Decreased markers of bone turnover in children and adolescents with type 1 diabetes

Bone and muscle differences in children and adolescents with type 1 diabetes: The mediating role of physical activity

Children with type 1 diabetes (T1D) experience an increased risk of fracture, which may be related to altered bone development. We aimed to assess differences in bone, muscle and physical activity (PA), and explore if better muscle and PA measures would mitigate bone differences between children and adolescents with T1D and typically developing peers (TDP). We matched 56 children and adolescents with T1D (mean age 11.9 yrs) and 56 TDP (11.5 yrs) by sex and maturity from 171 participants with T1D and 66 TDP (6-17 yrs). We assessed the distal radius and tibia with high-resolution peripheral quantitative computed tomography (HR-pQCT), and the radius and tibia shaft bone and muscle with pQCT. We also measured muscle function from force-related measures in neuromuscular performance tests (push-up, grip test, countermovement and long jump). We compared PA based on questionnaire scores and accelerometers between groups. Bone, muscle, and neuromuscular performance measures were compared using MANOVA. We used mediation to explore the role of PA and muscle in bone differences. Children and adolescents with T1D had 6-10 % lower trabecular density, bone volume fraction, thickness and number at both distal radius and tibia, and 11 % higher trabecular separation at the distal radius than TDP. They also had 3-16 % higher cortical and tissue mineral density, and cortical thickness at the distal radius, 5-7 % higher cortical density and 1-3 % higher muscle density at both shaft sites compared to TDP. PA mediated the between-group difference in trabecular number (indirect effect -0.04) at the distal radius. Children and adolescents with T1D had lower trabecular bone density and deficits in trabecular micro-architecture, but higher cortical bone density and thickness at the radius and tibia compared to TDP. They engaged in less PA but had comparable muscle measures to those of TDP. PA participation may assist in mitigating deficit in trabecular number observed in children and adolescents with T1D.

An Epidemiological Perspective on New Pediatric Cases of Type 1 Diabetes and Vitamin D Deficiency in South-East Romania: A Retrospective Study

OBJECTIVES

The aim of this study is to analyze the epidemiological characteristics and the biological profile of children from the southeast of Romania who have been newly diagnosed with type 1 diabetes (T1DM) and to investigate the potential relationships between vitamin D deficiency and the onset of this disease, especially in the context of the COVID-19 pandemic.

METHODS

This is a retrospective study that included 79 children under the age of 18 who were diagnosed with T1DM at the St. Ioan Galati Children's Emergency Clinical Hospital between 2018 and 2023. Their demographic data (age, sex, and home environment), medical history (family medical history, birth weight, Apgar score, and type of nutrition), and biological parameters, including glycemia, HbA1C, and vitamin D level, were collected. We used advanced statistical methods to compare the levels of vitamin D in the children with T1DM with a control group of nondiabetic children.

RESULTS

The demographic characteristics of new T1DM are a median age of 9 and female/male sex ratio of 1:3, with 50.6% living in urban areas, 59.5% with a normal body mass index, and 74.6% presenting with ketoacidosis. Vitamin D deficiency was found in 52% of diabetic cases compared to 2.53% in the nondiabetic controls.

CONCLUSIONS

There is an increasing incidence of pediatric T1DM. Diabetic ketoacidosis was frequently diagnosed as an initial manifestation and has frequently accompanied lower levels of vitamin D. Children with T1DM showed significant vitamin D deficiencies compared to the control group, highlighting the need for the monitoring and supplementation of this vitamin.

Bone metabolism in diabetes: a clinician's guide to understanding the bone-glucose interplay

Skeletal fragility is an increasingly recognised, but poorly understood, complication of both type 1 and type 2 diabetes. Fracture risk varies according to skeletal site and diabetes-related characteristics. Post-fracture outcomes, including mortality risk, are worse in those with diabetes, placing these people at significant risk. Each fracture therefore represents a sentinel event that warrants targeted management. However, diabetes is a very heterogeneous condition with complex interactions between multiple co-existing, and highly correlated, factors that preclude a clear assessment of the independent clinical markers and pathophysiological drivers for diabetic osteopathy. Additionally, fracture risk calculators and routinely used clinical bone measurements generally underestimate fracture risk in people with diabetes. In the absence of dedicated prospective studies including detailed bone and metabolic characteristics, optimal management centres around selecting treatments that minimise skeletal and metabolic harm. This review summarises the clinical landscape of diabetic osteopathy and outlines the interplay between metabolic and skeletal health. The underlying pathophysiology of skeletal fragility in diabetes and a rationale for considering a diabetes-based paradigm in assessing and managing diabetic bone disease will be discussed.

