Middle-aged premenopausal women with type 1 diabetes have lower bone mineral density and calcaneal quantitative ultrasound than nondiabetic women

O-linked β-N-acetylglucosaminylation may be a key regulatory factor in promoting osteogenic differentiation of bone marrow mesenchymal stromal cells

Cumulative evidence suggests that O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) plays an important regulatory role in pathophysiological processes. Although the regulatory mechanisms of O-GlcNAcylation in tumors have been gradually elucidated, the potential mechanisms of O-GlcNAcylation in bone metabolism, particularly, in the osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) remains unexplored. In this study, the literature related to O-GlcNAcylation and BMSC osteogenic differentiation was reviewed, assuming that it could trigger more scholars to focus on research related to O-GlcNAcylation and bone metabolism and provide insights into the development of novel therapeutic targets for bone metabolism disorders such as osteoporosis.

Type 1 diabetes

Type 1 diabetes is a chronic disease caused by autoimmune destruction of pancreatic β cells. Individuals with type 1 diabetes are reliant on insulin for survival. Despite enhanced knowledge related to the pathophysiology of the disease, including interactions between genetic, immune, and environmental contributions, and major strides in treatment and management, disease burden remains high. Studies aimed at blocking the immune attack on β cells in people at risk or individuals with very early onset type 1 diabetes show promise in preserving endogenous insulin production. This Seminar will review the field of type 1 diabetes, highlighting recent progress within the past 5 years, challenges to clinical care, and future directions in research, including strategies to prevent, manage, and cure the disease.

Rate of tarsal and metatarsal bone mineral density change in adults with diabetes mellitus and peripheral neuropathy: a longitudinal study

BACKGROUND

In people with diabetes (DM) and peripheral neuropathy (PN), loss of bone mineral density (BMD) in the tarsals and metatarsals contribute to foot complications; however, changes in BMD of the calcaneal bone is most commonly reported. This study reports rate of change in BMD of all the individual bones in the foot, in participants with DM and PN. Our aim was to investigate whether the rate of BMD change is similar across all the bones of the foot.

METHODS

Participants with DM and PN (n = 60) were included in this longitudinal cohort study. Rate of BMD change of individual bones was monitored using computed tomography at baseline and 6 months, 18 months, and 3-4 years from baseline. Personal factors (age, sex, medication use, step count, sedentary time, and PN severity) were assessed. A random coefficient model estimated rate of change of BMD in all bones and Pearson correlation tested relationships between personal factor variables and rate of BMD change.

RESULTS

Mean and calcaneal BMD decreased over the study period (p < 0.05). Individual tarsal and metatarsal bones present a range of rate of BMD change (-0.3 to -0.9%/year) but were not significantly different than calcaneal BMD change. Only age showed significant correlation with BMD and rate of BMD change.

CONCLUSION

The rate of BMD change did not significantly differ across different foot bones at the group level in people with DM and PN without foot deformity. Asymmetric BMD loss between individual bones of the foot and aging may be indicators of pathologic changes and require further investigation.

TRIAL REGISTRATION

Metatarsal Phalangeal Joint Deformity Progression-R01. Registered 25 November 2015, https://clinicaltrials.gov/ct2/show/NCT02616263.

Risk Factors and Outcomes After Surgical Reconstruction of Charcot Neuroarthropathy in Fracture Versus Dislocation Patterns

The primary aim of this study is to compare the preoperative risk factors and postoperative outcomes between Charcot neuroarthropathy patients with dislocation versus purely fracture pattern breakdown. The secondary aim is to compare the same factors between Charcot neuroarthropathy patients with dislocation versus fracture-dislocation pattern breakdown. A total of 55 patients with forefoot, midfoot, or hindfoot Charcot Neuroarthopathy were assessed at a mean follow up of 2.99 years. Bivariate analysis compared preoperative risk factors and postoperative outcomes, and segmented multivariable regression analysis was performed. Dislocation pattern Charcot had statistically significant higher rates of broken hardware (p = .05), mean age (p = .01), and revisional exostectomy (p = .01) compared to pure fracture pattern Charcot. Dislocation pattern Charcot was 12 times more likely to have revisions exostectomy (odds ratio [OR] 12.0, 95% confidence interval [CI] 1.84-78.37), and was 8 times more likely to have osteomyelitis (OR 7.8, 95% CI 1.4-42.7, p = .02) compared to the fracture-dislocation pattern Charcot. The patients with pure fracture pattern Charcot were 58.8 times more likely to have Charcot breakdown involvement of the talonavicular joint compared to the dislocation pattern cohort (OR 58.83, 95% CI 1.1-3220.3). Involvement of the talonavicular joint, in the fracture pattern Charcot associate with medial column collapse occurring at the onset of Charcot breakdown. The dislocation pattern in Charcot Neuroarthropathy demonstrated a higher propensity for residual collapse as demonstrated by the higher rates of broken hardware, osteomyelitis, and need for revisional exostectomy.

Single-cell RNA sequencing analysis reveals the relationship of bone marrow and osteopenia in STZ-induced type 1 diabetic mice

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scRNA-seq analysis reveals the profiles of bone marrow cells in STZ-induced T1D mice.

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scRNA-seq analysis reveals the heterogeneity of bone marrow immune cells in STZ-induced T1D mice.

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The ratio of BM-neutrophils to B lymphocytes is increased in the bone marrow of STZ-induced T1D mice.

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Osteopenia is occurred in STZ-induced T1D mice.

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This increased ratio is negatively correlated with osteopenia in STZ-induced T1D mice.

Introduction

Type 1 diabetes (T1D) is a multifactorial autoimmune disease. Broad knowledge about the genetics, epidemiology and clinical management of T1D has been achieved, but understandings about the cell varieties in the bone marrow during T1D remain limited.

Objectives

We aimed to present a profile of the bone marrow cells and reveal the relationship of bone marrow and osteopenia in streptozotocin (STZ)-induced T1D mice.

Methods

The whole bone marrow cells from the femurs and tibias of healthy (group C) and STZ-induced T1D mice (group D) were collected for single-cell RNA sequencing analysis. Single-cell flow cytometry and immunohistochemistry were performed to confirm the proportional changes among bone marrow neutrophils (BM-neutrophils) (Cxcr2⁺, Ly6g⁺) and B lymphocytes (Cd19⁺). X-ray and micro-CT were performed to detect bone mineral density. The correlation between the ratio of BM-neutrophils/B lymphocytes and osteopenia in STZ-induced T1D mice was analyzed by nonparametric Spearman correlation analysis.

Results

The bone marrow cells in groups C and D were divided into 12 clusters, and 249 differentially expressed genes were found. The diversity of CD45⁺ immune cells between groups C and D were greatly affected: the proportion of BM-neutrophils showed a significant increase while the proportion of B lymphocytes in group D showed a significant decrease. X-ray and micro-CT analyses confirmed that osteopenia occurred in group D mice. In addition, the results of single-cell flow cytometry and correlation analysis showed that the ratio of BM-neutrophils/B lymphocytes negatively correlated with osteopenia in STZ-induced T1D mice.

Conclusion

A single-cell RNA sequencing analysis revealed the profile and heterogeneity of bone marrow immune cells in STZ-induced T1D mice for the first time. The ratio of BM-neutrophils/B lymphocytes negatively correlated with osteopenia in STZ-induced T1D mice, which may enhance understanding for treating T1D and preventing T1D-induced osteopenia.

Lower bone mineral density and higher bone resorption marker levels in premenopausal women with type 1 diabetes in Japan

AIMS/INTRODUCTION

Type 1 diabetes is associated with poorer bone quality. Quantitative ultrasound provides an estimate of bone mineral density (BMD) and can also be used to evaluate bone quality, which is associated with an increased fracture risk in people with type 1 diabetes. The aim of this study was to evaluate the association between menopausal status and a bone turnover marker with heel BMD using quantitative ultrasound in women with type 1 diabetes and age- and body mass index-matched controls.

