Effects of metformin, rosiglitazone and insulin on bone metabolism in patients with type 2 diabetes

The effects of exenatide and insulin glargine treatments on bone turnover markers and bone mineral density in postmenopausal patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) related bone fracture. The effects of glucagon-like peptide-1 receptor analogs for the treatment of T2DM on bone are controversial in human studies. This study aimed to compare the effects of GLP-1 receptor analogs exenatide and insulin glargine treatment on bone turnover marker levels and bone mineral density (BMD) in postmenopausal female patients with T2DM. Thirty female patients with T2DM who were naive to insulin and incretin-based treatments, with spontaneous postmenopause, were randomized to exenatide or insulin glargine arms and were followed up for 24 weeks. BMD was evaluated using dual-energy X-ray absorptiometry and bone turnover markers by serum enzyme-linked immunosorbent assay. The body mass index significantly decreased in the exenatide group compared to the glargine group (P < .001). Receptor activator of nuclear factor kappa-B (RANK) and RANK ligand (RANKL) levels were significantly decreased with exenatide treatment (P = .009 and P = .015, respectively). Osteoprotegerin (OPG) level significantly increased with exenatide treatment (P = .02). OPG, RANK, RANKL levels did not change with insulin glargine treatment. No statistically significant difference was found between the pre- and posttreatment BMD, alkaline phosphatase, bone-specific alkaline phosphatase, and type 1 crosslinked N-telopeptide levels in both treatment arms. Despite significant weight loss with exenatide treatment, BMD did not decrease, OPG increased, and the resorption markers of RANK and RANKL decreased, which may reflect early antiresorptive effects of exenatide via the OPG/RANK/RANKL pathway.

Selected musculoskeletal disorders in patients with thyroid dysfunction, diabetes, and obesity

Many medical conditions affect the skeletal system and constitute independent risk factors for fractures. The action of thyroid hormones is necessary to maintain adequate development, mineralization, and bone strength. Untreated hyperthyroidism can lead to a decrease in bone mineral density (BMD), osteoporosis, and pathological fractures. In hypothyroidism, the changes in the quality of bone structure lead to an increase in the frequency of fractures. Excessive body weight negatively impacts fracture risk, increases the risk of osteoarthritis and accelerates the development of rheumatoid arthritis and osteoporosis. Type 1 and type 2 diabetes are associated with an increased risk of bone fractures despite different etiopathogenesis due to the duration of the disease and the pro-inflammatory state, the incorporation of advanced glycation end products (AGEs) into the bone matrix, and microvascular disorders. This study summarizes the current literature on the influence of thyroid dysfunction, obesity, and diabetes on the skeletal system.

Progress in the preparation and evaluation of glucose-sensitive microneedle systems and their blood glucose regulation

Glucose-sensitive microneedle systems (GSMSs) as an intelligent strategy for treating diabetes can well solve the problems of puncture pain, hypoglycemia, skin damage, and complications caused by the subcutaneous injection of insulin. According to the various functions of each component, herein, therapeutic GSMSs are reviewed based on three parts (glucose-sensitive models, diabetes medications, and microneedle body). Moreover, the characteristics, benefits, and drawbacks of three types of typical glucose-sensitive models (phenylboronic acid based polymer, glucose oxidase, and concanavalin A) and their drug delivery models are reviewed. In particular, phenylboronic acid-based GSMSs can provide a long-acting drug dose and controlled release rate for the treatment of diabetes. Moreover, their painless, minimally invasive puncture also greatly improves patient compliance, treatment safety, and potential application prospects.

Small-Molecule Loaded Biomimetic Biphasic Scaffold for Osteochondral Regeneration: An In Vitro and In Vivo Study

Osteoarthritis is a prevalent musculoskeletal disorder in the elderly, which leads to high rates of morbidity. Mesenchymal stem cells (MSCs) are a promising approach to promote tissue regeneration in the absence of effective long-term treatments. Small molecules are relatively inexpensive and can selectively alter stem cell behavior during their differentiation, making them an attractive option for clinical applications. In this study, we developed an extracellular matrix (ECM)-based biphasic scaffold (BPS) loaded with two small-molecule drugs, kartogenin (KGN) and metformin (MET). This cell-free biomimetic biphasic scaffold consists of a bone (gelatin/hydroxyapatite scaffold embedded with metformin [GHSM]) and cartilage (nano-gelatin fiber embedded with kartogenin [NGFK]) layer designed to stimulate osteochondral regeneration. Extracellular matrix (ECM)-based biomimetic scaffolds can promote native cell recruitment, infiltration, and differentiation even in the absence of additional growth factors. The biphasic scaffold (BPS) showed excellent biocompatibility in vitro, with mesenchymal stem cells (MSCs) adhering, proliferating, and differentiated on the biomimetic biphasic scaffolds (GHSM and NGFK layers). The biphasic scaffolds upregulated both osteogenic and chondrogenic gene expression, sulfated glycosaminoglycan (sGAG), osteo- and chondrogenic biomarker, and relative mRNA gene expression. In an in vivo rat model, histo-morphological staining showed effective regeneration of osteochondral defects. This novel BPS has the potential to enhance both subchondral bone repair and cartilage regeneration, demonstrating excellent effects on cell homing and the recruitment of endogenous stem cells.

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.

Low Bone Turnover Associates With Lower Insulin Sensitivity in Newly Diagnosed Drug-Naïve Persons With Type 2 Diabetes

CONTEXT

Bone turnover markers (BTMs) are lower in type 2 diabetes mellitus (T2D). The relationships between bone turnover, β-cell function, and insulin sensitivity in T2D are uncertain.

OBJECTIVE

To investigate if fasting levels of BTMs in persons with T2D are associated with β-cell function or insulin sensitivity.

METHODS

We defined three T2D phenotypes, the insulinopenic (low β-cell function, high insulin sensitivity), the classical (low β-cell function, low insulin sensitivity), and the hyperinsulinemic (high β-cell function, low insulin sensitivity) phenotypes, in the Danish Centre for Strategic Research T2D cohort using the homeostatic model assessment. We selected age- and gender-matched subgroups to represent the three T2D phenotypes, yielding 326 glucose-lowering treatment-naïve persons with T2D. Median values of BTMs between the three T2D phenotypes were compared. Regression models were applied to assess the association between BTMs, β-cell function, and insulin sensitivity adjusted for potential confounders.

RESULTS

Median serum levels of procollagen type I N-terminal propeptide, C-terminal telopeptide of type I collagen, and osteocalcin were higher in the insulinopenic phenotype (52.3 μg/L, IQR 41.6, 63.3; 259.4 ng/L, IQR 163.4, 347.7; and 18.0 μg/L, IQR 14.4, 25.2, respectively) compared with the classical (41.4, IQR 31.0, 51.4; 150.4 IQR 103.5, 265.1; 13.1, IQR 10.0, 17.6, respectively) and the hyperinsulinemic (43.7, IQR 32.3, 57.3; 163.3, IQR 98.9, 273.1; 15.7 IQR 10.2, 20.8, respectively) phenotypes (all P < .01). These differences persisted after adjustment for age, sex, waist to hip ratio, or fasting plasma glucose (P < .01).