Association between osteocalcin and residual β-cell function in children and adolescents newly diagnosed with type 1 diabetes: a pivotal study

PURPOSE

This pivotal study aimed to evaluate circulating levels of bone remodeling markers in children and adolescents at the onset of type 1 diabetes (T1D). Additionally, we assessed their correlation with glucose control, residual β-cell function, and the severity of presentation.

METHODS

In this single-center cross-sectional study, we recruited children and adolescents newly diagnosed with T1D at our tertiary-care Diabetes Centre. Anamnestic, anthropometric, clinical, and biochemical data at T1D diagnosis were collected. Basal and stimulated C-peptide levels were assessed, along with the following bone remodeling biomarkers: osteocalcin (OC), alkaline phosphatase (ALP), parathormone (PTH), 25-OH Vitamin D (25OH-D), and the C-terminal cross-linked telopeptide of type 1 collagen (CTX).

RESULTS

We enrolled 29 individuals newly diagnosed with T1D, with a slight male prevalence (51.7%). The mean age was 8.4 ± 3.7 years. A positive correlation between OC and stimulated C-peptide (R = 0.538; p = 0.026) and between PTH and serum HCO3- (R = 0.544; p = 0.025) was found. No other correlations between bone remodeling biomarkers and clinical variables were detected.

CONCLUSION

Our data showed a positive correlation between OC levels and residual β-cell function in children and adolescents at T1D presentation. Further longitudinal studies evaluating OC levels in pediatric subjects with T1D are needed to better understand the complex interaction between bone and glucose metabolisms.

Does metabolic control of the disease related with bone turnover markers in children with type 1 diabetes mellitus in Turkey?

BACKGROUND

The aim was to evaluate the effect of metabolic control on bone biomarkers in children with type I diabetes.

MATERIALS AND METHODS

The children were divided into two groups according to their glycated hemoglobin (HbA1c) (%) levels: a group with HbA1c levels < 8% (n = 16) and: a group with HbA1c levels > 8% (n = 18). The serum total oxidative status (TOS) (µmol/L), total antioxidant status (TAS) (mmol/L), alkaline phosphatase (ALP) (IU/L), osteocalcin (OC) (ng/ml), procollagen type-1-N-terminal peptide (P1NP) (ng/ml), and vitamin D (IU) levels and food consumption frequencies were determined.

RESULTS

When patients were classified according to HbA1c (%) levels, those with HbA1c levels < 8% were found to have lower TOS (µmol/L) values (8.7 ± 6.16, 9.5 ± 5.60) and higher serum OC (ng/mL) (24.2 ± 16.92, 22.0 ± 6.21) levels than those with HbA1c levels > 8% (p < 0.05). Regardless of the level of metabolic control, there was a statistically significant association between serum TOS (µmol/L) and P1NP (ng/ml) (p < 0.05) levels, with no group-specific relationship (HbA1c levels <%8 or HbA1c levels >%8).

CONCLUSION

HbA1c and serum TOS levels had an effect on bone turnover biomarkers in individuals with type I diabetes.

Effect of Calcium and Vitamin D Supplementation (Dairy vs. Pharmacological) on Bone Health of Underprivileged Indian Children and Youth with Type-1 Diabetes: A Randomized Controlled Trial

BACKGROUND

Bone health is affected by chronic childhood disorders including type-1 diabetes mellitus (T1DM). We conducted this randomized controlled trial with the objective of investigating the effect of 1-year supplementation of vitamin-D with milk or with pharmacological calcium on bone mass accrual in underprivileged Indian children and youth with T1DM.

METHODS

5 to 23year old (n = 203) underprivileged children and youth with T1DM were allocated to one of three groups: Milk (group A-received 200 ml milk + 1000 international unit (IU) vitamin-D3/day), Calcium supplement (group B-received 500 mg of calcium carbonate + 1000 IU of vitamin-D3/day) or standard of care/control (group C). Anthropometry, clinical details, biochemistry, diet (3-day 24-h recall), physical activity (questionnaires adapted for Indian children) and bone health parameters (using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography- DXA and pQCT respectively) were evaluated at enrolment and end of 12 month intervention.

