Long-term effects of lifestyle and metformin interventions in DPP on bone density

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.

Metformin treatment prevents experimental metabolic syndrome-induced femoral bone marrow adiposity in rats

OBJECTIVE.

Motivation for the study. Most research supports a negative association between metabolic syndrome and bone health, although there is an overall lack of consensus. Therefore, there is a need for research in this area to develop a better understanding. Main findings. Metabolic syndrome induced by a fructose-rich diet increases the adipogenic predisposition of bone marrow progenitor cells and femoral medullary adiposity in rats. Furthermore, this can be partially prevented by co-treatment with metformin. Implications. Experimental metabolic syndrome has negative effects on bone tissue and can be prevented by oral treatment with metformin as a normoglycemic drug. To determine the effect of metformin (MET) treatment on adipogenic predisposition of bone marrow progenitor cells (BMPC), bone marrow adiposity and bone biomechanical properties.

MATERIALS AND METHODS.

20 young adult male Wistar rats were sorted into four groups. Each of the groups received the following in drinking water: 100% water (C); 20% fructose (F); metformin 100 mg/kg wt/day (M); or fructose plus metformin (FM). After five weeks the animals were sacrificed. Both humeri were dissected to obtain BMPC, and both femurs were dissected to evaluate medullary adiposity (histomorphometry) and biomechanical properties (3-point bending). BMPC were cultured in vitro in adipogenic medium to evaluate RUNX2, PPAR-γ and RAGE expression by RT-PCR, lipase activity and triglyceride accumulation.

RESULTS.

The fructose-rich diet (group F) caused an increase in both triglycerides in vitro, and medullary adiposity in vivo; being partially or totally prevented by co-treatment with metformin (group FM). No differences were found in femoral biomechanical tests in vivo, nor in lipase activity and RUNX2/PPAR-γ ratio in vitro. DRF increased RAGE expression in BMPC, being prevented by co-treatment with MET.

CONCLUSIONS.

Metabolic syndrome induced by a fructose-rich diet increases femoral medullary adiposity and, in part, the adipogenic predisposition of BMPC. In turn, this can be totally or partially prevented by oral co-treatment with MET.

View on Metformin: Antidiabetic and Pleiotropic Effects, Pharmacokinetics, Side Effects, and Sex-Related Differences

Metformin is a synthetic biguanide used as an antidiabetic drug in type 2 diabetes mellitus, achieved by studying the bioactive metabolites of Galega officinalis L. It is also used off-label for various other diseases, such as subclinical diabetes, obesity, polycystic ovary syndrome, etc. In addition, metformin is proposed as an add-on therapy for several conditions, including autoimmune diseases, neurodegenerative diseases, and cancer. Although metformin has been used for many decades, it is still the subject of many pharmacodynamic and pharmacokinetic studies in light of its extensive use. Metformin acts at the mitochondrial level by inhibiting the respiratory chain, thus increasing the AMP/ATP ratio and, subsequently, activating the AMP-activated protein kinase. However, several other mechanisms have been proposed, including binding to presenilin enhancer 2, increasing GLP1 release, and modification of microRNA expression. Regarding its pharmacokinetics, after oral administration, metformin is absorbed, distributed, and eliminated, mainly through the renal route, using transporters for cationic solutes, since it exists as an ionic molecule at physiological pH. In this review, particular consideration has been paid to literature data from the last 10 years, deepening the study of clinical trials inherent to new uses of metformin, the differences in effectiveness and safety observed between the sexes, and the unwanted side effects. For this last objective, metformin safety was also evaluated using both VigiBase and EudraVigilance, respectively, the WHO and European databases of the reported adverse drug reactions, to assess the extent of metformin side effects in real-life use.