CONCLUSION

BTMs are lower in newly diagnosed persons with T2D characterized by low insulin sensitivity.

mTOR Signaling Pathway in Bone Diseases Associated with Hyperglycemia

The interplay between bone and glucose metabolism has highlighted hyperglycemia as a potential risk factor for bone diseases. With the increasing prevalence of diabetes mellitus worldwide and its subsequent socioeconomic burden, there is a pressing need to develop a better understanding of the molecular mechanisms involved in hyperglycemia-mediated bone metabolism. The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that senses extracellular and intracellular signals to regulate numerous biological processes, including cell growth, proliferation, and differentiation. As mounting evidence suggests the involvement of mTOR in diabetic bone disease, we provide a comprehensive review of its effects on bone diseases associated with hyperglycemia. This review summarizes key findings from basic and clinical studies regarding mTOR's roles in regulating bone formation, bone resorption, inflammatory responses, and bone vascularity in hyperglycemia. It also provides valuable insights into future research directions aimed at developing mTOR-targeted therapies for combating diabetic bone diseases.

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.

Biochemical Markers of Bone Fragility in Patients with Diabetes. A Narrative Review by the IOF and the ECTS

CONTEXT

The risk of fragility fractures is increased in both type 1 and type 2 diabetes. Numerous biochemical markers reflecting bone and/or glucose metabolism have been evaluated in this context. This review summarizes current data on biochemical markers in relation to bone fragility and fracture risk in diabetes.

METHODS

Literature review by a group of experts from the International Osteoporosis Foundation (IOF) and European Calcified Tissue Society (ECTS) focusing on biochemical markers, diabetes, diabetes treatments and bone in adults.

RESULTS

Although bone resorption and bone formation markers are low and poorly predictive of fracture risk in diabetes, osteoporosis drugs seem to change bone turnover markers in diabetics similarly to non-diabetics, with similar reductions in fracture risk. Several other biochemical markers related to bone and glucose metabolism have been correlated with BMD and/or fracture risk in diabetes, including osteocyte-related markers such as sclerostin, HbA1c and advanced glycation end products (AGEs), inflammatory markers and adipokines, as well as IGF-1 and calciotropic hormones.

CONCLUSION

Several biochemical markers and hormonal levels related to bone and/or glucose metabolism have been associated with skeletal parameters in diabetes. Currently, only HbA1c levels seem to provide a reliable estimate of fracture risk, while bone turnover markers could be used to monitor the effects of anti-osteoporosis therapy.

Anti-diabetic effects of fungal Ergosta-4, 6, 8(14), 22-tetraen-3-one from Pholiota adiposa

OBJECTIVE

Pholiota adiposa is a valuable edible and medicinal fungus. In this research, Ergosta-4, 6, 8(14), 22-tetraen-3-one (ETO) was obtained from Pholiota adiposa which is the first time to study the anti-diabetic and related mechanism.

METHODS

Ergosta-4, 6, 8 (14), 22-tetraen-3-one (ETO) was defined by IR and NMR. Relevant biochemical indicators were detected by ELISA assay, hematoxylin-eosin staining (H & E), fasting glucose levels (FBG), oral glucose tolerance test (OGTT), tissue homogenate biochemical measurements, immunohistochemical staining and western blot.

RESULTS

In this research, the ETO treatment groups exhibited a significant reduction in fasting blood glucose (FBG) levels, the High dose group (HD) was about 10 mmol/L lower than the diabetic control group (DC), and increase in body weight, the HD group weighed about 5 g more than the DC group on average. Also, the levels of triacylglycerol (TG), total cholesterol (TC), and low-density lipoprotein-cholesterol (LDL-C) were found to be decreased, while the levels of high-density superoxide dismutase (SOD), lipoproteincholesterol (HDL-C), catalase (CAT), and glutathione peroxidase (GSH-Px) were increased in the ETO treatment groups. The pancreatic and liver sections of diabetic control group (DC) exhibited several histopathological changes, but the ETO treatment groups exhibited improvements. ETO treatment led to the significant restoration of islet morphology and function. Moreover, the results of the western blot analysis indicate that ETO could be used for the treatment of diabetes, since it modifies part of the IRS1 / PI3K / AKT signaling pathway.

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.

The Relationships Between Glycated Hemoglobin and Bone Turnover Markers in Patients with Type 2 Diabetes but No Diabetic Nephropathy

Purpose

To investigate the relationships between glycated hemoglobin (HbA1c) level and bone turnover markers (BTMs) in patients with type 2 diabetes mellitus (T2DM) but no diabetic nephropathy.

Patients and Methods

Patients with T2DM were recruited at Hebei General Hospital in China. The participants were allocated to three groups: an HbA1c <7% group, an HbA1c 7%–9% group, and an HbA1c ≥9% group. Their general characteristics, biochemical indices, and BTM concentrations were recorded.

Results

The ages of the HbA1c <7% group and the HbA1c 7%–9% group were significantly higher than that of the HbA1c ≥9% group (P<0.05). The prevalence of a history of hypertension in the HbA1c 7%–9% group was significantly higher than that in the HbA1c ≥9% group. The circulating low-density lipoprotein-cholesterol concentration in the HbA1c ≥9% group and the apolipoprotein B concentration in the HbA1c 7%–9% group were significantly higher than those in the HbA1c <7% group (P<0.05). Compared with that in the HbA1c <7% group, the circulating 25-hydroxyvitamin D (25OHD) concentration was significantly lower in the HbA1c ≥9% group (P<0.05). Additionally, the circulating 25OHD and osteocalcin (OC) concentrations negatively correlated with HbA1c (P<0.05).

Conclusion

An increase in HbA1c is associated with gradual decreases in the circulating concentrations of 25OHD and OC.

Effects of continuous subcutaneous insulin infusion on the microstructures, mechanical properties and bone mineral compositions of lumbar spines in type 2 diabetic rats

Background

Continuous subcutaneous insulin infusion (CSII) for the treatment of type 2 diabetes (T2D) can improve the structure and strength of femur of rats, but the effect of CSII treatment on the lumbar spine of T2D rats is unknown. The purpose of this study is to investigate the effects of CSII on the microstructure, multi-scale mechanical properties and bone mineral composition of the lumbar spine in T2D rats.

Methods

Seventy 6-week-old male Sprague–Dawley (SD) rats were divided into two batches, each including Control, T2D, CSII and Placebo groups, and the duration of insulin treatment was 4-week and 8-week, respectively. At the end of the experiment, the rats were sacrificed to take their lumbar spine. Microstructure, bone mineral composition and nanoscopic-mesoscopic-apparentand-macroscopic mechanical properties were evaluated through micro-computed tomography (micro-CT), Raman spectroscopy, nanoindentation test, nonlinear finite element analysis and compression test.

Results

It was found that 4 weeks later, T2D significantly decreased trabecular thickness (Tb.Th), nanoscopic-apparent and partial mesoscopic mechanical parameters of lumbar spine (P < 0.05), and significantly increased bone mineral composition parameters of cortical bone (P < 0.05). It was shown that CSII significantly improved nanoscopic-apparent mechanical parameters (P < 0.05). In addition, 8 weeks later, T2D significantly decreased bone mineral density (BMD), bone volume fraction (BV/TV) and macroscopic mechanical parameters (P < 0.05), and significantly increased bone mineral composition parameters of cancellous bone (P < 0.05). CSII treatment significantly improved partial mesoscopic-macroscopic mechanical parameters and some cortical bone mineral composition parameters (P < 0.05).

Conclusions

CSII treatment can significantly improve the nanoscopic-mesoscopic-apparent-macroscopic mechanical properties of the lumbar spine in T2D rats, as well as the bone structure and bone mineral composition of the lumbar vertebrae, but it will take longer treatment time to restore the normal level. In addition, T2D and CSII treatment affected bone mineral composition of cortical bone earlier than cancellous bone of lumbar spine in rat. Our study can provide evidence for clinical prevention and treatment of T2D-related bone diseases.

FSH may mediate the association between HbA1c and bone turnover markers in postmenopausal women with type 2 diabetes

INTRODUCTION

Recent studies in postmenopausal women have found associations of follicle-stimulating hormone (FSH) levels with both glucose metabolism and bone turnover. The objective of the study was to investigate whether FSH may contribute to suppressed bone turnover markers (BTMs) in postmenopausal women with type 2 diabetes (T2D).

