Effect of metformin and insulin vs. placebo and insulin on whole body composition in overweight patients with type 2 diabetes: a randomized placebo-controlled trial

Exploring the protective effect of metformin against sarcopenia: insights from cohort studies and genetics

BACKGROUND

The impact of metformin on sarcopenia remains uncertain. This study aimed to investigate whether metformin influences sarcopenia risk and evaluate the effects of potential drug targets on sarcopenia traits.

METHODS

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) (n = 3549) to assess the association between metformin use and sarcopenia risk in elderly patients with type 2 diabetes. Mendelian randomization (MR) analysis using genome-wide association studies (GWAS) from UK Biobank (n = 1,366,167) and FinnGen (n = 218,007), with expression quantitative trait loci (eQTL) as instrumental variables, examined the causal effect of metformin-related targets on sarcopenia traits, while molecular docking explored the interaction between metformin and its drug targets.

RESULTS

Metformin use was associated with increased grip strength (OR = 2.46; 95% CI 1.49-2.38) and skeletal muscle mass (OR = 1.24; 95% CI 0.20-2.28), as well as reduced mortality (HR = 0.62; 95% CI 0.54-0.71). MR analysis suggested a possible link between GDF15 gene expression and sarcopenia traits, with no evidence of genetic confounding. Molecular docking indicated stable binding between metformin and GDF15.

CONCLUSION

This study suggests that metformin may lower sarcopenia risk, particularly in elderly patients with type 2 diabetes, with GDF15 identified as a promising target for sarcopenia treatment.

Metformin treatment reduces the incidence of osteoporosis: a two-sample Mendelian randomized study

It remains unclear whether the association between metformin and osteoporosis (OP) risk is causal. This two-sample Mendelian randomization (MR) study suggests a causal relationship between metformin treatment and a decrease in OP and fracture incidence, as well as an increase in bone mineral density (BMD) in the lumbar spine, femoral neck, and heel. Nonetheless, no significant causal effect is observed on forearm BMD.

PURPOSE

We utilize a MR approach to investigate the association between metformin treatment and the risk of OP.

METHODS

Metformin treatment was selected as exposures. Outcomes included OP; BMD at the forearm (FA), femoral neck (FN), and lumbar spine (LS); estimated heel bone mineral density (eBMD); and fracture. Summary statistics for exposures and outcomes were obtained from corresponding genome-wide association studies. Inverse variance-weighted (IVW) analysis was mainly applied; the weighted median (WM), penalized weighted median (PWM), maximum likelihood (ML), and MR-Egger regression (MR-Egger) method were also used to obtain robust estimates. A series of sensitivity analyses including Cochran's Q test, MR-Egger regression, leave-one-out analysis, and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) were used to detect pleiotropy or heterogeneity.

RESULTS

In the main analysis, IVW estimates demonstrated that metformin treatment had a definite causal effect on the risk of OP (odds ratio (OR): 0.859, 95% CI: 0.774-0.953, P = 0.004), LS-BMD (OR: 1.063, 95% CI: 1.023-1.105, P = 0.002), FN-BMD (OR: 1.034, 95% CI: 1.000-1.069, P = 0.049), eBMD (OR: 1.035, 95% CI: 1.023-1.047, P ≤ 0.001), and fracture(OR: 0.958, 95% CI: 0.928-0.989, P = 0.008). However, it did not have an effect on FA-BMD(OR: 1.050, 95% CI: 0.969-1.138, P = 0.237).

CONCLUSIONS

This study indicated that metformin treatment is significantly associated with a reduction in the risk of OP, fracture and higher LS-BMD, FN-BMD, and eBMD. However, there was no significant association with FA-BMD.

The bone-protective benefits of kaempferol combined with metformin by regulation of osteogenesis-angiogenesis coupling in OVX rats

This study was to investigate the potential mechanisms of treatment with metformin (Met) combined with kaempferol (Kae) against postmenopausal osteoporosis. Experiments were conducted in both ovariectomy (OVX)-induced osteoporosis rats and in vitro using RAW264.7 cells, MC3T3-E1 cells, and HUVECs. Results demonstrated the therapeutic effect of Met combined with Kae on osteoporosis. In vivo, Kae alone and in combination with Met treatments enhanced tibial trabecular microstructure, bone mineral density (BMD), and mechanical properties in OVX rats without causing hepatotoxicity and nephrotoxicity. It also reduced bone resorption markers (CTX-1 and TRAP) and increased the bone formation marker (PINP) level in the serum of OVX rats. The expression of bone resorption marker TRAP was reduced, while bone formation markers Runx2 and ALP were enhanced in the bone tissue of OVX rats. Furthermore, Met combined with Kae also promoted the expression of angiogenesis-related markers CD31 and VEGF in OVX rats. In vitro, MC3T3-E1s cells treated with Met combined with Kae showed higher expression of ALP, Runx2, and VEGF. Interestingly, the treatment did not directly promote HUVECs migration and angiogenesis, but enhanced osteoblast-mediated angiogenesis by upregulating VEGF levels. Additionally, Met combined with Kae treatment promoted VEGF secretion in MC3T3-E1, and activated the Notch intracelluar pathway by upregulating HES1 and HEY1 in HUVECs. Meantime, their stimulation on CD31 expression were inhibited by DAPT, a Notch signaling inhibitor. Overall, this study demonstrates the positive effects of Met combined with Kae on osteoporotic rats by promoting osteogenesis-angiogenesis coupling, suggesting their potential application in postmenopausal osteoporosis.

