Impact microindentation in men with impaired fasting glucose and type 2 diabetes

Lower microhardness along with less heterogeneous mineralization in the femoral neck of individuals with type 2 diabetes mellitus indicates higher fracture risk

There is still limited understanding of the microstructural reasons for the higher susceptibility to fractures in individuals with type 2 diabetes mellitus (T2DM). In this study, we examined bone mineralization, osteocyte lacunar parameters, and microhardness of the femoral neck trabeculae in 18 individuals with T2DM who sustained low-energy fracture (T2DMFx: 78 ± 7 years, 15 women and 3 men) and 20 controls (74 ± 7 years, 16 women and 4 men). Femoral necks of the T2DMFx subjects were obtained at a tertiary orthopedic hospital, while those of the controls were collected at autopsy. T2DMFx individuals had lower trabecular microhardness (P = .023) and mineralization heterogeneity (P = .001), and a tendency to a lower bone area with mineralization above 95th percentile (P = .058) than the controls. There were no significant intergroup differences in the numbers of osteocyte lacunae per bone area, mineralized lacunae per bone area, and total lacunae per bone area (each P > .05). After dividing the T2DMFx group based on the presence of vascular complications (VD) to T2DMFxVD (VD present) and T2DMFxNVD (VD absent), we observed that microhardness was particularly reduced in the T2DMFxVD group (vs. control group, P = .02), while mineralization heterogeneity was significantly reduced in both T2DMFx subgroups (T2DMFxNVD vs. control, P = .002; T2DMFxVD vs. control, P = .038). The observed changes in mineralization and microhardness may contribute to the increased hip fracture susceptibility in individuals with T2DM.

Assessment of bovine cortical bone fracture behavior using impact microindentation as a surrogate of fracture toughness

The fracture behavior of bone is critically important for evaluating its mechanical competence and ability to resist fractures. Fracture toughness is an intrinsic material property that quantifies a material's ability to withstand crack propagation under controlled conditions. However, properly conducting fracture toughness testing requires the access to calibrated mechanical load frames and the destructive testing of bone samples, and therefore fracture toughness tests are clinically impractical. Impact microindentation mimicks certain aspects of fracture toughness measurements, but its relationship with fracture toughness remains unknown. In this study, we aimed to compare measurements of notched fracture toughness and impact microindentation in fresh and boiled bovine bone. Skeletally mature bovine bone specimens (n = 48) were prepared, and half of them were boiled to denature the organic matrix, while the other half remained preserved in frozen conditions. All samples underwent a notched fracture toughness test to determine their resistance to crack initiation (KIC) and an impact microindentation test using the OsteoProbe to obtain the Bone Material Strength index (BMSi). Boiling the bone samples increased the denatured collagen content, while mineral density and porosity remained unaffected. The boiled bones also showed significant reduction in both KIC (P < .0001) and the average BMSi (P < .0001), leading to impaired resistance of bone to crack propagation. Remarkably, the average BMSi exhibited a high correlation with KIC (r = 0.86; P < .001). A ranked order difference analysis confirmed the excellent agreement between the 2 measures. This study provides the first evidence that impact microindentation could serve as a surrogate measure for bone fracture behavior. The potential of impact microindentation to assess bone fracture resistance with minimal sample disruption could offer valuable insights into bone health without the need for cumbersome testing equipment and sample destruction.

Assessment of bovine cortical bone fracture behavior using impact microindentation as a surrogate of fracture toughness

