Effects of Behavioral Weight Loss and Metformin on IGFs in Cancer Survivors: A Randomized Trial

Metformin and the PI3K/AKT signaling pathway: implications for cancer, cardiovascular, and central nervous system diseases

Recent findings have brought our understanding of diseases at the molecular level, highlighting upstream intracellular pathways as potential therapeutic targets. The PI3K/AKT pathway, a key regulator of cellular responses to environmental changes, is frequently altered in various diseases, making it a promising target for intervention. Metformin is the most known anti-diabetic agent that is known due to its effects on cancer, inflammatory-related diseases, oxidative stress, and other human diseases. It is clearly understood that metformin modulates the activity of the PI3K/AKT pathway leading to a wide variety of outcomes. This interaction has been well-studied in various diseases. Therefore, this review aims to examine PI3K/AKT-modulating properties of metformin in cancer, cardiovascular, and central nervous system diseases. Our findings indicate that metformin is effective in treating cancer and CNS diseases, and plays a role in both the prevention and treatment of cardiovascular diseases. These insights support the potential of metformin in comprehensive strategies for disease management.

Behavioral Weight Loss Programs for Cancer Survivors Throughout Maryland: Protocol for a Pragmatic Trial and Participant Characteristics

BACKGROUND

Clinical trials examining lifestyle interventions for weight loss in cancer survivors have been demonstrated to be safe, feasible, and effective. However, scalable weight loss programs are needed to support their widespread implementation. The ASPIRE trial was designed to evaluate real-world, lifestyle-based, weight loss programs for cancer survivors throughout Maryland.

OBJECTIVE

The objectives of this protocol paper are to describe the design of a nonrandomized pragmatic trial, study recruitment, and baseline characteristics of participants.

METHODS

Participants were aged ≥18 years, residing in Maryland, with a BMI ≥25 kg/m2, who reported a diagnosis of a malignant solid tumor, completed curative treatment, and had no ongoing or planned cancer treatment. Enrollment criteria were minimized to increase generalizability. The primary recruitment source was the Johns Hopkins Health System electronic health records (EHRs). Participants selected 1 of 3 remotely delivered weight loss programs: self-directed, app-supported, or coach-supported program.

RESULTS

Participants were recruited across all 5 geographic regions of Maryland. Targeted invitations using EHRs accounted for 287 (84.4%) of the 340 participants enrolled. Of the 5644 patients invited through EHR, 5.1% (287/5644) enrolled. Participants had a mean age of 60.7 (SD 10.8) years, 74.7% (254/340) were female, 55.9% (190/340) identified as non-Hispanic Black, 58.5% (199/340) had a bachelor's degree, and the average BMI was 34.1 kg/m2 (SD 5.9 kg/m2). The most common types of cancers were breast (168/340, 49.4%), prostate (72/340, 21.2%), and thyroid (39/340, 8.5%). The self-directed weight loss program (n=91) included 25 participants who agreed to provide weights through a study scale; the app-supported program (n=142) included 108 individuals who agreed to provide their weight measurements; and the coach-supported weight loss program included 107 participants. We anticipate final analysis will take place in the fall of 2024.

CONCLUSIONS

Using EHR-based recruitment efforts, this study took a pragmatic approach to reach and enroll cancer survivors into remotely delivered weight loss programs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04534309; https://clinicaltrials.gov/study/NCT04534309.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/54126.

The impact of metformin on weight and metabolic parameters in patients with obesity: A systematic review and meta-analysis of randomized controlled trials