MATERIALS AND METHODS

A total of 124 individuals recruited in Kyoto and Osaka, Japan - 62 women with type 1 diabetes (mean age 47.2 ± 17.3 years) and 62 age-, menopausal status-, sex- and body mass index-matched non-diabetic control individuals (mean age 47.3 ± 16.3 years) - were enrolled in this study. Heel BMD in the calcaneus was evaluated using ultrasonography (AOS-100NW, Hitachi-Aloka Medical, Ltd., Tokyo, Japan). A bone turnover marker was also measured.

RESULTS

The heel BMD Z-score was significantly lower in premenopausal women with type 1 diabetes than in the premenopausal control group, but not in postmenopausal women with type 1 diabetes. Levels of tartrate-resistant acid phosphatase-5b, a bone resorption marker, were significantly higher in premenopausal women with type 1 diabetes than in the premenopausal control group, but not in postmenopausal women with type 1 diabetes. The whole parathyroid hormone level was significantly lower in both pre- and postmenopausal women with type 1 diabetes.

CONCLUSIONS

Lower heel BMD, higher tartrate-resistant acid phosphatase-5b level and lower parathyroid hormone were observed in premenopausal women with type 1 diabetes. Premenopausal women with type 1 diabetes require osteoporosis precautions for postmenopause.

Can Resistance Exercise Be a Tool for Healthy Aging in Post-Menopausal Women with Type 1 Diabetes?

Due to improvements in diabetes care, people with type 1 diabetes (T1D) are living longer. Studies show that post-menopausal T1D women have a substantially elevated cardiovascular risk compared to those without T1D. As T1D may also accelerate age-related bone and muscle loss, the risk of frailty may be considerable for T1D women. Exercise and physical activity may be optimal preventative therapies to maintain health and prevent complications in this population: They are associated with improvements in, or maintenance of, cardiovascular health, bone mineral density, and muscle mass in older adults. Resistance exercise, in particular, may provide important protection against age-related frailty, due to its specific effects on bone and muscle. Fear of hypoglycemia can be a barrier to exercise in those with T1D, and resistance exercise may cause less hypoglycemia than aerobic exercise. There are currently no exercise studies involving older, post-menopausal women with T1D. As such, it is unknown whether current guidelines for insulin adjustment/carbohydrate intake for activity are appropriate for this population. This review focuses on existing knowledge about exercise in older adults and considers potential future directions around resistance exercise as a therapeutic intervention for post-menopausal T1D women.

Association Between Parental Type 1 and Type 2 Diabetes Diagnosis and Major Osteoporotic Fracture Risk in Adult Offspring: A Population-Based Cohort Study

OBJECTIVES

Previous research suggests an intergenerational influence of diabetes on bone health. We examined the association between parental diabetes and major osteoporotic fracture (MOF) risk in offspring.

METHODS

This population-based cohort study used de-identified administrative health data from Manitoba, Canada, which capture population-level records of hospitalizations, physician visits and drug dispensations. The cohort included individuals 40⁺ years with at least 1 parent identified in the data between 1997 and 2015. The exposure was parental diagnosis of diabetes since 1970; the outcome was offspring incident MOF diagnosis of the hip, forearm, spine or humerus. Both measures were identified from hospital and physician visit records using validated case definitions. Multivariable Cox proportional hazards regression models tested the association of parental diabetes and offspring MOF risk.

RESULTS

The cohort included 279,085 offspring; 48.5% were females and 86.8% were ≤44 years of age. Both parents were identified for 89.4% of the cohort; 36.7% had a parental diabetes diagnosis. During a median follow up of 12.0 (interquartile range, 6.0 to 18.0) years, 8,762 offspring had a MOF diagnosis. After adjusting for fracture risk factors, parental diabetes diagnosis was not associated with MOF risk, whether diagnosed in fathers (adjusted hazard ratio [aHR], 1.02; 95% confidence interval [CI], 0.97 to 1.08), mothers (aHR, 1.02; 95% CI, 0.97 to 1.07) or both parents (aHR, 1.01; 95% CI, 0.93 to 1.11). The results remained consistent in a stratified analysis by offspring sex, secondary analysis based on MOF site and sensitivity analyses.

CONCLUSIONS

The results indicate parental diabetes is not associated with offspring MOF risk.

Prevalence, Characteristics, and Associated Risk Factors of the Elderly with Hip Fractures: A Cross-Sectional Analysis of NHANES 2005-2010

Objective

This cross-sectional study was aimed to update the assessment of prevalence, characteristics, and risk factors of the elderly with hip fractures in a non-institutionalized American population.

Methods

This current study included a total of 31,034 participants from the existing National Health and Nutritional Examination Survey (NHANES) database from 2005 to 2010, and 4,265 participants aged 65 years and older were ultimately identified. Their condition of hip fractures was determined by method of questionnaires according to the orthopedic surgeons' diagnosis, and related epidemiological and demographic data were further collected. The univariate analysis was used to screen the risk factors of hip fractures in the elderly, and the logistic regression model was established to conduct the multivariate analysis.

Results

Of the total 4,265 participants with clear information of hip fractures in elderly, 127 individuals with hip fractures were identified according to results of questionnaires, exhibiting a prevalence of 28.49 per 1,000 (95% confidence interval [CI]=21.38-35.60) for males and 31.03 per 1,000 (95% CI=23.72-38.35) for females. The mean age of the elderly with hip fractures was 77.12±5.88 years and tumble (48.0%) was the primary factor. In univariate analysis, age, race, smoking, drinking alcohol, and combined with osteoporosis were regarded as risk factors. Multivariate analysis showed that age (80 years and older), living alone, smoking, combined with diabetes and osteoporosis were the independent risk factors.

Conclusion

Our nationwide data indicate the prevalence of hip fractures in the elderly is generally on the rise, and the female occupies a higher proportion. Age (especially aged 80 years and older), race (mainly Non-Hispanic white), smoking, drinking alcohol, living alone, combined with diabetes and osteoporosis may be closely linked to the occurrence of hip fractures in the elderly, although these variables still need to be verified in further prospective investigations.

Bone mineral density in patients with longstanding type 1 diabetes: Results from the Canadian Study of Longevity in Type 1 Diabetes

AIM

It is currently unclear if longstanding type 1 diabetes (T1D) affects bone mineral density (BMD).

METHODS

BMD measured by dual-energy X-ray absorptiometry and history of fragility fracture was determined in 75 T1D participants with ≥50 years of diabetes duration and 75 age- and sex-matched non-diabetic controls. BMD T-scores were determined for the lumbar spine (LS), total hip (TH) and femoral neck (FN).

RESULTS

T1D participants had median diabetes duration of 54 [52, 58] years, 41 (55%) were females, and mean A_1c was 7.3 ± 0.8%. T1D females had higher LS T-scores compared to female controls (-0.3 ± 1.2 vs. -1.1 ± 1.4, p = 0.014), lower FN T-scores (-1.5 ± 1.0 vs. -1.2 ± 0.9, p = 0.042) and more fragility fractures (7 (17%) vs. 1 (2%), p = 0.021). In T1D, higher A1c was associated with higher adjusted odds of fragility fracture (p = 0.006). T1D males and controls showed no difference in BMD or fractures.

CONCLUSIONS

There were no substantial differences in T-score between T1D and matched controls; however, T1D females showed higher BMD at the LS and possibly paradoxically higher fragility fractures compared to matched controls. These findings suggest that lower T-scores may not be associated with a history of fragility fracture in females with longstanding T1D and that other factors should be investigated.

Peripheral Neuropathy as a Component of Skeletal Disease in Diabetes

PURPOSE OF REVIEW

The goal of this review is to explore clinical associations between peripheral neuropathy and diabetic bone disease and to discuss how nerve dysfunction may contribute to dysregulation of bone metabolism, reduced bone quality, and fracture risk.

RECENT FINDINGS

Diabetic neuropathy can decrease peripheral sensation (sensory neuropathy), impair motor coordination (motor neuropathy), and increase postural hypotension (autonomic neuropathy). Together, this can impair overall balance and increase the risk for falls and fractures. In addition, the peripheral nervous system has the potential to regulate bone metabolism directly through the action of local neurotransmitters on bone cells and indirectly through neuroregulation of the skeletal vascular supply. This review critically evaluates existing evidence for diabetic peripheral neuropathy as a risk factor or direct actor on bone disease. In addition, we address therapeutic and experimental considerations to guide patient care and future research evaluating the emerging relationship between diabetic neuropathy and bone health.