MATERIALS AND METHODS

888 postmenopausal women with T2D, 352 nondiabetes (prediabetes plus normoglycemia) were included from the METAL study. HbA1c, sex hormones, 25-hydroxy vitamin D (25(OH)D), serum procollagen type I N-terminal propeptide (P1NP), and β-C-terminal telopeptide (β-CTX) were measured.

RESULTS

P1NP and β-CTX decreased in postmenopausal T2D women compared with nondiabetes controls (both p < 0.001). The major factors responsible for the changes in P1NP were HbA1c (β = - 0.050, p < 0.001), 25(OH)D (β = - 0.003, p = 0.006), FSH (β = 0.001, p = 0.044) and metformin (β = - 0.109, p < 0.001), for β-CTX were HbA1c (β = - 0.049, p < 0.001), body mass index (BMI) (β = - 0.011, p = 0.005), 25(OH)D (β = - 0.003, p = 0.003), FSH (β = 0.002, p = 0.022) and metformin (β = - 0.091, p = 0.001) in postmenopausal T2D women based on multivariate regression analysis. With the increase in HbA1c, FSH decreased significantly (p for trend < 0.001). Mediation analysis demonstrated that FSH partly mediated the suppression of LnP1NP and Lnβ-CTX by HbA1c (β = - 0.009 and - 0.010, respectively), and Lnβ-CTX by BMI (β = - 0.015) when multiple confounders were considered (all p < 0.05).

CONCLUSION

HbA1c was the crucial determinant contributing to the suppression of BTMs. FSH might play a novel mediation role in BTM suppression due to HbA1c or BMI.

Combination of metformin and exercise alleviates osteoarthritis in ovariectomized mice fed a high-fat diet

OBJECTIVE

To evaluate and compare the effects of the combined intervention of metformin and exercise on the degeneration of cartilage and subchondral bone in a mouse model of osteoarthritis (OA) induced by estrogen deficiency and obesity.

METHODS

56 female 3-month-old C57BL/6 mice underwent ovariectomy (OVX) (n = 40) or a sham operation (n = 16) and were randomized into seven groups (n = 8/group): 1) sham-operated mice with a normal diet (Sham), 2) OVX mice with a normal diet (OVX), 3) sham-operated mice with high-fat diet (HFD) (HSVX), 4) OVX mice with HFD (HOVX), 5) OVX mice with HFD + exercise (HOVE), 6) OVX mice with HFD + metformin (HOMX), and 7) OVX mice with HFD + metformin + exercise (HOME). Drug administration and exercise training were initiated 72 h after surgical operation. The pathology of OA was assessed by histomorphology analyses, immunohistochemistry (IHC), tartrate-resistant acid phosphatase (TRAP) staining, micro-computed tomography and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Histomorphological analysis revealed that OA was significantly exacerbated by the coexistence of estrogen deficiency and obesity and markedly alleviated by the combined intervention. In details, metformin plus exercise ameliorated the abnormal metabolic status and cartilage lesions, significantly increased aggrecan and collagen-II expression and decreased the expression of ADAMTS-4. Furthermore, combined intervention markedly improved bone degeneration, bone mass and microarchitecture of subchondral bone. And the intervention also increased the concentration of OCN and decreased the serum concentration of IL-1β and CTX-1 and glucose.

CONCLUSIONS

The coexistence of estrogen deficiency and obesity further aggravates abnormal metabolic pathology and articular degeneration, which could be prevented by the combination with metformin and exercise, suggesting that combined intervention may be a potential candidate for amelioration of the progression of OA.

Evaluation of hypoglycemic therapeutics and nutritional supplementation for type 2 diabetes mellitus management: An insight on molecular approaches

OBJECTIVE

This review aims to summarize the current management of type 2 diabetes principles, including oral hypoglycemic agents, types of insulin administration, diet maintenance, and various molecular approaches.

METHODS

A literature search was conducted in different databases such as Scopus, ScienceDirect, Google Scholar, and Web of Science by using the following keywords: type-2 diabetes mellitus (T2DM), first-line and second-line treatment, oral hypoglycemic agents, insulin administration, diet/nutritional therapy, gene and stem cell therapy, and diabetic complications.

RESULTS

The first-line treatment of T2DM includes administering oral hypoglycemic agents (OHAs) and second-line treatment by insulin therapy and some OHAs like Sulfonylurea's (SU). The oral hypoglycemic or oral antidiabetic drugs have the function of lowering glucose in the blood. Insulin therapy is recommended for people with A1C levels > 7.0, and insulin administration is evolved drastically from the syringe, pump, pen, inhalation, insulin jet, and patch. The use of OHAs and insulin therapy during glycemic control has a severe effect on weight gain and other side effects. Hence, diet maintenance (macro and micronutrients) and nutritional therapy guidelines were also reviewed/recommended for safe T2DM management. Besides, the recent progress in molecular approaches that focuses on identifying new targets for T2DM (i.e.) consisting of gene therapy, stem cell therapy, and the modulation of insulin signaling pathways for the regulation of glucose storage and uptake also discussed.

CONCLUSION

The analysis of all these key factors is necessary to develop a potential agent to cure T2DM and suggest that a combination of therapies will pave the way for advanced management of T2DM.

Bone Density and Structure in Overweight Men With and Without Diabetes

OBJECTIVE

Metabolic syndrome (MetS), type 1 diabetes (T1D), and type 2 diabetes, are associated with an increased risk of fractures; however, the impact of obesity on bone deficits in diabetes is unknown. We aimed to compare markers of bone structure, bone density, and bone turnover in non-diabetic overweight men with MetS and overweight men with T1D or T2D.

METHODS AND RESEARCH DESIGN

In this cross-sectional study we included participants from two previously described study cohorts consisting of participants with diabetes and participants with MetS. Participants underwent dual-energy X-ray absorptiometry measuring areal bone mineral density (aBMD) at the hip and lumbar spine, High Resolution peripheral Quantitative (HRpQCT) scan of the tibia and radius and measurement of circulating bone turnover markers. We compared groups with unpaired t test and performed multiple linear regression with adjustment for age, body mass index, and smoking.

RESULTS

We included 33 participants with T1D, 25 participants with T2D, and 34 participants with MetS. Bone turnover markers levels were comparable between T1D and MetS. aBMD at the hip was lower in T1D compared to MetS, also after adjustment. P1NP and Osteocalcin levels were lower among individuals with T2D compared to MetS, whereas aBMD were similar between the groups after multiple adjustments. We observed no difference in volumetric BMD at the tibia or radius between MetS and T1D and T2D, respectively. Participants with T2D had a higher trabecular number and lower trabecular separation compared to individuals with MetS at the tibia, which remained signficant after multiple adjustments.

CONCLUSION

In conclusion, we observed no clinically important differences in bone density or structure between men with T2D, T1D, or MetS. However, men with T2D displayed lower bone turnover compared to MetS highlighting that T2D per se and not obesity, is associated with low bone turnover.

Effects of a Lifestyle Intervention on Bone Turnover in Persons with Type 2 Diabetes: A Post Hoc Analysis of the U-TURN Trial

INTRODUCTION/PURPOSE

The increased risk of fractures with type 2 diabetes (T2D) is suggested to be caused by decreased bone turnover. Current international guidelines recommend lifestyle modifications, including exercise, as first-line treatment for T2D. The aim of this study was to investigate the effects of an exercise-based lifestyle intervention on bone turnover and bone mineral density (BMD) in persons with T2D.

