Osteoporosis and risk of fracture in patients with diabetes: an update

Serum bicarbonate concentration is associated with bone density in adults with type 2 diabetes mellitus: African American-Diabetes Heart Study

BACKGROUND

Osteoporosis is a significant cause of morbidity and mortality in the aging population. Individuals with type 2 diabetes mellitus (T2D) typically have higher bone density yet also a higher rate of fractures. Blacks, meanwhile, have a lower incidence of osteoporosis compared to European Americans. Serum bicarbonate may be a risk factor for bone loss, but studies are conflicting, and little is known about this relationship in T2D or Blacks.

METHODS

We examined the longitudinal relationship between serum bicarbonate and change in bone density in 300 participants with T2D in the African American-Diabetes Heart Study (AA-DHS). Serum bicarbonate was measured at baseline, and bone density was assessed using CT volumetric bone mineral density (vBMD) scans of the thoracic and lumbar vertebrae at baseline and after five years of follow-up. Multivariate linear regression models assessed associations between baseline serum bicarbonate and longitudinal change in vBMD, adjusted for multiple confounders.

RESULTS

The cohort was 50 % female, with mean age and T2D duration 55.1 years and 10.2 years, respectively. The mean baseline serum bicarbonate was 26.6 (SD 3.3) mEq/L; median baseline lumbar spine vBMD 179.3 (IQR 148.2, 208.9) mg/cm3, and median baseline thoracic spine vBMD 204.9 (IQR 171.6, 231.9) mg/cm3. In fully-adjusted analyses, each 1 mEq/L increase in baseline serum bicarbonate was significantly associated with 5-year relative increase in lumbar vBMD (0.94 mg/cm3, p < 0.001) and thoracic vBMD (1.35 mg/cm3, p < 0.001), without a clear threshold effect or differences by sex.

CONCLUSIONS

In this cohort of Blacks with T2D, higher baseline serum bicarbonate levels were associated with improved changes in bone density over time. Further studies are needed to determine if alkali supplementation would ameliorate loss of bone density in this population.

Molecular mechanisms and targeted therapy of progranulin in metabolic diseases

Progranulin (PGRN) is a secreted glycoprotein with cytokine-like properties, exerting tripartite mechanisms of inflammation suppression, tissue repair promotion, and metabolic regulation. This multifaceted functionality positions PGRN as a potential "multi-effect therapeutic strategy" for metabolic disorders characterised by cartilage degradation and imbalanced bone remodelling, potentially establishing it as a novel therapeutic target for such conditions. Osteoarthritis, rheumatoid arthritis, intervertebral disc degeneration, osteoporosis, periodontitis, and diabetes-related complications-representing the most prevalent metabolic diseases-currently lack effective treatments due to incomplete understanding of their precise pathogenic mechanisms. Recent studies have revealed that PGRN expression levels are closely associated with the onset and progression of these metabolic disorders. However, the exact regulatory role of PGRN in these diseases remains elusive, partly owing to its tissue-specific actions and context-dependent dual roles (anti-inflammatory vs. pro-inflammatory). In this review, we summarise the structure and functions of PGRN, explore its involvement in neurological disorders, immune-inflammatory diseases, and metabolic conditions, and specifically focus on its molecular mechanisms in metabolic diseases. Furthermore, we consolidate advances in targeting PGRN and the application of its engineered derivative, Atsttrin, in metabolic bone disorders. We also discuss potential unexplored mechanisms through which PGRN may exert influence within this field or other therapeutic domains. Collectively, this work aims to provide a new framework for elucidating PGRN's role in disease pathogenesis and advancing strategies for the prevention and treatment of metabolic disorders.

Complications of Foot and Ankle Fractures in Diabetics

Patients with diabetes have an increased risk of both foot and ankle fractures. Patients with mild disease may be managed similarly to the population with no diabetes, although patients with advanced diabetes are likely to require more robust fixation with prolonged periods of non-weight-bearing. All patients with diabetes should be screened for peripheral neuropathy, as this is a marker for poor outcomes following both surgical and nonsurgical management. The overall goal of treatment is to achieve a stable, plantigrade foot that fits into normal footwear, supports functional ambulation, and avoids ulceration.

Association of type 2 diabetes with osteoporosis and fracture risk: A systematic review and meta-analysis

BACKGROUND

Osteoporosis, a systemic skeletal disease characterized by low bone mass and increased fracture risk, poses significant social and economic challenges globally, while type 2 diabetes mellitus (T2DM), a prevalent metabolic disorder, has been linked to complex effects on bone health, including contradictory findings on its relationship with osteoporosis and fracture risk.

METHODS

We searched PubMed, Embase, Cochrane, and Web of Science Library to identify observational studies investigating whether people with T2DM have a higher risk of osteoporosis or fracture than people without diabetes. The time limit for literature retrieval was from the establishment of the database until March 2023. The quality of the studies was assessed using the Newcastle-Ottawa Scale and Agency for Healthcare Research and Quality checklist. The meta-analysis was conducted using Stata 15, and a random-effects model was used if I2 was > 50%. The Egger test was used to assess publication bias.

RESULTS

The results demonstrated that people with T2DM have a higher risk of osteoporosis. (relative risk, 1.841; 95% confidence interval, 1.219-2.780; P = .004). Similar results were demonstrated for fractures (relative risk, 1.21; 95% confidence interval, 1.09-1.31; P < .001). However, the results of the subgroup analysis showed no significant correlation between T2DM and fractures in univariate analysis, cross-sectional studies, Asia, Europe, Oceania, and vertebral fractures. However, a significant correlation was found in other subgroup analyses.

CONCLUSIONS

Osteoporosis and fractures are significantly associated with T2DM.

Etiological factors and clinical outcomes in extracapsular and intracapsular hip fractures among older adults: A gender-specific analysis

BACKGROUND

Compared to patients with intracapsular fractures (ICFs), those with extracapsular fractures (ECFs) had worse outcomes. However, most studies of risk factors for these fractures lacked relevant potential reasons, particularly nutritional status, and adjustment for confounding factors. Furthermore, less is known about their effects on clinical outcomes.

OBJECTIVE

To conduct a gender-specific analysis of community-dwelling individuals admitted with hip fractures to examine the association of clinical risk factors and health care measures.

DESIGN

Monocentric cross-sectional study.

SETTING

Orthopedic trauma department.

PARTICIPANTS

A total of 787 women and 318 men of similar mean age (±SD): 83.1 years (±8.6) and 82.5 years (±9.0), respectively.

MAIN OUTCOME MEASURES

Multivariable logistic regression analyzed risk factors including age, gender, dementia, stroke, ischemic heart disease, diabetes, prefracture mobility, alcohol consumption, American Society of Anesthesiologists grades, drug history, and nutrition status for assessing risk factors and outcomes associated with ECFs and ICFs.

RESULTS

Compared to ICFs, for each additional year of age, women had a 3% and men 4% greater association with ECFs. Among women only, ECFs were associated with risk of malnutrition: odds ratio [OR] = 1.70 (95% CI, 1.17-2.48) or malnourishment: OR = 1.93 (95% CI, 1.06-3.52), stroke: OR = 1.85 (95% CI, 1.16-2.97), and diabetes: OR = 1.92 (95% CI, 1.21-3.06). Women with ECFs were less likely to be discharged to their own homes: OR = 0.56 (95% CI, 0.38-0.83); but more likely to be discharged to a rehabilitation unit: OR = 1.81 (95% CI, 1.21-2.71) and readmitted to hospital within 30 days of discharge ≥1 time: OR: 2.39 (95% CI, 1.27-4.50) or ≥2 times: OR = 3.48 (95% CI, 1.05-11.57): they did not differ in discharge to residential or nursing care or in-hospital mortality. Among men, there were no differences in discharge destinations or readmissions between types of fractures.

CONCLUSIONS

Compared to ICFs, a greater number of risk factors associated with ECFs were identified more often in women than in men, and ECFs also have greater influences on clinical outcomes in women.

Liraglutide promotes osteogenic differentiation of mesenchymal stem cells by inhibiting M1 macrophage polarization and CXCL9 release in vitro

As a GLP-1 receptor agonist widely used in treating type 2 diabetes, liraglutide shows potential applications in bone tissue engineering. This study investigated liraglutide's direct effects on rat bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation and its regulatory mechanism through macrophage polarization. Results showed that liraglutide significantly enhanced BMSC migration and osteogenic differentiation. Additionally, liraglutide markedly inhibited M1 macrophage polarization induced by LPS and IFN-γ, reducing inflammatory factors CXCL9 and TNF-α secretion, possibly by partially reversing M1 macrophage regulatory signals (AMPK and NF-κB pathways). Compared to M1 macrophage-conditioned medium (M1-CM), conditioned medium from liraglutide-treated macrophages showed stronger promotion of BMSC osteogenic differentiation, though this effect was reversed by CXCL9 addition. The study demonstrates that liraglutide enhances BMSC osteogenic capacity both directly and by inhibiting M1 macrophage polarization and CXCL9 secretion, offering a new therapeutic option for severe bone defects with inflammatory responses.