RESULTS

Total body less head(TBLH) bone mineral content (BMC(g)) and bone mineral density (BMD(gm/cm2)) were significantly higher at end of study in girls in both supplemented groups (TBLHBMC-A-1011.8 ± 307.8, B-983.2 ± 352.9, C-792.8 ± 346.8. TBLHBMD-A-± 0.2, B-0.8 ± 0.2, C-0.6 ± 0.2, p < 0.05). Z score of lumbar spine bone mineral apparent density of supplemented participants of both sexes was significantly higher than controls (Boys- A-0.7 ± 1.1, B-0.6 ± 1.4, C- -0.7 ± 1.1; Girls- A-1.1 ± 1.1, B-0.9 ± 3.4, C- -1.7 ± 1.3, p < 0.05). A significantly higher percentage increase was found in cortical thickness in girls in both supplemented groups (A-17.9 ± 28.6, B-15.3 ± 16.5, C-7.6 ± 26.2); the differences remained after adjusting for confounders.

CONCLUSION

Supplementation with milk or pharmacological calcium (+vitaminD3) improved bone outcomes-particularly geometry in children with T1DM with more pronounced effect in girls. Pharmacological calcium may be more cost effective in optimising bone health in T1DM in resource limited settings.

Fracture patterns and associated risk factors in pediatric and early adulthood type 1 diabetes: Findings from a nationwide retrospective cohort study

PURPOSE

People with pediatric and early adulthood type 1 diabetes (T1D) might have a higher fracture risk at several sites compared to the general population. Therefore, we assessed the hazard ratios (HR) of various fracture sites and determined the risk factors associated with fractures among people with newly diagnosed childhood and adolescence T1D.

METHODS

All people from the UK Clinical Practice Research Datalink GOLD (1987-2017), below 20 years of age with a T1D diagnosis code (n = 3100) and a new insulin prescription, were included and matched 1:1 by sex, age, and practice to a control without diabetes. Cox regression was used to estimate HRs of any, major osteoporotic fractures (MOFs) and peripheral fractures (lower-arm and lower-legs) for people with T1D compared to controls. The analyses were adjusted for sex, age, diabetic complications, medication (glucocorticoids, anti-depressants, anxiolytics, bone medication, anti-convulsive), Charlson-comorbidity-index (CCI), hypoglycemia, falls and alcohol. T1D was further stratified by diabetes duration, presence of diabetic microvascular complications (retinopathy, nephropathy, and neuropathy) and boys versus girls.

RESULTS

The crude HRs for any fracture (HR: 1.30, CI95%: 1.11-1.51), lower-arm (HR: 1.22, CI95%: 1.00-1.48), and lower-leg fractures (HR: 1.54, CI95%: 1.11-2.13) were statistically significant increase in T1D compared to controls, but the effect disappeared in the adjusted analyses. For MOFs, no significant differences were seen. Risk factors in the T1D cohort were few, but the most predominantly one was a previous fracture (any fracture: HR: 2.00, CI95%: 1.70-2.36; MOFs: HR: 1.89, CI95%: 1.44-2.48, lower- arm fractures: HR: 2.08, CI95%: 1.53-2.82 and lower-leg fractures: HR: 2.08, CI95%: 1.34-3.25). Others were a previous fall (any fracture: HR: 1.54, CI95%: 1.20-1.97), hypoglycemia (Any fracture: HR: 1.46, CI95%: 1.21-1.77 and lower-leg fractures: HR: 2.34, CI95%: 1.47-3.75), and anxiolytic medication (Any fracture: HR: 1.52, CI95%: 1.10-2.11). Whereas girls had a lower risk compared to boys (Any fracture: HR: 0.78, CI95%: 0.67-0.90 and lower-arm fractures; HR: 0.51, CI95%: 0.38-0.68). The risk of any fracture in T1D did not increase with longer diabetes duration compared to controls (0-4 years: HR: 1.20, CI95%: 1.00-1.44; 5-9 years: HR: 1.17, CI95%: 0.91-1.50; <10 years: HR: 0.83, CI95%: 0.54-1.27). Similar patterns were observed for other fracture sites. Furthermore, one complication compared to none in T1D correlated with a higher fracture risk (1 complication: HR: 1.42, CI95%: 1.04-1.95).

CONCLUSION

The overall fracture risk was not increased in pediatric and early adulthood T1D; instead, it was associated with familiar risk factors and specific diabetes-related ones.