METHODS

Persons with T2D were randomized to either a 12-month lifestyle intervention (n = 64) or standard care (n = 34). The lifestyle intervention included five to six weekly aerobic training sessions, half of them combined with resistance training. Serum markers of bone turnover (osteocalcin, N-terminal propeptide of type-I procollagen, reflecting bone formation, and carboxyterminal collagen I crosslinks, reflecting bone resorption) and BMD (by DXA) were measured before the intervention and at follow-up.

RESULTS

From baseline to follow-up, s-propeptide of type-I procollagen increased by 34% (95% confidence interval [CI], 17%-50%), serum-carboxyterminal collagen I crosslink by 36% (95% CI, 1%-71%), and s-osteocalcin by 31% (95% CI, 11-51%) more in the lifestyle intervention group compared with standard care. Loss of weight and fat mass were the strongest mediators of the increased bone turnover. Bone mineral density was unaffected by the intervention (ΔBMD, 0.1%; 95% CI, -1.1% to 1.2%).

CONCLUSIONS

A 12-month intensive exercise-based lifestyle intervention led to a substantial but balanced increase in bone turnover in persons with T2D. The increased bone turnover combined with a preserved BMD, despite a considerable weight loss, is likely to reflect improved bone health and warrants further studies addressing the impact of exercise on risk of fractures in persons with T2D.

The antidiabetic drug metformin acts on the bone microenvironment to promote myeloma cell adhesion to preosteoblasts and increase myeloma tumour burden in vivo

Multiple myeloma is a haematological malignancy that is dependent upon interactions within the bone microenvironment to drive tumour growth and osteolytic bone disease. Metformin is an anti-diabetic drug that has attracted attention due to its direct antitumor effects, including anti-myeloma properties. However, the impact of the bone microenvironment on the response to metformin in myeloma is unknown. We have employed in vitro and in vivo models to dissect out the direct effects of metformin in bone and the subsequent indirect myeloma response. We demonstrate how metformin treatment of preosteoblasts increases myeloma cell attachment. Metformin-treated preosteoblasts increased osteopontin (OPN) expression that upon silencing, reduced subsequent myeloma cell adherence. Proliferation markers were reduced in myeloma cells cocultured with metformin-treated preosteoblasts. In vivo, mice were treated with metformin for 4 weeks prior to inoculation of 5TGM1 myeloma cells. Metformin-pretreated mice had an increase in tumour burden, associated with an increase in osteolytic bone lesions and elevated OPN expression in the bone marrow. Collectively, we show that metformin increases OPN expression in preosteoblasts, increasing myeloma cell adherence. In vivo, this translates to an unexpected indirect pro-tumourigenic effect of metformin, highlighting the importance of the interdependence between myeloma cells and cells of the bone microenvironment.

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.

Continuous subcutaneous insulin infusion ameliorates bone structures and mechanical properties in type 2 diabetic rats by regulating bone remodeling

Continuous subcutaneous insulin infusion (CSII) is an intensive insulin therapy for patients with type 2 diabetes mellitus (T2DM) who have poor glycemic control, but its effect on T2DM-related bone disorder is unclear. This study described the possible mechanisms by which CSII affects bone remodeling, structures, and mechanical properties in T2DM rats. Herein, male rats (6-week-old) were assigned randomly to 4-week and 8-week administration groups, each of which included healthy control, T2DM, CSII, and Placebo groups. Then, metabolic markers, bone formation and resorption markers in serum and protein expressions of osteoclastogenesis regulators in tibias were detected. Meanwhile, microstructures, nanostructures, macro-mechanical properties, nano-mechanical properties, and mineral compositions in femurs were evaluated. 4-week later, CSII treatment restored circulatory metabolites, bone formation and resorption markers, and osteoclastogenesis regulators, improved certain bone microstructures, decreased matrix mineralization, and increased fracture toughness in T2DM rats. For 8-week group, CSII treatment restored bone formation and resorption markers, osteoclastogenesis regulators, and bone microstructures, besides improved bone mineral compositions and nanostructures, enhanced bone mechanical properties such as fracture toughness, maximum load, elastic modulus, indentation modulus and hardness. Collectively, 8-week CSII treatment is more conducive to ameliorating bone structures and mechanical properties in T2DM rats by regulating bone remodeling compared with 4-week CSII treatment, thus improving whole bone quality and providing valuable information for clinical prevention and treatment of T2DM-related bone disorders.

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.

Hydroxycoumarin Scopoletin Inhibits Bone Loss through Enhancing Induction of Bone Turnover Markers in a Mouse Model of Type 2 Diabetes

Diabetes induces bone deterioration, which leads to increased risk of fracture, osteopenia, and osteoporosis. Thus, diabetes-associated bone fragility has been recognized as a diabetic complication. However, the pathophysiological effects of hyperglycemia on bone turnover remain unclear. Literature evidence demonstrates that anti-diabetic medications increase the risk of fractures in individuals with type 2 diabetes. Scopoletin is a naturally occurring hydroxycoumarin potentially exhibiting anti-inflammatory and antioxidant activities and ameliorating insulin resistance as an anti-diabetic agent. However, little is known regarding the effects of scopoletin on the impairment of bone remodeling that is caused by diabetes. The aim of this study was to identify that scopoletin was capable of inhibiting the impairment of bone remodeling and turnover in a mouse model of type 2 diabetes. Submicromolar scopoletin accelerated the formation TRAP-positive multinucleated osteoclasts (40.0 vs. 105.1%) and actin ring structures impaired by 33 mM glucose. Further, 1–20 μM scopoletin enhanced bone resorption and the induction of matrix-degrading enzymes in diabetic osteoclasts. The oral administration of 10 mg/kg scopoletin elevated serum RANKL/OPG ratio and osteocalcin level reduced in db/db mice along with an increase in BMD by ~6–14%; however, it was not effective in lowering blood glucose and hemoglobin glycation. In addition, the supplementation of scopoletin elevated the formation of trabecular bones and collagen fibers in femoral epiphysis and metaphysis with a thicker epiphyseal plate and cortical bones. Furthermore, 1–20 μM scopoletin enhanced ALP activity (4.39 vs. 7.02 nmol p-nitrophenyl phosphate/min/mg protein) and deposits of mineralized bone nodules in cultured osteoblasts reduced by 33 mM glucose. The treatment of diabetic osteoblasts with scopoletin stimulated the cellular induction of BMP-2 and osteopontin and Runx2 transcription. Accordingly, the administration of scopoletin protected mice from type 2 diabetes-associated bone loss through boosting bone remodeling via the robust induction of bone turnover markers of both osteoclasts and osteoblasts. These findings suggest that scopoletin could be a potential osteoprotective agent for the treatment of diabetes-associated bone loss and fractures.

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.

The role of autophagy in bone homeostasis

Autophagy is an evolutionarily conserved intracellular process and is considered one of the main catabolism pathways. In the process of autophagy, cells are digested nonselectively or selectively to recover nutrients and energy, so it is regarded as an antiaging process. In addition to the essential role of autophagy in cellular homeostasis, autophagy is a stress response mechanism for cell survival. Here, we review recent literature describing the pathway of autophagy and its role in different bone cell types, including osteoblasts, osteoclasts, and osteocytes. Also discussed is the mechanism of autophagy in bone diseases associated with bone homeostasis, including osteoporosis and Paget's disease. Finally, we discuss the application of autophagy regulators in bone diseases. This review aims to introduce autophagy, summarize the understanding of its relevance in bone physiology, and discuss its role and therapeutic potential in the pathogenesis of bone diseases such as osteoporosis.

