Diabetes mellitus and bone health: epidemiology, etiology and implications for fracture risk stratification

Risk of fracture incidence in prostate cancer survivors: a nationwide cohort study in South Korea

PURPOSE

We analyzed the risk of fracture in prostate cancer (PC) survivors compared to that in the general population in South Korea and according to the primary treatment.

METHODS

From 2007 to 2013, a total of 41,733 PC survivors newly diagnosed with PC in South Korea were identified and matched to non-cancer controls. Cox proportional hazards regression analysis was performed to determine the relative risk of fracture.

RESULTS

Compared to the matched controls, PC survivors had a higher risk of fracture (adjusted hazard ratio (aHR) 1.39; 95% confidence interval (CI) 1.33-1.45). Compared to the matched controls, the active surveillance/watchful waiting and radiotherapy group showed a similar risk of fracture (aHR 1.08; 95% CI 0.98-1.20, and aHR 1.04; 95% CI 0.63-1.73, respectively). PC survivors who underwent surgery showed a lower risk of fracture (aHR 0.89; 95% CI 0.82-0.96), while those who underwent surgery + androgen deprivation therapy (ADT) (aHR 1.41; 95% CI 1.26-1.57), radiotherapy + ADT (aHR 1.86; 95% CI 1.50-2.32), and only ADT (aHR 1.92; 95% CI 1.82-2.02) showed a higher risk of fracture than the control group.

CONCLUSION

The risk of fracture differed according to the primary treatment method for PC; survivors who underwent surgery had a lower risk of fracture compared to that of the general population. However, PC survivors treated with ADT showed a higher risk of fracture than the other PC treatment groups or the general population. Therefore, more attention and preventive bone care are required for PC survivors who receive ADT.

Multifactorial effects of hyperglycaemia, hyperinsulinemia and inflammation on bone remodelling in type 2 diabetes mellitus

Bones undergo continuous cycles of bone remodelling that rely on the balance between bone formation and resorption. This balance allows the bone to adapt to changes in mechanical loads and repair microdamages. However, this balance is susceptible to upset in various conditions, leading to impaired bone remodelling and abnormal bones. This is usually indicated by abnormal bone mineral density (BMD), an indicator of bone strength. Despite this, patients with type 2 diabetes mellitus (T2DM) exhibit normal to high BMD, yet still suffer from an increased risk of fractures. The activity of the bone cells is also altered as indicated by the reduced levels of bone turnover markers in T2DM observed in the circulation. The underlying mechanisms behind these skeletal outcomes in patients with T2DM remain unclear. This review summarises recent findings regarding inflammatory cytokine factors associated with T2DM to understand the mechanisms involved and considers potential therapeutic interventions.

Blockade of the colony-stimulating factor-1 receptor reverses bone loss in osteoporosis mouse models

BACKGROUND

Mice lacking either colony-stimulating factor-1 (CSF-1) or its receptor, CSF-1R, display osteopetrosis. Accordingly, genetic deletion or pharmacological blockade of CSF-1 prevents the bone loss associated with estrogen deficiency. However, the role of CSF-1R in osteoporosis models of type-1 diabetes (T1D) and ovariectomy (OVX) has not been examined. Thus, we evaluated whether CSF-1R blockade would relieve the bone loss in a model of primary osteoporosis (female mice with OVX) and a model of secondary osteoporosis (female with T1D) using micro-computed tomography.

METHODS

Female ICR mice at 10 weeks underwent OVX or received five daily administrations of streptozotocin (ip, 50 mg/kg) to induce T1D. Four weeks after OVX and 14 weeks after first injection of streptozotocin, mice received an anti-CSF-1R (2G2) antibody (10 mg/kg, ip; once/week for 6 weeks) or vehicle. At the last day of antibody administration, mice were sacrificed and femur and tibia were harvested for micro-computed tomography analysis.

RESULTS

Mice with OVX had a significant loss of trabecular bone at the distal femoral and proximal tibial metaphysis. Chronic treatment with anti-CSF-1R significantly reversed the trabecular bone loss at these anatomical sites. Streptozotocin-induced T1D resulted in significant loss of trabecular bone at the femoral neck and cortical bone at the femoral mid-diaphysis. Chronic treatment with anti-CSF-1R antibody significantly reversed the bone loss observed in mice with T1D.