Osteoporosis in Adrenal Insufficiency: Could Metformin be Protective?

Adrenal insufficiency (AI) is a serious disorder characterized by the adrenal glucocorticoid deficiency. Regardless of the etiology, AI patients need long-term replacement therapy for glucocorticoids and, in some cases, for mineralocorticoids. The replacement therapy cannot completely mirror the physiological secretion patterns, and therefore, glucocorticoid excess is a common sequela in AI patients. Moreover, due to the absence of the reliable clinical markers to monitor the adequacy of the replacement therapy, clinicians often over-treat the AI patients to avoid adrenal crisis. Long-term glucocorticoid use is associated with the loss of bone density and osteoporosis, increasing the risk of fractures. Moreover, glucocorticoid-induced hyperglycemia and type 2 diabetes mellitus further aggravates the bone disorders. In the recent years, ameliorating effects of metformin on glucocorticoid-induced bone disorders, as well as hyperglycemia, have been reported by a multitude of studies; and here, we reviewed and discussed the most recent findings regarding the positive effects of metformin on alleviating the bone disorders, and their implications in the AI patients.

Mineral and cross-linking in collagen fibrils: The mechanical behavior of bone tissue at the nano-scale

The mineralized collagen fibril is the main building block of hard tissues and it directly affects the macroscopic mechanics of biological tissues such as bone. The mechanical behavior of the fibril itself is determined by its structure: the content of collagen molecules, minerals, and cross-links, and the mechanical interactions and properties of these components. Advanced glycation end products (AGEs) form cross-links between tropocollagen molecules within the collagen fibril and are one important factor that is believed to have a major influence on the tissue. For instance, it has been shown that brittleness in bone correlates with increased AGEs densities. However, the underlying nano-scale mechanisms within the mineralized collagen fibril remain unknown. Here, we study the effect of mineral and AGEs cross-linking on fibril deformation and fracture behavior by performing destructive tensile tests using coarse-grained molecular dynamics simulations. Our results demonstrate that after exceeding a critical content of mineral, it induces stiffening of the collagen fibril at high strain levels. We show that mineral morphology and location affect collagen fibril mechanics: The mineral content at which this stiffening occurs depends on the mineral's location and morphology. Further, both, increasing AGEs density and mineral content lead to stiffening and increased peak stresses. At low mineral contents, the mechanical response of the fibril is dominated by the AGEs, while at high mineral contents, the mineral itself determines fibril mechanics.

Association Between Metabolic Health and Bone Mineral Density Using CT in Hepatocellular Carcinoma Patients Under 65: A Retrospective Chart Review

INTRODUCTION

Metabolic conditions such as diabetes, and dyslipidemia are prevalent in the United States (US), serving as potential risk factors for hepatocellular carcinoma (HCC). This study aimed to examine the association between various metabolic markers and Hounsfield Units (HU) from L1 vertebral CT scans as indicators of bone mineral density (BMD) in HCC patients under age 65.

METHODS

A cross-sectional analysis was conducted on HCC patients under 65. Correlational and regression analyses were used to assess the association of metabolic markers and other health variables with HU scores.

RESULTS

Race and age were significantly associated with HU scores in multivariate analyses, indicating these factors play a crucial role in bone health among HCC patients. Race showed a positive association, and age showed a negative association with HU scores. Fasting blood glucose had a significant negative correlation with BMD, but this relationship was not significant in univariate regression analysis. No significant correlations were found between HU scores and triglycerides, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), cholesterol/HDL ratio, LDL/HDL ratio, and hemoglobin A1C (HbA1c) levels.

CONCLUSION

Traditional metabolic markers may not be strong predictors of osteoporosis in this specific population. Further research with larger, more diverse populations and longitudinal data is necessary to understand better the factors contributing to BMD variations in HCC patients.

Association between nonalcoholic fatty liver disease and bone mineral density: Mendelian randomization and mediation analysis

Background

Observational studies have reported significant association between non-alcoholic fatty liver disease (NAFLD) and bone mineral density (BMD), a critical indicator of bone health. We aimed to investigate whether NAFLD is a cause for changes in BMD.

Methods

We selected 29 independent SNPs as instrumental variables for NAFLD. A range of Mendelian randomization (MR) methods, namely the inverse variance-weighted (IVW) method, weighted-median, weighted-mode, and MR-Egger regression, were utilized to determine the causal effects of NAFLD on BMD. Two-step MR analysis was conducted to determine the mediating effect of fasting glucose, insulin, glycosylated hemoglobin, low-density cholesterol, and body-mass index on the association between NAFLD and BMD. False-discovery-rate (FDR) was used to correct for multiple testing bias.

Results

The IVW-method indicated a significantly inverse association between genetically predicted NAFLD and total body BMD (β = -0.04, 95 % CI -0.07 to -0.02, FDR = 0.010). Notably, the relationship was more pronounced in participants over 60 years of age (β = -0.06, 95 % CI -0.11 to -0.02, FDR = 0.030). Inverse associations were observed in other subpopulations and in site-specific BMD, though they were not statistically significant after correcting for multiple testing. We observed a significantly positive association between NAFLD and the risk of osteoporosis. Consistency in results was observed across multiple MR methods and in the repeated analysis. Fasting glucose, insulin, and glycosylated hemoglobin mediated 25.4 % (95 % CI 17.6-31.5 %), 18.9 % (12.0-24.9 %), and 27.9 % (19.9-36.7 %) of the effect of NAFLD on BMD, respectively.

Conclusion

Our findings underscore a probable causal negative link between NAFLD and BMD, indicating that NAFLD might detrimentally affect bone health, especially in older individuals.

Nutrition and Bone Marrow Adiposity in Relation to Bone Health

Bone remodeling is energetically demanding process. Energy coming from nutrients present in the diet contributes to function of different cell type including osteoblasts, osteocytes and osteoclasts in bone marrow participating in bone homeostasis. With aging, obesity and osteoporosis the function of key building blocks, bone marrow stromal cells (BMSCs), changes towards higher accumulation of bone marrow adipose tissue (BMAT) and decreased bone mass, which is affected by diet and sex dimorphism. Men and women have unique nutritional needs based on physiological and hormonal changes across the life span. However, the exact molecular mechanisms behind these pathophysiological conditions in bone are not well-known. In this review, we focus on bone and BMAT physiology in men and women and how this approach has been taken by animal studies. Furthermore, we discuss the different diet interventions and impact on bone and BMAT in respect to sex differences. We also discuss the future perspective on precision nutrition with a consideration of sex-based differences which could bring better understanding of the diet intervention in bone health and weight management.

Favorable osteogenic activity of vericiguat doped in β-tricalcium phosphate: In vitro and in vivo studies

Recently, more and more studies have shown that guanylate cyclase, an enzyme that synthesizes cyclic guanosine monophosphate (cGMP), plays an important role in bone metabolism. Vericiguat (VIT), a novel oral soluble guanylate cyclase stimulator, directly generates cyclic guanosine monophosphate and reduce the death incidence from cardio-vascular causes or hospitalization. Recent studies have shown beneficial effects of VIT in animal models of osteoporosis, but very little is currently known about the effects of VIT on bone defects in the osteoporotic states. Therefore, in this study, β-tricalcium phosphate (β-TCP) was used as a carrier to explore the effect of local VIT administration on the repair of femoral metaphyseal bone defects in ovariectomized (OVX) rats. When MC3T3-E1 was cultured in the presence of H2H2, VIT, similar to Melatonin (MT), therapy could increase the matrix mineralization and ALP, SOD2, SIRT1, and OPG expression, reduce ROS and Mito SOX production, RANKL expression, Promote the recovery of mitochondrial membrane potential. In the OVX rat model, VIT increases the osteogenic effect of β-TCP and better results were obtained at a dose of 5 mg. Local use of VIT can inhibit increased OC, BMP2 and RUNX2 expressions in bone tissue, while decreased SOST and TRAP expressions by RT-PCR and immunohistochemistry. Thereby, VIT stimulates bone regeneration and is a promising candidate for promoting bone repair in osteoporosis.

Synergistic effect of metformin and vitamin D3 on osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells under high d-glucose conditions

Introduction

Vitamin D3 plays a vital role in bone health, with low levels of vitamin D3 being related to skeletal fragility, fractures, and metabolic disorders such as diabetes. Metformin is known as an antihyperglycemic agent for regulating blood sugar. A correlation between diabetes mellitus and osteoporosis is attracting considerable interest, and research to find the prevention and treatment is gradually being studied. In this study, we investigated the effect of metformin and vitamin D3 on osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells (AT-MSCs) under high d-glucose concentrations and optimized by combining vitamin D3 and metformin in the process.