Association of Insulin Glargine Treatment with Bone Mineral Density in Patients with Type 2 Diabetes Mellitus

PURPOSE

To assess the association of type 2 diabetes mellitus (T2DM) and insulin glargine treatment with bone mineral density (BMD) in Chinese people.

METHODS

This retrospective study included 50 subjects with T2DM: 25 received oral glucose-lowering medication (ORL group), and 25 received oral glucose-lowering medication in combination with insulin glargine injection (CGI group). Thirty non-diabetic control subjects were also included. BMD was measured at lumbar vertebrae 1-4 (L1-L4), spine bone mineral density (sBMD) results summary (L2-L4), femoral neck and trochanter by dual-energy x-ray absorptiometry.

RESULTS

Compared with non-diabetic controls, people with T2DM had significantly lower mean BMD at L2 (1.073±0.120 vs 0.984±0.158), L3 (1.094±0.129 vs 0.991±0.163) and L4 (1.089±0.130 vs 0.982±0.165) (all P<0.05), significantly lower levels of serum calcium (2.02±0.22 vs 2.27±0.17 mmol/L, P<0.05), PTH (24.19±9.71 vs 31.52±8.96 pg/mL, P<0.05), and higher serum phosphate levels (1.43±0.37 vs 1.20±0.15 mmol/L, P<0.05). The CGI group had higher L2, L3 and L4 BMD and sBMD (L2-L4) (P<0.05), higher serum calcium levels (2.19±0.11 vs 1.98±0.20 mmol/L, P<0.05) and lower serum phosphate levels (1.28±0.20 vs 1.58±0.43 mmol/L, P<0.05) versus the ORL group. BMD and serum calcium levels were associated with the application of insulin glargine.

CONCLUSION

These results suggest that insulin glargine may affect bone metabolism in patients diagnosed with T2DM. The study has implications for the selection of hypoglycemic agents for diabetic patients at risk of osteoporosis.

Glucose-Lowering Drugs and Fracture Risk-a Systematic Review

PURPOSE OF REVIEW

Diabetes mellitus (DM) is associated with increased fracture risk. The aim of this systematic review was to examine the effects of different classes of glucose-lowering drugs on fracture risk in patients with type 2 DM. The heterogeneity of the included studies did not allow formal statistical analyses.

RECENT FINDINGS

Sixty studies were included in the review. Metformin, dipeptidylpeptidase-IV inhibitors, glucagon-like peptide-1 receptor agonists, and sodium-glucose cotransporter 2-inhibitors do not appear to increase fracture risk. Results for insulin and sulphonylureas were more disparate, although there may be an increased fracture risk related to hypoglycemia and falls with these treatments. Glitazones were consistently associated with increased fracture risk in women, although the evidence was sparser in men. New glucose-lowering drugs are continuously being developed and better understanding of these is leading to changes in prescription patterns. Our findings warrant continued research on the effects of glucose-lowering drugs on fracture risk, elucidating the class-specific effects of these drugs.

Metformin attenuates trauma-induced heterotopic ossification via inhibition of Bone Morphogenetic Protein signalling

AMP‐activated protein kinase (AMPK) is an intracellular sensor of energy homoeostasis that is activated under energy stress and suppressed in energy surplus. AMPK activation leads to inhibition of anabolic processes that consume ATP. Osteogenic differentiation is a process that highly demands ATP during which AMPK is inhibited. The bone morphogenetic proteins (BMPs) signalling pathway plays an essential role in osteogenic differentiation. The present study examines the inhibitory effect of metformin on BMP signalling, osteogenic differentiation and trauma‐induced heterotopic ossification. Our results showed that metformin inhibited Smad1/5 phosphorylation induced by BMP6 in osteoblast MC3T3‐E1 cells, concurrent with up‐regulation of Smad6, and this effect was attenuated by knockdown of Smad6. Furthermore, we found that metformin suppressed ALP activity and mineralization of the cells, an event that was attenuated by the dominant negative mutant of AMPK and mimicked by its constitutively active mutant. Finally, administration of metformin prevented the trauma‐induced heterotopic ossification in mice. In conjuncture, AMPK activity and Smad6 and Smurf1 expression were enhanced by metformin treatment in the muscle of injured area, concurrently with the reduction of ALK2. Collectively, our study suggests that metformin prevents heterotopic ossification via activation of AMPK and subsequent up‐regulation of Smad6. Therefore, metformin could be a potential therapeutic drug for heterotopic ossification induced by traumatic injury.

High-fat diet effect on periapical lesions and hepatic enzymatic antioxidant in rats

AIMS

To evaluate the effects of a high-fat diet (HFD) on the progression of apical periodontitis (AP), local inflammation, systemic antioxidant status, and blood lipid profile in rats.

MAIN METHODS

Sixteen male Wistar rats were fed a standard diet (SD) or a HFD. At the sixth experimental week, the pulp chambers of the mandibular first molars were exposed to develop AP. A glucose tolerance test was performed the week before euthanasia. At the tenth experimental week, the animals were euthanized and the livers were collected to estimate catalase (CAT) and reduced glutathione (GSH) levels. Blood was acquired for biochemical analysis. The size of AP was estimated from radiographs and described as AP size-to-body weight ratio; inflammatory grade of AP was determined by histological analysis.

KEY FINDINGS

At the end of the experimental period, the rats fed the HFD had 30% less weight (P < 0.0001) and higher blood glucose levels after 30 min of sucrose intake (P < 0.05) than those fed the SD. Animals from the HFD group had lower levels of CAT (P < 0.01), but the same was not observed in the GSH levels. Plasma insulin and total cholesterol were not affected by the diet. The rats fed the HFD presented greater AP than those fed the SD (P < 0.05). However, the local inflammatory infiltrate was similar in both groups.

SIGNIFICANCE

The alterations promoted by the consumption of a HFD were not only observed systemically, but also locally, producing greater AP in rats than a SD.

The Future of Metformin in the Prevention of Diabetes-Related Osteoporosis

As a worldwide aging population is on the rise, osteoporosis (OS) is becoming a global health burden. Therefore, many researchers and health authorities are looking into the potential prevention and treatment of OS. Although previously regarded as two separate pathological processes, diabetes (DM) and OS are now regarded as two conditions that can occur together. It is now believed that OS can develop as a complication of DM. This relationship is further evidenced through a reduction in bone mineral density in type-1 diabetes with a resulting increased risk of fracture. Although bone mineral density in type-2 diabetes mellitus is normal or increased, there is also increased fragility due to decreased bone quality. These abnormal bone qualities tend to occur through the production of reduced bone microvasculature and advanced glycation end product, AGE. Interestingly, one of the most common treatments for DM, metformin (MF), shows a promising result on the protection of diabetes and non-diabetes related bone turnover. It is believed that MF modulates its effect through the adenosine monophosphate-activated protein kinase (AMPK) pathway. Recent data regarded AMPK as a vital mediator of homeostasis. It is involved not only in glucose metabolism but also in osteogenesis. AMPK can directly influence the production of mature and good quality bone by decreasing osteoclasts, increasing osteoblast formation, and enhancing bone mineral deposition. As an activator of AMPK, MF also upregulates osteogenesis. Furthermore, MF can influence osteogenesis through a non-AMPK pathway, such as the fructose 1-6 phosphatase pathway, by reducing glucose levels. While already recognized as a safe and effective treatment for DM, this article discusses whether MF can be used for the prevention and treatment of OS.

The effects of metformin on the bone filling ration around of TiAl6Va4 implants in non diabetic rats

Objectives

In this research it was aimed to that evaluation of the effects of systemic metformin administration on the periimplant bone tissue response of TiAl₆Va₄ implants in experimental rat model.