Dioscin: Therapeutic potential for diabetes and complications

Diabetes mellitus is a widespread metabolic disorder with increasing incidence worldwide, posing a considerable threat to human health because of its complications. Therefore, cost-effective antidiabetic drugs with minimal side effects are urgently needed. Dioscin, a naturally occurring compound, helps to reduce the complications of diabetes mellitus by regulating glucose and lipid metabolism, protecting islet β cells, improving insulin resistance, and inhibiting oxidative stress and inflammatory response. Plant-derived dioscin reduces the risk of toxicity and side effects associated with chemically synthesized drugs. It is a promising option for treating diabetes mellitus because of its preventive and therapeutic effects, which may be attributed to a variety of underlying mechanisms. However, data compiled by current studies are preliminary. Information about the molecular mechanism of dioscin remains limited, and no high-quality human experiments and clinical trials for testing its safety and efficacy have been conducted. As a resource for research in this area, this review is expected to provide a systematic framework for the application of dioscin in the treatment of diabetes mellitus and its complications.

Signs of a Glucose- and Insulin-Independent Gut-Bone Axis and Aberrant Bone Homeostasis in Type 1 Diabetes

CONTEXT

Gut hormones seem to play an important role in postprandial bone turnover, which also may be affected by postprandial plasma glucose excursions and insulin secretion.

OBJECTIVE

To investigate the effect of an oral glucose tolerance test (OGTT) and an isoglycemic intravenous glucose infusion (IIGI) on bone resorption and formation markers in individuals with type 1 diabetes and healthy controls.

METHODS

This observational case-control study, conducted at the Center for Clinical Metabolic Research, Gentofte Hospital, Hellerup, Denmark, included 9 individuals with C-peptide negative type 1 diabetes and 8 healthy controls matched for gender, age, and body mass index. Subjects underwent an OGTT and a subsequent IIGI. We analyzed changes in bone resorption assessed by measurements of carboxy-terminal type I collagen crosslinks (CTX) and in bone formation as assessed by procollagen type I N-terminal propeptide (PINP) concentrations.

RESULTS

Baseline CTX and PINP levels were similar in the 2 groups. Both groups exhibited significantly greater suppression of CTX during OGTT than IIGI. PINP levels were unaffected by OGTT and IIGI, respectively, in healthy controls. Participants with type 1 diabetes displayed impaired suppression of CTX-assessed bone resorption and inappropriate suppression of PINP-assessed bone formation during OGTT.

CONCLUSION

Our data suggest the existence of a gut-bone axis reducing bone resorption in response to oral glucose independently of plasma glucose excursions and insulin secretion. Subjects with type 1 diabetes showed impaired suppression of bone resorption and reduced bone formation during OGTT, which may allude to the reduced bone mineral density and increased fracture risk characterizing these individuals.

The Role of Oxidative Stress in Multiple Exercise-Regulated Bone Homeostasis

Bone is a tissue that is active throughout the lifespan, and its physiological activities, such as growth, development, absorption, and formation, are always ongoing. All types of stimulation that occur in sports play an important role in regulating the physiological activities of bone. Here, we track the latest research progress locally and abroad, summarize the recent, relevant research results, and systematically summarize the effects of different types of exercise on bone mass, bone strength and bone metabolism. We found that different types of exercise have different effects on bone health due to their unique technical characteristics. Oxidative stress is an important mechanism mediating the exercise regulation of bone homeostasis. Excessive high-intensity exercise does not benefit bone health but induces a high level of oxidative stress in the body, which has a negative impact on bone tissue. Regular moderate exercise can improve the body's antioxidant defense ability, inhibit an excessive oxidative stress response, promote the positive balance of bone metabolism, delay age-related bone loss and deterioration of bone microstructures and have a prevention and treatment effect on osteoporosis caused by many factors. Based on the above findings, we provide evidence for the role of exercise in the prevention and treatment of bone diseases. This study provides a systematic basis for clinicians and professionals to reasonably formulate exercise prescriptions and provides exercise guidance for patients and the general public. This study also provides a reference for follow-up research.