Methods

ROS production of AT-MSCs under high d-glucose conditions was measured by DCFH-DA assay. The differentiated AT-MSCs were analyzed by Alizarin Red S staining and optical density measurement. The investigation involved the examination of osteogenic master genes' expressions using quantitative reverse transcription polymerase chain reaction (qRT-PCR) techniques.

Results

Interestingly, the results have shown that human AT-MSCs will exhibit high ROS accumulation and low osteogenic differentiation capabilities, indicated by low calcium deposition, as well as low expression of indicative genes such as ALP, Runx-2 under high d-glucose conditions. The combination of vitamin D3 and metformin remarkedly accelerated the osteogenic differentiation of AT-MSCs under high d-glucose concentrations more effectively than the administration of either agent.

Conclusions

This study partially explains an aspect of an in vitro model for pre-clinical drug screening for osteoporosis-related diabetic pathological mechanisms, which can be applied for further research on the prevention or treatment of osteoporosis in diabetic patients.

Glycobiology in osteoclast differentiation and function

Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions. Certain glycans are ligands for lectins, which are carbohydrate-specific receptors. Bone is a complex tissue that provides mechanical support for muscles and joints, and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells, called osteoblasts, and bone-resorbing cells, called osteoclasts. Bone erosion occurs when bone resorption notably exceeds bone formation. Osteoclasts may be activated during cancer, leading to a range of symptoms, including bone pain, fracture, and spinal cord compression. Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases. The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology. Moreover, we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.

Does an Association among Sarcopenia and Metabolic Risk Factors Exist in People Older Than 65 Years? A Systematic Review and Meta-Analysis of Observational Studies

Sarcopenia is defined as the generalized and progressive loss of skeletal muscle strength and mass that may be affected by metabolic factors, although this relationship has been poorly studied. The aim of this review and meta-analysis was to analyze the relationship among the different metabolic risk factors and sarcopenia in people older than 65 years. Following the PRISMA 2020 guide, we searched for articles that studied the relationship among sarcopenia and metabolic risk factors in adults over 65 years of age, published between 2012 and 2022 in four databases: PubMed, Web of Science, Cochrane Plus, and CINAHL. A total of 370 articles were identified in the initial search, of which 13 articles were selected for inclusion in this review. It was observed that metabolic risk factors such as Body Mass Index, systolic and diastolic blood pressure, glucose, cholesterol, or triglycerides had a significant association with sarcopenia. There is evidence of the association of different metabolic risk factors with sarcopenia in adults over 65 years of age, so it is necessary to carry out studies that investigate different strategies that reduce the appearance of sarcopenia, and with it, the incidence of metabolic diseases.

Relationship Between Carotid Intima-Media Thickness and Osteoporosis in Type 2 Diabetic Patients: Cross-Sectional Study in the Third-Level Center

Aim: Although atherosclerosis and osteoporosis (OP) are seen in elderly patients, it is still a matter of research whether there is an age-independent relationship between them. In our study, we planned to investigate the relationship between carotid intima-media thickness (CIMT), OP, and bone turnover parameters in patients with type 2 diabetes mellitus (DM2) of both sexes. Materials and Methods: A total of 69 patients and 40 healthy volunteers with chronic diseases such as DM2, hypertension, hyperlipidemia, and OP. Group 1 had 27 patients with DM2 and OP, group 2 had 42 patients with DM2 and no OP, and group 3 had 40 healthy volunteers without DM2 and OP. Results: In the control group, CIMT was measured lower than the patients with DM2 (0.8 + 0.1 and 1.1 + 0.3, P < 0.001, respectively). Femur T score and lumbar T score values of patients with DM2 were lower than the control group (-0.48 + 1.1 and 0.7 + 0.6, P < 0.001, and -1.3 + 1.5 and 0.6 + 0.5, P < 0.001, respectively). Bone turnover markers in DM2 compared to the control group (C-terminal telopeptide of type 1 collagen: 240.9 ± 211.1 and 606.5 ± 200.8, P < 0.001; bone-specific alkaline phosphatase: 47.9 ± 15.5 and 431.5 ± 140, P < 0.001; and osteocalcin: 13.2 ± 5.0 and 19.7 ± 9.2, P < 0.001, respectively) were lower. Patients with femoral region (TSF) T score and lumbar region (TSL) T score below -2.5 were found to have higher CIMT values than those without (1.2 ± 0.23 mm and 0.9 ± 0.23 mm, P = 0.006, and 1.1 ± 0.28 mm and 0.95 ± 0.21 mm, P = 0.003, respectively). In linear regression analysis, age (β = 0.01, P < 0.001), OP (β = 0.166, P = 0.001), and DDM2 (β = 0.222, P = 0.04) were found to be effective on CIMT, while DM2 (β) = -0.754, P < 0.001), CIMT (β = -0.258, P = 0.021), body mass index (β = 0.355, P = 0.028), and age (β = -0.229, P = 0.029) were found to be independent factors on TSF. Conclusion: Bone turnover and bone mineral density are decreased in DM2 patients. In addition, subclinical atherosclerosis is more common in DM2 patients. Findings suggest that there is a relationship between subclinical atherosclerosis and OP due to metabolic factors other than age.

Metformin activates Wnt/β-catenin for the treatment of diabetic osteoporosis

BACKGROUND

With the deepening of social aging, the incidence rate of osteoporosis and diabetes continues to rise. More and more clinical studies show that diabetes is highly correlated with osteoporosis. Diabetes osteoporosis is considered as a metabolic bone disease of diabetes patients. This study aims to explore the role and mechanism of metformin (Met) in diabetic osteoporosis.

METHODS

Mouse MC3T3-E1 cells were treated with Met (0.5 mM) and exposed to high glucose (HG, 35 mM). The cells were cultured in an osteogenic medium for osteogenic differentiation, and the cell proliferation ability was determined using Cell Counting Kit-8; Alkaline phosphatase (ALP) activity detection and alizarin red staining were utilized to evaluate the effect of Met on MC3T3-E1 osteogenic differentiation. Western blot was used to detect the expressions of osteogenesis-related proteins (Runx2 and OCN) as well as Wnt/β-catenin signaling pathway-related proteins in MC3T3-E1 cells.

RESULTS

HG inhibited proliferation and calcification of MC3T3-E1 cells, down-regulated ALP activity, and the expression of Runx2 and OCN in MC3T3-E1 cells. Meanwhile, the activity of the Wnt/β-catenin signaling pathway was inhibited. Met treatment was found to significantly stimulate the proliferation and calcification of MC3T3-E1 cells under HG conditions, as well as increase the ALP activity and the protein expression level of Runx2 and OCN in the cells. As a result, osteogenic differentiation was promoted and osteoporosis was alleviated. Apart from this, Met also increased the protein expression level of Wnt1, β-catenin, and C-myc to activate the Wnt/β-catenin signaling pathway.

CONCLUSION

Met can stimulate the proliferation and osteogenic differentiation of MC3T3-E1 cells under HG conditions. Met may also treat diabetic osteoporosis through Wnt/β-catenin activation.

Epimedium for Osteoporosis Based on Western and Eastern Medicine: An Updated Systematic Review and Meta-Analysis

Background: The efficacy of conventional pharmacotherapy on osteoporosis was limited and accompanied with serious side effects. Epimedium might have the potential to be developed as agents to treat osteoporosis. The present systematic review and meta-analysis integrating Western medicine and Eastern medicine (“WE” medicine) was to evaluate the efficacy of Epimedium on osteoporosis.

Methods: Eleven electronic databases were searched to identify the randomized controlled trials (RCTs) comparing Epimedium as an adjunctive or alternative versus conventional pharmacotherapy during osteoporosis. Bone mineral density (BMD), effective rate, and Visual Analog Scale (VAS) were measured as primary outcomes. The secondary outcomes were pain relief time, bone metabolic markers, and adverse events. Research quality evaluation was conducted according to the modified Jadad scale. Review Manager 5.4 was utilized to perform analyses, and the data were pooled using a random-effect or fixed-effect model to calculate the weighted mean difference (WMD), standardized mean difference (SMD), risk ratio (RR), and 95% confidence intervals (CI).

Results: Twelve RCTs recruiting 1,017 patients were eligible. Overall, it was possible to verify that, in the Epimedium plus conventional pharmacotherapy group, BMD was significantly improved (p = 0.03), effective rate was significantly improved (p = 0.0001), and VAS was significantly decreased (p = 0.01) over those in control group. When compared to conventional pharmacotherapy, Epimedium used alone improved BMD (p = 0.009) and effective rate (p < 0.0001). VAS was lower (p < 0.00001), and the level of alkaline phosphatase (ALP) was significantly decreased (p = 0.01) in patients taking Epimedium alone compared with those given conventional pharmacotherapy. Results of subgroup analyses yielded that the recommended duration of Epimedium as an adjuvant was >3 months (p = 0.03), the recommended duration of Epimedium as an alternative was ≤3 months (p = 0.002), and Epimedium decoction brought more benefits (SMD = 2.33 [1.92, 2.75]) compared with other dosage forms. No significant publication bias was identified based on statistical tests (t = 0.81, p = 0.440).