There are conflicting data on the weight-reducing potential of metformin (MTF) in nondiabetic patients with obesity. The purpose of this systematic review and meta-analysis was to evaluate the effect of MTF on weight and cardiometabolic parameters in adults with overweight/obesity with or without nonalcoholic fatty liver disease (NAFLD) (CRD42018085512). We included randomized controlled trials (RCTs) in adults without diabetes mellitus, with mean body mass index (BMI) ≥ 25 kg/m2, with or without NAFLD, comparing MTF to placebo/control, lifestyle modification (LSM) or a US Food and Drug Administration-approved anti-obesity drug, reporting on weight or metabolic parameters, and extending over at least 3 months. We conducted a systematic search in MEDLINE, EMBASE, PubMed and the Cochrane Library without time limitation (until March 2022). We screened and selected eligible articles, abstracted relevant data, and assessed the risk of bias. All steps were in duplicate and independently. We conducted a random-effects model meta-analysis using Review Manager version 5.3, with prespecified subgroup analyses in case of heterogeneity. We identified 2650 citations and included 49 trials (55 publications). Compared to placebo, MTF was associated with a significant reduction in BMI (mean difference [MD] -0.56 [-0.74, -0.37] kg/m2; p < 0.0001), at doses ranging from 500 to 2550 mg/day, and with a significant percentage change in BMI of -2.53% (-2.90, -2.17) at the dose 1700 mg/day. There was no interaction by baseline BMI, MTF dose or duration, nor presence or absence of NAFLD. There was no significant difference between MTF and LSM. Orlistat was more effective than MTF (at doses of 1000-1700 mg/day) in terms of weight loss, with an MD in BMI of -3.17 (-5.88; -0.47) kg/m2, favouring the former. Compared to placebo/control, MTF improved insulin parameters, while no effect was detected when compared to LSM. A few small trials showed heterogenous effects on liver parameters in patients with NAFLD treated with MTF compared to placebo/control. There was a large variability in the expression of outcome measures and RCTs were of low quality. In conclusion, MTF was associated with a modest weight reduction in obese nondiabetic patients. Further high-quality and better powered studies are needed to examine the impact of MTF in patients with insulin resistance and NAFLD.

Metformin and Breast Cancer: Current Findings and Future Perspectives from Preclinical and Clinical Studies

Over the last several decades, a growing body of research has investigated the potential to repurpose the anti-diabetic drug metformin for breast cancer prevention and/or treatment. Observational studies in the early 2000s demonstrated that patients with diabetes taking metformin had decreased cancer risk, providing the first evidence supporting the potential role of metformin as an anti-cancer agent. Despite substantial efforts, two decades later, the exact mechanisms and clinical efficacy of metformin for breast cancer remain ambiguous. Here, we have summarized key findings from studies examining the effect of metformin on breast cancer across the translational spectrum including in vitro, in vivo, and human studies. Importantly, we discuss critical factors that may help explain the significant heterogeneity in study outcomes, highlighting how metformin dose, underlying metabolic health, menopausal status, tumor subtype, membrane transporter expression, diet, and other factors may play a role in modulating metformin's anti-cancer effects. We hope that these insights will help with interpreting data from completed studies, improve the design of future studies, and aid in the identification of patient subsets with breast cancer or at high risk for the disease who are most likely to benefit from metformin treatment.

Current status and frontier tracking of clinical trials on Metformin for cancer treatment

PURPOSE

Metformin has been used clinically for more than six decades. Over time, numerous remarkable effects of metformin beyond the clinic have been discovered and discussed. Metformin has been shown to have a favorable impact on cancer therapy in addition to its clinically recognized hypoglycemic effect. However, the antitumor efficacy of metformin in humans has not been clearly demonstrated yet. Hence, a systematic analysis of the existing trials is necessary.

METHODS

Here, we retrieved clinical trials from the Clinical Trials.gov database to overview the clinical development of metformin for the treatment of cancer, analyze existing clinical results, and summarize some promising applications for specific cancer therapies.

RESULTS

The potential application of metformin contains three directions: Firstly, improvement of metabolic factors associated with treatment effects, such as insulin resistance and peripheral neuropathy. Secondly, in combination with immune checkpoint blockade effects. Finally, use it for the endocrine treatment of hormone-dependent cancers.

CONCLUSION

Although the outcomes of metformin as a repurposed agent in some trials have been unsatisfactory, it still has the potential to be used in select cancer therapy settings.

Interventions for weight reduction in obesity to improve survival in women with endometrial cancer

BACKGROUND

This is an updated version of the original Cochrane Review published in Issue 2, 2018. Diagnoses of endometrial cancer are increasing secondary to the rising prevalence of obesity. Obesity plays an important role in promoting the development of endometrial cancer, by inducing a state of unopposed oestrogen excess, insulin resistance and inflammation. It also affects treatment, increasing the risk of surgical complications and the complexity of radiotherapy planning, and may additionally impact on subsequent survival. Weight-loss interventions have been associated with improvements in breast and colorectal cancer-specific survival, as well as a reduction in the risk of cardiovascular disease, which is a frequent cause of death in endometrial cancer survivors.

