Metformin use and risk of fracture: a systematic review and meta-analysis of observational studies

Bone Loss in Diabetes Mellitus: Diaporosis

The objective of this review is to examine the connection between osteoporosis and diabetes, compare the underlying causes of osteoporosis in various forms of diabetes, and suggest optimal methods for diagnosing and assessing fracture risk in diabetic patients. This narrative review discusses the key factors contributing to the heightened risk of fractures in individuals with diabetes, as well as the shared elements impacting the treatment of both diabetes mellitus and osteoporosis. Understanding the close link between diabetes and a heightened risk of fractures is crucial in effectively managing both conditions. There are several review articles of meta-analysis regarding diaporosis. Nevertheless, no review articles showed collected and well-organized medications of antidiabetics and made for inconvenient reading for those who were interested in details of drug mechanisms. In this article, we presented collected and comprehensive charts of every antidiabetic medication which was linked to fracture risk and indicated plausible descriptions according to research articles.

The paradox of bone mineral density and fracture risk in type 2 diabetes

Fracture risk in type 2 diabetes (T2D) patients is paradoxically increased despite no decrease in areal bone mineral density (BMD). This phenomenon, known as the "diabetic bone paradox", has been attributed to various factors including alterations in bone microarchitecture and composition, hyperinsulinemia and hyperglycemia, advanced glycation end products (AGEs), and comorbidities associated with T2D. Zhao et al. recently investigated the relationship between T2D and fracture risk using both genetic and phenotypic datasets. Their findings suggest that genetically predicted T2D is associated with higher BMD and lower fracture risk, indicating that the bone paradox is not observed when confounding factors are controlled using Mendelian randomization (MR) analysis. However, in prospective phenotypic analysis, T2D remained associated with higher BMD and higher fracture risk, even after adjusting for confounding factors. Stratified analysis revealed that the bone paradox may disappear when T2D-related risk factors are eliminated. The study also highlighted the role of obesity in the relationship between T2D and fracture risk, with BMI mediating a significant portion of the protective effect. Overall, managing T2D-related risk factors may be crucial in preventing fracture risk in T2D patients.

Potential Metabolic Pathways Involved in Osteoporosis and Evaluation of Fracture Risk in Individuals with Diabetes

Diabetes has a significant global prevalence. Chronic hyperglycemia affects multiple organs and tissues, including bones. A large number of diabetic patients develop osteoporosis; however, the precise relationship between diabetes and osteoporosis remains incompletely elucidated. The activation of the AGE-RAGE signaling pathway hinders the differentiation of osteoblasts and weakens the process of bone formation due to the presence of advanced glycation end products. High glucose environment can induce ferroptosis of osteoblasts and then develop osteoporosis. Hyperglycemia also suppresses the secretion of sex hormones, and the reduction of testosterone is difficult to effectively maintain bone mineral density. As diabetes therapy, thiazolidinediones control blood glucose by activating PPAR-γ. Activated PPAR-γ can promote osteoclast differentiation and regulate osteoblast function, triggering osteoporosis. The effects of metformin and insulin on bone are currently controversial. Currently, there are no appropriate tools available for assessing the risk of fractures in diabetic patients, despite the fact that the occurrence of osteoporotic fractures is considerably greater in diabetic individuals compared to those without diabetes. Further improving the inclusion criteria of FRAX risk factors and clarifying the early occurrence of osteoporosis sites unique to diabetic patients may be an effective way to diagnose and treat diabetic osteoporosis and reduce the risk of fracture occurrence.

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.

Association between obesity and age-related cataract: an updated systematic review and dose-response meta-analysis of prospective cohort studies

Objective

There are inconsistent findings on the association between obesity and age-related cataract (ARC). This systematic review was done to summarize available findings on the association between obesity [defined by body mass index (BMI)] and ARC by performing a dose-response meta-analysis on eligible prospective cohort studies.

Methods

We performed a systematic search in PubMed, Scopus, ISI Web of Knowledge, and Google Scholar until June 2022 to identify eligible publications.

Results

In total, 16 studies with a total sample size of 1,607,125 participants were included. Among all of these studies, there were 103,897 cases of ARC. In the follow-up periods ranging between 4 and 28 years, 4,870 cases of nuclear cataract, 1,611 cases of cortical cataract, and 1,603 cases of posterior subcapsular cataracts (PSC) were detected. By comparing the highest and lowest categories of BMI, we found that higher BMI was associated with an increased risk of ARC (RR: 1.18, 95% CI: 1.09-1.28) and PSC (RR: 1.44, 95% CI: 1.08-1.90). In the dose-response analysis, each 5 kg/m2 increase in BMI was associated with a 6 and 27% increased risk of ARC (RR: 1.06, 95% CI: 1.01-1.12) and PSC (RR: 1.27, 95% CI: 1.14-1.41), respectively. In addition, we found a positive association for cortical cataract among high-quality studies, in which higher BMI was associated with a 20% increased risk of cortical cataract (RR: 1.20, 95% CI: 1.02-1.42). In terms of nuclear cataract, we found no significant association either in the comparison between the highest and lowest categories of BMI or in the dose-response meta-analysis.

Conclusion

Obesity (defined by BMI) was associated with an increased risk of ARC, PSC, and cortical cataract in adults. However, such a positive association was not seen for nuclear cataract.

PROSPERO registration

CRD42022357132.