The fracture behavior of bone is critically important for assessing its mechanical competence and ability to resist fractures. Fracture toughness, which quantifies a material's resistance to crack propagation under controlled geometry, is regarded as the gold standard for evaluating a material's resistance to fracture. However properly conducting this test requires access to calibrated mechanical load frames the destruction of the bone samples, making it impractical for obtaining clinical measurement of bone fracture. Impact microindentation offers a potential alternative by mimicking certain aspects of fracture toughness measurements, but its relationship with mechanistic fracture toughness remains unknown. In this study, we aimed to compare measurements of notched fracture toughness and impact microindentation in fresh and boiled bovine bone. Skeletally mature bovine bone specimens (n=48) were prepared, and half of them were boiled to denature the organic matrix, while the other half remained preserved in frozen conditions. Notched fracture toughness tests were conducted on all samples to determine Initiation toughness (KIC), and an impact microindentation test using the OsteoProbe was performed to obtain the Bone Material Strength index. Boiling the bone samples resulted increased the denatured collagen without affecting mineral density or porosity. The boiled bones also showed significant reduction in both KIC (p < 0.0001) and the average Bone Material Strength index (p < 0.0001), leading to impaired resistance of bone to crack propagation. Remarkably, the average Bone Material Strength index exhibited a high correlation with KIC (r = 0.86; p < 0.001). The ranked order difference analysis confirmed excellent agreement between the two measures. This study provides the first evidence that impact microindentation could serve as a surrogate measure for bone fracture behavior. The potential of impact microindentation to non-destructively assess bone fracture resistance could offer valuable insights into bone health without the need for elaborate testing equipment and sample destruction.

Increased Bone Material Strength Index Is Positively Associated With the Risk of Incident Osteoporotic Fractures in Older Swedish Women

No previous studies have investigated the association between the bone material strength index (BMSi; an indicator of bone material properties obtained by microindentation) and the risk of incident fracture. The primary purpose of this prospective cohort study was to evaluate if BMSi is associated with incident osteoporotic fracture in older women and, secondarily, with prevalent fractures, anthropometric traits, or measurements of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA). In a population-based cohort, 647 women aged 75 to 80 years underwent bone microindentation using the OsteoProbe device. Data on clinical risk factors (CRFs), prevalent fractures, and incident fractures were collected using questionnaires, medical records, and a regional X-ray archive. BMD and vertebral fracture assessment (VFA) were assessed by DXA (Hologic, Discovery A). Associations between BMSi, anthropometrics, BMD, and prevalent fractures were investigated using correlation and linear and logistic regression. Cox proportional hazards and competing risks analysis by Fine and Gray were used to study the association between BMSi and the risk of fracture and mortality. BMSi was weakly associated with age (r = -0.13, p < 0.001) and BMI (r = -0.21, p < 0.001) and with BMD of lumbar spine (β = 0.09, p = 0.02) and total hip (β = 0.08, p = 0.05), but only after adjustments. No significant associations were found between BMSi and prevalent fractures (self-reported and/or VFA identified, n = 332). During a median follow-up time of 6.0 years, 121 major osteoporotic fractures (MOF), 151 any fractures, and 50 deaths occurred. Increasing BMSi (per SD) was associated with increased risk of MOF (hazard ratio [HR] = 1.29, 95% confidence interval [CI] 1.07-1.56), any fracture (HR = 1.29, 95% CI 1.09-1.53), and mortality (HR = 1.44, 95% CI 1.07-1.93). The risk of fracture did not materially change with adjustment for confounders, CRFs, femoral neck BMD, or when considering the competing risk of death. In conclusion, unexpectedly increasing BMSi was associated with greater fracture risk. The clinical relevance and potential mechanisms of this finding require further study. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Prediabetes and Fracture Risk Among Midlife Women in the Study of Women's Health Across the Nation

Importance

Whether prediabetes is associated with fracture is uncertain.

Objective

To evaluate whether prediabetes before the menopause transition (MT) is associated with incident fracture during and after the MT.

Design, Setting, and Participants

This cohort study used data collected between January 6, 1996, and February 28, 2018, in the Study of Women's Health Across the Nation cohort study, an ongoing, US-based, multicenter, longitudinal study of the MT in diverse ambulatory women. The study included 1690 midlife women in premenopause or early perimenopause at study inception (who have since transitioned to postmenopause) who did not have type 2 diabetes before the MT and who did not take bone-beneficial medications before the MT. Start of the MT was defined as the first visit in late perimenopause (or first postmenopausal visit if participants transitioned directly from premenopause or early perimenopause to postmenopause). Mean (SD) follow-up was 12 (6) years. Statistical analysis was conducted from January to May 2022.