OBJECTIVES

To evaluate the benefits and harm of weight-loss interventions, in addition to standard management, on overall survival and the frequency of adverse events in women with endometrial cancer who are overweight or obese compared with any other intervention, usual care, or placebo.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was from January 2018 to June 2022 (original review searched from inception to January 2018).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of interventions to facilitate weight loss in women with endometrial cancer who are overweight or obese undergoing treatment for, or previously treated for, endometrial cancer compared with any other intervention, usual care, or placebo.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were 1. overall survival and 2. frequency of adverse events. Our secondary outcomes were 3. recurrence-free survival, 4. cancer-specific survival, 5. weight loss, 6. cardiovascular and metabolic event frequency and 7. quality of Life. We used GRADE to assess certainty of evidence. We contacted study authors to obtain missing data, including details of any adverse events.

MAIN RESULTS

We identified nine new RCTs and combined these with the three RCTs identified in the original review. Seven studies are ongoing.  The 12 RCTs randomised 610 women with endometrial cancer who were overweight or obese. All studies compared combined behavioural and lifestyle interventions designed to facilitate weight loss through dietary modification and increased physical activity with usual care. Included RCTs were of low or very low quality, due to high risk of bias by failing to blind participants, personnel and outcome assessors, and significant loss to follow-up (withdrawal rate up to 28% and missing data up to 65%, largely due to the effects of the COVID-19 pandemic). Importantly, the short duration of follow-up limits the directness of the evidence in evaluating the impact of these interventions on any of the survival and other longer-term outcomes.  Combined behaviour and lifestyle interventions were not associated with improved overall survival compared with usual care at 24 months (risk ratio (RR) mortality, 0.23, 95% confidence interval (CI) 0.01 to 4.55, P = 0.34; 1 RCT, 37 participants; very low-certainty evidence). There was no evidence that such interventions were associated with improvements in cancer-specific survival or cardiovascular event frequency as the studies reported no cancer-related deaths, myocardial infarctions or strokes, and there was only one episode of congestive heart failure at six months (RR 3.47, 95% CI 0.15 to 82.21; P = 0.44, 5 RCTs, 211 participants; low-certainty evidence). Only one RCT reported recurrence-free survival; however, there were no events. Combined behaviour and lifestyle interventions were not associated with significant weight loss at either six or 12 months compared with usual care (at six months: mean difference (MD) -1.39 kg, 95% CI -4.04 to 1.26; P = 0.30, I2 = 32%; 5 RCTs, 209 participants; low-certainty evidence). Combined behaviour and lifestyle interventions were not associated with increased quality of life, when measured using 12-item Short Form (SF-12) Physical Health questionnaire, SF-12 Mental Health questionnaire, Cancer-Related Body Image Scale, Patient Health Questionnaire 9-Item Version or Functional Assessment of Cancer Therapy - General (FACT-G) at 12 months when compared with usual care (FACT-G: MD 2.77, 95% CI -0.65 to 6.20; P = 0.11, I2 = 0%; 2 RCTs, 89 participants; very low-certainty evidence). The trials reported no serious adverse events related to weight loss interventions, for example hospitalisation or deaths. It is uncertain whether lifestyle and behavioural interventions were associated with a higher or lower risk of musculoskeletal symptoms (RR 19.03, 95% CI 1.17 to 310.52; P = 0.04; 8 RCTs, 315 participants; very low-certainty evidence; note: 7 studies reported musculoskeletal symptoms but recorded 0 events in both groups. Thus, the RR and CIs were calculated from 1 study rather than 8).  AUTHORS' CONCLUSIONS: The inclusion of new relevant studies has not changed the conclusions of this review. There is currently insufficient high-quality evidence to determine the effect of combined lifestyle and behavioural interventions on survival, quality of life or significant weight loss in women with a history of endometrial cancer who are overweight or obese compared to those receiving usual care. The limited evidence suggests that there is little or no serious or life-threatening adverse effects due to these interventions, and it is uncertain if musculoskeletal problems were increased, as only one out of eight studies reporting this outcome had any events. Our conclusion is based on low- and very low-certainty evidence from a small number of trials and few women. Therefore, we have very little confidence in the evidence: the true effect of weight-loss interventions in women with endometrial cancer and obesity is currently unknown. Further methodologically rigorous, adequately powered RCTs are required with follow-up of five to 10 years of duration. These should focus on the effects of varying dietary modification regimens, and pharmacological treatments associated with weight loss and bariatric surgery on survival, quality of life, weight loss and adverse events.