Metformin accelerates bone fracture healing by promoting type H vessel formation through inhibition of YAP1/TAZ expression

Due to increasing morbidity worldwide, fractures are becoming an emerging public health concern. This study aimed to investigate the effect of metformin on the healing of osteoporotic as well as normal fractures. Type H vessels have recently been identified as a bone-specific vascular subtype that supports osteogenesis. Here, we show that metformin accelerated fracture healing in both osteoporotic and normal mice. Moreover, metformin promoted angiogenesis in vitro under hypoxia as well as type H vessel formation throughout fracture healing. Mechanistically, metformin increased the expression of HIF-1α, an important positive regulator of type H vessel formation, by inhibiting the expression of YAP1/TAZ in calluses and hypoxia-cultured human microvascular endothelial cells (HMECs). The results of HIF-1α or YAP1/TAZ interference in hypoxia-cultured HMECs using siRNA further suggested that the enhancement of HIF-1α and its target genes by metformin is primarily through YAP1/TAZ inhibition. Finally, overexpression of YAP1/TAZ partially counteracted the effect of metformin in promoting type H vessel-induced angiogenesis-osteogenesis coupling during fracture repair. In summary, our findings suggest that metformin has the potential to be a therapeutic agent for fractures by promoting type H vessel formation through YAP1/TAZ inhibition.

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.

The use of metformin, sulfonylurea compounds and insulin and the risk of hip fractures in diabetic patients: a systematic review and meta-analysis of observational studies

BACKGROUND

Hip fracture is a major health problem that occurs more often in the elderly, especially in diabetic patients. Some studies have been conducted regarding the effect of anti- diabetic drugs on fractures. But so far, no meta-analysis study has been conducted to investigate the effect of diabetic drugs on hip fractures. Therefore, this study investigated the relationship between anti-diabetic drugs (Metformin, Sulfonylurea, and insulin) with hip fractures.

METHODS

In this systematic review and meta analysis study, PubMed, Scopus, Google Scholar, and Web of Science databases were searched with specific keywords to find relevant studies. Two researchers included related studies after screening based on the title and full text. Cochran's Q and I2 tests were used to assess heterogeneity between studies. Publication bias between studies was evaluated for each drug using Egger's test. A 95% confidence interval was used for effect size significance. Overall, 49 studies, including 6,631,297 participants, were reviewed.

RESULTS

The results showed that metformin significantly reduced the risk of hip fracture (HR: 0.833, 95% CI: 0.759, 0.914, P:0.001). Consumption of sulfonylurea compounds was significantly associated with an increased risk of hip fracture. (HR: 1.175, 95% CI:1.068,1.293, P:0.001), The risk of hip fracture in patients receiving insulin was significantly higher than in diabetic patients who did not receive insulin. (HR:1.366, 95% CI:1.226,1.522, P:0.001).

CONCLUSION

The results of this study showed that taking metformin reduces the risk of hip fracture, and insulin and Sulfonylurea increase the risk of hip fracture.

Comparison of the Effects of Metformin and Thiazolidinediones on Bone Metabolism: A Systematic Review and Meta-Analysis

OBJECTIVES

Studies have shown that people with diabetes have a high risk of osteoporosis and fractures. The effect of diabetic medications on bone disease cannot be ignored. This meta-analysis aimed to compare the effects of two types of glucose-lowering drugs, metformin and thiazolidinediones (TZD), on bone mineral density and bone metabolism in patients with diabetes mellitus.

METHODS

This systematic review and meta-analysis were prospectively registered on PROSPERO, and the registration number is CRD42022320884. Embase, PubMed, and Cochrane Library databases were searched to identify clinical trials comparing the effects of metformin and thiazolidinediones on bone metabolism in patients with diabetes. The literature was screened by inclusion and exclusion criteria. Two assessors independently assessed the quality of the identified studies and extracted relevant data.

RESULTS

Seven studies involving 1656 patients were finally included. Our results showed that the metformin group had a 2.77% (SMD = 2.77, 95%CI [2.11, 3.43]; p < 0.00001) higher bone mineral density (BMD) than the thiazolidinedione group until 52 weeks; however, between 52 and 76 weeks, the metformin group had a 0.83% (SMD = -0.83, 95%CI: [-3.56, -0.45]; p = 0.01) lower BMD. The C-terminal telopeptide of type I collagen (CTX) and procollagen type I N-terminal propeptide (PINP) were decreased by 18.46% (MD = -18.46, 95%CI: [-27.98, -8.94], p = 0.0001) and 9.94% (MD = -9.94, 95%CI: [-16.92, -2.96], p = 0.005) in the metformin group compared with the TZD group.

Impact of sodium-glucose cotransporter-2 inhibitors on the risk of hip fracture in older patients in Japan using a nationwide administrative claims database: A matched case-control study

AIM

Some clinical trials have shown that sodium-glucose cotransporter-2 (SGLT2) inhibitors are associated with fracture risk. However, this notion remains controversial. This study aimed to evaluate hip fracture risk after the use of SGLT2 inhibitors while controlling for factors that may affect fracture risk. Furthermore, hip fracture risk is evaluated in relation to the SGLT2 inhibitors component and its concomitant use with other antidiabetic agents.

METHODS

Using large-scale real-world data, this case-control study investigated hospitalized patients between January 2018 and December 2020. Patients were aged 65-89 years and had been prescribed with SGLT2 inhibitors at least twice. Patients with hip fracture (cases) and those without (controls) were identified via 1:3 matching according to sex, age (±3 years), hospital size classification, and number of concomitant antidiabetic agents. Exposure to SGLT2 inhibitors of the cases and controls was compared with the use of multivariate conditional logistic regression.

RESULTS

After matching, 396 cases and 1081 controls were identified. The adjusted odds ratio for patients receiving treatment with SGLT2 inhibitors was 0.83 (95% confidence interval: 0.55-1.26), indicating no increase in hip fracture risk. Additionally, no increased risk was observed with respect to SGLT2 inhibitors by component or concomitant use with other antidiabetic agents.

CONCLUSION

Our study showed that SGLT2 inhibitors do not increase hip fractures in older patients. However, because the risk assessment of SGLT2 inhibitors by component and their concomitant use with other antidiabetic agents is based on a limited number of patients, it is important to interpret the results with caution. Geriatr Gerontol Int 2023; ••: ••-••.