Bone health in diabetes and prediabetes

Bone fragility has been recognized as a complication of diabetes, both type 1 diabetes (T1D) and type 2 diabetes (T2D), whereas the relationship between prediabetes and fracture risk is less clear. Fractures can deeply impact a diabetic patient’s quality of life. However, the mechanisms underlying bone fragility in diabetes are complex and have not been fully elucidated. Patients with T1D generally exhibit low bone mineral density (BMD), although the relatively small reduction in BMD does not entirely explain the increase in fracture risk. On the contrary, patients with T2D or prediabetes have normal or even higher BMD as compared with healthy subjects. These observations suggest that factors other than bone mass may influence fracture risk. Some of these factors have been identified, including disease duration, poor glycemic control, presence of diabetes complications, and certain antidiabetic drugs. Nevertheless, currently available tools for the prediction of risk inadequately capture diabetic patients at increased risk of fracture. Aim of this review is to provide a comprehensive overview of bone health and the mechanisms responsible for increased susceptibility to fracture across the spectrum of glycemic status, spanning from insulin resistance to overt forms of diabetes. The management of bone fragility in diabetic patient is also discussed.

Determinants of fracture in adults with type 1 diabetes in the USA: Results from the T1D Exchange Clinic Registry

AIMS

To examine the prevalence/determinants of fracture in the T1D Exchange Clinic Registry.

RESEARCH DESIGN/METHODS

Adults (≥18 years) with T1D duration ≥5 years, diagnosed before age 45 years completed a fracture questionnaire. Additional characteristics were collected from registry data. Only fractures reported as occurring after T1D diagnosis were included. Characteristics were compared between those with and without fractures.

RESULTS

Respondents included 756 adults (mean age 39 ± 16 years, 28% ≥50 years, 63% female, 90% non-Hispanic White, diabetes duration 24 ± 14 years); 48% reported ≥1 fracture since diagnosis. Of the 659 reported fractures, 24% involved metatarsal/toe, 21% metacarpal/fingers, 14% fibula/tibia, 5% hip/pelvis/femur and 3% vertebrae. Those with fracture were more likely to be older (43 ± 16 vs. 36 ± 14 years), have longer T1D duration (28 ± 14 vs. 20 ± 12 years), been diagnosed with T1D before age 20 years (79% vs. 71%) compared to those without fracture (all p-values < 0.01).

CONCLUSIONS

Data from this national sample suggest fractures in adults with T1D are common at young age and frequently involve peripheral sites. Age, longer diabetes duration, and T1D diagnosis prior to peak bone mass accrual are notable risk factors. Further research is needed to examine the impact of these determinants on fracture risk in T1D.

Fracture risk in young and middle-aged adults with type 1 diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Type 1 diabetes mellitus (T1DM) is associated with skeletal fragility. While previous meta-analyses have demonstrated an increased risk of fracture in individuals with T1DM, little is known about fracture risk in T1DM, in the absence of age-related confounders.

AIMS

To determine the risk of fracture in young and middle-aged adults with T1DM aged 18-50 years old.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Ovid MEDLINE, PubMed, EMBASE, EBM reviews and relevant conference abstracts.

STUDY INCLUSION CRITERIA

Studies of adults aged between 18-50 years with type 1 diabetes mellitus, with reported fracture outcomes.

PRIMARY OUTCOMES

Incident or prevalent fracture.

RESULTS

Six studies were included in the meta-analysis. A total of 1724 fractures occurred in 35 925 patients with T1DM and 48 253 fractures occurred in 2 455 016 controls. RR for all fractures was 1.88 (95% CI 1.52-2.32, P < .001). Fifty-six hip fractures occurred among 34 707 patients with T1DM and 594 hip fractures occurred in 2 295 177 controls. The RR of hip fractures was 4.40 (95% CI 2.58-7.50, P < .001). Females and males with T1DM had a RR of 5.79 (95% CI 3.55-9.44, P < .001) and 3.67 (95% CI 2.10-6.41, P < .001), respectively.

CONCLUSIONS

In the absence of age-related comorbidities, fracture risk remains significantly elevated in young and middle-aged adults with T1DM. Younger age does not mitigate against hip fracture risk in T1DM, and health professionals need to be aware of this risk. Further studies are needed to evaluate the mechanisms of fracture in T1DM.

Assessment of bone quality in patients with diabetes mellitus

Substantial evidence exists that diabetes mellitus is associated with an increased risk of osteoporotic fractures. Low bone strength as well as bone extrinsic factors are probably contributing to the increased bone fragility in diabetes. Bone density and quality are important determinants of bone strength. Although bone mineral density (BMD) and the fracture risk assessment tool (FRAX) are very useful clinical tools in assessing bone strength, they may underestimate the fracture risk in diabetes mellitus. Through advances in new technologies such as trabecular bone score (TBS) and peripheral quantitative computed tomography (pQCT), we can better assess the bone quality and fracture risk of patients with diabetes mellitus. Invasive assessments such as microindentation and histomorphometry have been great complement to the existing bone analysis techniques. Bone turnover markers have been found to be altered in diabetes mellitus patients and may be associated with fractures. This review will give a brief summary of the current development and clinical uses of these assessments.

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

Skeletal fractures can result when there are co-morbid conditions that negatively impact bone strength. Fractures represent an important source of morbidity and mortality, especially in older populations. Diabetes mellitus is a metabolic disorder that has reached worldwide epidemic proportions and is increasingly being recognized as a risk factor for fracture. Type 1 and Type 2 diabetes have different effects on bone mineral density but share common pathways, which lead to bone fragility. In this review, we discuss the available data on diabetes and fractures, bone density and the clinical implications for fracture risk stratification in current practice.

Does a Treadmill Running Exercise Contribute to Preventing Deterioration of Bone Mineral Density and Bone Quality of the Femur in KK-Ay Mice, a Type 2 Diabetic Animal Model?

Although it has been recently shown that type 2 diabetics have an increased risk of hip fracture, the effects of exercise therapy to prevent this have not been clarified. We examined whether a treadmill running exercise contributes to the bone mineral density (BMD) and bone microarchitecture of the femur and what kind of exercise intensity and duration are optimum in type 2 diabetes mellitus using KK-Ay diabetic mice. The mice were divided into two running groups, one fast speed and short duration (FS), the other slow speed and long duration (SL), and a group of controls with no running (CO). The running exercise was started when the mice were 8 weeks of age, and continued once a day 5 days per week for 10 weeks. Ten weeks after the start of the running exercise, the BMD of the proximal region and mid-diaphysis in the SL were significantly higher in comparison with that in the CO, whereas there was no difference in bone microarchitecture among the three groups. Blood glucose, insulin levels, and visceral fat contents in the SL were significantly lower than those in the CO and FS. Bone resorption protein and C-reactive protein levels in the SL were significantly lower than those in the CO. These results suggest that slow, long duration loading is better for both bone and glycemic control than fast, short duration loading in type 2 diabetes.

Imaging of diabetic bone

Diabetes is an important concern in terms of medical and socioeconomic costs; a high risk for low-trauma fractures has been reported in patients with both type 1 and type 2 diabetes. The mechanism involved in the increased fracture risk from diabetes is highly complex and still not entirely understood; obesity could play an important role: recent evidence suggests that the influence of fat on bone is mainly dependent on the pattern of regional fat deposition and that an increased amount of visceral adipose tissue negatively affects skeletal health.Correct and timely individuation of people with high fracture risk is critical for both prevention and treatment: Dual-energy X-ray Absorptiometry (currently the "gold standard" for diagnosis of osteoporosis) underestimates fracture risk in diabetic patients and therefore is not sufficient by itself to investigate bone status. This paper is focused on imaging, covering different modalities involved in the evaluation of skeletal deterioration in diabetes, discussing the limitations of conventional methods and exploring the potential of new tools and recent high-resolution techniques, with the intent to provide interesting insight into pathophysiology and fracture risk.

