Hypothesis: Those with type 1 diabetes acquire less bone mass in early 20s
The excess fracture risk in children with type 1 diabetes has been previously reported and is 14%-35% higher than the fracture risk in children without diabetes, Dr. Bouxsein explained. And “between 30% to 50% of kids [with type 1 diabetes] will have a fracture before the age of 18, so the excess fracture risk in diabetes is not clinically obvious,” she added.
However, “several lines of evidence strongly suggest that bone mass and microarchitecture at the time of peak bone mass (early 20s) is a major determinant of fracture risk throughout the lifespan,” she noted.
“Our hypothesis,” Dr. Bouxsein said, “is that the metabolic disruptions of diabetes, when they are present during the acquisition of peak bone mass, interfere with optimal bone development, and therefore may contribute to increased fracture risk later in life.”
Dr. Bachrach agreed that “peak bone strength is achieved by early adulthood, making childhood and adolescence important times to optimize bone health,” and that “peak bone strength is a predictor of lifetime risk of osteoporosis.”
“The diagnosis of pediatric osteoporosis is made when a child or teen sustains a vertebral fracture or femur fracture with minimal or no trauma,” she explained. “The diagnosis can also be made in a pediatric patient with low BMD [bone mineral density] for age in combination with a history of several long-bone fractures.”
Dr. Mitchell noted that type 1 diabetes is associated with a higher risk of fractures, which is sixfold in adults. In another study, she said, the group showed that in 10- to 16-year-old girls who’ve only had diabetes for a few years, “trabecular bone density is lower, they have lower estimated failure load, and longitudinally when we follow them, at least at the radius, we’re seeing bone loss at a relatively young age when we wouldn’t be expecting to see bone loss.”
80 girls enrolled, half had type 1 diabetes
Researchers enrolled 36 girls with type 1 diabetes and 44 girls without type 1 diabetes (controls) who were a mean age of 14.7 years and most (92%) were White. The girls with and without diabetes had similar rates of previous fractures (44% and 51%).
Those with diabetes had been diagnosed at a mean age of 9 years and had had diabetes for a mean of 4.6 years.
Researchers calculated participants’ total BPAQ scores based on type, duration, and frequency of bone-loading activities.
Participants had dual-energy X-ray absorptiometry scans to determine areal bone mineral density (BMD) at the total hip, femoral neck, lumbar spine, and whole body less head.
They also had high-resolution peripheral quantitative computed tomography at the distal tibia and radius to determine volumetric BMD, bone microarchitecture, and estimated bone strength (calculated using microfinite element analysis).
The two groups had similar total BPAQ scores (57.3 and 64.6), with a median score of 49.
BPAQ scores were positively associated with areal BMD at all sites (whole body, lumbar spine, total hip, femoral neck, and 1/3 radius) and with trabecular BMD and estimated failure load at the distal radius and tibia (P < .05 for all, adjusted for bone age).
Among participants with low physical activity (BPAQ below the median), compared with controls, those with type 1 diabetes had 6.6% lower aerial BMD at the lumbar spine (0.868 vs. 0.929 g/cm3; P = .04), 8% lower trabecular volumetric BMD at the distal radius (128.5 vs. 156.8 mg/cm3; P = .01), and 12% lower estimated failure load. Results at the distal tibia were similar.
Next steps
“More observational studies in males and females across a broader age spectrum would be helpful,” Dr. Bachrach noted. “The ‘gold standard’ model would be a long-term randomized controlled activity intervention study.”
“Further studies are underway [in girls and boys] using objective measures of activity including accelerometry and longitudinal observation to help confirm the findings from the current study,” Dr. Bouxsein said. “Ultimately, trials of activity interventions in children with [type 1 diabetes] will be the gold standard to determine to what extent physical activity can mitigate bone disease in [type 1 diabetes],” she agreed.
The study authors and Dr. Bachrach have reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.