A narrative review of diabetic bone disease: Characteristics, pathogenesis, and treatment

Recently, the increasing prevalence of diabetes mellitus has made it a major chronic illness which poses a substantial threat to human health. The prevalence of osteoporosis among patients with diabetes mellitus has grown considerably. Diabetic bone disease is a secondary osteoporosis induced by diabetes mellitus. Patients with diabetic bone disease exhibit variable degrees of bone loss, low bone mineral density, bone microarchitecture degradation, and increased bone fragility with continued diabetes mellitus, increasing their risk of fracture and impairing their ability to heal after fractures. At present, there is extensive research interest in diabetic bone disease and many significant outcomes have been reported. However, there are no comprehensive review is reported. This review elaborates on diabetic bone disease in the aspects of characteristics, pathogenesis, and treatment.

Childhood type 1 diabetes is associated with abnormal bone development

OBJECTIVE

To describe bone mineral density (BMD), bone structure, and fracture prevalence in adolescents with type 1 diabetes (T1D) and explore their associations with glycemic control and microvascular complications.

RESEARCH DESIGN AND METHODS

Cross sectional study of 64 adolescents (38 males) with T1D duration >10 years who underwent dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), fracture survey, plantar fascia thickness, and microvascular complications assessment.

RESULTS

Mean age was 16.6 ± 2.1 years, diabetes duration 12.8 ± 2.2 years and HbA1c 8.9 ± 1.7% (74 mmol/mol). Fracture prevalence was 50%. DXA areal BMD (Z-score) was reduced for femoral neck (-0.5 ± 1.3, p = 0.008) and arm (-0.4 ± 1.0, p < 0.001), while total areal BMD and lumbar spine BMD were normal. In pQCT (Z-score), trabecular volumetric BMD (vBMD) was reduced for tibia (-0.4 ± 0.8, p < 0.001) and radius (-0.8 ± 1.4, p < 0.001) whereas cortical vBMD was increased at both sites (tibia: 0.5 ± 0.6, p < 0.001, radius: 0.7 ± 1.5, p < 0.001). Muscle cross-sectional area (CSA) was reduced for upper (-0.6 ± 1.2, p < 0.001) and lower (-0.4 ± 0.7, p < 0.001) limbs. DXA total areal BMD was positively correlated with BMI (p < 0.01) and age at T1D diagnosis (p = 0.04). Lower radial bone CSA, total and lumbar spine BMD were associated with autonomic nerve dysfunction. HbA1c, diabetes duration, fracture history and other microvascular complications were not significantly associated with bone parameters.

CONCLUSIONS

Adolescents with childhood-onset T1D have site-specific bone deficits in upper and lower limbs but normal total and lumbar spine BMD. T1D appears to have differential effects on trabecular and cortical bone compartments. Future longitudinal analysis is warranted to examine whether these changes translate in to increased fracture risk.

Regulation of bone mass in endocrine diseases including diabetes

Hormonal regulation plays a key role in determining bone mass in humans. Both skeletal growth and bone loss in health and disease is critically controlled by endocrine factors and low bone mass is a feature of both excess and deficiency of a broad range of hormones. This article explores the impact of diabetes and thyroid, parathyroid, sex steroid and growth hormone disorders on bone mass and fracture risk. Evidence for current management strategies is provided along with suggested practice points and gaps in knowledge for future research.

Diabetic Bone Disease and Diabetic Myopathy: Manifestations of the Impaired Muscle-Bone Unit in Type 1 Diabetes

Type 1 diabetes is associated with complications affecting muscle and bone, with diabetic bone disease and diabetic myopathy becoming increasingly reported in the past few decades. This review is aimed at succinctly reviewing the literature on the current knowledge regarding these increasingly identified and possibly interconnected complications on the musculoskeletal system. Furthermore, this review summarizes several nonmechanical factors that could be mediating the development and progression of premature musculoskeletal decline in this population and discusses preventative measures to reduce the burden of diabetes on the musculoskeletal system.

Bone Density, Geometry, and Mass by Peripheral Quantitative Computed Tomography and Bone Turnover Markers in Children with Diabetes Mellitus Type 1

BACKGROUND

The type 1 diabetes mellitus (T1DM) is a chronic systemic autoimmune-mediated disease characterised by the insulin deficiency and hyperglycaemia. Its deleterious effect on bones concerns not only bone mass, density, and fracture risk but also may involve the linear growth of long bones. Studies on the lower leg in children with T1DM by pQCT have generated conflicting results, and most of the studies published so far focused only on a selected features of the bone. An additional information about growth, modelling, and remodelling processes can be gathered by the bone turnover marker measurement. The objective of the study was to evaluate bone mineral density, mass, and geometry using peripheral quantitative computed tomography as well as bone turnover markers in the patients with type 1 diabetes mellitus. Material and Methods. Bone mineral density, mass, and geometry on the lower leg using peripheral quantitative computed tomography and serum osteocalcin (OC) and carboxyterminal cross-linked telopeptide of type 1 collagen (CTx) were measured in 35 adolescents with T1DM (15 girls) aged 12.3-17.9 yrs. The results were compared to age- and sex-adjusted reference values for healthy controls.