Bone Metabolism and Fracture Risk in Diabetes Mellitus

Individuals with Type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) are at increased risk for fragility fractures. Bone mineral density (BMD) is decreased in T1DM but often normal or even elevated in T2DM when compared with age-matched non-DM populations. However, bone turnover is decreased in both T1DM and T2DM. The pathophysiologic mechanisms leading to bone fragility is multifactorial, and potentially leads to reduced bone formation, altered bone microstructure and decreased bone strength. Interestingly, different antidiabetic treatments may influence fracture risk due to effects on glycemic control, triggering of hypoglycemic events or osteoblastogenesis.

Bone disease in diabetes: another manifestation of microvascular disease?

Type 1 and type 2 diabetes are generally accepted to be associated with increased bone fracture risk. However, the pathophysiological mechanisms of diabetic bone disease are poorly understood, and whether the associated increased skeletal fragility is a comorbidity or a complication of diabetes remains under debate. Although there is some indication of a direct deleterious effect of microangiopathy on bone, the evidence is open to question, and whether diabetic osteopathy can be classified as a chronic, microvascular complication of diabetes remains uncertain. Here, we review the current knowledge of potential contributory factors to diabetic bone disease, particularly the association between diabetic microangiopathy and bone mineral density, bone structure, and bone turnover. Additionally, we discuss and propose a pathophysiological model of the effects of diabetic microvascular disease on bone, and examine the progression of bone disease alongside the evolution of diabetes.

Bone mineral density at femoral neck and lumbar spine in adults with type 1 diabetes: a meta-analysis and review of the literature

We performed a meta-analysis to evaluate the femoral neck and lumbar spine bone mineral density (BMD) in adults with type 1 diabetes (T1D) compared with controls. Adults with T1D have modestly lower BMD at femoral neck and lumbar spine than adults without diabetes.

INTRODUCTION

Fracture risk is four to sixfold higher in adults with T1D. Since BMD is one of the major contributors for fracture risk, we performed a meta-analysis to evaluate differences in femoral neck and lumbar spine BMD between adults with T1D and controls.

METHODS

MEDLINE, Ovid, and the Cochrane library and abstracts from various scientific meetings were searched. Studies reporting the femoral neck and/or lumbar spine BMD in adults (age > 20 years) with T1D in comparison with people without diabetes were selected. General linear mixed models were used to assess differences in BMD at femoral neck and lumbar spine between subjects with T1D and controls adjusting for age, sex, and dual x-ray absorptiometry (DXA) instruments.

RESULTS

Sixteen studies met the inclusion criteria. The femoral neck BMD was modestly lower in adults with T1D compared to controls (-0.055 g/cm²; 95% CI: -0.065, -0.045). There were no differences in lumbar spine BMD between adults with T1D and controls (0.0062 g/cm²; 95% CI -0.04, 0.016). However, in a sensitivity analysis, lumbar spine BMD was modestly lower in adults with T1D compared to controls (-0.035 g/cm²; -0.049, -0.02). Studies using Lunar DXA instruments have reported higher lumbar spine and femoral neck BMD compared to studies using Hologic DXA instruments.

CONCLUSION

Femoral neck and lumbar spine BMD were modestly lower in adults with T1D compared to controls. However, this modest reduction in femoral neck and lumbar spine BMD cannot explain much higher observed fracture risk in adults with T1D.

Bone health in subjects with type 1 diabetes for more than 50 years

AIMS

Few data regarding prevalence of and risk factors for poor bone health in aging individuals with long-standing T1D are available. In this study, we aim to describe the prevalence of bone fragility and to identify factors associated with low bone density in individuals with long-term T1D.

METHODS

We examined the prevalence of non-vertebral fractures in 985 subjects enrolled in the Joslin 50-Year Medalist Study and measured bone mineral density (BMD) by dual-energy X-ray absorptiometry at the femoral neck, lumbar spine and radius in a subset (65 subjects, mean age 62.6 years, duration 52.5 years, HbA1c 7.1%) with no significant clinical or demographic differences from the rest of the cohort.

RESULTS

Medalists have low prevalence of fractures (0.20% hip and 0.91% wrist) and normal Z-score values (spine +1.15, total hip +0.23, femoral neck -0.01, radius +0.26; p > 0.05 for differences vs. 0 at all sites). A significant relationship was found between lower BMD and higher total cholesterol, triglycerides and LDL levels, but not HbA1c. Low BMD at the femoral neck was associated with cardiovascular disease after adjustment for confounding factors: prevalence risk ratio of CVD [95% CI] 4.6 [1.2-18.1], p = 0.03. No other diabetic vascular complication was found to be associated with low BMD.

CONCLUSIONS

These are the first data regarding bone health in aging individuals who have had diabetes for 50 or more years. The low rates of non-vertebral fractures and the normal Z-score suggest the long T1D diabetes duration did not increase the risk of bone fractures in Medalists compared to non-diabetic peers. Additionally, the association with cardiovascular disease demonstrates the BMD differences in groups are likely not due to glycemic control alone.

DXA-Based Measurements in Diabetes: Can They Predict Fracture Risk?

In the absence of a fragility fracture, osteoporosis is usually diagnosed from bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA). Osteoporosis is an increasingly prevalent disease, as is diabetes [in particular type 2 diabetes (T2D)], in part due to aging populations worldwide. It has been suggested that an increased risk of fracture may be another complication ensuing from longstanding diabetes. The purpose of this review is to concentrate on skeletal parameters and techniques readily available from DXA scanning, and their utility in routine clinical practice for predicting fracture risk. In addition to BMD, other applications and measures from DXA include trabecular bone score (TBS), skeletal geometry and DXA-based finite-element analysis, vertebral fracture assessment, and body composition. In type 1 diabetes (T1D), BMD and FRAX^R (when secondary osteoporosis is included without BMD) only partially account for the excess risk of fracture in T1D. Consistent data exist to show that BMD and FRAX^R can be used to stratify fracture risk in T2D, but do not account for the increased risk of fracture. However, several adjustments to the FRAX score can be made as proxies for T2D to inform the use of FRAX by primary care practitioners. Examples include using the rheumatoid arthritis input (as a proxy for T2D), lumbar spine TBS (to adjust FRAX probability) or an altered hip T-score (lowered by 0.5 units). These adjustments can improve fracture risk prediction in T2D and help to avoid systematically underestimating the risk of osteoporosis-related fractures in those with diabetes.

Evaluation of bone mineral density among type 2 diabetes mellitus patients in South Karnataka

Background:

Diabetes is one of the world's biggest health problems and the disease affects almost all organ systems. The relationship between type 2 diabetes mellitus (T2DM) and bone mineral density (BMD) has been controversial. Early identification of reduction in bone mass in a diabetic patient may be helpful in preventing the bone loss and future fracture risks.

Objective:

The aim is to study the effect of T2DM on BMD among patients in South Karnataka.

Materials and Methods:

A cross-sectional study was conducted on 150 patients between 40 and 70 years of age which included 75 diabetic and 75 nondiabetic subjects. BMD was measured using qualitative ultrasound and the data were compared among age-matched subjects of both the groups. Statistical analysis was performed using unpaired Student's t-test and test of equality of proportions.

Results:

No significant difference was observed in bone density of both the groups. On further analyzing the data, incidence of osteoporosis was higher among diabetic subjects, whereas incidence of osteopenia was higher among nondiabetic subjects.

Conclusion:

Although significant difference in bone mineral density was not observed in both the groups, the incidence of osteoporosis was higher among type 2 diabetics. Hence, all type 2 diabetics should be evaluated for the risk of osteoporosis and should be offered appropriate preventive measures.

Epidemiology of Skeletal Health in Type 1 Diabetes

The skeleton is adversely affected by type 1 diabetes (T1D). Patients with T1D of both sexes have an increased risk of fracture that begins in childhood and extends across the entire lifespan. T1D is characterized by mild to modest deficits in bone density, structure, and microarchitecture. Current evidence suggests that the observed bone deficits in T1D are the result of impaired bone formation rather than increased bone resorption. There is emerging data that bone quality is impaired in T1D, which may explain the findings that fracture risk is elevated out of proportion to the degree of bone mineral deficit. In this review, we summarize the current knowledge regarding the epidemiology of skeletal health in T1D. Given the high individual and societal burden of osteoporotic fracture, there is an urgent need to better understand the etiology of T1D-related bone disease so that clinical strategies to prevent fracture can be developed.