Renal, cardiovascular, and safety outcomes of adding sodium-glucose cotransporter-2 inhibitors to insulin therapy in patients with type-2 diabetes: a meta-analysis

AIMS

To investigate the renal, cardiovascular, and safety outcomes when sodium-glucose cotransporter-2 inhibitors (SGLT2is) were added to insulin therapy in patients with type-2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

We searched Embase, PubMed, and Cochrane libraries for reports published up to Feb 2023. Randomized controlled trials (RCTs) comparing SGLT2is and insulin combination therapy (SGLT2is + INS group) with insulin therapy alone (INS group) in T2DM were included.

RESULTS

Fourteen RCTs involving six thousand one hundred twenty subjects with durations of 12-104 weeks were included. Compared with the insulin group, the SGLT2is + INS group showed decreased glycosylated hemoglobin values and insulin dosages (P < 0.00001). Meanwhile, the SGLT2is + INS group had a reduced urinary albumin/creatinine ratio (UACR) by 25.42 mg/g and uric acid concentration (P = 0.030; P = 0.001, respectively) but the estimated glomerular filtration rate (eGFR) and renal-related adverse events were unaffected (P = 0.070; P = 0.880, respectively). Blood pressure and body weight were lower in the SGLT2is + INS group (P < 0.01). However, the risk of genital infection was bigger when SGLT2is were added to insulin therapy (P < 0.00001), but the risks of severe hypoglycemia or urinary tract infection were equal between the two groups (P > 0.05).

CONCLUSION

Adding SGLT2is to insulin therapy in T2DM patients showed better glucose control and decreased albuminuria, uric acid, blood pressure, and body weight without a reduction in the eGFR.

Effects of metformin on bone mineral density and bone turnover markers: a systematic review and meta-analysis

OBJECTIVES

Metformin is associated with osteoblastogenesis and osteoclastogenesis. This study aims to investigate the impacts of metformin therapy on bone mineral density (BMD) and bone turnover markers.

DESIGN

Systematic review and meta-analysis of randomised controlled trials.

METHODS

Searches were carried out in PubMed, EMBASE, Web of science, Cochrane library, ClinicalTrials.gov from database inception to 26 September 2022. Two review authors assessed trial eligibility in accordance with established inclusion criteria. The risk of bias was assessed using the Cochrane Risk of Bias tool (RoB V.2.0). Data analysis was conducted with Stata Statistical Software V.16.0 and Review Manager Software V.5.3.

RESULTS

A total of 15 studies with 3394 participants were identified for the present meta-analysis. Our pooled results indicated that metformin had no statistically significant effects on BMD at lumbar spine (SMD=-0.05, 95% CI=-0.19 to 0.09, p=0.47, participants=810; studies=7), at femoral (MD=-0.01 g/cm2, 95% CI=-0.04 to 0.01 g/cm2, p=0.25, participants=601; studies=3) and at hip (MD=0.01 g/cm2, 95% CI=-0.02 to 0.03 g/cm2, p=0.56, participants=634; studies=4). Metformin did not lead to significant change in osteocalcin, osteoprotegerin and bone alkaline phosphatase. Metformin induced decreases in N-terminal propeptide of type I procollagen (MD=-6.09 µg/L, 95% CI=-9.38 to -2.81 µg/L, p=0.0003, participants=2316; studies=7) and C-terminal telopeptide of type I collagen (MD=-55.80 ng/L, 95% CI=-97.33 to -14.26 ng/L, p=0.008, participants=2325; studies=7).

CONCLUSION

This meta-analysis indicated that metformin had no significant effect on BMD. Metformin decreased some bone turnover markers as N-terminal propeptide of type I procollagen and C-terminal telopeptide of type I collagen. But the outcomes should be interpreted with caution due to several limitations.