Conclusions: Epimedium may improve BMD and effective rate and relieve pain as an adjuvant or alternative; Epimedium as an alternative might regulate bone metabolism, especially ALP, with satisfying clinical efficacy during osteoporosis. More rigorous RCTs are warranted to confirm these results.

Disparities in osteoporosis care among postmenopausal women in the United States

Osteoporosis and fragility fractures result in significant morbidity and mortality and contribute to substantial healthcare costs. Despite being a treatable disease, osteoporosis remains both underdiagnosed and undertreated in the US general population, with significant disparities in care between non-White and White women. These disparities are evident from screening to post-fracture treatment. Non-White women are less likely to be screened for osteoporosis, to be prescribed pharmacotherapy, or to receive treatment post-fracture; furthermore, the mortality rate after fracture is higher in non-White women. Given existing diagnostic and treatment disparities, additional studies and interventions are needed to optimize the bone health of Asian, Black, Hispanic, and Native American women, and to reduce morbidity and mortality from osteoporosis and fragility fractures.

Vibration therapy as an effective approach to improve bone healing in diabetic rats

OBJECTIVE

To investigate the effects of vibration therapy on fracture healing in diabetic and non-diabetic rats.

METHODS

148 rats underwent fracture surgery and were assigned to four groups: (1) SHAM: weight-matched non-diabetic rats, (2) SHAM+VT: non-diabetic rats treated with vibration therapy (VT), (3) DM: diabetic rats, and (4) DM+VT: diabetic rats treated with VT. Thirty days after diabetes induction with streptozotocin, animals underwent bone fracture, followed by surgical stabilization. Three days after bone fracture, rats began VT. Bone healing was assessed on days 14 and 28 post-fracture by serum bone marker analysis, and femurs collected for dual-energy X-ray absorptiometry, micro-computed tomography, histology, and gene expression.

RESULTS

Our results are based on 88 animals. Diabetes led to a dramatic impairment of bone healing as demonstrated by a 17% reduction in bone mineral density and decreases in formation-related microstructural parameters compared to non-diabetic control rats (81% reduction in bone callus volume, 69% reduction in woven bone fraction, 39% reduction in trabecular thickness, and 45% in trabecular number). These changes were accompanied by a significant decrease in the expression of osteoblast-related genes (Runx2, Col1a1, Osx), as well as a 92% reduction in serum insulin-like growth factor I (IGF-1) levels. On the other hand, resorption-related parameters were increased in diabetic rats, including a 20% increase in the callus porosity, a 33% increase in trabecular separation, and a 318% increase in serum C terminal telopeptide of type 1 collagen levels. VT augmented osteogenic and chondrogenic cell proliferation at the fracture callus in diabetic rats; increased circulating IGF-1 by 668%, callus volume by 52%, callus bone mineral content by 90%, and callus area by 72%; and was associated with a 19% reduction in circulating receptor activator of nuclear factor kappa beta ligand (RANK-L).

CONCLUSIONS

Diabetes had detrimental effects on bone healing. Vibration therapy was effective at counteracting the significant disruption in bone repair induced by diabetes, but did not improve fracture healing in non-diabetic control rats. The mechanical stimulus not only improved bone callus quality and quantity, but also partially restored the serum levels of IGF-1 and RANK-L, inducing bone formation and mineralization, thus creating conditions for adequate fracture repair in diabetic rats.

Effects and Mechanism of Zishen Jiangtang Pill on Diabetic Osteoporosis Rats Based on Proteomic Analysis

Objective

To explore the effect and mechanism of ZJP on DOP rats by proteomic analysis.

Materials and Methods

After the establishment of diabetes model by Streptozocin (STZ, 60 mg/kg), 40 Wistar rats were equally divided into normal group, model group (diabetic rats), high-dose group (3.0 g/kg/d ZJP), and low-dose group (1.5 g/kg/d ZJP) and received treatment for 3 months. Histological changes in bone and pancreas tissues were observed by hematoxylin and eosin staining, electron microscopy, and immunofluorescence. Proteomic and bioinformatic analyses were performed to identify the differentially expressed proteins. The fingerprint and active ingredients of ZJP were identified via high-performance liquid chromatography (HPLC).

Results

Compared with the model group, ZJP could rescue the weight, fasting blood glucose, and fasting insulin of rats in both high-dose and low-dose group. ZJP could also improve the microstructures of pancreatic islet cells, bone mass, and trabecular and marrow cavities in DOP rats. Bioinformatic analysis suggested that ZJP might influence DOP via multiple pathways, mainly including ribosomes, vitamin digestion and absorption, and fat digestion and absorption. The primary active ingredients, including notoginsenoside R1, ginsenoside Rg1, ginsenoside Re, icariin, and ginsenoside Rb1, were detected.

Conclusion

ZJP could significantly improve the histomorphology and ultrastructure of bone and islets tissues and might serve as an effective alternative medicine for the treatment of DOP.

Effects of GLP-1 Receptor Agonists on Bone Mineral Density in Patients with Type 2 Diabetes Mellitus: A 52-Week Clinical Study

INTRODUCTION

Hypoglycemic drugs affect the bone quality and the risk of fractures in patients with type 2 diabetes mellitus (T2DM). We aimed to investigate the effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and insulin on bone mineral density (BMD) in T2DM.

METHODS

In this single-blinded study, a total of 65 patients with T2DM were randomly assigned into four groups for 52 weeks: the exenatide group (n = 19), dulaglutide group (n = 19), insulin glargine group (n = 10), and placebo (n = 17). General clinical data were collected, and BMD was measured by dual-energy X-ray absorptiometry.

RESULTS

Compared with baseline, the glycosylated hemoglobin (HbA1c) decreased significantly in the exenatide (8.11 ± 0.24% vs. 7.40 ± 0.16%, P = 0.007), dulaglutide (8.77 ± 0.37% vs. 7.06 ± 0.28%, P < 0.001), and insulin glargine (8.57 ± 0.24% vs. 7.23 ± 0.25%, P < 0.001) groups after treatment. In the exenatide group, the BMD of the total hip increased. In the dulaglutide group, only the BMD of the femoral neck decreased (P = 0.027), but the magnitude of decrease was less than that in the placebo group; the BMD of L1-L4, femoral neck, and total hip decreased significantly (P < 0.05) in the placebo group, while in the insulin glargine group, the BMD of L2, L4, and L1-4 increased (P < 0.05). Compared with the placebo group, the BMD of the femoral neck and total hip in the exenatide group and the insulin glargine group were increased significantly (P < 0.05); compared with the exenatide group, the BMD of L4 in the insulin glargine group was also increased (P = 0.001).

CONCLUSIONS

Compared with the placebo, GLP-1RAs demonstrated an increase of BMD at multiple sites of the body after treatment, which may not exacerbate the consequences of bone fragility. Therefore, GLP-1RAs might be considered for patients with T2DM. This trial is registered with ClinicalTrials.gov NCT01648582.

Glyoxal-induced formation of advanced glycation end-products in type 1 collagen decreases both its strength and flexibility in vitro

The high plasma glucose induced in glucose metabolism disorders leads to the non-enzymatic glucose-dependent modification (glycation) of type 1 collagen, which is an essential component of bone tissue. The glycation of proteins induces the formation of advanced glycation end-products, such as carboxymethyl arginine, which is preferentially generated in glycated collagen. However, the effect of advanced glycation end-product formation on the characteristics of type 1 collagen remains unclear due to the lack of suitable in vitro experimental systems analyzing type 1 collagen. Here, we show that the glycation of type 1 collagen can be analyzed in vitro using a goldfish-scale bone model. Our study using these scales provides evidence that the advanced glycation end-product formation in type 1 collagen induced by glyoxal, the carboxymethyl arginine inducer, facilitates the crosslinking of type 1 collagen, decreasing both its strength and flexibility.

Lower bone mineral density and higher bone resorption marker levels in premenopausal women with type 1 diabetes in Japan

AIMS/INTRODUCTION

Type 1 diabetes is associated with poorer bone quality. Quantitative ultrasound provides an estimate of bone mineral density (BMD) and can also be used to evaluate bone quality, which is associated with an increased fracture risk in people with type 1 diabetes. The aim of this study was to evaluate the association between menopausal status and a bone turnover marker with heel BMD using quantitative ultrasound in women with type 1 diabetes and age- and body mass index-matched controls.

MATERIALS AND METHODS

A total of 124 individuals recruited in Kyoto and Osaka, Japan - 62 women with type 1 diabetes (mean age 47.2 ± 17.3 years) and 62 age-, menopausal status-, sex- and body mass index-matched non-diabetic control individuals (mean age 47.3 ± 16.3 years) - were enrolled in this study. Heel BMD in the calcaneus was evaluated using ultrasonography (AOS-100NW, Hitachi-Aloka Medical, Ltd., Tokyo, Japan). A bone turnover marker was also measured.