MECHANISMS IN ENDOCRINOLOGY: Mechanisms and evaluation of bone fragility in type 1 diabetes mellitus

Subjects with type 1 diabetes mellitus (T1DM) have decreased bone mineral density and an up to sixfold increase in fracture risk. Yet bone fragility is not commonly regarded as another unique complication of diabetes. Both animals with experimentally induced insulin deficiency syndromes and patients with T1DM have impaired osteoblastic bone formation, with or without increased bone resorption. Insulin/IGF1 deficiency appears to be a major pathogenetic mechanism involved, along with glucose toxicity, marrow adiposity, inflammation, adipokine and other metabolic alterations that may all play a role on altering bone turnover. In turn, increasing physical activity in children with diabetes as well as good glycaemic control appears to provide some improvement of bone parameters, although robust clinical studies are still lacking. In this context, the role of osteoporosis drugs remains unknown.

O-GlcNAcylation: a bridge between glucose and cell differentiation

Glucose is the major energy supply and a critical metabolite for most cells and is especially important when cell is differentiating. High or low concentrations of glucose enhances or inhibits the osteogenic, chondrogenic and adipogenic differentiation of cell via the insulin, transforming growth factor‐β and peroxisome proliferator‐activated receptor γ pathways, among others. New evidence implicates the hexosamine biosynthetic pathway as a mediator of crosstalk between glucose flux, cellular signalling and epigenetic regulation of cell differentiation. Extracellular glucose flux alters intracellular O‐GlcNAcylation levels through the hexosamine biosynthetic pathway. Signalling molecules that are important for cell differentiation, including protein kinase C, extracellular signal‐regulated kinase, Runx2, CCAAT/enhancer‐binding proteins, are modified by O‐GlcNAcylation. Thus, O‐GlcNAcylation markedly alters cell fate during differentiation via the post‐transcriptional modification of proteins. Furthermore, O‐GlcNAcylation and phosphorylation show complex interactions during cell differentiation: they can either non‐competitively occupy different sites on a substrate or competitively occupy a single site or proximal sites. Therefore, the influence of glucose on cell differentiation via O‐GlcNAcylation offers a potential target for controlling tissue homoeostasis and regeneration in ageing and disease. Here, we review recent progress establishing an emerging relationship among glucose concentration, O‐GlcNAcylation levels and cell differentiation.

Reduced Bone Mineral Density Is Associated with Celiac Disease Autoimmunity in Children with Type 1 Diabetes

OBJECTIVE

To evaluate the association between bone mineral density (BMD), glycemic control (hemoglobin A1c [HbA1c]), and celiac autoimmunity in children with type 1 diabetes mellitus (T1D) and in an appropriate control population.

STUDY DESIGN

BMD was assessed cross-sectionally in 252 children with T1D (123 positive for anti-tissue transglutaminase antibody [tTGA] and 129 matched children who were negative for tTGA). In addition, BMD was assessed in 141 children without diabetes who carried T1D-associated HLD-DR, DQ genotypes (71 positive for tTGA and 70 negative).

RESULTS

Children with T1D who were positive for tTGA had significantly worse BMD L1-L4 z-score compared with children with T1D who were negative for tTGA (-0.45 ± 1.22 vs 0.09 ± 1.10, P = .0003). No differences in growth measures, urine N-telopeptides, 25-hydroxyvitamin D, ferritin, thyroid stimulating hormone, or HbA1c were found. However, both higher HbA1c (β = -1.25 ± 0.85, P = .0016) and tTGA (β = -0.13 ± 0.05, P = .0056) were significant and independent predictors of lower BMD in multivariate analyses. No differences in BMD or other variables measured were found between children without diabetes who were positive vs negative for tTGA.

CONCLUSIONS

The results suggest a synergistic effect of hyperglycemia and celiac autoimmunity on low BMD.

Type 1 diabetes is associated with an increased risk of fracture across the life span: a population-based cohort study using The Health Improvement Network (THIN)

OBJECTIVE

This study was conducted to determine if type 1 diabetes is associated with an increased risk of fracture across the life span.

RESEARCH DESIGN AND METHODS

This population-based cohort study used data from The Health Improvement Network (THIN) in the U.K. (data from 1994 to 2012), in which 30,394 participants aged 0-89 years with type 1 diabetes were compared with 303,872 randomly selected age-, sex-, and practice-matched participants without diabetes. Cox regression analysis was used to determine hazard ratios (HRs) for incident fracture in participants with type 1 diabetes.

RESULTS

A total of 334,266 participants, median age 34 years, were monitored for 1.9 million person-years. HR were lowest in males and females age <20 years, with HR 1.14 (95% CI 1.01-1.29) and 1.35 (95% CI 1.12-1.63), respectively. Risk was highest in men 60-69 years (HR 2.18 [95% CI 1.79-2.65]), and in women 40-49 years (HR 2.03 [95% CI 1.73-2.39]). Lower extremity fractures comprised a higher proportion of incident fractures in participants with versus those without type 1 diabetes (31.1% vs. 25.1% in males, 39.3% vs. 32% in females; P < 0.001). Secondary analyses for incident hip fractures identified the highest HR of 5.64 (95% CI 3.55-8.97) in men 60-69 years and the highest HR of 5.63 (95% CI 2.25-14.11) in women 30-39 years.

CONCLUSIONS

Type 1 diabetes was associated with increased risk of incident fracture that began in childhood and extended across the life span. Participants with type 1 diabetes sustained a disproportionately greater number of lower extremity fractures. These findings have important public health implications, given the increasing prevalence of type 1 diabetes and the morbidity and mortality associated with hip fractures.

Different health behaviours and clinical factors associated with bone mineral density and bone turnover in premenopausal women with and without type 1 diabetes

BACKGROUND

Women with type 1 diabetes (T1DM) have an elevated fracture risk. We therefore compared the associations of health behaviours and clinical factors with bone mineral density (BMD) and bone remodelling between premenopausal women with and without T1DM to inform potential interventions.

METHODS

Participants included women with T1DM (n = 89) from the Wisconsin Diabetes Registry Study and age-matched and race-matched controls without diabetes (n = 76). Peripheral (heel and forearm) and central (hip and spine) BMD, markers of bone resorption and formation, bone cell signalling, glycaemic control, and kidney function were assessed. Health behaviours and medical history were self-reported.

RESULTS

In controls, but not in women with T1DM, older age was associated with lower bone resorption (p ≤ 0.006) and formation (p = 0.0007). Body mass index was positively associated with heel and forearm BMD in both controls and T1DM women (all p < 0.0001), but with hip and spine BMD only in controls (p ≤ 0.005). Worse glycaemic control during the previous 10 years, greater alcohol intake, history of smoking, and lack of physical activity were associated with poorer bone outcomes only in women with T1DM (all p ≤ 0.002), whereas use of hormonal contraceptives was related to low bone formation in both women with and without T1DM (all p ≤ 0.006). Diabetes duration, insulin dose, residual C-peptide, and kidney function were not associated with bone in T1DM.

CONCLUSIONS

Age and body mass index may not predict bone health in T1DM women. However, modifiable behaviours such as optimizing glycaemic control, limiting substance and hormonal contraceptive use, and increasing physical activity may improve bone health in T1DM women.

An update on diabetes related skeletal fragility

There are several mechanisms by which diabetes could affect bone mass and strength. These mechanisms include insulin deficiency; hyperglycemia; the accumulation of advanced glycation end products that may influence collagen characteristics; marrow adiposity and bone inflammation. Furthermore, associated diabetic complications and treatment with thaizolidinediones may also increase risk of fracturing. The following article provides its readers with an update on the latest information pertaining to diabetes related bone skeletal fragility. In the authors' opinion, future studies are needed in order to clarify the impact of different aspects of diabetes metabolism, glycemic control, and specific treatments for diabetes on bone. Given that dual energy x-ray absorptiometry is a poor predictor of bone morbidity in this group of patients, there is a need to explore novel approaches for assessing bone quality. It is important that we develop a better understanding of how diabetes affects bone in order to improve our ability to protect bone health and prevent fractures in the growing population of adults with diabetes.