Fast Mimicking Diets and Other Innovative Nutritional Interventions to Treat Patients with Breast Cancer

The impact of nutritional patterns on the risk of breast cancer (BC) is well investigated in the oncology literature, including the type of diets and caloric intake. While obesity and elevated body mass index are well-reported critical risk factors of BC occurrence, there is an expanding area of oncology assessing the impact of caloric intake and nutritional patterns in patients with cancer. Caloric restriction and fast mimicking alimentary regimens have been consistently reported to improve survival outcomes based on preclinical models. Moreover, emerging clinical evidence has paved the way for new metabolic approaches for the treatment of BC, in addition to the established therapeutic arsenal or as alternative options. In this chapter, our aim is to discuss the principal strategies of metabolic manipulation through nutritional interventions for patients with BC as an innovative area of cancer therapy.

Countermeasure development against space radiation-induced gastrointestinal carcinogenesis: Current and future perspectives

A significantly higher probability of space radiation-induced gastrointestinal (GI) cancer incidence and mortality after a Mars mission has been projected using biophysical and statistical modeling approaches, and may exceed the current NASA mandated limit of less than 3% REID (risk of exposure-induced death). Since spacecraft shielding is not fully effective against heavy-ion space radiation, there is an unmet need to develop an effective medical countermeasure (MCM) strategy against heavy-ion space radiation-induced GI carcinogenesis to safeguard astronauts. In the past, we have successfully applied a GI cancer mouse model approach to understand space radiation-induced GI cancer risk and associated molecular signaling events. We have also tested several potential MCMs to safeguard astronauts during and after a prolonged space mission. In this review, we provide an updated summary of MCM testing using the GI cancer mouse model approach, lessons learned, and a perspective on the senescence signaling targeting approach for desirable protection against space radiation-induced GI carcinogenesis. Furthermore, we also discuss some of the advanced senotherapeutic candidates/combinations as a potential MCM for space radiation-induced GI carcinogenesis.

Clinical interventions to break the obesity and cancer link: a narrative review

Excess body weight is a significant risk factor for the development and recurrence of many types of cancer. Patients with a history or current diagnosis of cancer who are overweight or have obesity have an increased risk of cancer treatment-related morbidity, recurrence, and decreased quality of life. Weight loss and maintenance of a healthy body weight may reduce cancer morbidity and recurrence in cancer survivors. While guidelines for cancer survivorship elaborate sufficiently on lifestyle interventions, little guidance is provided when considering additional therapies like anti-obesity pharmacotherapy or bariatric surgery for weight loss. This review will highlight and address current recommendations and feasible interventions that clinicians may consider to further reduce the incidence and recurrence of cancer in patients with obesity.

Increases in Circulating and Fecal Butyrate are Associated With Reduced Blood Pressure and Hypertension: Results From the SPIRIT Trial

Background Short chain fatty acids (SCFAs) are microbially derived end products of dietary fiber fermentation. The SCFA butyrate reduces blood pressure (BP) in mouse models. The association of SCFAs, including butyrate, with BP in humans is unclear, due in part to predominantly cross-sectional analyses and different biospecimens (blood versus fecal) for SCFA measurement. Longitudinal studies including both circulating and fecal SCFAs are lacking. Methods and Results We leveraged existing data from the SPIRIT (Survivorship Promotion In Reducing IGF-1 Trial), which randomized 121 adult cancer survivors with overweight/obesity to a behavioral weight-loss intervention, metformin, or self-directed weight-loss. Of participants with baseline serum and fecal SCFAs measured (n=111), a subset had serum (n=93) and fecal (n=89) SCFA measurements 12 months later. We used Poisson regression with robust error variance to estimate baseline associations of SCFAs with hypertension, and we assessed the percent change in SCFAs from baseline with corresponding 12-month changes in BP using multiple linear regression. Baseline fecal butyrate was inversely associated with prevalent hypertension (standardized PR [95%CI]: 0.71 [0.54, 0.92]). A 10% increase in fecal butyrate from baseline was associated with decreased systolic BP (β [95%CI]: -0.56 [-1.01, -0.10] mm Hg), and a 10% increase in serum butyrate was associated with decreased systolic (β [95%CI]: -1.39 [-2.15, -0.63] mm Hg) and diastolic (β [95%CI]: -0.55 [-1.03, -0.08] mm Hg) BPs. Butyrate associations with systolic BP were linear and not modified by sex, race, or intervention arm. Conclusions Increased serum or fecal butyrate is associated with lowered BP. Butyrate may be a target for SCFA-centered BP-lowering interventions. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02431676.