Exposure

Proportion of visits before the MT that women had prediabetes (fasting glucose, 100-125 mg/dL [to convert to millimoles per liter, multiply by 0.0555]), with values ranging from 0 (prediabetes at no visits) to 1 (prediabetes at all visits).

Main Outcomes and Measures

Time to first fracture after the start of the MT, with censoring at first diagnosis of type 2 diabetes, initiation of bone-beneficial medication, or last follow-up. Cox proportional hazards regression was used to examine the association (before and after adjustment for bone mineral density) of prediabetes before the MT with fracture during the MT and after menopause.

Results

This analysis included 1690 women (mean [SD] age, 49.7 [3.1] years; 437 Black women [25.9%], 197 Chinese women [11.7%], 215 Japanese women [12.7%], and 841 White women [49.8%]; mean [SD] body mass index [BMI] at the start of the MT, 27.6 [6.6]). A total of 225 women (13.3%) had prediabetes at 1 or more study visits before the MT, and 1465 women (86.7%) did not have prediabetes before the MT. Of the 225 women with prediabetes, 25 (11.1%) sustained a fracture, while 111 of the 1465 women without prediabetes (7.6%) sustained a fracture. After adjustment for age, BMI, and cigarette use at the start of the MT; fracture before the MT; use of bone-detrimental medications; race and ethnicity; and study site, prediabetes before the MT was associated with more subsequent fractures (hazard ratio for fracture with prediabetes at all vs no pre-MT visits, 2.20 [95% CI, 1.11-4.37]; P = .02). This association was essentially unchanged after controlling for BMD at the start of the MT.

Conclusions and Relevance

This cohort study of midlife women suggests that prediabetes was associated with risk of fracture. Future research should determine whether treating prediabetes reduces fracture risk.

Ultrashort Echo Time (UTE) MRI porosity index (PI) and suppression ratio (SR) correlate with the cortical bone microstructural and mechanical properties: Ex vivo study

Ultrashort echo time (UTE) MRI can image and consequently enable quantitative assessment of cortical bone. UTE-MRI-based evaluation of bone is largely underutilized due to the high cost and time demands of MRI in general. The signal ratio in dual-echo UTE imaging, known as porosity index (PI), as well as the signal ratio between UTE and inversion recovery UTE (IR-UTE) imaging, known as the suppression ratio (SR), are two rapid UTE-based bone evaluation techniques (∼ 5 mins scan time each), which can potentially reduce the time demand and cost in future clinical studies. This study aimed to investigate the correlations of PI and SR measures with cortical bone microstructural and mechanical properties. Cortical bone strips (n = 135) from tibial and femoral midshafts of 37 donors (61 ± 24 years old) were scanned using a dual-echo 3D Cones UTE sequence and a 3D Cones IR-UTE sequence for PI and SR calculations, respectively. Average bone mineral density, porosity, and pore size were measured using microcomputed tomography (μCT). Bone mechanical properties were measured using 4-point bending tests. The μCT measures showed significant correlations with PI (moderate to strong, R = 0.68-0.71) and SR (moderate, R = 0.58-0.68). Young's modulus, yield stress, and ultimate stress demonstrated significant moderate correlations with PI and SR (R = 0.52-0.62) while significant strong correlations with μCT measures (R > 0.7). PI and SR can potentially serve as fast and noninvasive (non-ionizing radiation) biomarkers for evaluating cortical bone in various bone diseases.

