Comparison of differences in bone microarchitecture in adult- versus juvenile-onset type 1 diabetes Asian males versus non-diabetes males: an observational cross-sectional pilot study

Use of noninvasive imaging to identify causes of skeletal fragility in adults with diabetes: a review

Diabetes, a disease marked by consistent high blood glucose levels, is associated with various complications such as neuropathy, nephropathy, retinopathy, and cardiovascular disease. Notably, skeletal fragility has emerged as a significant complication in both type 1 (T1D) and type 2 (T2D) diabetic patients. This review examines noninvasive imaging studies that evaluate skeletal outcomes in adults with T1D and T2D, emphasizing distinct skeletal phenotypes linked with each condition and pinpointing gaps in understanding bone health in diabetes. Although traditional DXA-BMD does not fully capture the increased fracture risk in diabetes, recent techniques such as quantitative computed tomography, peripheral quantitative computed tomography, high-resolution quantitative computed tomography, and MRI provide insights into 3D bone density, microstructure, and strength. Notably, existing studies present heterogeneous results possibly due to variations in design, outcome measures, and potential misclassification between T1D and T2D. Thus, the true nature of diabetic skeletal fragility is yet to be fully understood. As T1D and T2D are diverse conditions with heterogeneous subtypes, future research should delve deeper into skeletal fragility by diabetic phenotypes and focus on longitudinal studies in larger, diverse cohorts to elucidate the complex influence of T1D and T2D on bone health and fracture outcomes.

Bone Microarchitecture and Volumetric Mineral Density Assessed by HR-pQCT in Patients with 21- and 17α-Hydroxylase Deficiency

Due to disturbances in hormones and long-term glucocorticoid replacement therapy (GRT), congenital adrenocortical hyperplasia (CAH) patients are at risk of impaired bone structure and metabolism. This cross-sectional, case-control study aims to investigate for the first time bone microarchitecture features in 21-hydroxylase deficiency (21OHD; N = 38) and 17α-hydroxylase deficiency (17OHD; N = 16) patients using high-resolution peripheral quantitative computed tomography (HR-pQCT) by matching the same sex and similar age [21OHD vs. control: 29.5 (24.0-34.3) vs. 29.6 (25.9-35.2) years; 17OHD vs. controls: 29.0 (21.5-35.0) vs. 29.7 (24.6-35.3) years] with healthy controls (1:3). All patients underwent HR-pQCT scans of the nondominant radius and tibia, and had received GRT. Compared with corresponding controls, 17OHD cases had higher height (P < 0.001), weight (P = 0.013) and similar body mass index (BMI), while 21OHD had lower height (P < 0.001), similar weight and higher BMI (P < 0.001). 17OHD and 21OHD patients demonstrated various significant bone differences in most HR-pQCT indices, suggesting abnormalities in bone microarchitectures from healthy people. Further correlation analyses revealed that some characteristics, such as height and hormones, may contribute to the bone differences in HR-pQCT indices between two diseases. However, treatment dosage and time were not correlated, indicating that the current glucocorticoid doses may be within safety limits for bone impairment. Overall, our study for the first time revealed changes of bone microarchitecture in CAH patients and their potential relations with clinical characteristics. Further longitudinal researches are required to confirm these findings.

Bone deficits in children and youth with type 1 diabetes: A systematic review and meta-analysis

