will benefit, and propose criteria that could be used to monitor ongoing efficacy in different patients as these strategies are being validated.

SEARCH METHODS

Current methods to estimate the size of the ovarian reserve and its relationship to the timing of the menopausal transition and menopause were compiled, and publications establishing methods designed to slow loss of the ovarian reserve or to deliver additional ovarian PFs to patients were identified.

OUTCOMES

We review our current understanding of the consequences of reproductive aging in women, and compare different approaches that may extend ovarian function in women at risk for POI. We also provide modeling of primordial reserve decay in the presence of therapies that slow PF loss or boost PF numbers. An interactive online tool is provided that estimates how different interventions would impact the duration of ovarian function across the natural population. Modeling output shows that treatments that slow PF loss would need to be applied as early as possible and for many years to achieve significant delay of menopause. In contrast, treatments that add additional PFs should occur as late as possible relative to the onset of menopause. Combined approaches slowing ovarian reserve loss while also boosting numbers of (new) PFs would likely offer some additional benefits in delaying menopause.

WIDER IMPLICATIONS

Extending ovarian function, and perhaps the fertile lifespan, is on the horizon for at least some patients. Modeling ovarian aging with and without such interventions complements and helps guide the clinical approaches that will achieve this goal.

REGISTRATION NUMBER

Not applicable.

Impact of diabetes and metformin on cuproptosis and ferroptosis in breast cancer patients: an immunohistochemical analysis

OBJECTIVES

Breast cancer patients with diabetes are often associated with poor prognosis. This study aims to investigate the role of metformin in ferroptosis and cuproptosis in diabetic breast cancer patients and explore its potential impact on clinical outcomes.

METHODS

We retrospectively analyzed tissue samples from 16 breast cancer patients, including 5 non-diabetic and 11 diabetic patients (6 treated with metformin). Immunohistochemistry (IHC) staining was performed for cuproptosis (FDX1, DLAT), ferroptosis (ACSL4, GPX4), and glycolysis markers (LDHA, PKM2). Statistical analysis used quantitative results from immunohistochemistry.

RESULTS

Patients treated with metformin showed significantly higher expression of FDX1 and ACSL4, along with a significant decrease in GPX4 compared to other groups. Kaplan-Meier survival analysis revealed that high FDX1 expression was associated with longer survival in breast cancer patients. Correlation analysis showed a positive association between ACSL4 and FDX1 (R = 0.51, P = 0.045), suggesting a relationship between these markers.

CONCLUSIONS

Metformin may simultaneously enhance both cuproptosis and ferroptosis in breast cancer. FDX1 expression could serve as a prognostic marker for survival, especially in diabetic patients, providing insights into targeting metabolic and cell death pathways in breast cancer therapy.

Targeting AMPK as a potential treatment for hepatic fibrosis in MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease, and often progresses to hepatic fibrosis, cirrhosis, and liver failure. Despite its increasing prevalence, effective pharmacological treatments for MASLD-related fibrosis remain limited. Recent research has highlighted AMP-activated protein kinase (AMPK) as a key regulator of the processes that promote fibrogenesis, and AMPK activation shows potential in mitigating fibrosis. Advances in AMPK activators and deeper insights into their role in fibrotic pathways have recently revitalized interest in targeting AMPK for fibrosis treatment. This review discusses the molecular mechanisms linking AMPK to hepatic fibrosis and evaluates emerging AMPK-directed therapies. Furthermore, it addresses challenges in clinical translation. Importantly, we combine the latest mechanistic discoveries with recent therapeutic developments to provide a comprehensive perspective on AMPK as a target for hepatic fibrosis treatment.

Targeting the Electron Transport System for Enhanced Longevity

Damage to mitochondrial DNA (mtDNA) results in defective electron transport system (ETS) complexes, initiating a cycle of impaired oxidative phosphorylation (OXPHOS), increased reactive oxygen species (ROS) production, and chronic low-grade inflammation (inflammaging). This culminates in energy failure, cellular senescence, and progressive tissue degeneration. Rapamycin and metformin are the most extensively studied longevity drugs. Rapamycin inhibits mTORC1, promoting mitophagy, enhancing mitochondrial biogenesis, and reducing inflammation. Metformin partially inhibits Complex I, lowering reverse electron transfer (RET)-induced ROS formation and activating AMPK to stimulate autophagy and mitochondrial turnover. Both compounds mimic caloric restriction, shift metabolism toward a catabolic state, and confer preclinical-and, in the case of metformin, clinical-longevity benefits. More recently, small molecules directly targeting mitochondrial membranes and ETS components have emerged. Compounds such as Elamipretide, Sonlicromanol, SUL-138, and others modulate metabolism and mitochondrial function while exhibiting similarities to metformin and rapamycin, highlighting their potential in promoting longevity. The key question moving forward is whether these interventions should be applied chronically to sustain mitochondrial health or intermittently during episodes of stress. A pragmatic strategy may combine chronic metformin use with targeted mitochondrial therapies during acute physiological stress.

Xenotopic synthetic biology: Prospective tools for delaying aging and age-related diseases

Metabolic dysregulation represents one of the major driving forces in aging. Although multiple genetic and pharmacological manipulations are known to extend longevity in model organisms, aging is a complex trait, and targeting one's own genes may be insufficient to prevent age-dependent deterioration. An alternative strategy could be to use enzymes from other species to reverse age-associated metabolic changes. In this review, we discuss a set of enzymes from lower organisms that have been shown to affect various metabolic parameters linked to age-related processes. These enzymes include modulators of steady-state levels of amino acids (METase, ASNase, and ADI), NADPH/NADP+ and/or reduced form of coenzyme Q (CoQH2)/CoQ redox potentials (NDI1, AOX, LbNOX, TPNOX, EcSTH, RquA, LOXCAT, Grubraw, and ScURA), GSH (StGshF), mitochondrial membrane potential (mtON and mito-dR), or reactive oxygen species (DAAO and KillerRed-SOD1). We propose that leveraging non-mammalian enzymes represents an untapped resource that can be used to delay aging and age-related diseases.

Meeting metformin again for the first time

New evidence convincingly shows that metformin, a drug that reduces circulating glucose, acts by inhibiting mitochondrial complex I.