Bilateral Calcaneal Avulsion Fracture Complicated with a Delayed Achilles Tendon Rupture in a Patient with Diabetes: A Case Report

CASE

A sixty-five-year-old man with diabetes mellitus had bilateral calcaneal avulsion fracture without a history of trauma. Both fractures were treated surgically with modified tension-band wiring, cerclage wiring, and screws. Six months after the surgery on the left side, the patient had a left Achilles tendon rupture proximal to its insertion into the calcaneus.

CONCLUSION

Calcaneal avulsion fractures are rare but often have complications. Even if these fractures are managed by well-established treatment methods, an unanticipated complication, namely a delayed Achilles tendon rupture, can occur in patients with diabetes.

Association between bone mineral density and type 1 diabetes mellitus: a meta-analysis of cross-sectional studies

A few studies have investigated the relationship between type 1 diabetes mellitus (T1DM) and bone mineral density (BMD) values. This meta-analysis was performed to explore differences between T1DM and healthy individuals in BMD values measured at five bone sites.We searched the database of PubMed for cross-sectional studies about the association of T1DM and BMD, and a meta-analysis was conducted.The results suggested significant association between T1DM and decreased BMD values of total body. The pooled mean differences (MDs) were -0.06 [95% confidence interval (CI): -0.11, -0.01] for all people. As for the association between T1DM and spine BMD values, the pooled MDs were -0.04 (95% CI: -0.07, -0.01) for males and -0.03 (95% CI: -0.06, 0.00) for females <20 years old. As for femur BMD values, the pooled MDs were -0.06 (95% CI: -0.13, 0.00) for all people, -0.03 (95% CI: -0.06, -0.01) for females and -0.04(95% CI: -0.05, -0.02) for males. As for hip BMD values, the pooled MDs were -0.06 (95% CI: -0.08, -0.04) for females. As for forearm BMD values, the pooled MDs were -0.01 (95% CI: -0.02, 0.00) for females.The results of this meta-analysis suggest the overall association between T1DM and reduced BMD values. Notably, the influence of T1DM on BMD seems to depend on gender or patient's age. Reduced BMD values may occur early after T1DM diagnosis. Future clinical and basic research studies are needed to further understand the mechanisms of decreased BMD values in T1DM patients.

The effect of diabetic neuropathy on foot bones: a systematic review and meta-analysis

AIMS

It is proposed that diabetic neuropathy may affect peripheral bone. Direct innervation of bone as well as neural control over its vascular supply and muscular influences may be affected by diabetes-induced peripheral neuropathies. Associated changes to bone may contribute to the occurrence of foot bone pathology in this population. This systematic review aims to examine the literature related to the effect of diabetic neuropathy on foot bones.

METHODS

Studies examining relationships between neuropathy and indicators of bone health (e.g. bone mineral density) in populations with diabetes were sought. Relevant publications were obtained from searches in MEDLINE, CINAHL and Embase in the period up to March 2013. Meta-analysis was performed using a random effects model in the statistical package Stata version 12.1.

RESULTS

Ten studies met the inclusion criteria and were included in the narrative synthesis. All studies were cross-sectional or case-control in design. Four of the 10 included studies found results indicating poorer bone health in those with diabetes and neuropathy compared with those with diabetes without neuropathy. Seven of the 10 studies were able to be included in a meta-analysis. The mean pooled effect was -0.36 (95% CI -0.76 to 0.04; P = 0.08), indicating a non-significant trend towards poorer bone health in those with diabetic neuropathy.

CONCLUSIONS

We did not find a significant relationship between presence of neuropathy in those with diabetes and poorer peripheral bone health. However, methodological limitations of the included studies mean further research is required to investigate this theoretical relationship.

Diabetes, depressive symptoms, and inflammation in older adults: results from the Health, Aging, and Body Composition Study

OBJECTIVE

Up-regulated levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP) are common to both type 2 diabetes mellitus (T2DM) and elevated depressive symptoms, yet little attention has been given to the biological mechanisms associated with these co-morbidities. This study examined the association between inflammation and both T2DM and elevated depressive symptoms.

METHODS

Baseline data were analyzed from 3009 adults, aged 70-79, participating in the Health, Aging, and Body Composition Study. Diabetes was assessed per self-report, medication use, fasting glucose and/or glucose tolerance tests. Elevated depressive symptoms were categorized using the Center for Epidemiologic Studies Depression scale (cut-score≥20). Log-transformed IL-6, TNF-α, and CRP were analyzed using ANCOVA.

RESULTS

Participants with T2DM and elevated depressive symptoms (T2DM+DEP n=14) demonstrated significantly (p<.05) higher IL-6 compared to (T2DM Only n=628), (DEP Only n=49), and (No T2DM or DEP n=2067) groups following covariate adjustment. Similarly, participants with T2DM+DEP (n=14) had significantly (p<.05) higher CRP, after covariate adjustment, compared to DEP Only (n=50) and No T2DM or DEP groups (n=2153). No association was observed for TNF-α.

CONCLUSIONS

These findings provide evidence that inflammation is associated with T2DM and elevated depressive symptoms. Participants with T2DM+DEP demonstrated the highest IL-6 levels compared to all other groups. Greater CRP levels were also observed in T2DM, but not elevated depressive symptoms, which may suggest that differential associations between T2DM and depressive symptoms exist for various inflammatory markers. Further investigation into these associations could aid in understanding the biological pathways underlying both T2DM and depressive symptoms.

Hormone replacement therapy for women with type 1 diabetes mellitus

BACKGROUND

There is conflicting information about the impact of the menopause on glycaemic control amongst women with type 1 diabetes. Some menopausal women with type 1 diabetes are treated with hormone replacement therapy (HRT) but the effects of this treatment have, to date, not been established.

OBJECTIVES

To assess the effects of HRT for women with type 1 diabetes mellitus.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, CINAHL and PsycINFO from their inception to June 2012. The last search was run for all databases on 18 June 2012.

SELECTION CRITERIA

We selected randomised controlled trials or controlled clinical trials that involved peri- or postmenopausal women with type 1 diabetes undergoing HRT as an intervention.

DATA COLLECTION AND ANALYSIS

Two researchers independently applied the inclusion criteria to the identified studies and assessed risk of bias. Disagreements were resolved by discussion or by intervention by a third party. Descriptive analysis was conducted for the review.

MAIN RESULTS

Ninety-two publications were screened. No studies met the inclusion criteria exclusively but one study that included both type 1 and type 2 diabetes participants was considered. This randomised clinical trial (RCT) compared HRT (N = 27) with placebo (N = 29) over 12 months. The outcome measures were cardiovascular risk factors, including lipid profile, glycaemic control, blood pressure and body weight. No significant differences between placebo and HTR were detected. Patient-important outcomes like all-cause mortality, cardiovascular disease, diabetic complications or health-related quality of life were not investigated.

AUTHORS' CONCLUSIONS

There is a lack of evidence around the use of HRT in women with type 1 diabetes. The one study that has been undertaken in this area is underpowered. More RCTs are required in the area to examine the impact of HRT on glycaemic control and cardiovascular outcomes.

Phalangeal quantitative ultrasound and metabolic control in pre-menopausal women with type 1 diabetes mellitus

BACKGROUND

Several studies have reported increased fracture risk in Type 1 diabetes mellitus (T1DM). Quantitative Ultrasound (QUS) provides information on the structure and elastic properties of bone, which are important determinants of fracture risk, along with bone mineral density.

AIM

To study phalangeal sites by QUS, examine bone turnover markers and analyze association between these factors with metabolic control in a population of pre-menopausal women with T1DM.

MATERIAL AND METHODS

Thirty-five T1DM pre-menopausal women (mean age 34.5 ± 6.8 yr) attending the Diabetic Outpatients Clinic in the Department of Internal Medicine, University of Messina, were consecutively enrolled and divided into two groups, taking into account the mean value of glycated hemoglobin in the last three years. Twenty healthy age-matched women served as controls. Phalangeal ultrasound measurements [Amplitude Dependent Speed of Sound (AD-SoS), Ultrasound Bone Profile Index (UBPI), TScore, Z-Score] were performed using a DBM Sonic Bone Profiler. Osteocalcin and deoxypyridinoline served as markers of bone formation and bone resorption, respectively.