Materials and method

Firstly TiAl₆Va₄ implants were inserted surgically in the metaphyseal part of the tibial bone and after, the rats were randomly separated into two groups: Controls (CNT) (n = 10) and Metformin group (M) (n = 10). No additional treatment was applied to the controls during the 4-week experimental period. Rats received 40 mg/kg metformin in every day during the four week experimental period in M group. At the end of the 28-day follow-up period, the TiAl₆Va₄ implants with surrounding bone were used for the histopathologic analysis. To analysis of the datas between M and CNT Student-T Test was used.

Result

Periimplant bone tissue filling ratios (%) were detected higher in M group compared with the CNT (P < 0.05).

Conclusion

Systemic administration of metformin may increases titanium implant osseointegration in non-diabetic rats.

Effect of Metformin vs. Placebo in Combination with Insulin Analogues on Bone Markers P1NP and CTX in Patients with Type 2 Diabetes Mellitus

Preclinical studies have shown a potential osteoanabolic effect of metformin but human studies of how metformin affects bone turnover are few. A post hoc sub-study analysis of an 18-month multicenter, placebo-controlled, double-blinded trial in type 2 diabetes mellitus (T2DM), randomizing participants to metformin versus placebo both in combination with different insulin analogue regimens (Metformin + Insulin vs. Placebo + Insulin). Patients were not treatment naive at baseline, 83% had received metformin, 69% had received insulin, 57.5% had received the combination of metformin and insulin before entering the study. Bone formation and resorption were assessed by measuring, N-terminal propeptide of type I procollagen (P1NP) and C-terminal telopeptide of type I collagen (CTX) at baseline and end of study. The influence of gender, age, smoking, body mass index (BMI), T2DM duration, glycosylated hemoglobin A1c (HbA1c), c-reactive protein (CRP) and insulin dosage was also included in the analyses. The levels of bone formation marker P1NP and bone resorption marker CTX increased significantly in both groups during the trial. P1NP increased less in the Metformin + Insulin compared to the placebo + insulin group (p = 0.001) (between group difference change), while the increases in CTX levels (p = 0.11) were not different. CRP was inversely associated (p = 0.012) and insulin dosage (p = 0.011) was positively related with change in P1NP levels. BMI (p = 0.002) and HbA1C (p = 0.037) were inversely associated with change in CTX levels. During 18 months of treatment with metformin or placebo, both in combination with insulin, bone turnover increased in both groups. But the pattern was different as the bone formation marker (P1NP) increased less during Metformin + Insulin treatment, while change in bone resorption (CTX) was not significantly different between the two groups.

Chitosan Coating of TiO2 Nanotube Arrays for Improved Metformin Release and Osteoblast Differentiation

Background

Ineffective integration has been recognized as one of the major causes of early orthopedic failure of titanium-based implants. One strategy to address this problem is to develop modified titanium surfaces that promote osteoblast differentiation. This study explored titanium surfaces modified with TiO2 nanotubes (TiO2 NTs) capable of localized drug delivery into bone and enhanced osteoblast cell differentiation.

Materials and Methods

Briefly, TiO2 NTs were subjected to anodic oxidation and loaded with Metformin, a widely used diabetes drug. To create surfaces with sustainable drug-eluting characteristics, TiO2 NTs were spin coated with a thin layer of chitosan. The surfaces were characterized via scanning electron microscopy, atomic force microscopy, and contact angle measurements. The surfaces were then exposed to mesenchymal bone marrow stem cells (MSCs) to evaluate cell adhesion, growth, differentiation, and morphology on the modified surfaces.

Results

A noticeable increase in drug release time (3 days vs 20 days) and a decrease in burst release characteristics (85% to 7%) was observed in coated samples as compared to uncoated samples, respectively. Chitosan-coated TiO2 NTs exhibited a considerable enhancement in cell adhesion, proliferation, and genetic expression of type I collagen, and alkaline phosphatase activity as compared to uncoated TiO2 NTs.

Conclusion

TiO2 NT surfaces with a chitosan coating are capable of delivering Metformin to a bone site over a sustained period of time with the potential to enhance MSCs cell attachment, proliferation, and differentiation.

Intelligent therapeutic decision support for 30 days readmission of diabetic patients with different comorbidities

The significance of medication therapy in managing comorbid diabetes is vital for maintaining the overall wellness of patients and reducing the cost of healthcare. Thus, using appropriate medication or medication combinations will be necessary for improved person-centred care and reduce complications associated with diagnosis and treatment. This study explains an intelligent decision support framework for managing 30 days unplanned readmission (30_URD) of comorbid diabetes using the Random Forest (RF) algorithm and Bayesian Network (BN) model. After the analysis of the medical records of 101,756 de-identified diabetic patients treated with 21 medications for 28 comorbidity combinations, the optimal medications for minimizing the likelihood of early readmissions were determined. This approach can help for identifying and managing most vulnerable patients thereby giving room to enhance post-discharge monitoring through clinical specialist supports to build critical-self management skills that will minimize the cost of diabetes care.

Skeletal effects of plyometric exercise and metformin in ovariectomized rats

Estrogen deficiency causes bone loss and skeletal muscle dysfunction, and attenuates the musculoskeletal effects of exercise. The anti-diabetic drug metformin has been suggested to promote beneficial skeletal effects. To explore whether metformin can improve musculoskeletal training response during estrogen deficiency, we investigated the skeletal effects of plyometric exercise and metformin, in an ovarectomized (OVX) rat model of osteoporosis. Female Sprague Dawley rats, 12 weeks of age, rats were allocated to a sham-operated group (Sham), and four OVX groups; metformin (OVX-Met), exercise (OVX-Ex), combined metformin and exercise (OVX-MetEx) and a control group (OVX-Ctr), n = 12/group. Dual X-ray absorptiometry, micro computed tomography, fracture toughness testing, histomorphometry and plasma analyses were performed to explore skeletal effects. All intervention groups exhibited a higher gain in femoral bone mineral density (BMD) than OVX-Ctr (p < .01). The combined intervention also resulted in a higher gain in femoral and spine BMD compared to OVX-Met (p < .01). Both exercise groups displayed improved microarchitecture, including both cortical and trabecular parameters (p < .05). This was most evident in the OVX-MetEx group where several indices were at sham level or superior to OVX-Ctr (p < .05). The OVX-MetEx group also exhibited an enhanced toughening effect compared to the other OVX groups (p < .05). The beneficial skeletal effects seemed to be mediated by inhibition of bone resorption and stimulation of bone formation. The training response (i.e. jumping height) was also greater in the metformin treated rats compared to OVX-Ex (p < .01), indicating a performance-enhancing effect of metformin. Both exercise groups displayed higher lean mass than OVX-Ctr (p < .05). In conclusion, the combination of plyometric exercise and metformin improved trabecular microarchitecture and bone material properties relative to OVX controls. However, no additive effect of the combined intervention was observed compared to exercise alone.

Antidiabetic and antiosteoporotic pharmacotherapies for prevention and treatment of type 2 diabetes-induced bone disease: protocol for two network meta-analyses

INTRODUCTION

Patients with type 2 diabetes mellitus (T2DM) are at risk for a variety of severe debilitating effects. One of the most serious complications experienced by patients with T2DM are skeletal diseases caused by changes in the bone microenvironment. As a result, patients with T2DM are at risk for higher prevalence of fragility fractures. There are a variety of treatments available for counteracting this effect. Some antidiabetic medications, such as metformin, have been shown to have a positive effect on bone health without the addition of additional drugs into patients' treatment plans. Chinese randomised controlled trial (RCT) studies have also proposed antiosteoporotic pharmacotherapies as a viable alternative treatment strategy. Previous network meta-analyses (NMAs) and meta-analyses regarding this topic did not include all available RCT trials, or only performed pairwise comparisons. We present a protocol for a two-part NMA that incorporates all available RCT data to provide the most comprehensive ranking of antidiabetics (part I) and antiosteoporotic (part II) pharmacotherapies in terms of their ability to decrease fracture incidences, increase bone mineral density (BMD) and improve indications of bone turnover markers (BTMs) in adult patients with T2DM.