RESULTS

The heel BMD Z-score was significantly lower in premenopausal women with type 1 diabetes than in the premenopausal control group, but not in postmenopausal women with type 1 diabetes. Levels of tartrate-resistant acid phosphatase-5b, a bone resorption marker, were significantly higher in premenopausal women with type 1 diabetes than in the premenopausal control group, but not in postmenopausal women with type 1 diabetes. The whole parathyroid hormone level was significantly lower in both pre- and postmenopausal women with type 1 diabetes.

CONCLUSIONS

Lower heel BMD, higher tartrate-resistant acid phosphatase-5b level and lower parathyroid hormone were observed in premenopausal women with type 1 diabetes. Premenopausal women with type 1 diabetes require osteoporosis precautions for postmenopause.

Sanhuang Jiangtang tablet protects type 2 diabetes osteoporosis via AKT-GSK3β-NFATc1 signaling pathway by integrating bioinformatics analysis and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Sanhuang Jiangtang tablet (SHJTT), has been widely used to treat type 2 diabetes mellitus (T2DM). However, the potential and mechanism of SHJTT in treating type 2 diabetes osteoporosis (T2DOP) has not been reported.

AIM OF THE STUDY

The aim of this work was to investigate the role and the underlying molecular mechanism of SHJTT in managing type 2 diabetes osteoporosis.

MATERIALS AND METHODS

The target genes of each component consisting of SHJTT were obtained by searching the ETCM database. The target genes of osteoporosis and diabetes were individually acquired by analyzing the DisGeNET and OMIM disease databases. Then the potential therapeutic genes were obtained from the intersection of the herbal medicine targets and the disease targets which were imported into the R and STRING platform for the analysis of GO terms, KEGG pathways and PPI network. The key modules of PPI network were constructed by Cytoscape software. Finally, leptin receptor deficiency (db/db) mice were confirmed as an animal model of type 2 diabetic osteoporosis (T2DOP) through phenotype assessment and the key genes of SHJTT against T2DOP were validated by quantitative real-time PCR (qRT-PCR).

RESULTS

A total of 786 target genes of SHJTT were obtained from ETCM. Simultaneously, a total of 3906 osteoporosis and type 2 diabetes associated targets were acquired from DisGeNET and OMIM databases. Then, 97 common targets were found by overlapping them. On the basis of the GO and KEGG enrichment analysis and PPI network, we found that the related pathway of SHJTT in type 2 diabetes osteoporosis was AKT-GSK3β-NFATc1 pathway which is tightly associated with osteoclast differentiation. The expression of key genes including Akt1, Mapk3, Gsk3β, Mmp9, Nfkb1 were significantly down-regulated by SHJTT in T2DOP mice (p < 0.05).

CONCLUSIONS

SHJTT had a protective effect on T2DOP via regulating AKT-GSK3β-NFATc1 signaling pathway. This study might provide a theoretical basis for the application of SHJTT for the treatment of type 2 diabetic osteoporosis.

Diabetes and Bone Fragility: SGLT2 Inhibitor Use in the Context of Renal and Cardiovascular Benefits

PURPOSE OF REVIEW

Type 2 diabetes mellitus (T2DM) has been shown to negatively impact bone quality and increase fracture risk. While the pathophysiology of bone fragility in T2DM is not clear and likely multifactorial, medications used to treat T2DM are increasingly scrutinized for their potential role in aberrant bone metabolism. Sodium-glucose co-transporter 2 (SGLT2) inhibitors are gaining popularity in patients with T2DM. In addition to lowering blood glucose, there is evidence that these drugs offer cardiac and renal benefit to individuals with T2DM, leading to FDA-approved indications for use in at-risk individuals. At the same time, there remain concerns that SGLT2 inhibitors, specifically canagliflozin, have adverse effects on bone metabolism and increase fracture risk in T2DM. This review seeks to further clarify the impact of these agents on the skeleton.

RECENT FINDINGS

SGLT2 inhibitors may indirectly disrupt calcium and phosphate homeostasis, contribute to weight loss, and cause hypotension, resulting in bone mineral density (BMD) losses and increased falls. The true long-term impact of SGLT2 inhibitors on the diabetic skeleton is still unclear; this review summarizes the results in studies investigating the impact of SGLT2 inhibitors on fracture risk in T2DM. Whereas studies performed with dapagliflozin and empagliflozin have not shown an increased risk of bone fractures compared with placebo, some studies have shown increased markers of bone turnover and reduced bone mineral density with canagliflozin treatment. While an increased fracture risk was observed with canagliflozin in the CANVAS trial (HR 1.26; 95% CI 1.04, 1.52), an increased risk was not seen in the CANVAS-R (HR 0.86) or CREDENCE (HR 0.98) trials. There is substantial evidence of the cardiac and renal protective benefits of SGLT2 inhibitors. There does not appear to be an increased fracture risk with the use of dapagliflozin or empagliflozin. Given the possible association between canagliflozin and adverse bone outcomes described in CANVAS, canagliflozin use should be pursued in individuals with T2DM only after careful consideration of the individual's skeletal risk.

GLP-1 promotes osteogenic differentiation of human ADSCs via the Wnt/GSK-3β/β-catenin pathway

Glucagon-like peptide-1 (GLP-1) analogues are promising anti-diabetic drugs which had been shown to have beneficial effects on bone metabolism in clinical practice, but the molecular mechanism remains unclear. In this study, we evaluated whether GLP-1 can affect the "intestine-fat-bone axis" via the Wnt/GSK-3β/β-catenin pathway. We established a diabetic mouse model and then treated mice with GLP-1 analogue liraglutide. The results showed that after liraglutide treatment, glucose tolerance and insulin tolerance were significantly improved in diabetic mice as expected. Moreover, osteogenic markers such as collagenⅠ, Runx2 and OCN were upregulated; and the adipogenic differentiation markers C/EBP-α and PPAR-γ were downregulated, these results indicated that liraglutide could ameliorate the osteogenic metabolism in diabetic mice. In the cell model, human ADSCs (hADSCs) were cultured and induced to undergo osteogenic and adipogenic differentiation under high glucose conditions in vitro and then treated with GLP-1. The results showed that GLP-1 repressed the induction of adipocyte differentiation biomarkers and the secretion of GSK-3β in a dose-dependent manner. In addition, GLP-1 enhanced the expression of osteoblastogenic biomarkers, such as OCN, Runx2 and collagenⅠ, and promoted osteoblastic mineralization. These effects were substantially suppressed by the Wnt signal recombinant human DKK-1 or activated by Wnt pathway agonist LiCl. Silencing of GSK-3β showed that the levels of β-catenin, GSK-3β and Runx2 were significantly increased by 2.46-, 2.05-, 4.44-fold after GLP-1 treatment compared to that observed in the GSK-3β lentiviral group, respectively. We conclude that GLP-1 promotes the osteogenic differentiation of hADSCs via the Wnt/GSK-3β/β-catenin pathway.

Chondroitin Sulfate Prevents STZ Induced Diabetic Osteoporosis through Decreasing Blood Glucose, AntiOxidative Stress, Anti-Inflammation and OPG/RANKL Expression Regulation

Chondroitin sulfate (CS) has antioxidative, anti-inflammatory, anti-osteoarthritic and hypoglycemic effects. However, whether it has antidiabetic osteoporosis effects has not been reported. Therefore, in this study, we established a STZ-induced diabetic rat model; CS (500 mg kg⁻¹ d⁻¹) was orally administrated for eight weeks to study its preventive effects on diabetic osteoporosis. The results showed that eight weeks of CS treatment improved the symptoms of diabetes; the CS-treated group has increased body weight, decreased water or food intake, decreased blood glucose, increased bone-mineral density, repaired bone morphology and decreased femoral osteoclasts and tibia adipocytes numbers. After CS treatment, bone histomorphometric parameters returned to normal, the levels of serum inflammatory cytokines (IL-1β, IL-6 and TNF-α) decreased significantly, serum SOD, GPX and CAT activities increased and MDA level increased. In the CS-treated group, the levels of serum ALP, CTX-1, TRACP 5b, osteocalcin and RANKL decreased and the serum RUNX 2 and OPG levels increased. Bone immunohistochemistry results showed that CS can effectively increase the expression of OPG and RUNX2 and reduce the expression of RANKL in diabetic rats. All of these indicate that CS could prevent STZ induced diabetic osteoporosis—mainly through decreasing blood glucose, antioxidative stress, anti-inflammation and regulation of OPG/RANKL expression. CS can therefore effectively prevent bone loss caused by diabetes.