CONCLUSION

Our results demonstrate that blockade of CSF-1R signaling reverses bone loss in two different mouse models of osteoporosis.

Prevalence and risk factors for osteoporotic fracture among adults with comorbidities in Al-Ahsaa, Saudi Arabia

Background and Aims

Little is known about the prevalence of osteoporotic fracture, its sociodemographic correlates, and its comorbid conditions among the adult population of the Kingdome of Saudi Arabia (KSA). Hence, the present work aimed to assess the prevalence of adults at high risk of osteoporotic fracture in the presence of its known risk factors. As well, to determine the most commonly associated comorbidities of osteoporosis in Saudi Arabia.

Methods

A cross-sectional study was performed among 518 Saudi adults aged over 45 years in Al-Ahsaa city, KSA. The Arabic version of the fracture risk assessment FRAX without bone mineral density (BMD) was presented in an online questionnaire.

Results

The 10-year risk for major osteoporotic fracture was found in 50.81% of the participants; 23.48% of them were at high risk and 25.71% at moderate risk. Also, 26.27% of the respondents were at high risk of hip fracture. Significant correlates of osteoporotic fractures included female gender (P = 0.003), old age (P = 0.000), age at menopause (P = 0.000), low body mass index (BMI; P = 0.000), previous fracture (P = 0.000), alcohol consumption (P = 0.000), positive family history (P = 0.000), corticosteroids (P = 0.000), rheumatoid arthritis (P = 0.000), thyroid hyperactivity (P = 0.000), gonadal insufficiency (P = 0.000), chronic liver disease (P = 0.000), nutritional, or gestational disease (P = 0.000).

Conclusion

More than a third of the surveyed population had osteoporosis, which was associated with many sociodemographic and clinical characteristics. Therefore, early interventions for osteoporosis and the prevention of other comorbidities may improve the outcome of osteoporosis.

Knowledge, Perceptions and Concerns of Diabetes -Associated Complications Among Individuals Living with Type 1 and Type 2 Diabetes Mellitus

The purpose of this study was to investigate the knowledge, perceptions and concerns of individuals living with diabetes mellitus regarding the disorder and its associated long-term health complications. Individuals living with type 1 (N = 110) and type 2 (N = 100) diabetes were surveyed at the Diabetes Centre at University Hospital Galway (Ireland). A questionnaire was used to record respondent's perceptions and concerns about living with diabetes and developing associated long-term health complications, especially diabetes-induced osteopathy. Participants' responses revealed a variety of perspectives. Individuals with type 1 diabetes had a deeper understanding of the aetiology of diabetes and were more concerned about its complications than individuals with type 2 diabetes. The most recognized complications identified by the participants were retinopathy (92% type 1; 83% type 2), amputations (80% type 1; 70% type 2) and nephropathy (83% type 1; 63% type 2). Diabetes-related osteopathy was under-recognized, with 37% (type 1) and 23% (type 2) of respondents identifying bone fractures as a diabetes-related complication. Enhancing the patient awareness of this under-recognized diabetes-associated complication and ensuring that preventative measures are incorporated within health care programmes may offer methodologies to address this complication clinically.

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.

Osteoporosis and vascular calcification: A shared scenario

Osteoporosis is a systemic skeletal disease, characterised by low bone mass and deterioration in the micro-architecture of bone tissue, which causes increased bone fragility and consequently greater susceptibility to fractures. It is the most frequent metabolic bone disease in our population, and fractures resulting from osteoporosis are becoming more common. Furthermore, vascular calcification is a recognised risk factor of cardiovascular morbidity and mortality that historically has been considered a passive and degenerative process. However, it is currently recognised as an active process, which has histopathological characteristics, mineral composition and initiation and development mechanisms characteristic of bone formation. Paradoxically, patients with osteoporosis frequently show vascular calcifications. Traditionally, they have been considered as independent processes related to age, although more recent epidemiological studies have shown that there is a close relationship between the loss of bone mass and vascular calcification, regardless of age. In fact, both conditions share risk factors and pathophysiological mechanisms. These include the relationship between proteins of bone origin, such as osteopontin and osteoprotegerin (OPG), with vascular pathology, and the intercellular protein system RANK/RANKL/OPG and the Wnt signalling pathway. The mechanisms linked in both pathologies should be considered in clinical decisions, given that treatments for osteoporosis could have unforeseen effects on vascular calcification, and vice versa. In short, a better understanding of the relationship between both entities can help in proposing strategies to reduce the increasing prevalence of vascular calcification and osteoporosis in the aging population.