METHODS AND ANALYSIS

We will search Medical Literature Analysis and Retrieval System Online, Excerpta Medica Database, PubMed, Web of Science, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Controlled Trials and Chinese literature sources (China National Knowledge Infrastructure, Chongqing VIP Information, Wanfang Data, Wanfang Med Online) for RCTs, which fit our criteria. We will include adult patients with T2DM who have taken antidiabetics (part I) or antiosteoporotic (part II) therapies with relevant outcome measures in our study. We will perform title/abstract and full-text screening as well as data extraction in duplicate. Risk of bias will be evaluated in duplicate for each study, and the quality of evidence will be examined using Confidence in Network Meta-Analysis in accordance to the Grading of Recommendations Assessment, Development and Evaluation framework. We will use R and gemtc to perform the NMA. We will report changes in BMD and BTMs in either weighted or standardised mean difference, and we will report fracture incidences as ORs. We will use the Surface Under the Cumulative Ranking Curve scores to provide numerical estimates of the rankings of interventions.

ETHICS AND DISSEMINATION

The study will not require ethics approval. The findings of the two-part NMA will be disseminated in peer-reviewed journals and presented at conferences. We aim to produce the most comprehensive quantitative analysis regarding the management of T2DM bone disease. Our analysis should be able to provide physicians and patients with up-to-date recommendations for antidiabetic medications and antiosteoporotic pharmacotherapies for maintaining bone health in patients with T2DM.

PROSPERO REGISTRATION NUMBER

CRD42019139320.

Pathophysiology and Management of Type 2 Diabetes Mellitus Bone Fragility

Individuals with type 2 diabetes mellitus (T2DM) have an increased risk of bone fragility fractures compared to nondiabetic subjects. This increased fracture risk may occur despite normal or even increased values of bone mineral density (BMD), and poor bone quality is suggested to contribute to skeletal fragility in this population. These concepts explain why the only evaluation of BMD could not be considered an adequate tool for evaluating the risk of fracture in the individual T2DM patient. Unfortunately, nowadays, the bone quality could not be reliably evaluated in the routine clinical practice. On the other hand, getting further insight on the pathogenesis of T2DM-related bone fragility could consent to ameliorate both the detection of the patients at risk for fracture and their appropriate treatment. The pathophysiological mechanisms underlying the increased risk of fragility fractures in a T2DM population are complex. Indeed, in T2DM, bone health is negatively affected by several factors, such as inflammatory cytokines, muscle-derived hormones, incretins, hydrogen sulfide (H2S) production and cortisol secretion, peripheral activation, and sensitivity. All these factors may alter bone formation and resorption, collagen formation, and bone marrow adiposity, ultimately leading to reduced bone strength. Additional factors such as hypoglycemia and the consequent increased propensity for falls and the direct effects on bone and mineral metabolism of certain antidiabetic medications may contribute to the increased fracture risk in this population. The purpose of this review is to summarize the literature evidence that faces the pathophysiological mechanisms underlying bone fragility in T2DM patients.

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.

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.

The use of metformin, insulin, sulphonylureas, and thiazolidinediones and the risk of fracture: Systematic review and meta-analysis of observational studies

Certain glucose-lowering medications have been implicated in the risk of fracture. While there is convincing evidence from randomized controlled trials (RCTs) that thiazolidinedione use is associated with a higher risk of fracture, the effects of metformin, insulin, and sulphonylureas on the risk of fracture remain equivocal because these medications are not generally investigated in RCTs. A meta-analysis of observational studies to provide further insights into the association between the use of metformin, insulin, sulphonylureas, or thiazolidinediones and the risk of fracture was performed. PubMed and Web of Science databases were searched to identify relevant observational studies. A random effects model was used to estimate the summary relative risks (RRs) with 95% confidence intervals (CIs). The use of insulin (RR 1.49, 95% CI 1.29, 1.73; n = 23 studies), sulphonylureas (RR 1.30, 95% CI 1.18, 1.43; n = 10), and thiazolidinediones (RR 1.24, 95% CI 1.13, 1.35; n = 14) was associated with an increased risk of fracture, whereas the use of metformin was associated with a reduced risk of fracture (RR 0.86, 95% CI 0.75, 0.99; n = 12). Regarding types of thiazolidinediones, both pioglitazone (RR 1.38, 95% CI 1.23, 1.54; n = 5) and rosiglitazone (RR 1.34, 95% CI 1.14, 1.58; n = 5) were positively associated with the risk of fracture. In summary, there is compelling evidence to discourage the use of thiazolidinediones in individuals with an increased risk of fracture, whereas metformin appears to have a good safety profile for the risk of fracture. The reduced risk of fracture with metformin could possibly be due to the reduced overall risk of fracture among metformin users, as this medication is typically prescribed in the early stages of type 2 diabetes mellitus. The use of insulin or sulphonylureas may increase fracture risk; this risk is most likely attributed to an increased risk of hypoglycaemia-induced falls. Further confirmation by additional RCTs is required to determine whether the observed association between the use of metformin, insulin, or sulphonylureas and the risk of fracture is due to treatment with these medications or confounding factors.

Relationships of social support, health-promoting lifestyles, glycemic control, and bone turnover among adults with type 2 diabetes

AIM

There is increasing evidence that hyperglycemia, oxidative stress, and the accumulation of advanced glycation end products in type 2 diabetes mellitus (T2DM) can lead to the deterioration of bone remodeling. The purpose of this study was to explore relationships of social support, health-promoting lifestyles, glycated hemoglobin (HbA1c) levels, and serum bone turnover markers (BTMs, including procollagen type I amino-terminal propeptide [PINP] and β-isomerised carboxy-terminal cross-linking telopeptide of type I collagen [β-CTX]) among individuals with T2DM.

METHODS

A total of 175 subjects were recruited by convenience sampling and divided into three groups based on their HbA1c levels. Statistical strategies of Spearman's correlation coefficient and multiple linear regression were used in this cross-sectional study.

RESULTS

There was a positive association between PINP and β-CTX, whereas the HbA1c level was inversely correlated with BTMs. Moreover, scores of both PINP and β-CTX were different in genders, males having lower levels of BTMs than females after adjustment for weight. Furthermore, both social support and health-promoting lifestyles were negatively correlated with HbA1c levels, whereas they did not significantly relate to declines in PINP and β-CTX.

CONCLUSION

High HbA1c levels detrimentally influence bone formation and bone resorption, and males with T2DM might be more susceptible to osteoporosis because of their relatively lower levels of BTMs. However, social support and health-promoting lifestyles could contribute to better glycemic control.