RESULTS

Both sexes reveal lower than zero Z-scores for lower leg 66% total cortical bone cross-sectional area to muscle cross-sectional area ratio (-0.97 ± 1.02, p = 0.002517 and -0.98 ± 1.40, p = 0.007050, respectively) while tibia 4% trabecular bone density Z-score was lowered in boys (-0.67 ± 1.20, p = 0.02259). In boys in Tanner stage 5 bone mass and dimensions were diminished in comparison to Tanner stages 3 and 4, while in girls, such a phenomenon was not observed. Similarly, bone formation and resorption were decreased in boys but not in girls. Consistently, bone turnover markers correlated positively with bone size, dimensions, and strength in boys only.

CONCLUSIONS

T1DM patients revealed a decreased ratio of cortical bone area/muscle area, reflecting disturbed adaptation of the cortical shaft to the muscle force. When analyzing bone mass and dimensions, boys in Tanner stage 5 diverged from "less-mature" individuals, which may suggest that bone development in these individuals was impaired, affecting all three: mass, size, and strength. Noted in boys, suppressed bone metabolism may result in impairment of bone strength because of inadequate repair of microdamage and accumulation of microfractures.

Fracture risk assessment in diabetes mellitus

Growing evidence suggests that diabetes mellitus is associated with an increased risk of fracture. Bone intrinsic factors (such as accumulation of glycation end products, low bone turnover, and bone microstructural changes) and extrinsic factors (such as hypoglycemia caused by treatment, diabetes peripheral neuropathy, muscle weakness, visual impairment, and some hypoglycemic agents affecting bone metabolism) probably contribute to damage of bone strength and the increased risk of fragility fracture. Traditionally, bone mineral density (BMD) measured by dual x-ray absorptiometry (DXA) is considered to be the gold standard for assessing osteoporosis. However, it cannot fully capture the changes in bone strength and often underestimates the risk of fracture in diabetes. The fracture risk assessment tool is easy to operate, giving it a certain edge in assessing fracture risk in diabetes. However, some parameters need to be regulated or replaced to improve the sensitivity of the tool. Trabecular bone score, a noninvasive tool, indirectly evaluates bone microstructure by analyzing the texture sparsity of trabecular bone, which is based on the pixel gray level of DXA. Trabecular bone score combined with BMD can effectively improve the prediction ability of fracture risk. Quantitative computed tomography is another noninvasive examination of bone microstructure. High-resolution peripheral quantitative computed tomography can measure volume bone mineral density. Quantitative computed tomography combined with microstructure finite element analysis can evaluate the mechanical properties of bones. Considering the invasive nature, the use of microindentation and histomorphometry is limited in clinical settings. Some studies found that the changes in bone turnover markers in diabetes might be associated with fracture risk, but further studies are needed to confirm this. This review focused on summarizing the current development of these assessment tools in diabetes so as to provide references for clinical practice. Moreover, these tools can reduce the occurrence of fragility fractures in diabetes through early detection and intervention.

Impaired soft and hard callus formation during fracture healing in diet-induced obese mice as revealed by 3D contrast-enhanced computed tomography imaging

The impact of diabetes mellitus on bone fracture healing is clinically relevant as the patients experience delayed fracture healing. Even though efforts have been made to understand the detrimental effects of type 2 diabetes mellitus (T2DM) on the fracture healing process, the exact mechanisms causing the pathophysiological outcomes remain unclear. The aim of this study was to assess alterations in bone fracture healing (tibial fracture surgery, intramedullary pinning) of diet-induced obese (DIO) mice, and to investigate the in vitro properties of osteochondroprogenitors derived from the diabetic micro-environment. High-resolution contrast-enhanced microfocus X-ray computed tomography (CE-CT) enabled a simultaneous 3D assessment of the amount and spatial distribution of the regenerated soft and hard tissues during fracture healing and revealed that osteogenesis as well as chondrogenesis are altered in DIO mice. Compared to age-matched lean controls, DIO mice presented a decreased bone volume fraction and increased callus volume and adiposity at day 14 post-fracture. Of note, bone turnover was found altered in DIO mice relative to controls, evidenced by decreased blood serum osteocalcin and increased serum CTX levels. The in vitro data revealed that not only the osteogenic and adipogenic differentiation of periosteum-derived cells (PDCs) were altered by hyperglycemic (HG) conditions, but also the chondrogenic differentiation. Elevated PPARγ expression in HG conditions confirmed the observed increase in differentiated adipocytes in vitro. Finally, chondrogenesis-related genes COL2 and COL10 were downregulated for PDCs treated with HG medium, confirming that chondrogenic differentiation is compromised in vitro and suggesting that this may affect callus formation and maturation during the fracture healing process in vivo. Altogether, these results provide novel insights into the alterations of long bone fracture repair and suggest a link between HG-induced dysfunctionality of osteochondroprogenitor differentiation and fracture healing impairment under T2DM conditions.