Reference Intervals for Bone Impact Microindentation in Healthy Adults: A Multi-Centre International Study

Impact microindentation (IMI) is a novel technique for assessing bone material strength index (BMSi) in vivo, by measuring the depth of a micron-sized, spherical tip into cortical bone that is then indexed to the depth of the tip into a reference material. The aim of this study was to define the reference intervals for men and women by evaluating healthy adults from the United States of America, Europe and Australia. Participants included community-based volunteers and participants drawn from clinical and population-based studies. BMSi was measured on the tibial diaphysis using an OsteoProbe in 479 healthy adults (197 male and 282 female, ages 25 to 98 years) across seven research centres, between 2011 and 2018. Associations between BMSi, age, sex and areal bone mineral density (BMD) were examined following an a posteriori method. Unitless BMSi values ranged from 48 to 101. The mean (± standard deviation) BMSi for men was 84.4 ± 6.9 and for women, 79.0 ± 9.1. Healthy reference intervals for BMSi were identified as 71.0 to 97.9 for men and 59.8 to 95.2 for women. This study provides healthy reference data that can be used to calculate T- and Z-scores for BMSi and assist in determining the utility of BMSi in fracture prediction. These data will be useful for positioning individuals within the population and for identifying those with BMSi at the extremes of the population.

Peripheral quantitative computed tomography-derived bone parameters in men with impaired fasting glucose and diabetes

INTRODUCTION

Individuals with type 2 diabetes mellitus (T2DM) are at higher risk of fracture, but paradoxically do not have reduced bone mineral density. We investigated associations between peripheral quantitative computed tomography (pQCT) and glycaemia status.

MATERIALS AND METHODS

Participants were men (n = 354, age 33-92 year) from the Geelong Osteoporosis Study. Diabetes was defined by fasting plasma glucose (FPG) ≥ 7.0 mmol/L, self-report of diabetes and/or antihyperglycaemic medication use and impaired fasting glucose (IFG) as FPG 5.6-6.9 mmol/L. Bone measures were derived using pQCT (XCT2000) at 4% and 66% radial and tibial sites. Linear regression was used, adjusting for age, body mass index and socio-economic status.

RESULTS

At the 4% site, men with T2DM had lower adjusted bone total area, trabecular area and cortical area at the radius (all - 6.2%) and tibia (all - 6.4%) compared to normoglycaemia. Cortical density was higher for T2DM at the radius (+ 5.8%) and tibia (+ 8.0%), as well as adjusted total bone density at the tibial site (+ 6.1%). At the 66% site, adjusted total bone area and polar stress strain index were lower for T2DM at the radius (- 4.3% and - 8.0%). Total density was also higher for T2DM (+ 1.2%). Only cortical density at the 4% tibial site was different between IFG and normoglycaemia in adjusted analyses (+ 4.5%).

CONCLUSION

Men with T2DM had lower total bone area, trabecular area, cortical area and polar stress strain index than the other two groups; however, total density and cortical density were higher. Only one difference was observed between IFG and normoglycaemia; increased tibial cortical density.

Increased Cortical Porosity, Reduced Cortical Thickness, and Reduced Trabecular and Cortical Microhardness of the Superolateral Femoral Neck Confer the Increased Hip Fracture Risk in Individuals with Type 2 Diabetes

Individuals with diabetes mellitus type 2 (T2DM) have approximately 30% increased risk of hip fracture; however, the main cause of the elevated fracture risk in those subjects remains unclear. Moreover, micromechanical and microarchitectural properties of the superolateral femoral neck-the common fracture-initiating site-are still unknown. We collected proximal femora of 16 men (eight with T2DM and eight controls; age: 61 ± 10 years) at autopsy. After performing post-mortem bone densitometry (DXA), the superolateral neck was excised and scanned with microcomputed tomography (microCT). We also conducted Vickers microindentation testing. T2DM and control subjects did not differ in age (p = 0.605), body mass index (p = 0.114), and femoral neck bone mineral density (BMD) (p = 0.841). Cortical porosity (Ct.Po) was higher and cortical thickness (Ct.Th) was lower in T2DM (p = 0.044, p = 0.007, respectively). Of trabecular microarchitectural parameters, only structure model index (p = 0.022) was significantly different between T2DM subjects and controls. Control group showed higher cortical (p = 0.002) and trabecular bone microhardness (p = 0.005). Increased Ct.Po and decreased Ct.Th in T2DM subjects increase the propensity to femoral neck fracture. Apart from the deteriorated cortical microarchitecture, decreased cortical and trabecular microhardness suggests altered bone composition of the superolateral femoral neck cortex and trabeculae in T2DM. Significantly deteriorated cortical microarchitecture of the superolateral femoral neck is not recognized by standard DXA measurement of the femoral neck.

