A new paper in JAMA Network Open determines whether type 2 diabetes mellitus (T2DM) increases the risk of fractures in older women.
Study: Type 2 Diabetes and Fracture Risk in Older Women. Image Credit: Barabasa / Shutterstock.com
How does diabetes affect other organs?
Diabetes affects over 500 million individuals worldwide, and its prevalence is expected to continue to rise. Only about 4% of these individuals are diagnosed with type 1 diabetes mellitus, whereas the remaining 96% of people with diabetes are diagnosed with T2DM. Diabetes mellitus results in multi-organ systemic damage, including renal failure, cardiovascular disease, retinopathy, neuropathy, and reduced physical function.
T2DM is also associated with an increased risk of fractures, with this risk varying with the duration and treatment of the condition. Potential reasons for this association include the accumulation of end-glycation products (AGEs) on bone strength, lower bone turnover, altered epigenetic markers like micro-ribonucleic acids (microRNAs) regulating bone strength, or changes in bone marrow fat deposits.
Prior research suggests that women with T2DM have higher bone mineral density (BMD) but weaker bone microstructure and cortical porosity. The current study further examined the high risk of fractures in women with T2DM and determined whether this risk was due to poor physical function or weaker bone structure.
About the study
The current study included 3,008 women between 75 and 80 years of age. These individuals were part of the Sahlgrenska University Hospital Prospective Evaluation of Risk of Bone Fractures study, which prospectively evaluates the risk of bone fractures in older women.
Data collection was performed using questionnaires, anthropometric examination, assessment of physical function, dual-energy x-ray absorptiometry (DEXA) measurement of bone density, and advanced computed tomography (CT). In a small subset of individuals, bone microindentation testing was also performed as a mechanical measure to determine the bone material strength index.
Clinical risk factors like smoking, the use of glucocorticosteroids, rheumatoid arthritis, drinking, and previous fractures in the patient’s or parental history were noted.
What did the study show?
Higher bone strength
A total of 294 women in the study cohort had T2DM, of whom the mean age was 78 years. The T2DM group had 9% higher body weight, 19% higher body mass, and 6.3% greater limb lean mass.
Vitamin D levels were 7% lower in the T2DM group, whereas calcium and creatinine levels were 1.6% and 4.7% higher in the T2DM group, respectively. The use of medications for osteoporosis was lower in study participants with T2DM; however, these individuals were more likely to be prescribed statins and antihypertensive medications.
After compensating for body mass and age, women with T2DM had higher BMD at the hip and lumbar spine as compared to those without T2DM. BMD was not associated with treatment duration or type.
Cortical area and density at the tibia were higher in women with T2DM. Trabecular bone volume fraction was also 8.7% higher in this group, thus suggesting better bone microarchitecture. Stiffness and ultimate failure load were higher at all bone sites in the T2DM group.
Fracture risk by treatment group
Over a median follow-up period of 7.3 years, 1,071 new fractures were reported, 853 of which were major osteoporotic fractures (MOFs) and 232 hip fractures. T2DM was associated with a higher risk of other illnesses but a lower overall risk of MOF and hip fracture at baseline.
Women prescribed insulin had a 71% higher fracture risk and 90% higher MOF risk as compared to controls. With oral medication, the T2DM group had a 27% higher risk of fracture overall but not for MOF or hip fractures. Women who were not prescribed any treatment or had a shorter duration of treatment were not at an increased risk for fractures.
T2DM and physical function
Physical function measures were globally impaired in women with T2DM, who had about 10% weaker grip strength, 10% slower walking speed, and 14% slower to get up and start moving compared to controls. Prolonged treatment and insulin use were associated with worse physical function despite better bone measures.
Mortality vs. fracture risk
A diagnosis of T2DM, prolonged duration of T2DM, and insulin treatment were associated with an increased mortality risk by 54%, 75%, and 200%, respectively, as compared to a 40% increased risk among those prescribed oral diabetes medications. When adjusted for the competing risk of death, any-fracture and MOF risks were each 21% higher, whereas the hip fracture risk was 25% higher in the T2DM group.
Glycemic control
Women with the highest glycated hemoglobin (HbA1C) levels, which reflects the poorest long-term glycemic control, and those not prescribed osteoporosis medication at any point, had a 2.3- and 4.6-fold increased risk of any hip fractures, respectively, compared to controls.
Even after compensating for age, body mass, other risk factors, and BMD, T2DM was associated with a 26% increased fracture risk. Women with worse physical function were 50% more likely to experience any fracture and MOF. Falls and new fractures were reported more frequently in women with T2DM.
Conclusions
Physical activity is lower and physical performance is impaired in T2D, and it is clear that poor physical performance is independently associated with fracture risk.”
The study findings suggest that the primary risk factor for higher fracture incidence among older women with T2DM is poor physical function rather than reduced bone density.
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