The Role of Bone Cell Energetics in Altering Bone Quality and Strength in Health and Disease

PURPOSE OF REVIEW

Bone quality and strength are diminished with age and disease but can be improved by clinical intervention. Energetic pathways are essential for cellular function and drive osteogenic signaling within bone cells. Altered bone quality is associated with changes in the energetic activity of bone cells following diet-based or therapeutic interventions. Energetic pathways may directly or indirectly contribute to changes in bone quality. The goal of this review is to highlight tissue-level and bioenergetic changes in bone health and disease.

RECENT FINDINGS

Bone cell energetics are an expanding field of research. Early literature primarily focused on defining energetic activation throughout the lifespan of bone cells. Recent studies have begun to connect bone energetic activity to health and disease. In this review, we highlight bone cell energetic demands, the effect of substrate availability on bone quality, altered bioenergetics associated with disease treatment and development, and additional biological factors influencing bone cell energetics. Bone cells use several energetic pathways during differentiation and maturity. The orchestration of bioenergetic pathways is critical for healthy cell function. Systemic changes in substrate availability alter bone quality, potentially due to the direct effects of altered bone cell bioenergetic activity. Bone cell bioenergetics may also contribute directly to the development and treatment of skeletal diseases. Understanding the role of energetic pathways in the cellular response to disease will improve patient treatment.

Hip and vertebral fracture risk after initiating antidiabetic drugs in Japanese elderly: a nationwide study

INTRODUCTION

We aimed to clarify the risks of initiating antidiabetic drugs for fractures using a nationwide health insurance claims database (NDBJ).

MATERIALS AND METHODS

Patients aged ≥ 65 years initiating antidiabetic drugs at the outpatient department were enrolled after a 180-day period without prescribed antidiabetic drugs and followed with during 2012-2018 using NDBJ. The adjusted hazard risks (HRs) of each antidiabetic drug (thiazolidine, alpha-glucosidase inhibitor, dipeptidyl peptidase-4 [DPP-4] inhibitor, sulfonylurea, glinide, and insulin) for fractures compared with biguanide were obtained adjusting for age, gender, polypharmacy, dementia, and the other antidiabetic drugs.

RESULTS

The DPP-4 inhibitor was the most often prescribed antidiabetic drug followed by biguanide with prescribed proportions of 71.7% and 12.9%. A total of 4,304 hip fractures and 9,388 vertebral fractures were identified among the 966,700 outpatient participants. Compared with biguanide, insulin, alpha-glucosidase inhibitor, and DPP-4 inhibitor were related to increased hip fracture risks. Vertebral fracture risk was higher in outpatients prescribed with insulin, thiazolidine, and DPP-4 inhibitor compared with biguanide. Patients prescribed insulin for hip and vertebral fractures' adjusted HRs were 2.17 (95% CI 1.77-2.66) and 1.45 (95% CI 1.24-1.70), respectively. Those prescribed DPP-4 inhibitor for hip and vertebral fractures' adjusted HRs were 1.27 (95% CI 1.15-1.40) and 1.20 (95% CI 1.12-1.28), respectively.

CONCLUSIONS

Initiating insulin increased the risk of not only hip fractures but also vertebral fractures. Patients initiating antidiabetic drugs had increased risks of hip and vertebral fractures compared with those initiating biguanide independently for age, gender, polypharmacy, and dementia in the Japanese elderly.

Risk of fracture caused by anti-diabetic drugs in individuals with type 2 diabetes: A network meta-analysis

AIMS

Diabetes is associated with increased risk of fracture. This study aims to evaluate the correlation between anti-diabetic agents and fracture risk in patients with type 2 diabetes.

METHODS

Literature research was conducted using PubMed, Embase, and ClinicalTrials.gov. Search-term included "type 2 diabetes," "fracture," "randomized controlled trial," and seven kinds of anti-diabetic agents. Random-effect models established fractures in the follow-up period as the primary outcome. A network meta-analysis was performed to compare available treatments within a single Bayesian analytical framework.

RESULTS

A total of 191,361 patients were included in 161 studies, with 2916 fractures. DPP-4i (risk ratio [RR] 1.76 [95 % confidence interval (CI) 1.21-2.55]), SGLT-2i (RR 1.5 [95 % CI 1.05-2.16]) and placebo (RR 1.44 [95 % CI 1.04-1.98]) increased fracture risk when compared to GLP1-RA. GLP1-RA (RR 0.5 [95 % CI 0.31-0.79]) and SU (RR 0.56 [95 % CI 0.41-0.77]) provided greater protection against fracture than TZD. DPP-4i increased fracture risk when compared to SU (RR 1.55 [95 % CI 1.08-2.22]), and was comparable in effect to TZD.

CONCLUSIONS

GLP1-RA offered better protection against fracture than placebo. Insulin and SU had effects comparable with GLP1-RA. SU offered greater protection against fractures than TZD and DPP-4i. SGLT-2i increased risk of fracture when compared to GLP1-RA.

Unfavorable effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on the skeletal system of nondiabetic rats

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new class of antidiabetic drugs, acting by inhibiting the reabsorption of glucose in the kidneys. They turned out to improve cardiovascular and renal outcomes not only in patients with type 2 diabetes but also in nondiabetic patients. At present, they are more and more widely used in patients without diabetes. Since there were concerns that SGLT2 inhibitors may increase fracture risk in diabetes, the aim of the study was to examine the effect of dapagliflozin and canagliflozin on the musculoskeletal system of nondiabetic, healthy rats. The experiments were carried out on mature female rats, divided into the control rats and rats treated with dapagliflozin (1.4 mg/kg p.o.) or canagliflozin (4.2 mg/kg p.o.) for 4 weeks. Serum bone turnover markers, skeletal muscle strength and mass, bone mass, density, histomorphometric parameters and mechanical properties were determined. Administration of the drugs did not affect the skeletal muscle mass and strength. There was no effect on serum bone turnover markers, and bone mass and composition. However, administration of both drugs resulted in disorders of cancellous bone microarchitecture and worsening of bone mechanical properties. In conclusion, both SGLT2 inhibitors unfavorably affected the skeletal system of healthy rats.