Protective influence of rosiglitazone against time-dependent deterioration of boar spermatozoa preserved at 17°C

Spermatozoa are highly specialized cells, and energy metabolism plays an important role in modulating sperm viability and function. Rosiglitazone is an antidiabetic drug in the thiazolidinedione class that regulates metabolic flexibility and glucose uptake in various cell types, but its effects on boar sperm metabolism are unknown. In this study, we investigated the potential effect of rosiglitazone against time-dependent deterioration of boar spermatozoa during liquid preservation at 17°C. Freshly ejaculated semen was diluted with Beltsville Thawing Solution (BTS) containing different concentrations of rosiglitazone, and the motility, membrane and acrosome integrity of sperm were detected. Besides, we measured glucose uptake capacity, l-lactate production level, mitochondrial membrane potential, adenosine triphosphate (ATP) content and mitochondrial reactive oxygen species (mROS) production of sperm after boar semen had been incubated with or without rosiglitazone, iodoacetate (glycolysis inhibitor) and rotenone (electron transport chain inhibitor) for 5 days. The addition of rosiglitazone significantly enhanced sperm quality and had a strong protective effect on the sperm membrane and acrosome integrity during storage. BTS containing 50 μM rosiglitazone maintained the total motility of liquid-preserved sperm above 60% for 7 days. Rosiglitazone improved sperm quality by regulating energy metabolism manner of preserved sperm, protected the sperm mitochondrial membrane potential, enhanced sperm ATP production and in the meanwhile reduced mROS through enhancing glycolysis but not oxidative phosphorylation. The data suggested the practical feasibility of using rosiglitazone for improving boar spermatozoa quality during semen preservation.

Diabetes and bone

Bone disease is a serious complication to diabetes. Patients with type 1 diabetes (T1D) and type 2 diabetes (T2D) suffer from an increased risk of fracture, most notably at the hip, compared with patients without diabetes. Confounders such as patient sex, age, body mass index, blood glucose status, fall risk, and diabetes medications may influence the fracture risk. Different underlying mechanisms contribute to bone disease in patients with diabetes. Bone quality is affected by low bone turnover in T1D and T2D, and furthermore, incorporation of advanced glycation end-products, changes in the incretin hormone response, and microvascular complications contribute to impaired bone quality and increased fracture risk. Diagnosis of bone disease in patients with diabetes is a challenge as current methods for fracture prediction such as bone mineral density T-score and fracture risk assessment tools underestimate fracture risk for patients with T1D and T2D. This review focuses on bone disease and fracture risk in patients with diabetes regarding epidemiology, underlying disease mechanisms, and diagnostic methods, and we also provide considerations regarding the management of diabetes patients with bone disease in terms of an intervention threshold and different treatments.

Association between glycosylated hemoglobin A1c and bone biochemical markers in type 2 diabetic postmenopausal women: a cross-sectional study

BACKGROUND

type 2 diabetes mellitus (T2DM) is a complicated disease that can affect bone health, but the change in bone biochemical markers caused by T2DM was controversial, so the aim of this study was to investigate whether there was a discrepancy in the levels of bone biochemical markers between postmenopausal women with T2DM and non-diabetic women and to explore the relationship between the level of glycosylated hemoglobin A1c (HbA1c) and bone biochemical markers in these subjects.

METHODS

A total of 237 type 2 diabetic postmenopausal women visiting the First Affiliated Hospital of Anhui Medical University from January 2017 to October 2018 and 93 healthy postmenopausal women were retrospectively enrolled. The differences in the levels of bone biochemical markers between patients and controls were analyzed by one-way ANOVA or chi-square test. The relationship between HbA1c and bone biochemical markers was analyzed by multivariate regression, forest plot and fitted curve.

RESULTS

Bone formation markers including N-MID osteocalcin and procollagen type 1 amino-terminal pro-peptide (PINP) were decreased in postmenopausal women with T2DM compared to controls (17.42 ± 9.50 vs 23.67 ± 7.58, p < 0.001; 48.47 ± 27.27 vs 65.86 ± 21.06, p < 0.001, respectively), but the bone resorption markers β-crossLaps (β-CTX) was no difference between the two groups (0.57 ± 0.28 vs 0.55 ± 0.21, p = 0.868). Multivariate regression showed that HbA1c was inversely associated with N-MID osteocalcin and PINP after adjusting for age, BMI, menopause^'s years, diabetic duration, TC, TG, HDL-c, LDL-c, creatinine, UA and eGFR. The adjusted coefficients for N-MID osteocalcin and PINP per 1% HbA1c decrease were - 0.71 (- 1.19, - 0.22) and - 1.79 (- 3.30, - 0.28), respectively. A segmentation effect was seen in the fitted curve between HbA1c and β-CTX with an inflection point at 7.4% of HbA1c, the highest quartile of β-CTX (> = 0.74 ng/ml) showed a significantly negative with HbA1c. No significant association was seen between HbA1c and other biochemical markers.

CONCLUSIONS

Our study found that bone formation was inhibited in postmenopausal women with T2DM, but bone resorption was not affected, and poor glycemic control was related to lower levels of bone formation, may increase the risk of bone fracture in postmenopausal women with T2DM.

Update on the impact of type 2 diabetes mellitus on bone metabolism and material properties

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide, especially as a result of our aging society, high caloric intake and sedentary lifestyle. Besides the well-known complications of T2DM on the cardiovascular system, the eyes, kidneys and nerves, bone strength is also impaired in diabetic patients. Patients with T2DM have a 40-70% increased risk for fractures, despite having a normal to increased bone mineral density, suggesting that other factors besides bone quantity must account for increased bone fragility. This review summarizes the current knowledge on the complex effects of T2DM on bone including effects on bone cells, bone material properties and other endocrine systems that subsequently affect bone, discusses the effects of T2DM medications on bone and concludes with a model identifying factors that may contribute to poor bone quality and increased bone fragility in T2DM.

Skeletal Fragility in Type 2 Diabetes Mellitus

Type 2 diabetes (T2D) is associated with an increased risk of fracture, which has been reported in several epidemiological studies. However, bone mineral density in T2D is increased and underestimates the fracture risk. Common risk factors for fracture do not fully explain the increased fracture risk observed in patients with T2D. We propose that the pathogenesis of increased fracture risk in T2D is due to low bone turnover caused by osteocyte dysfunction resulting in bone microcracks and fractures. Increased levels of sclerostin may mediate the low bone turnover and may be a novel marker of increased fracture risk, although further research is needed. An impaired incretin response in T2D may also affect bone turnover. Accumulation of advanced glycosylation endproducts may also impair bone strength. Concerning antidiabetic medication, the glitazones are detrimental to bone health and associated with increased fracture risk, and the sulphonylureas may increase fracture risk by causing hypoglycemia. So far, the results on the effect of other antidiabetics are ambiguous. No specific guideline for the management of bone disease in T2D is available and current evidence on the effects of antiosteoporotic medication in T2D is sparse. The aim of this review is to collate current evidence of the pathogenesis, detection and treatment of diabetic bone disease.

Clinical utility of bone markers in various diseases

Measurements of bone markers (BMs) in peripheral blood or urine are a pivotal part of bone research within modern clinical medicine. In recent years the use of BMs increased substantially as they can be useful either to diagnose bone (related) disease and to follow its natural history, but also to monitor the effects of interventions. However, the use of BMs is still complicated mainly due to (pre)analytical variability of these substances, limited accessibility of assays, variable cut-off values in different countries and laboratories and heterogeneous results with regard to clinical implications of measuring BMs in several studies. This review will provide the clinician with a practical guide, based on current evidence, in which circumstances to test which bone markers for optimal diagnostic purposes, in order to improve patient care in different areas of bone diseases including Paget's disease, primary osteoporosis, tumor induced osteomalacia, hypophosphatemic rickets, van Buchem disease, chronic kidney disease, rheumatoid arthritis, neoplasma/multiple myeloma, type 2 diabetes mellitus and primary hyperparathyroidism. The clinician should consider fasting state, recent fractures, aging, menopausal status, concomitant liver and kidney disease when ordering and interpreting BM measurements as these factors might result in misleading BM concentrations. We found that BMs are clearly useful in the current diagnosis of tumor induced osteomalacia, van Buchem disease, Paget's disease and hypophosphatemic rickets. In addition, BMs are useful to monitor disease activity in chronic kidney disease, Paget's disease and are useful to monitor treatment adherence in osteoporosis.