Weight Loss Interventions and Skeletal Health in Persons with Diabetes

PURPOSE OF REVIEW

Weight loss is recommended for improving glycemic control and reducing cardiovascular risk factors in persons with diabetes. However, both diabetes and weight loss have been associated with detrimental skeletal health. This review aims to summarize recent study findings on the effects of lifestyle interventions for weight loss on skeletal health among persons with type 2 diabetes (T2D).

RECENT FINDINGS

A few large-scale observational studies have demonstrated an increased fragility fracture risk associated with weight loss among persons with T2D. Randomized control trials in persons with T2D also have shown that intentional lifestyle interventions for weight loss are associated with a greater decrease in bone mineral density (BMD) and an increase in the risk of fracture. The biological mechanisms underlying the compromised bone health during lifestyle interventions for weight loss are complex and not yet conclusive. However, there is evidence to suggest that bone loss and increased fracture risk during intentional weight loss may be mitigated by some intervention approaches, such as high protein intake, calcium supplementation, and resistance and balance training. There is still a lack of studies investigating the effects of different interventions for weight loss on skeletal health among persons with T2D. However, certain types of diet and physical activity intervention combined with bone monitoring and fracture risk prediction may help achieve weight loss goals and maintain skeletal health among persons with T2D during intentional weight loss.

Causative or associative: A critical review of the role of advanced glycation end-products in bone fragility

The accumulation of advanced glycation end-products (AGEs) in the organic matrix of bone with aging and chronic disease such as diabetes is thought to increase fracture risk independently of bone mass. However, to date, there has not been a clinical trial to determine whether inhibiting the accumulation of AGEs is effective in preventing low-energy, fragility fractures. Moreover, unlike with cardiovascular or kidney disease, there are also no pre-clinical studies demonstrating that AGE inhibitors or breakers can prevent the age- or diabetes-related decrease in the ability of bone to resist fracture. In this review, we critically examine the case for a long-standing hypothesis that AGE accumulation in bone tissue degrades the toughening mechanisms by which bone resists fracture. Prior research into the role of AGEs in bone has primarily measured pentosidine, an AGE crosslink, or bulk fluorescence of hydrolysates of bone. While significant correlations exist between these measurements and mechanical properties of bone, multiple AGEs are both non-fluorescent and non-crosslinking. Since clinical studies are equivocal on whether circulating pentosidine is an indicator of elevated fracture risk, there needs to be a more complete understanding of the different types of AGEs including non-crosslinking adducts and multiple non-enzymatic crosslinks in bone extracellular matrix and their specific contributions to hindering fracture resistance (biophysical and biological). By doing so, effective strategies to target AGE accumulation in bone with minimal side effects could be investigated in pre-clinical and clinical studies that aim to prevent fragility fractures in conditions that bone mass is not the underlying culprit.

Investigation on the sensitivity of indentation devices for detection of fatigue loading induced damage in bovine cortical bone

Daily physiological activities subject our skeletal system to cyclic loading with varying frequencies and magnitudes. These loadings interact with the microstructure of bone and create microdamage, which can cause stress-induced injuries if not repaired on the time. The early detection is required to prevent the complications associated with these fractures. In the present study, to examine fatigue loading-induced damage in cortical bone, the sensitivity of four different indentation devices was investigated. For this, cortical bone samples were fatigued in four-point bending configuration at 0.5 Hz, 2 Hz and 4 Hz frequencies. Following the fatigue loading, cyclic reference point indentation (cRPI), impact reference point indentation (iRPI), Vickers microhardness and nanoindentation tests were performed on the bone samples. Results show that indentation devices are sensitive to detect fatigue loading induced damage only in 0.5 Hz group samples on compressive region. On the other hand, the sensitivity of indentation devices for tensile stress-induced damage is not clear. Also, histological examination of fatigued bone samples shows a significant increase in the crack density and crack length with fatigue loading only for the 0.5 Hz group samples. The present study provides insight into the sensitivity of different indentation devices to fatigue loading induced damage, which could be helpful in the development of new devices for the early diagnosis of stress induced injuries.

