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

Risk factors for bone fractures in type 2 diabetes and the impact of once-weekly exenatide: insights from an EXSCEL post-hoc analysis

AIMS

We investigated bone fracture predictors in people with T2D enrolled in the EXenatide Study of Cardiovascular Event Lowering (EXSCEL) and evaluated the effects of once-weekly exenatide (EQW) on incident bone fractures.

METHODS

EXSCEL randomised 14,752 people to EQW 2 mg or placebo with a median follow-up of 3.2 years. In this post-hoc analysis, baseline features associated with incident bone fractures were evaluated with multivariable Cox proportional hazard regression models, accounting for age and sex as confounders. Incidence rates were compared between study arms, and time-to-event analyses performed using Cox-proportional hazard models.

RESULTS

The primary outcome occurred in 168 (1.1 %) participants. The presence of neuropathy at baseline was associated with a 50 % higher risk (hazard ratio [HR] 1.50, 95 % confidence interval [CI] 1.10-2.05, P = 0.010) of incident bone fractures, while taking metformin at baseline was associated with a 47 % lower risk (HR 0.53, 95 %CI 0.39-0.73, P < 0.001). Incidence rates of bone fractures were similar in the EQW group and in the placebo group (HR 1.11, 95 %CI 0.82-1.51, P = 0.49).

CONCLUSIONS

Bone fractures in people with T2D occur more frequently in those with diabetic neuropathy, but less frequently in those taking metformin. No evidence was seen of any impact of EQW treatment on bone fractures.

The effect of antidiabetic drugs on bone metabolism: a concise review

Diabetes mellitus (DM) is a complex metabolic disorder characterized by chronic hyperglycemia, which derives from either insufficient insulin production [type 1 diabetes mellitus (T1DM)] or both impaired insulin sensitivity along with inadequate insulin production [type 2 diabetes mellitus (T2DM)] and affects millions of people worldwide. In addition to the adverse effects of DM on classical target organs and tissues, skeletal health can also be adversely affected. There is considerable evidence linking DM with osteoporosis. The fracture risk in patients with DM differs upon the type of diabetes, and it appears to be related to the type of anti-diabetic treatment. Antidiabetic drugs may have various effects on bone health. Most of them have neutral or even favorable effects on bone metabolism with the exception of thiazolidinediones (TZDs). Some studies suggest that TZDs may have negative impact on bone health by decreasing bone formation and increasing the fracture risk. There are also limited studies linking the use of canagliflozin, a Sodium-glucose contransporter-2 inhibitor (SGLT2i), with increased fracture risk. On the other hand, therapies that are based on incretin effect, like Dipeptidyl peptidase-4 inhibitors (DPP-4i) and Glucagon-like peptide-1 receptor agonizts (GLP-1RAs) might have positive effects on bone health by promoting bone formation. Herein we review the impact of antidiabetic drugs on bone health, highlighting the potential benefits and risks associated with these medications in an attempt to contribute to the development of personalized treatment strategies for individuals with DM.

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.

Hypoglycemic agents and bone health; an umbrella systematic review of the clinical trials' meta-analysis studies

BACKGROUND

No clear consensus exists regarding the safest anti-diabetic drugs with the least adverse events on bone health. This umbrella systematic review therefore aims to assess the published meta-analysis studies of randomized controlled trials (RCTs) conducted in this field.

METHODS

All relevant meta-analysis studies of RCTs assessing the effects of anti-diabetic agents on bone health in patients with diabetes mellitus (DM) were collected in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). English articles published until 15 March 2023 were collected through the search of Cochrane Library, Scopus, ISI Web of Sciences, PubMed, and Embase using the terms "Diabetes mellitus", "anti-diabetic drugs", "Bone biomarker", "Bone fracture, "Bone mineral density" and their equivalents. The methodological and evidence quality assessments were performed for all included studies.

