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Cortical bone microstructure, tibia density deficits seen with type 2 diabetes, high HbA1c
Type 2 diabetes and increased HbA1c are associated with deficits in cortical bone microstructure and bone density at the distal tibia, according to research presented at the American Society for Bone and Mineral Research 2014 Annual Meeting.
Although it is still uncertain whether the cortical bone deficits explain increased lower leg fracture risks seen in patients with diabetes, the findings identify target areas to investigate the mechanism responsible for skeletal fragility.
“Diabetic bone may be characterized by specific deficits to cortical bone, which are not captured by traditional DXA bone mineral density tests,” Elizabeth J. Samelson, PhD, of the Institute for Aging Research at Hebrew SeniorLife, Harvard Medical School, told Endocrine Today.
Elizabeth J. Samelson
Samelson and colleagues conducted a community-based study involving 627 adults (367 women, 260 men; mean age, 65 years) to compare bone microarchitecture by high-resolution peripheral quantitative computed tomography (HRpQCT) in patients with type 2 diabetes (31 women, 40 men) and healthy individuals and determine relationships with HbA1c.
Participants, all from the Framingham Offspring Cohort, were evaluated for type 2 diabetes and had HbA1c measured at baseline; diabetes was defined as glucose >126 mg/dl or use of diabetes medication. They all underwent HRpQCT scanning at the tibia and radius at 6 years.
The researchers used linear regression to calculate means and correlations for the association between volumetric bone mineral density (vBMD), geometry and microstructure indices of trabecular and cortical bone and type 2 diabetes and HbA1C. Adjustments were made for age, sex and weight.
Patients with type 2 diabetes exhibited higher numbers than healthy patients at the tibia for
total vBMD (291.06 mg/cm3 vs. 284.53 mg/cm3), trabecular vBMD (184.13 mg/cm3 vs. 175.09 mg/cm3) and trabecular number (2.15 1/mm vs. 2.07 1/mm); the differences were not significant.
Conversely, patients with type 2 diabetes demonstrated significantly lower numbers than healthy patients for cortical vBMD (796.74 mg/cm3 vs. 814 mg/cm3) and cortical porosity (11.17% vs. 10.03%).
Similar results were seen with increasing HbA1c, with trabecular indices better with higher levels but cortical bone indices worse; the significance was limited to trabecular number.
No other differences were seen in HRpQCT bone indices between groups or based on HbA1c level. At the radius, no significant associations were seen between bone HRpQCT indices and type 2 diabetes or HbA1C.
“Older adults with type 2 diabetes have increased risk of fracture but higher bone mass density than those without diabetes,” Samelson said. “ If deficits to cortical bone explain increased skeletal fragility in type 2 diabetes, then future therapies that target cortical bone strength can reduce fracture risk in this vulnerable and growing population.” — by Allegra Tiver
For more information: Samelson E. Abstract 1083. Presented at: American Society for Bone and Mineral Research 2014 Annual Meeting; Sept. 12-15, 2014; Houston.
Disclosures: Samelson reports no relevant disclosures.