Evaluation of Quality and Bone Microstructure Alterations in Patients with Type 2 Diabetes: A Narrative Review

Bone fragility is a common complication in subjects with type 2 diabetes mellitus (T2DM). However, traditional techniques for the evaluation of bone fragility, such as dual-energy X-ray absorptiometry (DXA), do not perform well in this population. Moreover, the Fracture Risk Assessment Tool (FRAX) usually underestimates fracture risk in T2DM. Importantly, novel technologies for the assessment of one microarchitecture in patients with T2DM, such as the trabecular bone score (TBS), high-resolution peripheral quantitative computed tomography (HR-pQCT), and microindentation, are emerging. Furthermore, different serum and urine bone biomarkers may also be useful for the evaluation of bone quality in T2DM. Hence, in this article, we summarize the limitations of conventional tools for the evaluation of bone fragility and review the current evidence on novel approaches for the assessment of quality and bone microstructure alterations in patients with T2DM.

Effect of Teriparatide on Bone Mineral Density and Trabecular Bone Score in Type 2 Diabetic Patients with Osteoporosis: A Retrospective Cohort Study

The BMDs of the lumbar spine, whole femur, and femoral neck and TBS were measured. Change in BMD or TBS was defined as the BMD or TBS at follow-up, performed 1 year after baseline, minus baseline BMD or TBS. Results: This retrospective cohort study included 93 patients, of whom 52 received no medication, 26 received bisphosphonates, and 15 received weekly teriparatide. BMD of the lumbar spine increased in all three groups. There was no change in BMD of the whole femur and femoral neck in the no medication and bisphosphonates groups, whereas the BMD of the whole femur (from 0.73 (0.15) to 0.74 (0.15) g/cm², p = 0.011) and femoral neck (from 0.59 (0.16) to 0.60 (0.16) g/cm², p = 0.011) in the teriparatide group increased. The change in BMD of the femoral neck (no medication; −0.002 (0.034) g/cm², bisphosphonates; −0.0001 (0.024) g/cm², and teriparatide; 0.017 (0.022) g/cm², p = 0.091) or TBS (no medication; −0.007 (0.051), bisphosphonates; −0.058 (0.258), and teriparatide; 0.021 (0.044), p = 0.191) in the teriparatide group tended to be higher than that in the other groups, although there was no statistically significant difference. Conclusions: Teriparatide increased the BMD of the femoral neck and TBS in osteoporosis patients with type 2 diabetes mellitus, compared to bisphosphonates and no medication.

Associations between parameters of peripheral quantitative computed tomography and bone material strength index

BACKGROUND

Bone material strength index (BMSi) is measured in vivo using impact microindentation (IMI). However, the associations between BMSi and other bone measures are not clear. This study investigated whether bone parameters derived by peripheral quantitative computed tomography (pQCT) are associated with BMSi.

METHODS

Participants were men (n = 373, ages 34-96 yr) from the Geelong Osteoporosis Study. BMSi was measured using an OsteoProbe (Active Life Scientific, USA). Bone measures were obtained at both the radius (n = 348) and tibia (n = 342) using pQCT (XCT 2000 Stratec Medizintechnik, Germany). Images were obtained at 4% and 66% of radial and tibial length. Associations between pQCT parameters and BMSi were tested using Spearman's correlation and multivariable regression used to determine independent associations after adjustment for potential confounders. Models were checked for interaction terms.