Treatment of Diabetes and Osteoporosis—A Reciprocal Risk?

Diabetes mellitus is a metabolic and systematic disorder that requires individualized therapy. The disease leads to various consequences, resulting in the destruction of tissues and organs. The aforementioned outcomes also include bone mineral disorders, caused by medications as well as diet therapy and physical activity. Some drugs may have a beneficial effect on both bone mineral density and the risk of fractures. Nevertheless, the impact of other medications remains unknown. Focusing on pharmacotherapy in diabetes may prevent bone mineral disorders and influence both the treatment and quality of life in patients suffering from diabetes mellitus. On the other hand, anti-osteoporosis drugs, such as antiresorptive or anabolic drugs, as well as drugs with a mixed mechanism of action, may affect carbohydrate metabolism, particularly in patients with diabetes. Therefore, the treatment of diabetes as well as osteoporosis prevention are vital for this group of patients.

Bone marrow adiposity in diabetes and clinical interventions

PURPOSE OF REVIEW

This study aims to review bone marrow adipose tissue (BMAT) changes in people with diabetes, contributing factors, and interventions.

RECENT FINDINGS

In type 1 diabetes (T1D), BMAT levels are similar to healthy controls, although few studies have been performed. In type 2 diabetes (T2D), both BMAT content and composition appear altered, and recent bone histomorphometry data suggests increased BMAT is both through adipocyte hyperplasia and hypertrophy. Position emission tomography scanning suggests BMAT is a major source of basal glucose uptake. BMAT is responsive to metabolic interventions.

SUMMARY

BMAT is a unique fat depot that is influenced by metabolic factors and proposed to negatively affect the skeleton. BMAT alterations are more consistently seen in T2D compared to T1D. Interventions such as thiazolidinedione treatment may increase BMAT, whereas metformin treatment, weight loss, and exercise may decrease BMAT. Further understanding of the role of BMAT will provide insight into the pathogenesis of diabetic bone disease and could lead to targeted preventive and therapeutic strategies.

Risk of Fracture With Dipeptidyl Peptidase-4 Inhibitors, Glucagon-like Peptide-1 Receptor Agonists, or Sodium-Glucose Cotransporter-2 Inhibitors in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Network Meta-analysis Combining 177 Randomized Controlled Trials With a Median Follow-Up of 26 weeks

Aim: This study aims to investigate the association between the use of dipeptidyl peptidase-4 inhibitors (DPP-4i), glucagon-like peptide-1 receptor agonists (GLP-1 RAs), or sodium-glucose cotransporter-2 inhibitors (SGLT-2i) and the risk of fracture among patients with type 2 diabetes mellitus.

Methods: Medline, Embase, Cochrane Library, and Clinical-Trials.gov databases were searched for randomized controlled trials (RCTs). Network meta-analysis was performed for total fracture and a series of secondary outcomes.

Results: A total of 177 RCTs (n = 165,081) involving the risk of fracture were identified (a median follow-up of 26 weeks). DPP-4i, GLP-1 RAs, and SGLT-2i did not increase total fracture risk compared with insulin (odds ratio: 0.86, 95% confidence interval: 0.39–1.90; 1.05, 0.54–2.04; 0.88, and 0.39–1.97, respectively), metformin (1.41, 0.48–4.19; 1.72, 0.55–5.38; 1.44, 0.48–4.30), sulfonylureas (0.77, 0.50–1.20; 0.94, 0.55–1.62; 0.79, 0.48–1.31), thiazolidinediones (0.82, 0.27–2.44; 1.00, 0.32–3.10; 0.83, 0.27–2.57), α-glucosidase inhibitor (4.92, 0.23–103.83; 5.99, 0.28–130.37; 5.01, 0.23–107.48), and placebo (1.04, 0.84–1.29; 1.27, 0.88–1.83; 1.06, 0.81–1.39).

Conclusions: The use of DPP-4i, GLP-1 RAs, or SGLT-2i is unlikely to increase the risk of fracture among type 2 diabetes mellitus patients.

Mapping Knowledge Landscapes and Emerging Trends of the Links Between Bone Metabolism and Diabetes Mellitus: A Bibliometric Analysis From 2000 to 2021

Background

Diabetes mellitus (DM) have become seriously threatens to human health and life quality worldwide. As a systemic metabolic disease, multiple studies have revealed that DM is related to metabolic bone diseases and always induces higher risk of fracture. In view of this, the links between bone metabolism (BM) and DM (BMDM) have gained much attention and numerous related papers have been published. Nevertheless, no prior studies have yet been performed to analyze the field of BMDM research through bibliometric approach. To fill this knowledge gap, we performed a comprehensive bibliometric analysis of the global scientific publications in this field.

Methods

Articles and reviews regarding BMDM published between 2000 and 2021 were obtained from the Web of Science after manually screening. VOSviewer 1.6.16, CiteSpace V 5.8.R3, Bibliometrix, and two online analysis platforms were used to conduct the bibliometric and visualization analyses.

Results

A total of 2,525 documents including 2,255 articles and 270 reviews were retrieved. Our analysis demonstrated a steady increasing trend in the number of publications over the past 22 years (R2 = 0.989). The United States has occupied the leading position with the largest outputs and highest H-index. University of California San Francisco contributed the most publications, and Schwartz AV was the most influential author. Collaboration among institutions from different countries was relatively few. The journals that published the most BMDM-related papers were Bone and Osteoporosis International. Osteoporosis and related fractures are the main bone metabolic diseases of greatest concern in this field. According to co-cited references result, “high glucose environment,” “glycation end-product” and “sodium-glucose co-transporter” have been recognized as the current research focus in this domain. The keywords co-occurrence analysis indicated that “diabetic osteoporosis,” “osteoarthritis,” “fracture risk,” “meta-analysis,” “osteogenic differentiation,” “bone regeneration,” “osteogenesis,” and “trabecular bone score” might remain the research hotspots and frontiers in the near future.