Antidiabetic drug administration prevents bone mineral density loss: Evidence from a two-sample Mendelian randomization study

The aim of this study was to investigate the effect of common antidiabetic drugs on BMD by two-sample Mendelian randomization (MR). The single nucleotide polymorphisms that were strongly associated with insulin, metformin, rosiglitazone and gliclazide were extracted as instrumental variables (IVs) for MR analysis. The inverse variance weighted (IVW) method was used as the primary MR method to assess the causal effect of antidiabetic drugs on BMD, and other MR methods, including Weighted median, MR Egger and Weighted mode, were used for complementary analysis. Reliability and stability were assessed by the leave-one-out test. In the present work, IVW estimation of the causal effect of insulin on heel BMD demonstrated that there was a null effect of insulin on heel BMD (β = 0.765; se = 0.971; P = 0.430), while metformin treatment had a positive effect on heel BMD (β = 1.414; se = 0.460; P = 2.118*10-3). The causal relationship between rosiglitazone and heel BMD analysed by IVW suggested that there was a null effect of rosiglitazone on heel BMD (β = -0.526; se = 1.744; P = 0.763), but the causal effect of gliclazide on heel BMD evaluated by IVW demonstrated that there was a positive effect of gliclazide on heel BMD (β = 2.671; se = 1.340; P = 0.046). In summary, the present work showed that metformin and gliclazide have a role in reducing BMD loss in patients with diabetes and are recommended for BMD loss prevention in diabetes.

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.

Insulin resistance and skeletal health

PURPOSE OF REVIEW

Bone fragility is a complication of type 2 diabetes (T2D), and insulin resistance is suspected to contribute to diabetes-related bone deficits. This article provides an overview of emerging clinical research involving insulin resistance and bone health by summarizing recent publications, identifying existing knowledge gaps, and suggesting 'next steps' for this evolving field of research.

RECENT FINDINGS

Clinical studies in children and adults report greater bone density in people with increased insulin resistance, but these associations are often attenuated when adjusting for body size. Advancements in bone imaging methods allow for assessment of nuanced characteristics of bone quality and strength that extend beyond standard bone mineral density assessment methods. For example, several recent studies focusing on lumbar spine trabecular bone score, a relatively new measure of trabecular bone quality from dual-energy X-ray absorptiometry, have reported generally consistent inverse associations with insulin resistance. Longitudinal studies using advanced imaging methods capable of evaluating trabecular bone microstructure and strength, such as high-resolution peripheral quantitative computed tomography, are lacking. Studies in younger individuals are sparse, but emerging data suggest that peak bone mass attainment might be threatened by diabetes progression, and increased visceral fat, suppressed muscle-bone unit, advanced glycation end-products, sedentary lifestyle, and poor diet quality might contribute to diabetes effects on bone. Prospective studies during the transition from adolescence to young adulthood are required.

SUMMARY

Insulin resistance is a main feature of T2D, which is suspected to contribute to subclinical diabetes-related threats to bone health. Future clinical studies should focus on the critical years surrounding peak bone mass and peak bone strength attainment using contemporary imaging techniques.

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.

Association of metformin use with fracture risk in type 2 diabetes: A systematic review and meta-analysis of observational studies

AIMS

Increasing evidence suggests that metformin can affect bone metabolism beyond its hypoglycemic effects in diabetic patients. However, the effects of metformin on fracture risk in type 2 diabetes mellitus (T2DM) patients remain unclear. A systematic review and meta-analysis were performed in this study to evaluate the association between metformin application and fracture risk in T2DM patients based on previous studies published until June 2021.

METHODS

A systematic search was performed to collect publications on metformin application in T2DM patients based on PubMed, Embase, Cochran, and Web of Science databases. Meta-analysis was performed by using a random-effects model to estimate the summary relative risks (RRs) with 95% confidence intervals (CIs). Subgroup analyses based on cohort/case-control and ethnicity and sensitivity analyses were also performed.

RESULTS

Eleven studies were included in the meta-analysis. Results demonstrated metformin use was not significantly associated with a decreased risk of fracture (RR, 0.91; 95% CI, 0.81-1.02; I^{2 =} 96.8%). Moreover, metformin use also demonstrated similar results in subgroup analyses of seven cohort studies and four case-control studies, respectively (RR, 0.90; 95% CI, 0.76-1.07; I^{2 =} 98.0%; RR, 0.96; 96% CI, 0.89-1.03; I^{2 =} 53.7%). Sensitivity analysis revealed that there was no publication bias.

CONCLUSION

There was no significant correlation between fracture risk and metformin application in T2DM patients. Due to a limited number of existing studies, further research is needed to make a definite conclusion for clinical consensus.