Correlation between bone density and abdominal fat distribution in postmenopausal women with type 2 diabetes

Objective To explore the change of bone density (BMD), the characteristic of abdominal fat distribution, and the correlation between them in postmenopausal women with type 2 diabetes. Methods This study involved 111 subjects who had ceased menstruation for 1 year, including 62 postmenopausal women with T2DM and 49 healthy controls. All the subjects underwent quantitative CT (QCT scanning) at the Department of Radiology of Beijing Geriatric Hospital from January to August 2017. BMD at the middle level of L2~4 vertebrae was measured and named L2BMD, L3BMD, and L4BMD, respectively, and average BMD was then calculated. Meanwhile, the tissue composition module of QCT software was used to measure the total adipose area (TAA), visceral adipose area (VAA), and subcutaneous adipose area (SAA), and the ratio of VAA to SAA (V/S) was calculated. For statistical analysis, the Mann-Whitney rank sum test was used to compare the data between groups, and Spearman correlation analysis was adopted to verify the correlation between BMD and the characteristic of abdominal fat distribution. Results Adjusted age and body mass index did not differ significantly between the two groups. In the control group, BMD values in a descending order was L2BMD (87.40), L3BMD (86.08), and L4BMD (79.27), and the values in the diabetic group were L3BMD (64.95), L4BMD (64.70), and L2BMD (63.75). L2BMD was significantly lower in the diabetic group than in the control group (Z=-2.368, P=0.018), while L3BMD, L4BMD, and average BMD did not differ significantly between the two groups. TAA, VAA, SAA, and V/S in the control group were 311.40, 125.80, 246.80, and 0.5, respectively, and the corresponding values in the diabetic group were 319.50, 136.70, 177.85, and 0.80. Although VAA did not differ significantly between the two groups, VAA and V/S were significantly higher and SAA was significantly lower in the diabetic group than in the control group (Z=-1.207, P=0.028; Z=-5.589, P<0.001; Z=-4.171, P<0.001). Spearman correlation analysis showed that in the control group, average BMD had a negative correlation with VAA and SAA (r=-0.352, P=0.042; r=-0.311, P=0.032), and in the diabetic group, average BMD had a negative correlation with VAA, SAA, and V/S (r=-0.309, P=0.023; r=-0.263, P=0.030; r=-0.281, P=0.039). Conclusion Average BMD is not significantly different between postmenopausal women with T2DM and healthy controls, but postmenopausal womem with T2DM have higher VAA and V/S. There is a correlation between abdominal fat distribution and bone density, and VAA has the highest correlation in both groups. Key words: Type 2 diabetes; Postmenopausal; Quantitative CT; Bone mineral density; Abdominal adipose