Conclusion

As a cross-discipline research field, the links between bone metabolism and diabetes mellitus are attracting increased attention. Osteoporosis and related fractures are the main bone metabolic diseases of greatest concern in this field. These insights may be helpful for clinicians to recognize diabetic osteopenia and provide more attention and support to such patients.

Treat more than heat-New therapeutic implications of Cimicifuga racemosa through AMPK-dependent metabolic effects

BACKGROUND

Cimicifuga racemosa extracts (CRE) have obtained a "well-established use status" in the treatment of postmenopausal (i.e., climacteric) complaints, which predominantly include vasomotor symptoms such as hot flushes and sweating, as well as nervousness, irritability, and metabolic changes. Although characteristic postmenopausal complaints are known for a very long time and the beneficial effects of CRE on climacteric symptoms are well accepted, both the pathophysiology of postmenopausal symptoms and the mechanism of action of CREs are not yet fully understood. In particular, current hypotheses suggest that changes in the α-adrenergic and serotonergic signaling pathways secondary to estrogen depletion are responsible for the development of hot flushes.

PURPOSE

Some of the symptoms associated with menopause cannot be explained by these hypotheses. Therefore, we attempted to extend our classic understanding of menopause by integrating of partly age-related metabolic impairments.

METHODS

A comprehensive literature survey was performed using the PubMed database for articles published through September 2021. The following search terms were used: (cimicifuga OR AMPK) AND (hot flush* OR hot flash* OR menopaus* OR osteoporos* OR cancer OR antioxida* OR cardiovasc*). No limits were set with respect to language, and the references cited in the articles retrieved were used to identify additional publications.

RESULTS

We found that menopause is a manifestation of the general aging process, with specific metabolic changes that aggravate menopausal symptoms, which are accelerated by estrogen depletion and associated neurotransmitter dysregulation. Cimicifuga extracts with their metabolic effects mitigate climacteric symptoms but may also modulate the aging process itself. Central to these effects are effects of CRE on the metabolic key regulator, the AMP-activated protein kinase (AMPK).

CONCLUSIONS

As an extension of this effect dimension, other off-label indications may appear attractive in the sense of repurposing of this herbal treatment.

Targeting Sirt1, AMPK, Nrf2, CK2, and Soluble Guanylate Cyclase with Nutraceuticals: A Practical Strategy for Preserving Bone Mass

There is a vast pre-clinical literature suggesting that certain nutraceuticals have the potential to aid the preservation of bone mass in the context of estrogen withdrawal, glucocorticoid treatment, chronic inflammation, or aging. In an effort to bring some logical clarity to these findings, the signaling pathways regulating osteoblast, osteocyte, and osteoclast induction, activity, and survival are briefly reviewed in the present study. The focus is placed on the following factors: the mechanisms that induce and activate the RUNX2 transcription factor, a key driver of osteoblast differentiation and function; the promotion of autophagy and prevention of apoptosis in osteoblasts/osteoclasts; and the induction and activation of NFATc1, which promotes the expression of many proteins required for osteoclast-mediated osteolysis. This analysis suggests that the activation of sirtuin 1 (Sirt1), AMP-activated protein kinase (AMPK), the Nrf2 transcription factor, and soluble guanylate cyclase (sGC) can be expected to aid the maintenance of bone mass, whereas the inhibition of the serine kinase CK2 should also be protective in this regard. Fortuitously, nutraceuticals are available to address each of these targets. Sirt1 activation can be promoted with ferulic acid, N1-methylnicotinamide, melatonin, nicotinamide riboside, glucosamine, and thymoquinone. Berberine, such as the drug metformin, is a clinically useful activator of AMPK. Many agents, including lipoic acid, melatonin, thymoquinone, astaxanthin, and crucifera-derived sulforaphane, can promote Nrf2 activity. Pharmacological doses of biotin can directly stimulate sGC. Additionally, certain flavonols, notably quercetin, can inhibit CK2 in high nanomolar concentrations that may be clinically relevant. Many, though not all, of these agents have shown favorable effects on bone density and structure in rodent models of bone loss. Complex nutraceutical regimens providing a selection of these nutraceuticals in clinically meaningful doses may have an important potential for preserving bone health. Concurrent supplementation with taurine, N-acetylcysteine, vitamins D and K2, and minerals, including magnesium, zinc, and manganese, plus a diet naturally high in potassium, may also be helpful in this regard.

Unmasking Fracture Risk in Type 2 Diabetes: The Association of Longitudinal Glycemic Hemoglobin Level and Medications

CONTEXT

Fracture risk is underestimated in people with type 2 diabetes (T2D).

OBJECTIVE

To investigate the longitudinal relationship of glycated hemoglobin (HbA1c) and common medications on fracture risk in people with T2D.

METHODS

This retrospective population-based cohort study was conducted using de-identified claims and electronic health record data obtained from the OptumLabs Data Warehouse for the period January 1, 2007, to September 30, 2015. For each individual, the study was conducted within a 2-year HbA1c observation period and a 2-year fracture follow-up period. A cohort of 157 439 individuals with T2D [age ≥ 55 years with mean HbA1c value ≥ 6%] were selected from 4 018 250 US Medicare Advantage/Commercial enrollees with a T2D diagnosis. All fractures and fragility fractures were measured.

RESULTS

With covariates adjusted, poor glycemic control in T2D individuals was associated with an 29% increase of all fracture risk, compared with T2D individuals who had adequate glycemic control (HR: 1.29; 95% CI, 1.22-1.36). Treatment with metformin (HR: 0.88; 95% CI, 0.85-0.92) and DPP4 inhibitors (HR: 0.93; 95% CI, 0.88-0.98) was associated with a reduced all fracture risk, while insulin (HR: 1.26; 95% CI, 1.21-1.32), thiazolidinediones (HR: 1.23; 95% CI, 1.18-1.29), and meglitinides (HR: 1.12; 95% CI, 1.00-1.26) were associated with an increased all fracture risk (All P value < 0.05). Bisphosphonates were associated similarly with increased fracture risk in the T2D and nondiabetic groups.