RESULTS

Weak associations were observed between total bone density (radius 4%; r = +0.108, p = 0.046, tibia 4%; r = +0.115, p = 0.035), cortical density (tibia 4%; r = +0.123, p = 0.023) and BMSi. The associations were independent of weight, height, and glucocorticoid use (total bone density: radius 4%; β = 0.020, p = 0.006, tibia 4%; β = 0.020, p = 0.027 and cortical density: radius 4%; β = 4.160, p = 0.006, tibia 4%; β = 0.038, p = 0.010). Associations with bone mass were also observed at the 66% radial and tibial site, independent of age, weight, and glucocorticoid use (β = 4.160, p = 0.053, β = 1.458, p = 0.027 respectively). Total area at the 66% tibial site was also associated with BMSi (β = 0.010, p = 0.012), independent of weight and glucocorticoid use. No interaction terms were identified.

CONCLUSION

There were weak associations detected between some pQCT-derived bone parameters and BMSi.

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.

Evidence of impaired bone quality in men with type 1 diabetes: a cross-sectional study

OBJECTIVE

Type 1 diabetes (T1D) is associated with substantial fracture risk. Bone mineral density (BMD) is, however, only modestly reduced, suggesting impaired bone microarchitecture and/or bone material properties. Yet, the skeletal abnormalities have not been uncovered. Men with T1D seem to experience a more pronounced bone loss than their female counterparts. Hence, we aimed to examine different aspects of bone quality in men with T1D.

DESIGN AND METHODS

In this cross-sectional study, men with T1D and healthy male controls were enrolled. BMD (femoral neck, total hip, lumbar spine, whole body) and spine trabecular bone score (TBS) were measured by dual x-ray absorptiometry, and bone material strength index (BMSi) was measured by in vivo impact microindentation. HbA1c and bone turnover markers were analyzed.

RESULTS

Altogether, 33 men with T1D (43 ± 12 years) and 28 healthy male controls (42 ± 12 years) were included. Subjects with T1D exhibited lower whole-body BMD than controls (P = 0.04). TBS and BMSi were attenuated in men with T1D vs controls (P = 0.016 and P = 0.004, respectively), and T1D subjects also had a lower bone turnover. The bone parameters did not differ between subjects with or without diabetic complications. Duration of disease correlated negatively with femoral neck BMD but not with TBS or BMSi.

CONCLUSIONS

This study revealed compromised bone material strength and microarchitecture in men with T1D. Moreover, our data confirm previous studies which found a modest decrease in BMD and low bone turnover in subjects with T1D. Accordingly, bone should be recognized as a target of diabetic complications.

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.

Associations between Bone Material Strength Index, Calcaneal Quantitative Ultrasound, and Bone Mineral Density in Men

Objectives

Impact micro-indentation (IMI) measures bone material strength index (BMSi) in vivo. This study investigated how IMI is associated with calcaneal quantitative ultrasound and bone densitometry parameters in men.

Methods

BMSi was measured on the tibial plateau using the OsteoProbe in 377 men (age 33-96 years) from the Geelong Osteoporosis Study. Broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI) were assessed at the calcaneus using an ultrasonometer. Areal BMD was measured at several skeletal sites using dual-energy x-ray absorptiometry. Linear associations between parameters were tested using Pearson’s correlation. Multivariable regression techniques were used to determine associations between BMSi and other measures of bone, independent of confounders.

Results

BMSi was negatively correlated with age (r = –0.171, P = .001), weight (r = –0.100, P = .052), and body mass index (r = –0.187, P = .001), and positively with height (r = +0.109, P = .034). There was some evidence to support a positive association between BMSi and BUA (β = 0.052, P = .037), SOS (β = 0.013, P = .144), and SI (β = 0.036, P = .051). After age adjustment, this association was attenuated. No correlations were observed between BMSi and BMD at any skeletal site (r values ranged from –0.006 to +0.079, all P ≥ .13).

Conclusion

There was a small positive association between BMSi and quantitative ultrasound (QUS) parameters, which were not independent of age. No associations were detected between BMSi and BMD. This suggests that BMSi and QUS are capturing common age-dependent properties of bone. Further research on the utility of IMI alone and complementary to conventional bone testing methods for predicting fracture risk is warranted.