RESULTS

T1DM women with poor metabolic control showed lower phalangeal QUS values compared to healthy controls (p<0.01) and T1DM women with good metabolic control (p<0.05). No significant differences in QUS measurements were detected between T1DM women with good metabolic control and healthy controls. Lower bone formation and increased bone resorption, although not statistically significant, were observed in patients with poor metabolic control in comparison to patients with good metabolic control.

CONCLUSIONS

Poor metabolic control may worsen the quality of bone in T1DM. Phalangeal QUS could be considered as a tool to screen T1DM women for osteoporosis in pre-menopausal age.

Beyond glycemic control in diabetes mellitus: effects of incretin-based therapies on bone metabolism

Diabetes mellitus (DM) and osteoporosis (OP) are common disorders with a significant health burden, and an increase in fracture risk has been described both in type 1 (T1DM) and in type 2 (T2DM) diabetes. The pathogenic mechanisms of impaired skeletal strength in diabetes remain to be clarified in details and they are only in part reflected by a variation in bone mineral density. In T2DM, the occurrence of low bone turnover together with a decreased osteoblast activity and compromised bone quality has been shown. Of note, some antidiabetic drugs (e.g., thiazolidinediones, insulin) may deeply affect bone metabolism. In addition, the recently introduced class of incretin-based drugs (i.e., GLP-1 receptor agonists and DPP-4 inhibitors) is expected to exert potentially beneficial effects on bone health, possibly due to a bone anabolic activity of GLP-1, that can be either direct or indirect through the involvement of thyroid C cells. Here we will review the established as well as the putative effects of incretin hormones and of incretin-based drugs on bone metabolism, both in preclinical models and in man, taking into account that such therapeutic strategy may be effective not only to achieve a good glycemic control, but also to improve bone health in diabetic patients.

Characteristics of diabetic osteopenia in KK-Ay diabetic mice

We examined the bone mineral density (BMD) of the proximal region and the mid-diaphysis of the femur using dual energy X-ray absorption (DXA), the blood osteocalcin level and the blood glucose level every five weeks from 8 to 23 weeks old in KK-Ay diabetic mice. The BMD of the proximal region after 18 weeks old was significantly lower when compared with that at 8 weeks old (p<0.05), whereas there was no significant difference in the BMD of the mid-diaphysis at each week. The BMD of the proximal region at 18 weeks old was significantly lower than that in ddY mice, used as controls (p<0.05). The blood osteocalcin level at 18 weeks old was significantly lower than that at 8 weeks old and that in 18-week-old ddY mice (p<0.05). There was significant negative correlation between the blood glucose level and the BMD of the proximal region (r=-0.64, p<0.05). These results suggest that type 2 diabetes exerts an influence only on spongy bone, not on cortical bone, and that the BMD in the proximal region of the femur seems to be affected by blood glucose level, parallel with the progression of diabetes, through the blood osteocalcin level. In the present study, we show the characteristics of diabetic osteopenia in KK-Ay mice, an animal model of type 2 diabetes.

Human bone marrow adiposity is linked with serum lipid levels not T1-diabetes

Increased marrow adiposity is often associated with bone loss. Little is known about the regulation of marrow adiposity in humans. Marrow adiposity is increased in several mouse models including type I (T1)-diabetic mice, which also display bone loss. However, the impact of metabolic disease on marrow adiposity in humans has yet to be examined. This study measured bone marrow adiposity levels with iterative decomposition of water and fat with echo asymmetry and least-squares estimation magnetic resonance imaging and determined their relationship with T1-diabetes, bone mineral density (BMD), and serum lipid levels. Participants were adult T1-diabetic patients (glycosylated hemoglobin averaging 7.70%±0.4%) and age- and body-mass-index-matched nondiabetic subjects. Consistent with previous reports, serum osteocalcin levels were lower in subjects with T1-diabetes compared to controls (reaching statistical significance in females) and negatively correlated with disease duration (r=-0.50, P<.01). Furthermore, femur neck BMD inversely correlated with diabetes severity (r=-0.417, P<.05). While marrow adiposity was not altered by T1-diabetes, there was a striking positive correlation between vertebral, femur, and tibia marrow adiposity and serum lipid levels (low-density lipoprotein, total cholesterol, cholesterol:high-density lipoprotein ratio, and triglyceride; r≥0.383), reaching a significance of P<.001 in some comparisons. Marrow adiposity also displayed strong intrasubject correlations at multiple bone sites (r≥0.411, P<.05), increased with age (r=0.410, P<.05 at vertebral sites), and was reciprocally related to bone density (r≥-0.378, P<.05). Taken together, our data suggest that marrow adiposity may be an indicator of elevated serum lipid levels and decreased bone density.

Trabecular bone histomorphometry in humans with Type 1 Diabetes Mellitus

Patients with Type 1 Diabetes Mellitus (DM) have markedly increased risk of fracture, but little is known about abnormalities in bone microarchitecture or remodeling properties that might give insight into the pathogenesis of skeletal fragility in these patients. We report here a case-control study comparing bone histomorphometric and micro-CT results from iliac biopsies in 18 otherwise healthy subjects with Type 1 Diabetes Mellitus with those from healthy age- and sex-matched non-diabetic control subjects. Five of the diabetics had histories of low-trauma fracture. Transilial bone biopsies were obtained after tetracycline labeling. The biopsy specimens were fixed, embedded, and scanned using a desktop μCT at 16 μm resolution. They were then sectioned and quantitative histomorphometry was performed as previously described by Recker et al. [1]. Two sections, >250 μm apart, were read from the central part of each biopsy. Overall there were no significant differences between diabetics and controls in histomorphometric or micro-CT measurements. However, fracturing diabetics had structural and dynamic trends different from nonfracturing diabetics by both methods of analysis. In conclusion, Type 1 Diabetes Mellitus does not result in abnormalities in bone histomorphometric or micro-CT variables in the absence of manifest complications from the diabetes. However, diabetics suffering fractures may have defects in their skeletal microarchitecture that may underlie the presence of excess skeletal fragility.

Bone Status in Activity-Restricted Pregnant Women Assessed Using Calcaneal Quantitative Ultrasound

Objective:

Pregnancy-induced bone loss may be further exacerbated by activity restriction (AR). The authors compared the bone status of AR hospitalized (≥7 days) pregnant women in the third trimester to ambulatory (AM) women at the same gestational age, using a prospective cross-sectional design.

Method:

AR was quantified in AR women by daily step counts using a pedometer for 7 consecutive days. Bone status was evaluated in the left and right calcaneus bones of both AR ( n = 13) and AM ( n = 20) women using quantitative ultrasound (QUS).

Results:

AR women took an average of 1,504 ± 1,377 steps/day. Speed of sound scores (1,543.05 ± 41.97 m/s vs. 1,569.60 ± 46.12 m/s) and broadband ultrasound attenuation (BUA) scores (107.93 ± 9.59 dB/MHz vs. 114.69 ± 17.06 dB/MHz) were not different between the AR and AM groups, respectively ( p > .05). However, bone stiffness index (SI) scores (84.0 ± 16.2 vs. 95.8 ± 22.1, respectively, p < .05) were different between groups, indicating a greater relative risk of future fracture in the AR women.

Conclusion:

Increased fracture risk appears to be a negative side effect incurred through an average of 16 days of hospitalized AR in late pregnancy. Further investigations using a larger sample size are necessary to evaluate the effect of antepartum AR on bone status in the postpartum period to determine if bone status is further attenuated by breastfeeding or if recovery occurs with resumption of ambulation and return of menses and to assess future risk in these women as they age. Prenatal care providers should be made aware of these risks.

