Type 2 diabetes is associated with increased bone mineral density in Mexican-American women

Background Our purpose was to determine whether type 2 diabetes is associated with altered bone mineral density (BMD) and whether fasting serum insulin levels are correlated with BMD. Methods In a population-based family study of Mexican-Americans, we obtained measurements of BMD, diabetes status (by 2-h oral glucose tolerance test), obesity, and serum insulin concentrations in 600 subjects from 34 families. Analyses were stratified by sex and conditioned on the pedigree structure to account for residual correlations among related individuals. Results Women with diabetes had significantly higher BMD at hip than women without diabetes (p = 0.03) even after adjustment for age, body mass index (BMI), and menopause status. BMD at spine was also higher in diabetic women than in nondiabetic women, although the association was no longer statistically significant after adjustment for BMI. Diabetes was not associated with BMD in men. In nondiabetic men and women, insulin levels were significantly correlated with BMD after adjustment for age and other lifestyle covariates, but correlations were diminished and were no longer statistically significant after further adjustment for body mass index. Conclusions These results suggest that Mexican-American women with type 2 diabetes have higher BMD compared to their nondiabetic counterparts, with the association independent of obesity at hip, although not at spine or forearm. Increased BMD was also correlated with serum insulin levels, although this association was not independent of obesity. Longitudinal studies may be required to better define the mechanisms underlying the observed association between BMD and diabetes.