Metformin coordinates osteoblast/osteoclast differentiation associated with ischemic osteonecrosis

In this study, we aimed to identify a candidate drug that can activate endogenous Angiopoietin 1 (Ang1) expression via drug repositioning as a pharmacological treatment for avascular osteonecrosis. After incubation with 821 drugs from the Food and Drug Administration (FDA)-approved drug library, Ang1 expression in U2OS cell culture media was examined by ELISA. Metformin, the first-line medication for treatment of type 2 diabetes, was selected as a candidate for in vitro and in vivo experimental evaluation. Ang1 was induced, and alkaline phosphatase activity was increased by metformin treatment in U2OS and MG63 cells. Wound healing and migration assay showed increased osteoblastic cell mobility by metformin treatment in U2OS and MG63 cells. Metformin upregulated expression of protein markers for osteoblastic differentiation in U2OS and MG63 cells but inhibited osteoclastic differentiation in Raw264.7 cells. Metformin (25 mg/kg) protected against ischemic necrosis in the epiphysis of the rat femoral head by maintaining osteoblast/osteocyte function and vascular density but inhibiting osteoclast activity in the necrotic femoral head. These findings provide novel insight into the specific biomarkers that are targeted and regulated by metformin in osteoblast differentiation and contribute to understanding the effects of these FDA-approved small-molecule drugs as novel therapeutics for ischemic osteonecrosis.

Insulin impedes osteogenesis of BMSCs by inhibiting autophagy and promoting premature senescence via the TGF-β1 pathway

The dysfunction of bone marrow stromal cells (BMSCs) may be a core factor in Type 2 diabetes mellitus (T2DM) associated osteoporosis. However, the underlying mechanism is not well understood. Here, we delineated the critical role of insulin impeding osteogenesis of BMSCs in T2DM. Compared with BMSCs from healthy people (H-BMSCs), BMSCs from T2DM patient (DM-BMSCs) showed decreased osteogenic differentiation and autophagy level, and increased senescent phenotype. H-BMSCs incubated in hyperglycemic and hyperinsulinemic conditions similarly showed these phenotypes of DM-BMSCs. Notably, enhanced TGF-β1 expression was detected not only in DM-BMSCs and high-glucose and insulin-treated H-BMSCs, but also in bone callus of streptozocin-induced diabetic rats. Moreover, inhibiting TGF-β1 signaling not only enhanced osteogenic differentiation and autophagy level of DM-BMSCs, but also delayed senescence of DM-BMSCs, as well as promoted mandible defect healing of diabetic rats. Finally, we further verified that it was TGF-β receptor II (TβRII), not TβRI, markedly increased in both DM-BMSCs and insulin-treated H-BMSCs. Our data revealed that insulin impeded osteogenesis of BMSCs by inhibiting autophagy and promoting premature senescence, which it should be responsible for T2DM-induced bone loss, at least in part. These findings suggest that inhibiting TGF-β1 pathway may be a potential therapeutic target for T2DM associated bone disorders.

Role of Metformin on Osteoblast Differentiation in Type 2 Diabetes

Metformin, an effective hypoglycemic, can modulate different points of malignant mass, polycystic ovary syndrome (PCOS), cardiovascular diseases, tuberculosis, and nerve regeneration. Recently, the effect of metformin on bone metabolism has been analyzed. Metformin relies on organic cation transporters (OCT1), a polyspecific cell membrane of the solute carrier 22A (SLC22A) gene family, to facilitate its intracellular uptake and action on complex I of the respiratory chain of mitochondria. These changes activate the cellular energy sensor AMP-activated protein kinase (AMPK). Thus, the increased cellular AMP/ATP ratio causes a dramatic and progressive activation of insulin and lysosomes, resulting in a decrease in intracellular glucose level, which promotes osteoblast proliferation and differentiation. AMPK also phosphorylates runt-related transcription factor 2 (Runx2) at S118, the lineage-specific transcriptional regulators, to promote osteogenesis. Metformin phosphorylates extracellular signal-regulated kinase (ERK), stimulates endothelial and inducible nitric oxide synthases (e/iNOS), inhibits the GSK3β/Wnt/β-catenin pathway, and promotes osteogenic differentiation of osteoblasts. The effect of metformin on hyperglycemia decreases intracellular reactive oxygen species (ROS) and advanced glycation end-products (AGEs) in collagen, and reduced serum levels of insulin-like growth factors (IGF-1) were beneficial for bone formation. Metformin has a certain effect on microangiopathy and anti-inflammation, which can induce osteoporosis, activate the activity of osteoclasts, and inhibit osteoblast activity, and has demonstrated extensive alteration in bone and mineral metabolism. The aim of this review was to elucidate the mechanisms of metformin on osteoblasts in insulin-deficient diabetes.

Effect of Dipeptidyl Peptidase-4 Inhibitors on the Risk of Bone Fractures in a Korean Population

BACKGROUND

There have been equivocal results in studies of the effects of dipeptidyl peptidase-4 inhibitors (DPP-4i) on fractures. In this study, we analyzed the effect of DPP-4i on bone fracture risk in a Korean population.

METHODS

We extracted subjects (n = 11,164) aged 50 years or older from the National Health Insurance Service-National Sample Cohort 2.0 from 2009 to 2014. Our control group included subjects without diabetes (n = 5,582), and our treatment groups with diabetes included DPP-4i users (n = 1,410) and DPP-4i non-users (n = 4,172). The primary endpoint was the incidence of a composite outcome consisting of osteoporosis diagnosis, osteoporotic fractures, vertebral fractures, non-vertebral fractures, and femoral fractures. The secondary endpoint was the incidence of each individual component of the composite outcome. Survival analysis was performed with adjustment for age, gender, diabetes complications severity index, Charlson comorbidity index, hypertension medication, and dyslipidemia treatment.

RESULTS

The incidence of the composite outcome per 1,000 person-years was 0.089 in DPP-4i users, 0.099 in DPP-4i non-users, and 0.095 in controls. There was no significant difference in fracture risk between DPP-4i users and DPP-4i non-users or controls after the adjustments (P > 0.05). The incidences of osteoporosis diagnosis, osteoporotic fractures, vertebral fractures, non-vertebral fractures, and femoral fractures were not significantly different between DPP-4i users and non-users. The results of subgroup analyses by gender and age were consistent.

CONCLUSION

DPP-4i had no significant effect on the risk of fractures in a Korean population.

The prevalence of osteoporosis among Iranian postmenopausal women with type 2 diabetes: A systematic review and meta-analysis

Osteoporosis is the most common metabolic bone disorder that is common in postmenopausal women with type 2 diabetes. Different studies have reported different prevalence of osteoporosis. This systematic review and meta-analysis was conducted to estimate the pooled prevalence of osteoporosis in Iranian postmenopausal women with type 2 diabetes. Search for eligible articles was performed using the keywords of osteoporosis, osteopenia, bone mineral density, OP, bone loss, Post menopaus*, diabetes, hyperglycemia, and Iran, and their possible combinations in the following databases: Scientific Information Database (SID), MagIran, PubMed, Scopus, and Web of Science. Heterogeneity between studies was examined with I2. The data were analyzed using the meta-analysis method and random effects model with Stata version 11.0. The analysis of 4 papers with a sample size of 562 showed that the prevalence of osteoporosis in the lumbar spine and femoral neck of the Iranian post-menopausal women with type II diabetes was 25.26% (95% CI: 7.22-30.30) and 17.45% (95% CI: 0.25-34.65), respectively. Also, the prevalence of osteopenia in the lumbar spine and femoral neck of these patients was 45.23% (95% CI: 40.66-49.79) and 44.53% (95% CI: 36.60-52.47), respectively. There was no relationship between the prevalence of osteoporosis and osteopenia with sample size, year of publication, age and body mass index. Osteoporosis and osteopenia are prevalent in women, so healthy lifestyle education for these postmenopausal women are necessary to reduce the prevalence of these problems.

Empagliflozin Contributes to Polyuria via Regulation of Sodium Transporters and Water Channels in Diabetic Rat Kidneys

Besides lowering glucose, empagliflozin, a selective sodium-glucose cotransporter-2 (SGLT2) inhibitor, have been known to provide cardiovascular and renal protection due to effects on diuresis and natriuresis. However, the natriuretic effect of SGLT2 inhibitors has been reported to be transient, and long-term data related to diuretic change are sparse. This study was performed to assess the renal effects of a 12-week treatment with empagliflozin (3 mg/kg) in diabetic OLETF rats by comparing it with other antihyperglycemic agents including lixisenatide (10 μg/kg), a glucagon-like peptide receptor-1 agonist, and voglibose (0.6 mg/kg), an α-glucosidase inhibitor. At 12 weeks of treatment, empagliflozin-treated diabetic rats produced still high urine volume and glycosuria, and showed significantly higher electrolyte-free water clearance than lixisenatide or voglibose-treated diabetic rats without significant change of serum sodium level and fractional excretion of sodium. In empagliflozin-treated rats, renal expression of Na⁺-Cl^- cotransporter was unaltered, and expressions of Na⁺/H⁺ exchanger isoform 3, Na⁺-K⁺-2Cl^- cotransporter, and epithelial Na⁺ channel were decreased compared with control diabetic rats. Empagliflozin increased an expression of aquaporin (AQP)7 but did not affect AQP3 and AQP1 protein expressions in diabetic kidneys. Despite the increased expression in vasopressin V2 receptor, protein and mRNA levels of AQP2 in empagliflozin-treated diabetic kidneys were significantly decreased compared to control diabetic kidneys. In addition, empagliflozin resulted in the increased phosphorylation of AQP2 at S261 through the increased cyclin-dependent kinases 1 and 5 and protein phosphatase 2B. These results suggest that empagliflozin may contribute in part to polyuria via its regulation of sodium channels and AQP2 in diabetic kidneys.