Potential explanatory factors for higher incident hip fracture risk in older diabetic adults

Type 2 diabetes is associated with higher fracture risk. Diabetes-related conditions may account for this risk. Cardiovascular Health Study participants (N = 5641; 42.0% men; 15.5% black; 72.8±5.6 years) were followed 10.9 ± 4.6 years. Diabetes was defined as hypoglycemic medication use or fasting glucose (FG) ≥126 mg/dL. Peripheral artery disease (PAD) was defined as ankle-arm index <0.9. Incident hip fractures were from medical records. Crude hip fracture rates (/1000 person-years) were higher for diabetic vs. non-diabetic participants with BMI <25 (13.6, 95% CI: 8.9–20.2 versus 11.4, 95% CI: 10.1–12.9) and BMI ≥25 to <30 (8.3, 95% CI: 5.7–11.9 versus 6.6, 95% CI: 5.6–7.7), but similar for BMI ≥30. Adjusting for BMI, sex, race, and age, diabetes was related to fractures (HR = 1.34; 95% CI: 1.01–1.78). PAD (HR = 1.25 (95% CI: 0.92–1.57)) and longer walk time (HR = 1.07 (95% CI: 1.04–1.10)) modified the fracture risk in diabetes (HR = 1.17 (95% CI: 0.87–1.57)). Diabetes was associated with higher hip fracture risk after adjusting for BMI though this association was modified by diabetes-related conditions.

Glycaemic control is positively associated with prevalent fractures but not with bone mineral density in patients with Type 1 diabetes

AIM

There are conflicting data regarding the risk of osteoporosis in patients with Type 1 diabetes. We investigated an association between diabetes, bone mineral density and prevalent fractures.

METHODS

A single-centre, cross-sectional study of men and pre-menopausal women with Type 1 diabetes (n = 128) and a matched control group (n = 77) was conducted. The primary outcome measure was bone mineral density and secondary measures were markers of bone metabolism and prevalent fractures.

RESULTS

Hip and total body bone mineral densities were significantly lower in women with diabetes compared with control subjects. In men, no difference in bone mineral density was found. A multivariate regression analysis in women with diabetes revealed higher BMI as the strongest predictor of higher total hip, femoral neck and total body bone mineral density, whereas previous fractures were inversely associated with total hip bone mineral density and C-terminal telopeptide of type I collagen with total body bone mineral density. Poor long-term glycaemic control was not associated with low bone mineral density. Fracture frequency was higher in patients with diabetes compared with control subjects (1.64 vs. 0.62 per 100 patient-years; P < 0.05). In a multivariable model, long-term HbA(1c) control was associated with increased clinical fracture prevalence (OR 1.92; 95% CI 1.09-2.75) in those with diabetes.

CONCLUSIONS

Type 1 diabetes contributes to low bone mineral density in women. Previous fractures and low BMI were strong predictors of impaired bone mineral density and should therefore be considered in risk estimation. Fractures are more frequent in Type 1 diabetes. Long-term hyperglycaemia may account for impaired bone strength, independently from bone mineral density.

Menopausal bone changes and incident fractures in diabetic women: a cohort study

SUMMARY

The purpose of this study was to evaluate the rate of bone loss and incident fractures in women with diabetes mellitus (DM) across menopause. During menopause, DM women experienced bone mineral density (BMD) loss that was faster at hip and slower at spine and had a higher risk of fractures, perhaps because of their earlier menopause. The increasing DM epidemic will contribute to higher fracture burden.

INTRODUCTION

Women with DM have a higher risk of fractures independent of age, body mass index (BMI), and BMD. Our objective is to evaluate if women with DM experience greater bone loss and more fractures across menopause.

METHODS

Two thousand one hundred seventy one women, aged 42 to 52 years at baseline (1996), enrolled in the Study of Women's Health Across the Nation (SWAN), a prospective study, with 8 years of annual follow up. One thousand three hundred forty six (62%) completed annual visit 7 (2004). Women with baseline fasting blood glucose level of ≥126 mg/dl and those being treated for diabetes were designated as DM. Annual assessment of menopausal stage, BMD, and urinary N-telopeptide (NTx) were carried out. Rate of change in BMD across menopause and annual self-report data for risk of incident fractures by DM status were determined.

RESULTS

Despite higher baseline BMD at hip (p = <0.001), and lumbar spine (p = <0.001), rate of decline in BMD was faster at hip (β = -0.45 vs. -0.11 gm/cm(2)/year, p = <0.001) for DM women, compared to non-DM. However, lumbar spine bone loss was slower in women with DM as compared to non-DM women (β = 0.04 vs. -0.25 gm/cm(2)/year, p = 0.004). DM women experienced menopause 3 years earlier than non-DM women (p = 0.002), and age adjusted incident fractures were two fold higher in women with DM compared to non-DM (RR = 2.20, 95% CI: 1.26-3.85, p = <0.006).

CONCLUSIONS

BMD loss is greater in hip and slower at spine in DM women during menopausal transition. Women with DM have a higher risk of fractures, perhaps because of their earlier menopause.

Bone metabolic abnormalities associated with well-controlled type 1 diabetes (IDDM) in young adult women: a disease complication often ignored or neglected

OBJECTIVES

This investigation on a homogenous cohort of young adult Caucasian type 1 diabetic (IDDM) patients (1) aimed at studying the occurrence of low bone mineral density (BMD) at an early stage prior to menopause (i.e., during the first decade after peak bone mass) and (2) elucidating the possible mechanisms underlying IDDM-induced bone complication.

METHODS

Twenty-seven female patients with insulin-treated and well-controlled diabetes, without renal complications, and 32 well-matched healthy controls, aged between 30 and 40 years and fulfilling rigorous inclusion criteria to minimize bone-confounding factors, were enrolled. Areal BMD was evaluated by dual energy X-ray absorptiometry at axial (lumbar spine) and appendicular (femur) sites, using diagnostic WHO reference (T-scores). Osteoblast functions, bone metabolism, related key minerals, and 2 osteoclast-stimulating calciotropic hormones regulating their serum levels were assessed biochemically.

RESULTS

The number of cases with low BMD (T-score below -1.1 SD) was almost 2-fold greater (p < 0.01) in the IDDM group. BMD was significantly lower in this group for 3 lumbar sites (p < 0.01) and femur Ward's triangle (p < 0.05). Bone formation was reduced, as evidenced by the suppressions of osteocalcin (OC; p < 0.01) and IGF-I (p < 0.001). However, bone alkaline phosphatase (bALP) was induced (p < 0.01), in contrast to what is usually observed in cases of reduced bone formation. Correlated total ALP activity was also significantly increased. There was no change in the specific marker of bone resorption (urinary deoxypyridinoline). Serum calcium was significantly elevated, particularly after adjustment for albumin (p < 0.001), despite lower 1,25(OH)(2)D(3) (p < 0.001) and no elevation of PTH. All significant bone-related biochemical changes were significantly correlated with glycosylated hemoglobin, a clinical indicator of long-term glycemic control, indicating a direct effect of the disease.

CONCLUSIONS

Bone loss in the IDDM group results from a decrease in bone formation rather than an increase of bone resorption. The induction of bALP is indicative of impaired osteoblast differentiation and maturation, which delayed (down-regulated) later stages of matrix mineralization, as evidenced by lower OC and BMD.

Celiac autoimmunity in children with type 1 diabetes: a two-year follow-up

OBJECTIVE

To determine the benefits of screening for celiac autoimmunity via immunoglobulin A transglutaminase autoantibodies (TG) in children with type 1 diabetes (T1D).

STUDY DESIGN

We followed up 79 screening-identified TG+ and 56 matched TG- children with T1D for 2 years to evaluate growth, bone mineral density, nutritional status, and diabetes control. TG+ subjects self-selected to gluten-free or gluten-containing diet.

RESULTS

Of the initial cohort, 80% were available for reexamination after 2 years. TG+ subjects had consistently lower weight z-scores and higher urine N-telopeptides than TG- subjects, but similar measures of bone density and diabetes outcomes. TG+ children who remained on a gluten-containing diet had lower insulin-like growth factor binding protein 3 z-scores compared with TG+ subjects who reported following a gluten-free diet. Children who continued with high TG index throughout the study had lower bone mineral density z-scores, ferritin, and vitamin D 25OH levels, compared with the TG- group.

CONCLUSIONS

No significant adverse outcomes were identified in children with T1D with screening-identified TG+ who delay therapy with a gluten-free diet for 2 years. Children with persistently high levels of TG may be at greater risk. The optimal timing of screening and treatment for celiac disease in children with T1D requires further investigation.