Compromised cortical bone compartment in type 2 diabetes mellitus patients with microvascular disease

Objective and design: Patients with type 2 diabetes mellitus (T2D) have an increased fracture risk despite a normal or elevated bone mineral density (BMD). The aim of this cross-sectional in vivo study was to assess parameters of peripheral bone microarchitecture, estimated bone strength and bone remodeling in T2D patients with and without diabetic microvascular disease (MVD+ and MVD- respectively) and to compare them with healthy controls. Methods: Fifty-one T2D patients (MVDC group: n=25) were recruited from Funen Diabetic Database and matched for age, sex and height with 51 healthy subjects. High-resolution peripheral quantitative tomography (HR-pQCT) was used to assess bone structure at the non-dominant distal radius and tibia. Estimated bone strength was calculated using finite element analysis. Biochemical markers of bone turnover were measured in all participants. Results: After adjusting for BMI, MVD+ patients displayed lower cortical volumetric BMD (P=0.02) and cortical thickness (P=0.02) and higher cortical porosity at the radius (P=0.02) and a trend towards higher cortical porosity at the tibia (P=0.07) compared to controls. HR-pQCT parameters did not differ between MVD- and control subjects. Biochemical markers of bone turnover were significantly lower in MVD+ and MVD- patients compared to controls (all P< 0.01). These were no significant correlations between disease duration, glycemic control (average glycated hemoglobin over the previous 3 years) and HR-pQCT parameters. Conclusion: Cortical bone deficits are not a characteristic of all T2D patients but of a subgroup characterized by the presence of microvascular complications. Whether this influences fracture rates in these patients needs further investigation.