In a small, cross-sectional study of 10- to 16-year-old girls with and without type 1 diabetes, both groups were equally physically active based on their responses to the Bone-Specific Physical Activity Questionnaire (BPAQ).
However, among the more sedentary girls (with BPAQ levels below the median), those with type 1 diabetes had poorer markers of bone health on imaging tests compared to the girls without diabetes.
“The harmful effect of [type 1 diabetes] on bone health in girls is most pronounced in girls with less weight-bearing activity,” the researchers summarize in a poster presented Sept. 9 at the 2022 American Society of Bone and Mineral Research (ASBMR) Annual Meeting.
However, this is early research and more studies are needed, the group warns.
‘Ongoing studies using objective measures of physical activity, as well as intervention studies, will clarify whether increasing physical activity can improve bone health and reduce fracture risk in this vulnerable group,’ they conclude.
“If you look at the sedentary kids, there’s a big discrepancy between the kids with diabetes and the control kids, and that’s when we look at the radius or the tibia or the trabecular bone density or the estimated failure load,” senior author Deborah M. Mitchell , MD, explained Medscape Medical News at the poster session.
“However, if we look at the kids who are more physically active, we really don’t see that much of a difference [in bone health] between children with and without diabetes,” said Mitchell, a pediatric endocrinologist at Massachusetts General Hospital and an assistant professor at Harvard Medical School in Boston, Massachusetts.
But she also acknowledged, “There are all sorts of caveats, including the fact that this is retrospective questionnaire data.”
However, if more rigorous studies confirm these findings, “physical activity may be a really powerful tool for improving bone quality in children with type 1 diabetes.”
“This study suggests that bone-enhancing physical activity can significantly improve skeletal health in children [type 1 diabetes] and should give hope to patients and their families that they can take steps to prevent or lessen the impact of diabetes on bone,” said co-author and new ASBMR President Mary L. Bouxsein, PhD Medscape Medical News in an email.
“We interpret this data as an important reason to advocate for increasing the time spent in moderate-to-vigorous bone-loading activity,” said Bouxsein, professor in the Department of Orthopedic Surgery at Harvard Medical School, “although the ‘dose’ is expressed in hours per day or episodes per week to promote optimal bone health has yet to be determined.”
“Ongoing debate”, “Need stronger evidence”
Asked for comment, Laura K. Bachrach, MD, who was not involved in the research, noted, “Activity favors the development of bone strength through effects on bone geometry more than ‘density,’ and conversely, a lack of physical activity may retard progress affect in diameter and thickness of the cortical bone.”
“However, there is an ongoing debate about the impact of type 1 diabetes on bone health and the factors that determine risk,” said Bachrach, a pediatric endocrinologist at Stanford Children’s Health, Palo Alto, California Medscape Medical News in an email.
The current results suggest “that physical activity in adolescent girls offers protection against possible side effects of type 1 diabetes,” said Bachrach, who discussed childhood bone fragility in a video commentary for Medscape in 2021.
The strengths of the study, she noted, “include the rigor and expertise of the investigators, the use of multiple surrogates that capture bone geometry/microarchitecture, and the inclusion of healthy local controls.”
“The study is limited by the cross-sectional design and the subjects who chose to be active or not,” she added. “More evidence of the protective effect of activity on bone health in type 1 diabetes would require a randomized longitudinal interventional study, as suggested by the study authors.”
Hypothesis: People with type 1 diabetes acquire less bone mass in their early 20s
The increased risk of fractures in children with type 1 diabetes has been previously reported and is 14% to 35% higher than the risk of fractures in children without diabetes, Bouxsein explained. And “between 30% and 50% of the children [with type 1 diabetes] will sustain a fracture before age 18, so the increased risk of fracture in diabetes is not clinically apparent,” she added.
“However, multiple pieces of evidence strongly suggest that bone mass and microarchitecture at peak bone mass (early 20s) is an important determinant of fracture risk throughout the lifespan,” she noted.
“Our hypothesis,” Bouxsein said, “is that the metabolic disorders of diabetes, if they occur during the acquisition of maximum bone mass, may impair optimal bone development and therefore contribute to an increased risk of fracture later in life.”
Bachrach agreed that “maximum bone strength is reached in early adulthood, making childhood and adolescence important times for optimizing bone health” and that “maximum bone strength is a predictor of lifetime risk of osteoporosis”.
“The diagnosis of pediatric osteoporosis is made when a child or teenager sustains a fractured spine or femur with minimal or no trauma,” she explained. “The diagnosis can also be made in a pediatric patient with low BMD for age combined with a history of multiple long bone fractures.”
Mitchell found that type 1 diabetes is associated with a higher risk of fracture, which is six times higher 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, “their trabecular bone density is lower, they have lower estimated failure loads and longitudinal when we Follow them, at least at the radius, we see bone loss at a relatively young age when we wouldn’t expect bone loss.
80 girls enrolled, half had type 1 diabetes
The researchers enrolled 36 girls with type 1 diabetes and 44 girls without type 1 diabetes (controls), who had a mean age of 14.7 years and most (92%) were white. The girls with and without diabetes had similar rates of prior fractures (44% and 51%, respectively).
Those with diabetes were diagnosed at an average age of 9 years and had had diabetes for an average of 4.6 years.
Researchers calculated participants’ total BPAQ levels based on the type, duration, and frequency of bone-loading activities.
Participants received dual-energy X-ray absorptiometry (DXA) scans to determine areal bone mineral density (BMD) at the total hip, femoral neck, lumbar spine, and total body excluding the head.
They also had high-resolution peripheral quantitative computed tomography (HR-pQCT) of 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 mean 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 fracture load at the distal radius and tibia (P < 0.05 for all, adjusted for bone age).
Among participants with low physical activity (BPAQ below the median), those with type 1 diabetes had a 6.6% lower air BMD at the lumbar spine (0.868 vs. 0.929 g/cm) compared to controls3; P = 0.04), 8% lower trabecular volumetric BMD at the distal radius (128.5 vs. 156.8 mg/cm3; P = 0.01) and 12% lower estimated failure load. The results at the distal tibia were similar.
Next Steps
“Further observational studies in men and women across a broader age range would be helpful,” Bachrach noted. “The ‘gold standard’ model would be a long-term randomized controlled activity intervention study.”
“Further studies are in progress [in girls and boys] using objective measures of activity including accelerometer and longitudinal observation to help confirm the findings from the current study,” Bouxsein said. “Ultimately, attempts at activity interventions in children with [type 1 diabetes] will be the gold standard for determining the extent to which physical activity can alleviate bone disease [type 1 diabetes],” She agreed.
The study authors and Bachrach did not report any relevant financial relationships.
ASBMR Annual Meeting 2022. Presented 9 September 2022. Abstract FRI-60.
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