Metformin treatment is associated with an increase in bone mineral density in type 2 diabetes mellitus patients in China: a retrospective single center study

AIMS

- To investigate the association between metformin and bone mineral density (BMD) in a large cohort of Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

- A total of 11,458 T2DM patients aged ≥ 40 years were included. Information on demographic, anthropometric and clinical characteristics was collected from medical records. BMD at lumbar spine (LS), femoral neck (FN), and total hip(TH) was assessed by dual-energy X-ray absorptiometry.

RESULTS

- Overall prevalence of osteopenia and osteoporosis was 37.4% and 10.3%, and was lower in patients on metformin (34.6% vs 38.3% and 7.1% vs 11.3%, both P < 0.001). Patients who had a lower BMI, older age, and lower estimated glomerular filtration rate (eGFR), had more osteoporosis, lower BMD (osteoporosis or osteopenia), and a lower T-score at LS, FN and TH. Metformin use and male sex was associated with a higher BMD. Metformin treatment was also independently associated with higher T-score at LS, FN and TH (β values of 0.120, 0.082 and 0.108; all P < 0.001), and lower odds ratio of osteoporosis (OR = 0.779, 95%CI: 0.648-0.937, P = 0.008) or low BMD (OR = 0.834, 95%CI: 0.752 - 0.925, P = 0.001). However, when analyzed by sex, this association of a lower odds ratio for osteoporosis with metformin was only significant in women (OR= 0.775, 95% CI: 0.633-0.948; P = 0.013).

CONCLUSIONS

- Metformin treatment was associated with a higher T-score and a lower odds ratio of osteopenia and osteoporosis, especially in the female population, independent of age, BMI, and eGFR.

The Function of Metformin in Aging-Related Musculoskeletal Disorders

Metformin is a widely accepted first-line hypoglycemic agent in current clinical practice, and it has been applied to the clinic for more than 60 years. Recently, researchers have identified that metformin not only has an efficient capacity to lower glucose but also exerts anti-aging effects by regulating intracellular signaling molecules. With the accelerating aging process and mankind’s desire for a long and healthy life, studies on aging have witnessed an unprecedented boom. Osteoporosis, sarcopenia, degenerative osteoarthropathy, and frailty are age-related diseases of the musculoskeletal system. The decline in motor function is a problem that many elderly people have to face, and in serious cases, they may even fail to self-care, and their quality of life will be seriously reduced. Therefore, exploring potential treatments to effectively prevent or delay the progression of aging-related diseases is essential to promote healthy aging. In this review, we first briefly describe the origin of metformin and the aging of the movement system, and next review the evidence associated with its ability to extend lifespan. Furthermore, we discuss the mechanisms related to the modulation of aging in the musculoskeletal system by metformin, mainly its contribution to bone homeostasis, muscle aging, and joint degeneration. Finally, we analyze the protective benefits of metformin in aging-related diseases of the musculoskeletal system.

Metformin for Cardiovascular Protection, Inflammatory Bowel Disease, Osteoporosis, Periodontitis, Polycystic Ovarian Syndrome, Neurodegeneration, Cancer, Inflammation and Senescence: What Is Next?

Diabetes is accompanied by several complications. Higher prevalence of cancers, cardiovascular diseases, chronic kidney disease (CKD), obesity, osteoporosis, and neurodegenerative diseases has been reported among patients with diabetes. Metformin is the oldest oral antidiabetic drug and can improve coexisting complications of diabetes. Clinical trials and observational studies uncovered that metformin can remarkably prevent or alleviate cardiovascular diseases, obesity, polycystic ovarian syndrome (PCOS), osteoporosis, cancer, periodontitis, neuronal damage and neurodegenerative diseases, inflammation, inflammatory bowel disease (IBD), tuberculosis, and COVID-19. In addition, metformin has been proposed as an antiaging agent. Numerous mechanisms were shown to be involved in the protective effects of metformin. Metformin activates the LKB1/AMPK pathway to interact with several intracellular signaling pathways and molecular mechanisms. The drug modifies the biologic function of NF-κB, PI3K/AKT/mTOR, SIRT1/PGC-1α, NLRP3, ERK, P38 MAPK, Wnt/β-catenin, Nrf2, JNK, and other major molecules in the intracellular signaling network. It also regulates the expression of noncoding RNAs. Thereby, metformin can regulate metabolism, growth, proliferation, inflammation, tumorigenesis, and senescence. Additionally, metformin modulates immune response, autophagy, mitophagy, endoplasmic reticulum (ER) stress, and apoptosis and exerts epigenetic effects. Furthermore, metformin protects against oxidative stress and genomic instability, preserves telomere length, and prevents stem cell exhaustion. In this review, the protective effects of metformin on each disease will be discussed using the results of recent meta-analyses, clinical trials, and observational studies. Thereafter, it will be meticulously explained how metformin reprograms intracellular signaling pathways and alters molecular and cellular interactions to modify the clinical presentations of several diseases.