Protective Effects of Ligustroflavone, an Active Compound from Ligustrum lucidum, on Diabetes-Induced Osteoporosis in Mice: A Potential Candidate as Calcium-Sensing Receptor Antagonist

Ligustroflavone is one major compound contained in active fraction from Fructus Ligustri Lucidi (the fruit of Ligustrum lucidum), which could regulate parathyroid hormone (PTH) levels and improve calcium balance by acting on calcium-sensing receptors (CaSR). This study aimed to explore the potency of ligustroflavone as a CaSR antagonist and its protective effects against diabetic osteoporosis in mice. LF interacted well with the allosteric site of CaSR shown by molecular docking analysis, increased PTH release of primary parathyroid gland cells and suppressed extracellular calcium influx in HEK-293 cells. The serum level of PTH attained peak value at 2 h and maintained high during the period of 1 h and 3 h than that before treatment in mice after a single dose of LF. Treatment of diabetic mice with LF inhibited the decrease in calcium level of serum and bone and the enhancement in urinary calcium excretion as well as elevated circulating PTH levels. Trabecular bone mineral density and micro-architecture were markedly improved in diabetic mice upon to LF treatment for 8 weeks. LF reduced CaSR mRNA and protein expression in the kidneys of diabetic mice. Taken together, ligustroflavone could transiently increase PTH level and regulate calcium metabolism as well as prevent osteoporosis in diabetic mice, suggesting that ligustroflavone might be an effective antagonist on CaSR.

Osteoporosis complicating some inborn or acquired diseases

Osteoporosis in chronic diseases is very frequent and pathogenetically varied. It complicates the course of the underlying disease by the occurrence of fractures, which aggravate the quality of life and increase the mortality of patients from the underlying disease. The secondary deterioration of bone quality in chronic diseases, such as diabetes of type 1 and type 2 and/or other endocrine and metabolic disorders, as well as inflammatory diseases, including rheumatoid arthritis - are mostly associated with structural changes to collagen, altered bone turnover, increased cortical porosity and damage to the trabecular and cortical microarchitecture. Mechanisms of development of osteoporosis in some inborn or acquired disorders are discussed.

Metformin; an old antidiabetic drug with new potentials in bone disorders

The prevalence of diabetes mellitus especially type 2 diabetes mellitus is increasing all over the world. In addition to cardiomyopathy and nephropathy, diabetics are at higher risk of mortality and morbidity due to greater risk of bone fractures and skeletal abnormalities. Patients with diabetes mellitus have lower bone quality in comparison to their non-diabetic counterparts mainly because of hyperglycemia, toxic effects of advanced glycosylation end-products (AGEs) on bone tissue, and impaired bone microvascular system. AGEs may also contribute to the development of osteoarthritis further to osteoporosis. Therefore, glycemic control in diabetic patients is vital for bone health. Metformin, a widely used antidiabetic drug, has been shown to improve bone quality and decrease the risk of fractures in patients with diabetes in addition to glycemic control and improving insulin sensitivity. AMP activated protein kinase (AMPK), the key molecule in metformin antidiabetic mechanism of action, is also effective in signaling pathways involved in bone physiology. This review, discusses the molecules linking diabetes and bone turnover, role of AMPK in bone metabolism, and the effect of metformin as an activator of AMPK on bone disorders and malignancies.

Association Between Bone Mineral Density, Bone Turnover Markers, and Serum Cholesterol Levels in Type 2 Diabetes

Purpose: The association between bone mineral density (BMD), bone turnover markers, and serum cholesterol in healthy population has already been proved. However, in patients with type 2 diabetes mellitus (T2D), it has not been adequately analyzed. In this study, we investigated the correlation between BMD, bone turnover markers, and serum cholesterol levels in people with T2D. Methods: We enrolled 1,040 men and 735 women with T2D from Zhongshan Hospital between October 2009 and January 2013. Their general condition, history of diseases and medication, serum markers, and BMD data were collected. We used logistic regression analysis to identify the association between serum cholesterol levels and BMD as well as bone turnover markers. Results: In multivariate regression analysis, we observed that in men with T2D, high high-density lipoprotein-cholesterol and total cholesterol levels were significantly associated with low total lumbar, femur neck, and total hip BMD, while low-density lipoprotein-cholesterol level was only inversely associated with total lumbar and femur neck BMD. Total cholesterol and low-density lipoprotein-cholesterol levels were also negatively associated with osteocalcin, procollagen type I N-terminal propeptide, and β-crosslaps. In women with T2D, high-density lipoprotein-cholesterol level was observed to be negatively correlated with total lumbar, femur neck, and total hip BMD, while total cholesterol and low-density lipoprotein-cholesterol levels were only associated with BMD at the total lumbar. Furthermore, total cholesterol was also negatively associated with osteocalcin, procollagen type I N-terminal propeptide, and β-crosslaps; high-density lipoprotein-cholesterol was only related to osteocalcin and parathyroid hormone, while low-density lipoprotein-cholesterol was only related to β-crosslaps in women. Conclusion: Our study suggests a significantly negative correlation between serum cholesterol levels and BMD in both men and women with T2D. The associations between serum cholesterol levels and bone turnover markers were also observed in T2D patients.

Pharmacological rescue of diabetic skeletal stem cell niches

Diabetes mellitus (DM) is a metabolic disease frequently associated with impaired bone healing. Despite its increasing prevalence worldwide, the molecular etiology of DM-linked skeletal complications remains poorly defined. Using advanced stem cell characterization techniques, we analyzed intrinsic and extrinsic determinants of mouse skeletal stem cell (mSSC) function to identify specific mSSC niche-related abnormalities that could impair skeletal repair in diabetic (Db) mice. We discovered that high serum concentrations of tumor necrosis factor-α directly repressed the expression of Indian hedgehog (Ihh) in mSSCs and in their downstream skeletogenic progenitors in Db mice. When hedgehog signaling was inhibited during fracture repair, injury-induced mSSC expansion was suppressed, resulting in impaired healing. We reversed this deficiency by precise delivery of purified Ihh to the fracture site via a specially formulated, slow-release hydrogel. In the presence of exogenous Ihh, the injury-induced expansion and osteogenic potential of mSSCs were restored, culminating in the rescue of Db bone healing. Our results present a feasible strategy for precise treatment of molecular aberrations in stem and progenitor cell populations to correct skeletal manifestations of systemic disease.

Targeted disruption of adenosine kinase in myeloid monocyte cells increases osteoclastogenesis and bone resorption in mice

Adenosine kinase (ADK) serves an important role in intracellular adenosine clearance via phosphorylating adenosine to AMP. The role of adenosine and its receptors in the maintenance of bone homeostasis is well studied, particularly in osteoclastogenesis and bone resorption; however, the function of ADK in bone metabolism is still unclear. In the present study, utilizing the cre/floxp recombination system, mice with conditional loss of ADK function in myeloid monocyte cells were used to assess the effect of ADK deficiency on bone metabolism. Mice were evaluated by means of gross observation and bone histomorphometric analysis. Ex vivo osteoclast differentiation and bone resorption were also examined using genetic deletion and pharmacologic inhibition of ADK in osteoclasts. Compared with control mice, the results of the present study demonstrate that adult mice lacking ADK in the myeloid monocyte cells had reduced body weight and nasoanal length. The results of bone histomorphometric analysis revealed that bone mass was significantly decreased and osteoclastic parameters were increased in the study mice. Furthermore, in vitro cell culture revealed that inhibition of ADK function promoted osteoclast differentiation and bone resorption. Osteoclast‑associated gene expression, including tartrate‑resistant acid phosphatase, nuclear factor of activated T‑cells, cytoplasmic 1, matrix metalloproteinase 9, Cathepsin K and calcitonin receptor, was also significantly increased. These results suggest that mice with ADK deficiency have reduced bone formation due to increased osteoclastogenesis and bone resorption. The present study provides further insight into the mechanism by which ADK serves a key role in bone metabolism.

Molecular Modulation of Osteoblasts and Osteoclasts in Type 2 Diabetes

Diabetes is a common disease affecting majority of populations worldwide. Since 1980, there has been an increase in the number of people diagnosed as prediabetic and diabetic. Diabetes is characterized by high levels of circulating glucose and leads to most microvascular and macrovascular complications such as retinopathy, nephropathy, neuropathy, stroke, and myocardial infarction. Bone marrow vascular disruption and increased adiposity are also linked to various complications in type II diabetes mellitus. In addition to these complications, type 2 diabetic patients also have fragile bones caused by faulty mineralization mainly due to increased adiposity among diabetic patients that affects both osteoblast and osteoclast functions. Other factors that increase fracture risk in diabetic patients are increased oxidative stress, inflammation, and drugs administered to diabetic patients. This review reports the modulation of different pathways that affect bone metabolism in diabetic conditions.