An update on therapies for the treatment of diabetes-induced osteoporosis

Introduction: Currently, 424 million people aged between 20 and 79 years worldwide are diabetic. More than 25% of adults aged over 65 years in North America have Type 2 diabetes mellitus (DM). Diabetes-induced osteoporosis (DM-OS) is caused by chronic hyperglycemia, advanced glycated end products and oxidative stress. The increase in the prevalence of DM-OS has prompted researchers to develop new biological therapies for the management of DM-OS. Areas covered: This review covered the current and novel biological agents used in the management of DM-OS. Data were retrieved from PubMed, Scopus, American Diabetes Association and International Osteoporosis Foundation websites, and ClinicalTrials.gov. The keywords for the search included: DM, osteoporosis, and management. Expert opinion: Several biological molecules have been examined in order to find efficient drugs for the treatment of DM-OS. These biological agents include anti-osteoporosis drugs: net anabolics (parathyroid hormone/analogs, androgens, calcilytics, anti-sclerostin antibody), net anti-resorptive osteoporosis drugs (calcitonin, estrogen, selective estrogen receptor modulators, bisphosphonates, RANKL antibody) and anti-diabetic drugs (alpha glucosidase inhibitors, sulfonylureas, biguanides, meglitinides, thiazolidinediones, GLP-1 receptor agonists, dipeptidylpeptidase-4 inhibitors, sodium glucose co-transporter-2 inhibitors, insulin). Biological medications that effectively decrease hyperglycemia and, at the same time, maintain bone health would be an ideal drug/drug combination for the treatment of DM-OS.

Simvastatin attenuates tibial bone loss in rats with type 1 diabetes and periodontitis

Background

Diabetes induces long bone loss and aggravation of periodontitis-induced alveolar bone loss. Simvastatin (SIM), which is a lipid-lowering agent is known to have an anabolic effect on bone. Therefore, we investigated effect of SIM on tibial and alveolar bone loss in type 1 diabetic rats with periodontitis.

Methods

Rats were divided into control (C), diabetes with periodontitis (DP), and diabetes with periodontitis treated with SIM (DPS) groups. DP and DPS groups were intravenously injected with streptozotocin (50 mg/kg), and C group was injected with citrate buffer. Seven days later (day 0), periodontitis was induced by ligatures of mandibular first molars. DP and DPS groups were orally administered vehicle or SIM (30 mg/kg) from day 0 to days 3, 10, or 20. Alveolar and tibial bone loss was measured using histological and m-CT analysis alone or in combination. Osteoclast number and sclerostin-positive osteocytes in tibiae were evaluated by tartrate-resistant acid phosphatase and immunohistochemical staining, respectively. Glucose, triglyceride (TG), cholesterol (CHO), and low-density lipoprotein (LDL) were evaluated.

Results

Consistent with diabetes induction, the DP group showed higher glucose and TG levels at all timepoints and higher CHO levels on day 20 than C group. Compared to the DP group, the DPS group exhibited reduced levels of glucose (day 3), TG (days 10 and 20), CHO, and LDL levels (day 20). Bone loss analysis revealed that the DP group had lower bone volume fraction, bone mineral density, bone surface density, and trabecular number in tibiae than C group at all timepoints. Interestingly, the DPS group exhibited elevation of these indices at early stages compared to the DP group. The DPS group showed reduction of osteoclasts (day 3) and sclerostin-positive osteocytes (days 3 and 20) compared with the DP group. There was no difference in alveolar bone loss between DP and DPS groups.

Conclusions

These results suggest that SIM attenuates tibial, but not alveolar bone loss in type 1 diabetic rats with periodontitis. Moreover, attenuation of tibial bone loss by SIM may be related to inhibition of osteoclast formation and reduction of sclerostin expression.