RESULTS

From among 2220 potentially eligible studies, 71 meta-analyses on diabetic patients were included. Sodium-glucose cotransporter-2 inhibitors (SGLT-is) showed no or equivalent effect on the risk of fracture. Dipeptidyl peptidase-4 inhibitors (DPP-4is) and Glucagon-like peptide-1 receptor agonists (GLP-1Ras) were reported to have controversial effects on bone fracture, with some RCTs pointing out the bone protective effects of certain members of these two medication classes. Thiazolidinediones (TZDs) were linked with increased fracture risk as well as higher concentrations of C-terminal telopeptide of type I collagen (CTx), a bone resorption marker.

CONCLUSION

The present systematic umbrella review observed varied results on the association between the use of anti-diabetic drugs and DM-related fracture risk. The clinical efficacy of various anti-diabetic drugs, therefore, should be weighed against their risks and benefits in each patient.

Bone effects of metformin monotherapy and its combination with teneligliptin: A 12-week follow-up study in patients with type 2 diabetes mellitus

AIMS

The skeletal effects of metformin monotherapy and in combination with teneligliptin are not well illustrated in patients with T2DM. To address this, we conducted an observational study to evaluate the effect of these oral hypoglycemic agents on bone turnover markers.

METHODS

We recruited patients with T2DM and first-ever prescribed metformin monotherapy or metformin combined with teneligliptin from a tertiary care teaching hospital in New Delhi, North India. Both bone formation and resorption markers, IL-6 and PTD, were estimated along with glycated hemoglobin at baseline and 12 weeks.

RESULTS

In both groups, hbA1c levels decreased significantly from baseline to 12 weeks. In the metformin-treated group, β-CTX, sRANKL, IL-6, and PTD decreased significantly, and no significant changes were observed in P1NP, OC, BAP, or OPG at 12 weeks from baseline. In the metformin + teneligliptin group, BAP, β-CTX, sRANKL, IL-6, and PTD decreased significantly, and no significant changes were observed in P1NP, OC, or OPG after 12 weeks from baseline.

CONCLUSIONS

The positive bone outcome of metformin or teneligliptin was linked to bone resorption rather than bone formation and was independent of changes in HbA1c or PTD. However, these results must be confirmed with well-designed RCTs with more extended follow-up periods.

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.

Reduced High-Density Lipoprotein Cholesterol Is an Independent Determinant of Altered Bone Quality in Women with Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is associated with an increased fracture risk. Our study aimed to explore differences in bone alterations between T2DM women and controls and to assess clinical predictors of bone impairment in T2DM. For this observational case control study, we recruited 126 T2DM female patients and 117 non-diabetic, age- and BMI-comparable women, who underwent clinical examination, routine biochemistry and dual-energy X-ray absorptiometry (DXA) scans for bone mineral density (BMD) and trabecular bone score (TBS) assessment-derived indexes. These were correlated to metabolic parameters, such as glycemic control and lipid profile, by bivariate analyses, and significant variables were entered in multivariate adjusted models to detect independent determinants of altered bone status in diabetes. The T2DM patients were less represented in the normal bone category compared with controls (5% vs. 12%; p = 0.04); T2DM was associated with low TBS (OR: 2.47, C.I. 95%: 1.19–5.16, p = 0.016) in a regression model adjusted for age, menopausal status and BMI. In women with T2DM, TBS directly correlated with plasma high-density lipoprotein cholesterol (HDL-c) (p = 0.029) and vitamin D (p = 0.017) levels. An inverse association was observed with menopausal status (p < 0.001), metabolic syndrome (p = 0.014), BMI (p = 0.005), and waist circumference (p < 0.001). In the multivariate regression analysis, lower HDL-c represented the main predictor of altered bone quality in T2DM, regardless of age, menopausal status, BMI, waist circumference, statin treatment, physical activity, and vitamin D (p = 0.029; R2 = 0.47), which likely underlies common pathways between metabolic disease and bone health in diabetes.