A behavioral weight-loss intervention, but not metformin, decreases a marker of gut barrier permeability: results from the SPIRIT randomized trial

Background/Objectives:

Lipopolysaccharide-binding protein (LBP), a biomarker of gut barrier permeability to lipopolysaccharides, is higher in adults with obesity and type 2 diabetes. Behavioral weight loss and metformin have distinct effects on the gut microbiome, but their impact on gut permeability to lipopolysaccharides is unknown. This study’s objective was to determine the effects of a behavioral weight loss intervention or metformin treatment on plasma LBP.

Subjects/Methods:

SPIRIT was a randomized trial of adults with overweight or obesity. Participants were randomized to one of three arms: metformin treatment, coach-directed behavioral weight loss on a DASH diet, or self-directed care (control). Of 121 participants, a random subset (n=88) was selected to have LBP measured at baseline, 6-months, and 12-months post intervention. Intervention effects on LBP over time were assessed using generalized estimating equations (GEE). We also examined whether the intervention effects were modified by change in diet and weight.

Results:

Arms were balanced by sex (83% female), race (51% white), and age (mean 60 years), with no differences in baseline LBP (median 4.23 μg/mL). At 1 year, mean weight change was −3.00% in the metformin arm, −3.02% in the coach-directed behavioral weight-loss arm, and +0.33% in the self-directed (control) arm. The corresponding change in LBP was +1.03, −0.98, +1.03 μg/mL. The behavioral weight-loss reduced LBP compared to self-directed care (β=−0.17, 95% CI: −0.33 to −0.01); no other between-arm comparisons were significant. Participants who reduced dietary fat showed the greatest reductions in 6-month LBP (β=−2.84, 95% CI: −5.17 to −0.50).

Conclusions:

Despite similar weight loss in the behavioral weight loss and metformin arms, only the behavioral weight loss intervention reduced LBP compared to control. Lifestyle weight loss interventions that promote a DASH diet may be effective at reducing gut barrier permeability to lipopolysaccharides.

Randomized trial of two artificial intelligence coaching interventions to increase physical activity in cancer survivors

Physical activity (PA) has numerous health benefits. Personalized coaching may increase adherence to PA recommendations, but it is challenging to deliver personalized coaching in a scalable manner. The objective of our study was to determine whether novel artificially intelligent (AI) coaching interventions increase PA among overweight or obese, physically inactive cancer survivors compared to a control arm that receives health information. We conducted a single-center, three-arm randomized trial with equal allocation to (1) voice-assisted AI coaching delivered by smart speaker (MyCoach), (2) autonomous AI coaching delivered by text message (SmartText), and (3) control. Data collection was automated via sensors and voice technology, effectively masking outcome ascertainment. The primary outcome was change in mean steps per day from baseline to the end of follow-up at 4 weeks. Of the 42 randomized participants, 91% were female, and 36% were Black; mean age was 62.1 years, and mean BMI was 32.9 kg/m². The majority were breast cancer survivors (85.7%). At the end of 4 weeks follow-up, steps increased in the MyCoach arm by an average of 3618.2 steps/day; the net gain in this arm was significantly greater [net difference = 3568.9 steps/day (95% CI: 1483–5655), P value <0.001] compared to control arm, and [net difference = 2160.6 steps/day (95% CI: 11–4310), P value 0.049] compared to SmartText. In conclusion, AI-based voice-assisted coaching shows promise as a practical method of delivering scalable, individualized coaching to increase physical activity in sedentary cancer survivors. Additional research is needed to replicate these findings in a broader population of cancer survivors and to investigate the effects of these interventions in the general population.