Bone accrual in children and adolescents with type 1 diabetes: current knowledge and future directions

PURPOSE OF REVIEW

Skeletal fragility is now recognized as a significant complication of type 1 diabetes (T1D). Many patients with T1D develop the disease in childhood and prior to the attainment of peak bone mass and strength. This manuscript will review recent studies investigating the effects of T1D on skeletal development.

RECENT FINDINGS

Mild-to-moderate deficits in bone density, structure, and mineral accrual were reported early in the course of T1D in some but not all studies. Childhood-onset disease was associated with a more severe skeletal phenotype in some adult studies. Lower than expected bone mass for muscle size was been described. Hemoglobin A1c was negatively associated with bone density and structure in several studies, though the mechanism was not clear.

SUMMARY

The use of advanced imaging techniques has shown that the adverse effects of T1D on the developing skeleton extend beyond bone density to include abnormalities in bone size, shape, microarchitecture, and strength. Despite these gains, a uniform understanding of the pathophysiology underlying skeletal fragility in this disorder remains elusive. Longitudinal studies, especially in association with interventions to reduce hyperglycemia or improve muscle strength, are needed to inform bone healthcare in T1D.

Future studies using histomorphometry in type 1 diabetes mellitus

PURPOSE OF REVIEW

This article reviews the current state of research in type 1 diabetes and bone, focusing on human bone turnover markers and histomorphometry.

RECENT FINDINGS

Bone turnover markers have been used for decades to document static bone turnover status in a variety of diseases but especially in diabetes. Two new studies focus on dynamic testing conditions to examine the acute effects of insulin and exercise on bone turnover. Publications of human bone histomorphometry in type 1 diabetes are few but there are several new studies currently underway.

SUMMARY

Here, we review the most recent literature on human bone turnover markers and histomorphometry. Low bone turnover is thought to be a major underlying factor in bone fragility in T1DM. Further studies in human transilial bone biopsies will be helpful in determining the mechanisms.

Advanced glycation endproducts and bone quality: practical implications for people with type 2 diabetes

PURPOSE OF REVIEW

Individuals with type 2 diabetes (T2D) are at increased risk of fracture, often despite normal bone density. This observation suggests deficits in bone quality in the setting of abnormal glucose homeostasis. The goal of this article is to review recent developments in our understanding of how advanced glycation end products (AGEs) are incorporated into the skeleton with resultant deleterious effects on bone health and structural integrity in patients with T2D.

RECENT FINDINGS

The adverse effects of skeletal AGE accumulation on bone remodeling and the ability of the bone to deform and absorb energy prior to fracture have been demonstrated both at the bench as well as in small human studies; however, questions remain as to how these findings might be better explored in large, population-based investigations.

SUMMARY

Hyperglycemia drives systemic, circulating AGE formation with subsequent accumulation in the bone tissue. In those with T2D, studies suggest that AGEs diminish fracture resistance, though larger clinical studies are needed to better define the direct role of longstanding AGE accumulation on bone strength in humans as well as to motivate potential interventions to reverse or disrupt skeletal AGE deposition with the goal of fracture prevention.

