Physical Function as Key Factor in Fracture Risk for Older Women with Type 2 Diabetes: JAMA

"In the cohort study of 3,008 older women, including 294 with type 2 diabetes, T2D was linked to higher fracture risk and improved bone mineral density (BMD) and microarchitecture but did not affect bone material strength. However, physical function was notably impaired in those with T2D," the researchers reported.

The reasons for the increased fracture risk in T2D are not fully understood. Considering this, Michail Zoulakis, Sahlgrenska Osteoporosis Centre, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden, and colleagues aimed to determine if worse physical function or poorer skeletal characteristics explain the increased fracture risk in T2D.

For this purpose, the researchers conducted a prospective observational study utilizing the Sahlgrenska University Hospital Prospective Evaluation of Risk of Bone Fractures cohort, focusing on older women in the Gothenburg area from March 2013 to May 2016. Incident fracture data was followed up until March 2023, with data analysis conducted from June to December 2023.

Participants' exposure data were gathered through questionnaires, as well as measurements of anthropometrics, physical function, and bone density using dual-energy x-ray absorptiometry (DXA) and high-resolution peripheral computed tomography (HR-pQCT). A subset of participants also underwent bone microindentation to evaluate the bone material strength index (BMSi).

The primary outcomes included baseline assessments of bone characteristics and physical function and radiographically verified incident fractures.

The following were the key findings of the study:

• Of 3008 women aged 75 to 80 years, 294 women with T2D (mean age, 77.8 years) were compared with 2714 women without diabetes (mean age, 77.8 years).
• Women with T2D had higher BMD at all sites (total hip, 4.4% higher; femoral neck (FN), 4.9% higher; and lumbar spine, 5.2% higher) than women without.
• At the tibia, women with T2D had 7.4% greater cortical area and 1.3% greater density, as well as 8.7% higher trabecular bone volume fraction.
• There was no difference in BMSi (T2D mean, 78.0 versus controls, 78.1).
• Women with T2D had lower performance on all physical function tests.
• The study found 9.7% lower grip strength, 9.9% slower gait speed, and 13.9% slower timed up-and-go time than women without diabetes.
• During a median follow-up of 7.3 years, 1071 incident fractures, 853 major osteoporotic fractures (MOF), and 232 hip fractures occurred.
• In adjusted (for age, body mass index, clinical risk factors, and FN BMD) Cox regression models, T2D was associated with an increased risk of any fracture (HR, 1.26) and MOF (HR, 1.25).

"The findings suggest that type 2 diabetes is linked to higher BMD and improved bone microarchitecture, with no difference in bone material strength index (BMSi). However, T2D was also associated with reduced physical function, indicating that diminished physical ability is likely the primary factor contributing to the increased fracture risk observed in women with T2D," the researchers concluded.

Reference:

Zoulakis M, Johansson L, Litsne H, Axelsson K, Lorentzon M. Type 2 Diabetes and Fracture Risk in Older Women. JAMA Netw Open. 2024;7(8):e2425106. doi:10.1001/jamanetworkopen.2024.25106