CONCLUSION

Longitudinal 2-year HbA1c is independently associated with elevated all fracture risk in T2D individuals during a 2-year follow-up period. Metformin and DPP4 inhibitors can be used for management of T2D fracture risk.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

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.

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.

Observational study methods used to assess pharmacotherapy effects of type 2 diabetes on fracture risk: a scoping review protocol

OBJECTIVE

The objective of this review is to summarize observational research methods employed to study fracture risk and the use of type 2 diabetes mellitus medications. The methods summary will be used as a case study to illustrate current practices in the study of medication effects on fracture risk.

INTRODUCTION

Observational studies examining drug effects on fracture risk fill knowledge gaps left by clinical trials but require specific design considerations. In recent years, several pharmacoepidemiologic studies have examined fracture risk as a possible adverse effect of type 2 diabetes mellitus medications using varying methodologies; these studies can illustrate design considerations for studies of fracture risk.

INCLUSION CRITERIA

This scoping review will consider peer-reviewed observational studies that examine the effects of type 2 diabetes mellitus medications on fracture risk. Primary literature comprising empirical pharmacoepidemiologic studies, such as cohort, case-control, case-crossover, self-controlled, case series, and case-cohort designs, that evaluate fracture risk associated with at least one type 2 diabetes mellitus medication will be eligible. Studies without use of an administrative database and those with an experimental, cross-sectional, or time-series design will be excluded.

METHODS

This scoping review will follow JBI methodology for scoping reviews. MEDLINE (Ovid), Embase (Ovid), and CINAHL Plus with Full Text (EBSCO) will be searched from January 1, 2000 (to capture recent methodologies) to the present to identify eligible articles. After de-duplication, titles and abstracts will be screened independently by two reviewers, then full texts will be reviewed. Data on study methods will be extracted from eligible texts using a piloted form developed by the authors, and study methods will be aggregated in tabular format.

High body mass index and sleep problems during pregnancy: A meta-analysis and meta-regression of observational studies

Despite the well-established correlation of weight and sleeping problems, little is known about the nature of the association. The present study examined whether pregnant women with high body mass index have a risk of developing sleep problems, and identified any covariates that affect this relationship. We systematically searched electronic databases, specialized journals, various clinical trial registries, grey literature databases and the reference list of the identified studies. All observational studies were obtained from inception until 9 August 2020. The Newcastle-Ottawa Scale was adopted to assess the quality of studies. Stata software was used to conduct meta-analysis and meta-regression. Forty-six observational studies involving 2,240,804 participants across 16 countries were included. Quality assessment scores ranged from 4 to 10 (median = 6). Meta-analyses revealed that the risk of sleep apnea, habitual snoring, short sleep duration and poor sleep quality is increased in pregnant women with high body mass index, but not for daytime sleepiness, insomnia or restless legs syndrome. Subgroup differences were detected on body mass index between different regions, nature of population, year of publication, age group and study quality. Random-effects meta-regression analyses showed that year and quality of publication were covariates on the relationships between pre-pregnant body mass index and sleep apnea risk. Our review shows that sleep apnea, habitual snoring, short sleep duration and poor sleep quality are important concerns for pregnant women with high body mass index. Developing screening and targeted interventions is recommended to promote efficacious perinatal care.

Management of bone fragility in type 2 diabetes: Perspective from an interdisciplinary expert panel

AIM

Bone fragility is increasingly recognized as a relevant complication of type 2 diabetes (T2D) and diabetic patients with fragility fractures have higher mortality rates than non diabetic individuals or diabetic patients without fractures. However, current diagnostic approaches for fracture risk stratification, such as bone mineral density measurement or the use of risk assessment algorithms, largely underestimate fracture risk in T2D patients. A multidisciplinary expert panel was established in order to in order to formulate clinical consensus recommendations on bone health assessment and management of fracture risk in patients with T2D.

DATA SYNTHESIS

The following key questions were addressed: a) which are the risk factors for bone fragility in T2D?, b) which diagnostic procedures can be currently used to stratify fracture risk in T2D patients?, c) which are the effects of antidiabetic treatments on bone?, and d) how to prevent and treat bone fragility in T2D patients? Based on the available data members of this panel suggest that the stratification of fracture risk in patients with diabetes should firstly rely on the presence of a previous fragility fracture and on the individual risk profile, with the inclusion of T2D-specific risk factors (namely T2D duration above 10 yrs, presence of chronic T2D complications, use of insulin or thiazolidinediones and persistent HbA1c levels above 8% for at least 1 year). Two independent diagnostic approaches were then suggested in the presence or the absence of a prevalent fragility fracture, respectively.

CONCLUSIONS

Clinical trials in T2D patients at risk for fragility fractures are needed to determine the efficacy and safety of available antiresorptive and anabolic agents in this specific setting.

Metformin: Is It the Well Wisher of Bone Beyond Glycemic Control in Diabetes Mellitus?

Both diabetes mellitus and osteoporosis constitute a notable burden in terms of quality of life and healthcare costs. Diabetes mellitus affecting the skeletal system has been gaining attention in recent years and is now getting recognized as yet another complication of the disease, known as diabetic bone disease. As this condition with weaker bone strength increases fracture risk and reduces the quality of life, so much attention is being paid to investigate the molecular pathways through which both diabetes and its therapy are affecting bone metabolism. Out of many therapeutic agents currently available for managing diabetes mellitus, metformin is one of the most widely accepted first choices worldwide. The purpose of this review is to describe the effects of biguanide-metformin on bone metabolism in type 2 diabetes mellitus including its plausible mechanisms of action on the skeleton. In vitro studies suggest that metformin directly stimulates osteoblasts differentiation and may inhibit osteoclastogenesis by increasing osteoprotegerin expression, both through activation of the AMPK signaling pathway. Several studies in both preclinical and clinical settings report the favorable effects of metformin on bone microarchitecture, bone mineral density, bone turnover markers, and fracture risk. However, animal studies were not specific in terms of the diabetic models used and clinical studies were associated with several confounders. The review highlights some of these limitations and provide future recommendations for research in this area which is necessary to better understand the role of metformin on skeletal outcomes in diabetes.