Deficits in bone mineral and weaker bone structure in children with type 1 diabetes (T1D) may contribute to a lifelong risk of fracture. However, there is no meta-analysis comparing bone properties beyond density between children with T1D and typically developing children (TDC). This meta-analysis aimed to assess differences and related factors in bone mineral content (BMC), density, area, micro-architecture and estimated strength between children with T1D and TDC. We systematically searched MEDLINE, Embase, CINAHL, Web of Science, Scopus, Cochrane Library databases, and included 36 in the meta-analysis (2222 children and youth with T1D, 2316 TDC; mean age ≤18 yrs., range 1-24). We estimated standardized mean differences (SMD) using random-effects models and explored the role of age, body size, sex ratio, disease duration, hemoglobin A1c in relation to BMC and areal density (aBMD) SMD using meta-regressions. Children and youth with T1D had lower total body BMC (SMD: -0.21, 95% CI: -0.37 to -0.05), aBMD (-0.30, -0.50 to -0.11); lumbar spine BMC (-0.17, -0.28 to -0.06), aBMD (-0.20, -0.32 to -0.08), bone mineral apparent density (-0.30, -0.48 to -0.13); femoral neck aBMD (-0.21, -0.33 to -0.09); distal radius and tibia trabecular density (-0.38, -0.64 to -0.12 and -0.35, -0.51 to -0.18, respectively) and bone volume fraction (-0.33, -0.56 to -0.09 and -0.37, -0.60 to -0.14, respectively); distal tibia trabecular thickness (-0.41, -0.67 to -0.16); and tibia shaft cortical content (-0.33, -0.56 to -0.10). Advanced age was associated with larger SMD in total body BMC (-0.13, -0.21 to -0.04) and aBMD (-0.09; -0.17 to -0.01) and longer disease duration with larger SMD in total body aBMD (-0.14; -0.24 to -0.04). Children and youth with T1D have lower BMC, aBMD and deficits in trabecular density and micro-architecture. Deficits in BMC and aBMD appeared to increase with age and disease duration. Bone deficits may contribute to fracture risk and require attention in diabetes research and care. STUDY REGISTRATION: PROSPERO (CRD42020200819).

Imaging techniques to study diabetic bone disease

PURPOSE OF REVIEW

This review article presents the most recent research on bone fragility in individuals with diabetes from a medical imaging perspective.

RECENT FINDINGS

The widespread availability of dual-energy X-ray absorptiometry (DXA) and trabecular bone score (TBS) software has led to recent assessments of bone fragility with this texture parameter in several studies of type 2 diabetes mellitus (T2D), but in few of type 1 diabetes mellitus (T1D). Although most studies show a trend of reduced TBS values in T2D independent of areal bone mineral density (aBMD) of the lumbar spine, some studies also show the limitations of TBS in both T2D and T1D. Given the limitations of DXA to assess bone strength and investigate the etiology of bone fragility in diabetes, more investigators are incorporating three-dimensional (3D) medical imaging techniques in their studies. Recent use of 3D medical imaging to assess bone fragility in the setting of diabetes has been mostly limited to a few cross-sectional studies predominantly incorporating high-resolution peripheral quantitative computed tomography (HR-pQCT). Although HR-pQCT studies indicate higher tibial cortical porosity in subjects with T2D, results are inconsistent in T1D due to differences in study designs, sample sizes, and subject characteristics, among other factors. With respect to central CT, recent studies support a previous finding in the literature indicating femoral neck geometrical impairments in subjects with T2D and provide encouraging results for the incorporation of finite element analysis (FEA) to assess bone strength in studies of T2D. In the recent literature, there are no studies assessing bone fragility in T1D with QCT, and only two studies used pQCT reporting tibial and radial impairments in young women and children with T1D, respectively. Magnetic resonance imaging (MRI) has not been recently used in diabetic studies of bone fragility.

SUMMARY

As bone fragility in diabetes is not explained by DXA-derived aBMD and given the limitations of cross-sectional studies, it is imperative to use 3D imaging techniques for longitudinal assessments of the density, quality, and microenvironment of bone to improve our understanding of the effects of diabetes on bone and reduce the risk of fracture in this large and vulnerable population of subjects with diabetes.

The pattern of incident fractures according to fracture site in people with T1D

Higher incidences of fractures are seen in people with type 1 diabetes (T1D), but knowledge on different fracture sites is sparse. We found a higher incidence mainly for distal fracture sites in people with T1D compared to controls. It must be further studied which fractures attributed to the higher incidence rates (IRs) at specific sites.

INTRODUCTION

People with T1D have a higher incidence of fractures compared to the general population. However, sparse knowledge exists on the incidence rates of individual fracture sites. Therefore, we examined the incidence of various fracture sites in people with newly treated T1D compared to matched controls.

METHODS

All people from the UK Clinical Practice Research Datalink GOLD (1987-2017), of all ages with a T1D diagnosis code (n = 6381), were included. People with T1D were matched by year of birth, sex, and practice to controls (n = 6381). Fracture IRs and incidence rate ratios (IRRs) were calculated. Analyses were stratified by fracture site and sex.