ClinicalTrials.gov Identifier: NCT03212079, July 11, 2017, https://clinicaltrials.gov/ct2/show/NCT03212079.

Effects of a Behavioral Weight Loss Intervention and Metformin Treatment on Serum Urate: Results from a Randomized Clinical Trial

Background: Lower body mass index (BMI) has been associated with lower serum urate (SU), but only in observational studies. We sought to determine the effects of behavioral weight loss and metformin treatment on SU in a randomized trial. Methods and Findings: The Survivorship Promotion In Reducing IGF-1 Trial (SPIRIT) was a parallel three-arm randomized controlled trial of overweight/obese adult cancer survivors without gout at a single center in Maryland, United States. Participants were randomized to: (1) coach-directed weight loss (behavioral telephonic coaching), (2) metformin (up to 2000 mg daily), or (3) self-directed weight loss (informational brochures; reference group). SU and BMI were assessed at baseline and at 3, 6, and 12 months post-randomization. The 121 participants had a mean ± standard deviation (SD) age of 60 ± 9 years, 79% were female, and 45% were Black. At baseline, BMI was 35 ± 5 kg/m², and SU was 5.6 ± 1.3 mg/dL. Compared to the self-directed group, at 12 months, the coach-directed group reduced BMI by 0.9 kg/m² (95% confidence interval (CI): -1.5, -0.4) and metformin reduced BMI by 0.6 kg/m² (95% CI: -1.1, -0.1). However, compared to the self-directed group, the coach-directed group unexpectedly increased SU by 0.3 mg/dL (95% CI: 0.05, 0.6), and metformin non-significantly increased SU by 0.2 mg/dL (95% CI: -0.04, 0.5); these effects were attenuated when analyses included change in estimated glomerular filtration rate (eGFR). Conclusions: In this randomized trial of cancer survivors without gout, reductions in BMI either increased or did not change SU, potentially due to effects on eGFR. These results do not support a focus on BMI reduction for SU reduction; however, long-term studies are needed. ClinicalTrials.gov Registration: NCT02431676.

Metformin Affects Gut Microbiome Composition and Function and Circulating Short-Chain Fatty Acids: A Randomized Trial

OBJECTIVE

To determine the longer-term effects of metformin treatment and behavioral weight loss on gut microbiota and short-chain fatty acids (SCFAs).

RESEARCH DESIGN AND METHODS

We conducted a 3-parallel-arm, randomized trial. We enrolled overweight/obese adults who had been treated for solid tumors but had no ongoing cancer treatment and randomized them (n = 121) to either 1) metformin (up to 2,000 mg), 2) coach-directed behavioral weight loss, or 3) self-directed care (control) for 12 months. We collected stool and serum at baseline (n = 114), 6 months (n = 109), and 12 months (n = 105). From stool, we extracted microbial DNA and conducted amplicon and metagenomic sequencing. We measured SCFAs and other biochemical parameters from fasting serum.

RESULTS

Of the 121 participants, 79% were female and 46% were Black, and the mean age was 60 years. Only metformin treatment significantly altered microbiota composition. Compared with control, metformin treatment increased amplicon sequence variants for Escherichia (confirmed as Escherichia coli by metagenomic sequencing) and Ruminococcus torques and decreased Intestinibacter bartlettii at both 6 and 12 months and decreased the genus Roseburia, including R. faecis and R. intestinalis, at 12 months. Effects were similar in comparison of the metformin group with the behavioral weight loss group. Metformin versus control also increased butyrate, acetate, and valerate at 6 months (but not at 12 months). Behavioral weight loss versus control did not significantly alter microbiota composition but did increase acetate at 6 months (but not at 12 months). Increases in acetate were associated with decreases in fasting insulin. Additional whole-genome metagenomic sequencing of a subset of the metformin group showed that metformin altered 62 metagenomic functional pathways, including an acetate-producing pathway and three pathways in glucose metabolism.

CONCLUSIONS

Metformin, but not behavioral weight loss, impacted gut microbiota composition at 6 months and 12 months. Both metformin and behavioral weight loss altered circulating SCFAs at 6 months, including increasing acetate, which correlated with lower fasting insulin. Future research is needed to elucidate whether the gut microboime mediates or modifies metformin's health effects.