Diabetes and Osteoporosis: Part I, Epidemiology and Pathophysiology

Both diabetes and osteoporosis are increasingly prevalent diseases, in part owing to aging populations worldwide. Epidemiologic data have shown that other organs may be adversely affected by diabetes, including the skeleton, in what has become known as diabetes-induced osteoporosis, which represents the combined impact of conventional osteoporosis with the additional fracture burden attributed to diabetes. There is an increased risk of fracture in patients with Type 1 and Type 2 diabetes, and some antidiabetic medications also may contribute to increased risk of fracture in diabetes.

Diabetes and Bone Involvement in Primary Hyperparathyroidism: Literature Review and Our Personal Experience

BACKGROUND

Primary hyperparathyroidism (PHPT) and type 2 diabetes mellitus (T2DM) are common endocrine disorders impacting on skeletal health, whose concomitant occurrence is becoming more frequent.

PATIENTS AND METHODS

We searched the PubMed database from the National Library of Medicine about the relationship between T2DM and its treatment and bone manifestations of PHPT. Thereafter, we retrospectively evaluated a consecutive series of 472 PHPT patients. Among them 55 were also affected by T2DM. At the diagnosis of PHPT we compared bone turnover markers and bone densitometry between 55 patients with and 417 without T2DM and in the former group according to antidiabetic treatment.

RESULTS

Few data are available about T2DM and PHPT bone involvement, studies about T2DM treatments and PHPT bone manifestations are lacking. Among patients with PHPT of our series, those with T2DM were older, had a lower prevalence of osteitis fibrosa cystica, higher lumbar and femoral T-scores than the remaining patients. No difference was disclosed among the diabetic patients according to ongoing antidiabetic treatment, even though modern treatments were under-represented.

CONCLUSIONS

No clinical study specifically evaluated the impact of T2DM on bone involvement in PHPT. In our experience, diabetic patients resulted more frequently "mild asymptomatic" than non-diabetic patients and showed a lower prevalence of radiological PHPT bone manifestations. The treatment of T2DM does not seem to affect the biochemical or clinical features of PHPT in our series. Further studies are needed to fully disclose the influence of T2DM and antidiabetic treatment on bone health in patients with PHPT.

Effects of Anti-Diabetic Drugs on Fracture Risk: A Systematic Review and Network Meta-Analysis

PURPOSE

Available data on the effects of anti-diabetic drugs on fracture risk are contradictory. Therefore, our study aimed to analyze all available data on the effects of anti-diabetic drugs on fracture risk in type 2 diabetes mellitus (T2DM) patients.

METHODS

Embase, Medline, ClinicalTrials.gov, and Cochrane CENTRAL were searched for relevant trials. All data analyses were performed with STATA (12.0) and R language (3.6.0). Risk ratio (RR) with its 95% confidence interval (CI) was calculated by combining data for the fracture effects of anti-diabetic drugs, including sodium-glucose co-transporter 2 (SGLT2) inhibitors, dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 (GLP-1) receptor agonists, meglitinides, α-glucosidase inhibitors, thiazolidinediones, biguanides, insulin, and sulfonylureas.

RESULTS

One hundred seventeen eligible randomized controlled trials (RCTs) with 221,364 participants were included in this study. Compared with placebo, trelagliptin (RR 3.51; 1.58-13.70) increased the risk of fracture, whereas albiglutide (RR 0.29; 0.04-0.93) and voglibose (RR 0.03; 0-0.11) decreased the risk of fracture. Other medications were comparable in terms of their effects on fracture risk, and no statistical significance was observed. In terms of fractures, voglibose (0.01%) may be the safest option, and trelagliptin (13.64%) may be the worst. Sensitivity analysis results were consistent with those of the main analysis. No statistically significant differences were observed in the regression coefficients of age (1.03; 0.32-2.1), follow-up duration (0.79; 0.27-1.64), and sex distribution (0.63; 0.15-1.56).

CONCLUSIONS

We found varied results on the association between the use of anti-diabetic drugs and fracture risk. Specifically, trelagliptin raised the risk of fracture, whereas voglibose and albiglutide showed benefit with statistical difference. Other drugs were comparable in terms of their effects on fracture risk. Some drugs (omarigliptin, sitagliptin, vildagliptin, saxagliptin, empagliflozin, ertugliflozin, rosiglitazone, pioglitazone, and nateglinide) may increase the risk of fracture, while others (such as dulaglutide, exenatide, liraglutide, semaglutide, lixisenatide, linagliptin, alogliptin, canagliflozin, dapagliflozin, glipizide, gliclazide, glibenclamide, glimepiride, metformin, and insulin) may show benefits. The risk of fracture was independent of age, sex distribution, and the duration of exposure to anti-diabetic drugs. When developing individualized treatment strategies, the clinical efficacy of anti-diabetic drugs must be weighed against their benefits and risks brought about by individual differences of patients.

SYSTEMATIC REVIEW REGISTRATION

This Systematic Review was prospectively registered on the PROSPERO (https://www.crd.york.ac.uk/PROSPERO/, registration number CRD42020189464).

Association between combined treatment with SGLT2 inhibitors and metformin for type 2 diabetes mellitus on fracture risk: a meta-analysis of randomized controlled trials

This study analyzed the effects of combination therapy with sodium-glucose transporter-2 inhibitors (SGLT2is) and metformin on fracture risk. Summarizing available randomized controlled trials, we found that SGLT2is combined with metformin therapy did not influence fracture risk compared with metformin monotherapy or other comparators in patients with T2DM.

INTRODUCTION

No study is available evaluating the association between sodium-glucose transporter-2 inhibitors (SGLT2is) in combination with metformin use and fracture risk. Our study aimed to investigate the fracture risk of combination therapy with SGLT2is and metformin in patients with type 2 diabetes mellitus (T2DM).