Low bone turnover in premenopausal women with type 2 diabetes mellitus as an early process of diabetes-associated bone alterations: a cross-sectional study

BACKGROUND

Individuals with Diabetes Mellitus (DM) are at increased risk for fracture due to the decrease in bone strength and quality. Serum procollagen type I intact N-terminal (P1NP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX) as markers of bone formation and resorption, respectively, have been reported to be decreased in T2DM. It remains unclear whether diabetes-associated alterations in the bone turnover of T2DM individuals are related to the longer duration of the disease or may occur earlier. Furthermore, previous studies on BTMs in T2DM individuals have mostly been done in postmenopausal women with T2DM, which might have masked the DM-induced alterations of bone turnover with concurrent estrogen deficiency. This study aims to assess the levels of serum P1NP and CTX as markers of bone turnover in premenopausal women with and without T2DM.

METHODS

This cross-sectional study involves 41 premenopausal women with T2DM, and 40 premenopausal women without DM. Sampling was done consecutively. P1NP and CTX measurement was done using the electrochemi-luminescence immunoassay (ECLIA) method. Other data collected include levels of HbA1C, ALT, creatinine, eGFR and lipid profile.

RESULTS

Median (interquartile range) P1NP in T2DM is 29.9 ng/ml (24.7-41.8 ng/ml), while in non-DM is 37.3 ng/ml, (30.8-47.3 ng/ml; p = 0.007). Median (interquartile range) CTX in T2DM is 0.161 ng/ml (0.106-0.227 ng/ml), while in non-DM is 0.202 ng/ml (0.166-0.271 ng/ml; p = 0.0035). Levels of P1NP and CTX in the T2DM group did not correlate with the duration of disease, age, BMI or the levels of HbA1C.

CONCLUSIONS

Premenopausal women with T2DM indeed have lower bone turnover when compared with non-DM controls. This significantly lower bone turnover process starts relatively early in the premenopausal age, independent of the duration of DM. Gaining understanding of the early pathophysiology of altered bone turnover may be key in developing preventive strategies for diabetoporosis.

Fat, Sugar, and Bone Health: A Complex Relationship

With people aging, osteoporosis is expected to increase notably. Nutritional status is a relatively easily-modified risk factor, associated with many chronic diseases, and is involved in obesity, diabetes, and coronary heart disease (CHD), along with osteoporosis. Nutrients, such as fats, sugars, and proteins, play a primary function in bone metabolism and maintaining bone health. In Western nations, diets are generally high in saturated fats, however, currently, the nutritional patterns dominating in China continue to be high in carbohydrates from starch, cereals, and sugars. Moreover, high fat or high sugar (fructose, glucose, or sucrose) impart a significant impact on bone structural integrity. Due to diet being modifiable, demonstrating the effects of nutrition on bone health can provide an approach for osteoporosis prevention. Most researchers have reported that a high-fat diet consumption is associated with bone mineral density (BMD) and, as bone strength diminishes, adverse microstructure changes occur in the cancellous bone compartment, which is involved with lipid metabolism modulation disorder and the alteration of the bone marrow environment, along with an increased inflammatory environment. Some studies, however, demonstrated that a high-fat diet contributes to achieving peak bone mass, along with microstructure, at a younger age. Contrary to these results, others have shown that a high-fructose diet consumption leads to stronger bones with a superior microarchitecture than those with the intake of a high-glucose diet and, at the same time, research indicated that a high-fat diet usually deteriorates cancellous bone parameters, and that the incorporation of fructose into a high-fat diet did not aggravate bone mass loss. High-fat/high-sucrose diets have shown both beneficial and detrimental influences on bone metabolism. Combined, these studies showed that nutrition exerts different effects on bone health. Thus, a better understanding of the regulation between dietary nutrition and bone health might provide a basis for the development of strategies to improve bone health by modifying nutritional components.

Fracture risk in patients with type 2 diabetes mellitus and possible risk factors: a systematic review and meta-analysis

Aim

Patients with type 2 diabetes mellitus (T2DM) have an increased risk of bone fractures. A variable increase in fracture risk has been reported depending on skeletal site, diabetes duration, study design, insulin use, and so on. The present meta-analysis aimed to investigate the association between T2DM with fracture risk and possible risk factors.

Methods

Different databases including PubMed, Institute for Scientific Information, and Scopus were searched up to May 2016. All epidemiologic studies on the association between T2DM and fracture risk were included. The relevant data obtained from these papers were analyzed by a random effects model and publication bias was assessed by funnel plot. All analyses were done by R software (version 3.2.1) and STATA (version 11.1).

Results

Thirty eligible studies were selected for the meta-analysis. We found a statistically significant positive association between T2DM and hip, vertebral, or foot fractures and no association between T2DM and wrist, proximal humerus, or ankle fractures. Overall, T2DM was associated with an increased risk of any fracture (summary relative risk =1.05, 95% confidence interval: 1.04, 1.06) and increased with age, duration of diabetes, and insulin therapy.

Conclusion

Our findings strongly support an association between T2DM and increased risk of overall fracture. These findings emphasize the need for fracture prevention strategies in patients with diabetes.

MECHANISMS IN ENDOCRINOLOGY: Diabetes mellitus, a state of low bone turnover - a systematic review and meta-analysis

OBJECTIVE

To investigate the differences in bone turnover between diabetic patients and controls.

DESIGN

A systematic review and meta-analysis.

METHODS

A literature search was conducted using the databases Medline at PubMed and EMBASE. The free text search terms 'diabetes mellitus' and 'bone turnover', 'sclerostin', 'RANKL', 'osteoprotegerin', 'tartrate-resistant acid' and 'TRAP' were used. Studies were eligible if they investigated bone turnover markers in patients with diabetes compared with controls. Data were extracted by two reviewers.

RESULTS

A total of 2881 papers were identified of which 66 studies were included. Serum levels of the bone resorption marker C-terminal cross-linked telopeptide (-0.10 ng/mL (-0.12, -0.08)) and the bone formation markers osteocalcin (-2.51 ng/mL (-3.01, -2.01)) and procollagen type 1 amino terminal propeptide (-10.80 ng/mL (-12.83, -8.77)) were all lower in patients with diabetes compared with controls. Furthermore, s-tartrate-resistant acid phosphatase was decreased in patients with type 2 diabetes (-0.31 U/L (-0.56, -0.05)) compared with controls. S-sclerostin was significantly higher in patients with type 2 diabetes (14.92 pmol/L (3.12, 26.72)) and patients with type 1 diabetes (3.24 pmol/L (1.52, 4.96)) compared with controls. Also, s-osteoprotegerin was increased among patients with diabetes compared with controls (2.67 pmol/L (0.21, 5.14)).

CONCLUSIONS

Markers of both bone formation and bone resorption are decreased in patients with diabetes. This suggests that diabetes mellitus is a state of low bone turnover, which in turn may lead to more fragile bone. Altered levels of sclerostin and osteoprotegerin may be responsible for this.

Associated Factors of Bone Mineral Density and Osteoporosis in Elderly Males

BACKGROUND

Low bone mineral density and osteoporosis is prevalent in elderly subjects. This study aimed to determine the associated factors of bone mineral density and osteoporosis in elderly males.

METHODS

All participants of the Amirkola health and ageing project cohort aged 60 years and older entered the study. Bone mineral density at femoral neck and lumbar spine was assessed by the dual energy X-ray absorptiometry (DXA) method. Osteoporosis was diagnosed by the international society for clinical densitometry criteria and the association of bone mineral density and osteoporosis with several clinical, demographic and biochemical parameters. Multiple logistic regression analysis was used to determine independent associations.

RESULTS

A total of 553 patients were studied and 90 patients (16.2%) had osteoporosis at either femoral neck or lumbar spine. Diabetes, obesity, metabolic syndrome, overweight, and quadriceps muscle strength > 30 kg, metabolic syndrome, abdominal obesity and education level were associated with higher bone mineral density and lower prevalence of osteoporosis, whereas age, anemia, inhaled corticosteroids and fracture history were associated with lower bone mineral density and higher prevalence of osteoporosis (P = 0.001). After adjustment for all covariates, osteoporosis was negatively associated only with diabetes, obesity, overweight, and QMS > 30 kg and positively associated with anemia and fracture history. The association of osteoporosis with other parameters did not reach a statistical level.

CONCLUSIONS

The findings of the study indicate that in elderly males, diabetes, obesity and higher muscle strength was associated with lower prevalence of osteoporosis and anemia, and prior fracture with higher risk of osteoporosis. This issue needs further longitudinal studies.