Prediabetes and osteoporotic fracture risk: A meta-analysis of prospective cohort studies

Bone Health in Patients With Type 2 Diabetes

The association between type 2 diabetes mellitus (T2DM) and skeletal fragility is complex, with effects on bone at the cellular, molecular, and biomechanical levels. As a result, people with T2DM, compared to those without, are at increased risk of fracture, despite often having preserved bone mineral density (BMD) on dual-energy x-ray absorptiometry (DXA). Maladaptive skeletal loading and changes in bone architecture (particularly cortical porosity and low cortical volumes, the hallmark of diabetic osteopathy) are not apparent on routine DXA. Alternative imaging modalities, including quantitative computed tomography and trabecular bone score, allow for noninvasive visualization of cortical and trabecular compartments and may be useful in identifying those at risk for fractures. Current fracture risk calculators underestimate fracture risk in T2DM, partly due to their reliance on BMD. As a result, individuals with T2DM, who are at high risk of fracture, may be overlooked for commencement of osteoporosis therapy. Rather, management of skeletal health in T2DM should include consideration of treatment initiation at lower BMD thresholds, the use of adjusted fracture risk calculators, and consideration of metabolic and nonskeletal risk factors. Antidiabetic medications have differing effects on the skeleton and treatment choice should consider the bone impacts in those at risk for fracture. T2DM poses a unique challenge when it comes to assessing bone health and fracture risk. This article discusses the clinical burden and presentation of skeletal disease in T2DM. Two clinical cases are presented to illustrate a clinical approach in assessing and managing fracture risk in these patients.

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

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

The association between prediabetes and bone mineral density: A meta-analysis

BACKGROUND

Prediabetes is an intermediate metabolic state between euglycaemia and diabetes, including three different definitions: impaired fasting glucose, impaired glucose tolerance, and mildly elevated glycated haemoglobin (HbA1c) (range 5.7%-6.4%). The effect of prediabetes on bone mineral density (BMD) has not been established. Therefore, we performed a meta-analysis to evaluate the association between prediabetes and BMD.

METHODS

We retrieved studies related to prediabetes and BMD from PubMed, Web of Science, and Embase databases from January 1990 to December 2022. All data were analysed using the random effects model. Statistical heterogeneity was tested by I2 . Subgroup analysis was performed after each study-level variable was pre-defined by meta-regression.

RESULTS

A total of 17 studies were included involving 45,788 patients. We detected a significant overall association of prediabetes with increased spine BMD (weighted mean difference [WMD] = 0.01, 95% CI [0.00, 0.02], p = 0.005; I2  = 62%), femur neck (FN) BMD (WMD = 0.01, 95% CI [0.00, 0.01], p < 0.001; I2  = 19%), and femur total (FT) BMD (WMD = 0.02, 95% CI [0.01, 0.03], p < 0.001; I2  = 51%). Several variables leading to heterogeneity were defined by meta-regression, including age, sex, region, study type, dual-energy X-ray absorptiometry scanner manufacturer, and prediabetes definition. Subgroup analyses indicated that the association of prediabetes with increased BMD was stronger in men, Asians, and older adults over 60 years of age.

CONCLUSIONS

Current evidence shows that prediabetes is strongly associated with increased BMD of the spine, FN, and FT. The association was stronger among males, Asians, and older adults over 60 years of age.

Factors associated with fragility fractures in type 2 diabetes: An analysis of the randomised controlled Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study

AIMS

Fracture risk is elevated in some type 2 diabetes patients. Bone fragility may be associated with more clinically severe type 2 diabetes, although prospective studies are lacking. It is unknown which diabetes-related characteristics are independently associated with fracture risk. In this post-hoc analysis of fracture data from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial (ISRCTN#64783481), we hypothesised that diabetic microvascular complications are associated with bone fragility.

MATERIALS AND METHODS

The FIELD trial randomly assigned 9795 type 2 diabetes participants (aged 50-75 years) to receive oral co-micronised fenofibrate 200 mg (n = 4895) or placebo (n = 4900) daily for a median of 5 years. We used Cox proportional hazards models to identify baseline sex-specific diabetes-related parameters independently associated with incident fractures.

RESULTS

Over 49,470 person-years, 137/6138 men experienced 141 fractures and 143/3657 women experienced 145 fractures; incidence rates for the first fracture of 4∙4 (95% CI 3∙8-5∙2) and 7∙7 per 1000 person-years (95% CI 6∙5-9∙1), respectively. Fenofibrate had no effect on fracture outcomes. In men, baseline macrovascular disease (HR 1∙52, 95% CI 1∙05-2∙21, p = 0∙03), insulin use (HR 1∙62, HR 1∙03-2∙55, p = 0∙03), and HDL-cholesterol (HR 2∙20, 95% CI 1∙11-4∙36, p = 0∙02) were independently associated with fracture. In women, independent risk factors included baseline peripheral neuropathy (HR 2∙04, 95% CI 1∙16-3∙59, p = 0∙01) and insulin use (HR 1∙55, 95% CI 1∙02-2∙33, p = 0∙04).

CONCLUSIONS

Insulin use and sex-specific complications (in men, macrovascular disease; in women, neuropathy) are independently associated with fragility fractures in adults with type 2 diabetes.

Contributors to impaired bone health in type 2 diabetes

Type 2 diabetes (T2D) is associated with numerous complications, including increased risk of fragility fractures, despite seemingly protective factors [e.g., normal bone mineral density and increased body mass index(BMI)]. However, fracture risk in T2D is underestimated by current fracture risk calculators. Importantly, post-fracture mortality is worse in T2D following any fracture, highlighting the importance of identifying high-risk patients that may benefit from targeted management. Several diabetes-related factors are associated with increased fracture risk, including exogenous insulin therapy, vascular complications, and poor glycaemic control, although detailed comprehensive studies to identify the independent contributions of these factors are lacking. The underlying pathophysiological mechanisms are complex and multifactorial, with different factors contributing during the course of T2D disease. These include obesity, hyperinsulinaemia, hyperglycaemia, accumulation of advanced glycation end products, and vascular supply affecting bone-cell function and survival and bone-matrix composition. This review summarises the current understanding of the contributors to impaired bone health in T2D, and proposes an updated approach to managing these patients.