METHODS

PubMed, Embase, ClinicalTrials.gov site, and the Cochrane Library databases were scrutinized for all eligible randomized controlled trials (RCTs). The summarized odds ratios (ORs) and their 95% confidence intervals (CI) were calculated using Review Manager 5.3 software.

RESULTS

A total of 25 RCTs involving 19,500 participants with T2DM were included in our studies. There were 88 fracture cases in the SGLT2is in combination with metformin therapy group and 79 in the control group. SGLT2is combined with metformin use did not influence fracture risk compared with metformin monotherapy or other comparators in patients with T2DM (OR = 0.97, 95% CI 0.71-1.32). After stratification by drug type, follow-up time, control regimen, and type of fracture, the upshots were still stable.

CONCLUSION

SGLT2is and metformin combination therapy did not influence fracture risk compared with metformin monotherapy or other comparators in patients with T2DM.

PROSPERO REGISTRATION NUMBER

CRD42020168435.

The Use of Metformin to Increase the Human Healthspan

Metformin is a safe, effective and useful drug for glucose management in patients with diabetes. However in recent years, more attention has been paid to the possibility of using metformin as an anti-aging drug. It was shown to significantly increase the lifespan in some model organisms and delay the onset of age-associated declines. The current review summarizes advances in clinical research on the potential role of metformin in the field of lifespan and healthspan extension. Growing amounts of evidence from clinical trials suggest that metformin can effectively reduce the risk of many age-related diseases and conditions, including cardiometabolic disorders, neurodegeneration, chronic inflammation and frailty. Metformin also holds promise as a drug that could be repurposed for chemoprevention or adjuvant therapy for certain types of cancer. Moreover, metformin induces autophagy by activation of AMPK and can thus be potentially used to promote heathspan by hormesis-like mechanisms. Although long-term intake of metformin is associated with low risk of adverse events, well-designed clinical trials are still required to uncover the potential use of this drug as a geroprotector.

Metformin therapy and hip fracture risk among patients with type II diabetes mellitus: A population-based cohort study

BACKGROUND

This study aimed to investigate the potential association of exposure to metformin therapy with the risk of hip fracture in adult patients with type II diabetes. We included patients with diabetes who were registered in the 2010 sample cohort database of the National Health Insurance Service in South Korea.

METHODS

The patients who had been prescribed continuous oral metformin therapy for a 1-year period in 2010 were defined as the metformin group, while those who were not prescribed metformin during the same period were classified as the control group. The primary endpoint of this study was the development of hip fracture between January 2011 and December 2015.

RESULTS

A total of 64,878 patients (31,300 patients in the metformin group and 32,439 patients in the control group) were included in this study. Among those, 1655 patients (2.6%) had experienced a hip fracture. After a propensity score matching, a total of 37,378 patients (18,689 patients in each group) were included in the analysis. Using a time-dependent Cox regression analysis on the propensity score-matched cohort, the exposure to metformin was not significantly associated with the development of hip fracture compared to the control group (hazard ratio: 1.00, 95% confidence interval: 0.86 to 1.16; P = 0.985). Similar results were observed using sensitivity analysis of a multivariable time-dependent Cox regression model of the entire cohort (hazard ratio: 0.78, 95% confidence interval: 0.36 to 1.69; P = 0.525).

CONCLUSIONS

This population-based cohort study in South Korea showed that there was no significant association between the exposure to metformin therapy and hip fracture in patients with type II diabetes mellitus.

Metformin use is associated with a lower risk of osteoporosis in adult women independent of type 2 diabetes mellitus and obesity. REDLINC IX study

Metformin may decrease cell senescence, including bone; hence we aimed at evaluating the association between metformin use and osteoporosis. This was a cross-sectional study carried out in 1259 Latin American adult women aged 40 or more who were not on anti-osteoporotic drugs, were on metformin and had a bone densitometry performed. Of the whole sample, 40.3% reported being on metformin (at least 1 year), 30.2% had type 2 diabetes mellitus and 22.6% had osteoporosis. Median (interquartile range) body mass index (BMI) for the whole cohort was 27.7 (4.6) kg/m² and 30.2% had type 2 diabetes mellitus. Current use of hormone therapy, calcium, and vitamin D corresponded respectively to 10.7%, 47.7%, and 43.1% of all surveyed women. A logistic regression model was used to analyze the association of osteoporosis with various covariates incorporated into the model such as age (OR: 1.07, 95% CI: 1.05-1.09), BMI (OR: 0.92, 95% CI: 0.89-0.96) and metformin use (OR: 0.44, 95% CI: 0.32-0.59). Metformin use, regardless of the presence of type 2 diabetes or obesity, was associated with a lower risk of osteoporosis in adult women. We propose that one explanation for this observation could be the effect of the drug over cellular senescence.

The Interplay Between Bone and Glucose Metabolism

The multiple endocrine functions of bone other than those related to mineral metabolism, such as regulation of insulin sensitivity, glucose homeostasis, and energy metabolism, have recently been discovered. In vitro and murine studies investigated the impact of several molecules derived from osteoblasts and osteocytes on glucose metabolism. In addition, the effect of glucose on bone cells suggested a mutual cross-talk between bone and glucose homeostasis. In humans, these mechanisms are the pivotal determinant of the skeletal fragility associated with both type 1 and type 2 diabetes. Metabolic abnormalities associated with diabetes, such as increase in adipose tissue, reduction of lean mass, effects of hyperglycemia per se, production of the advanced glycation end products, diabetes-associated chronic kidney disease, and perturbation of the calcium-PTH-vitamin D metabolism, are the main mechanisms involved. Finally, there have been multiple reports of antidiabetic drugs affecting the skeleton, with differences among basic and clinical research data, as well as of anti-osteoporosis medication influencing glucose metabolism. This review focuses on the aspects linking glucose and bone metabolism by offering insight into the most recent evidence in humans.