Bone-a-Petite: Engineering Exosomes towards Bone, Osteochondral, and Cartilage Repair

Recovery from bone, osteochondral, and cartilage injuries/diseases has been burdensome owing to the damaged vasculature of large defects and/or avascular nature of cartilage leading to a lack of nutrients and supplying cells. However, traditional means of treatment such as microfractures and cell-based therapy only display limited efficacy due to the inability to ensure cell survival and potential aggravation of surrounding tissues. Exosomes have recently emerged as a powerful tool for this tissue repair with its complex content of transcription factors, proteins, and targeting ligands, as well as its unique ability to home in on target cells thanks to its phospholipidic nature. They are engineered to serve specialized applications including enhancing repair, anti-inflammation, regulating homeostasis, etc. via means of physical, chemical, and biological modulations in its deriving cell culture environments. This review focuses on the engineering means to functionalize exosomes for bone, osteochondral, and cartilage regeneration, with an emphasis on conditions such as osteoarthritis, osteoporosis, and osteonecrosis. Finally, future implications for exosome development will be given alongside its potential combination with other strategies to improve its therapeutic efficacy in the osteochondral niche.

Mechanisms of altered bone remodeling in children with type 1 diabetes

Bone loss associated with type 1 diabetes mellitus (T1DM) begins at the onset of the disease, already in childhood, determining a lower bone mass peak and hence a greater risk of osteoporosis and fractures later in life. The mechanisms underlying diabetic bone fragility are not yet completely understood. Hyperglycemia and insulin deficiency can affect the bone cells functions, as well as the bone marrow fat, thus impairing the bone strength, geometry, and microarchitecture. Several factors, like insulin and growth hormone/insulin-like growth factor 1, can control bone marrow mesenchymal stem cell commitment, and the receptor activator of nuclear factor-κB ligand/osteoprotegerin and Wnt-b catenin pathways can impair bone turnover. Some myokines may have a key role in regulating metabolic control and improving bone mass in T1DM subjects. The aim of this review is to provide an overview of the current knowledge of the mechanisms underlying altered bone remodeling in children affected by T1DM.

Role of osteogenic Dickkopf-1 in bone remodeling and bone healing in mice with type I diabetes mellitus

Type 1 diabetes mellitus (T1DM) is associated with low bone mass and a higher risk for fractures. Dickkopf-1 (Dkk1), which inhibits Wnt signaling, osteoblast function, and bone formation, has been found to be increased in the serum of patients with T1DM. Here, we investigated the functional role of Dkk1 in T1DM-induced bone loss in mice. T1DM was induced in 10-week-old male mice with Dkk1-deficiency in late osteoblasts/osteocytes (Dkk1^f/f;Dmp1-Cre, cKO) and littermate control mice by 5 subsequent injections of streptozotocin (40 mg/kg). Age-matched, non-diabetic control groups received citrate buffer instead. At week 12, calvarial defects were created in subgroups of each cohort. After a total of 16 weeks, weight, fat, the femoral bone phenotype and the area of the bone defect were analyzed using µCT and dynamic histomorphometry. During the experiment, diabetic WT and cKO mice did not gain body weight compared to control mice. Further they lost their perigonadal and subcutaneous fat pads. Diabetic mice had highly elevated serum glucose levels and impaired glucose tolerance, regardless of their Dkk1 levels. T1DM led to a 36% decrease in trabecular bone volume in Cre− negative control animals, whereas Dkk1 cKO mice only lost 16%. Of note, Dkk1 cKO mice were completely protected from T1DM-induced cortical bone loss. T1DM suppressed the bone formation rate, the number of osteoblasts at trabecular bone, serum levels of P1NP and bone defect healing in both, Dkk1-deficient and sufficient, mice. This may be explained by increased serum sclerostin levels in both genotypes and the strict dependence on bone formation for bone defect healing. In contrast, the number of osteoclasts and TRACP 5b serum levels only increased in diabetic control mice, but not in Dkk1 cKO mice. In summary, Dkk1 derived from osteogenic cells does not influence the development of T1DM but plays a crucial role in T1DM-induced bone loss in male mice by regulating osteoclast numbers.

Bone metabolism regulation: Implications for the treatment of bone diseases

Bone cells in the human body are continuously engaged in cellular metabolism, including the interaction between bone cells, the interaction between the erythropoietic cells of the bone marrow and stromal cells, for the remodeling and reconstruction of bone. Osteoclasts and osteoblasts play an important role in bone metabolism. Diseases occur when bone metabolism is abnormal, but little is known about the signaling pathways that affect bone metabolism. The study of these signaling pathways will help us to use the relevant techniques to intervene, so as to improve the condition. The study of these signaling pathways will help us to use the relevant techniques to intervene, so as to improve the condition. I believe they will shine in the diagnosis and treatment of future clinical bone diseases.