RESULTS

The IR of all fractures was significantly higher in people with T1D compared to controls (IRR: 1.39 (CI95%: 1.24-1.55)). Compared to controls, the IRR for people with T1D was higher for several fracture sites including carpal (IRR: 1.41 (CI95%: 1.14-1.75)), clavicle (IRR: 2.10 (CI95%: 1.18-3.74)), foot (IRR: 1.70 (CI95%: 1.23-2.36)), humerus (IRR: 1.46 (CI95%: 1.04-2.05)), and tibia/fibula (IRR: 1.67 CI95%: 1.08-2.59)). In women with T1D, higher IRs were seen at the ankle (IRR: 2.25 (CI95%: 1.10-4.56)) and foot (IRR: 2.11 (CI95%: 1.27-3.50)), whereas in men with T1D, higher IRs were seen for carpal (IRR: 1.45 (CI95%: 1.14-1.86)), clavicle (IRR: 2.13 (CI95%: 1.13-4.02)), and humerus (IRR: 1.77 (CI95%: 1.10-2.83)) fractures.

CONCLUSION

The incidence of carpal, clavicle, foot, humerus, and tibia/fibula fractures was higher in newly treated T1D, but there was no difference at other fracture sites compared to controls. Therefore, the higher incidence of fractures in newly treated people with T1D has been found mainly for distal fracture sites.

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.

Are diabetes microvascular complications risk factors for fragility fracture?

PURPOSE OF REVIEW

We describe relationships between microvascular complications and bone fragility fracture in the context of diabetes. We highlight gaps in knowledge and suggest areas of further study.

RECENT FINDINGS

Evidence in type 1 diabetes (T1D) demonstrates that low bone mineral density (BMD) is associated with microvascular complications and linked to increased fracture risk. Of note, the low BMD does not solely explain bone fragility. Microvascular disease also has been linked to compromised bone microarchitecture and poorer bone quality. Moreover, microvascular complications may indirectly increase the rate of fragility fracture through increasing fall propensity; however, to date no conclusive studies have assessed microvascular disease and fracture risk independent of falls.In the other hand, individuals with type 2 diabetes (T2D) have increased fracture risk despite high BMD. Data suggest microvascular disease mediates microarchitectural changes by increasing cortical porosity and is associated with lower bone turnover. There is no direct evidence linking microangiopathy to fracture incidence.

SUMMARY

Taken together present evidence suggests associations between diabetic bone disease, fragility fracture, and microvascular disease. Data are more convincing for T1D than T2D. Further studies are required to confirm whether microvascular disease is itself causative of fracture or merely a contributory factor to fragility fracture for persons with diabetes.

Liraglutide Inhibits Osteoclastogenesis and Improves Bone Loss by Downregulating Trem2 in Female Type 1 Diabetic Mice: Findings From Transcriptomics

BACKGROUND

The mechanisms of bone fragility in type 1 diabetes (T1D) are not fully understood. Whether glucagon-like peptide-1 receptor (GLP-1R) agonists could improve bone quality in T1D context also remains elusive.

AIMS

We aimed to explore the possible mechanisms of bone loss in T1D and clarify whether liraglutide has effects on bone quality of T1D mice using transcriptomics.

METHODS

Female streptozotocin-induced diabetic C57BL/6J mice were randomly divided into four groups and received the following treatments daily for 8 weeks: saline as controls, insulin, liraglutide, and liraglutide combined with insulin. These groups were also compared with non-STZ-treated normal glucose tolerance (NGT) group. Trunk blood and bone tissues were collected for analysis. Three tibia from each of the NGT, saline-treated, and liraglutide-treated groups were randomly selected for transcriptomics.

RESULTS

Compared with NGT mice, saline-treated T1D mice manifested markedly hyperglycemia and weight loss, and micro-CT revealed significantly lower bone mineral density (BMD) and deficient microarchitectures in tibias. Eight weeks of treatment with liraglutide alone or combined with insulin rescued the decreased BMD and partly corrected the compromised trabecular microarchitectures. Transcriptomics analysis showed there were 789 differentially expressed genes mainly mapped to osteoclastogenesis and inflammation pathways. The RT-qPCR verified that the gene expression of Trem2, Nfatc1, Trap, and Ctsk were significantly increased in the tibia of T1D compared with those in the NGT group. Liraglutide treatment alone or combined with insulin could effectively suppress osteoclastogenesis by downregulating the gene expression of Trem2, Nfatc1, Ctsk, and Trap.

CONCLUSIONS

Taken together, increased osteoclastogenesis with upregulated expression of Trem2 played an important role in bone loss of T1D mice. Liraglutide provided protective effects on bone loss in T1D mice by suppressing osteoclastogenesis.