Relative fracture risk in patients with diabetes mellitus, and the impact of insulin and oral antidiabetic medication on relative fracture risk
To test the hypothesis that bone mineral density (BMD) is lower in children with insulin-dependent diabetes mellitus (IDDM), we measured BMD of the lumbar vertebrae (L-2 to L-4) by dual-photon absorptiometry in 31 boys and 25 girls, mean age 12.3 years, with IDDM of varying clinical duration (range 0.1 to 14.8 years). Mean standard deviation scores (z scores) were determined for L-2-L-4 BMD, weight, height, weight percentile, and weight-adjusted L-2-L-4 BMD index (L-2-L-4 BMD/weight), with reference data from a previously described white, nondiabetic, age-matched control group (n = 221). Compared with nondiabetic control subjects, male patients with short-term IDDM and all female patients with IDDM did not have significantly different L-2-L-4 BMD, weight, weight percentile, height, or BMD index. Boys with IDDM longer than 1 year had significantly lower weight, weight percentile, and height than did age-matched control subjects. When L-2-L-4 BMD of boys with long-term diabetes was corrected for weight, the L-2-L-4 BMD index was significantly greater than that of control subjects, indicating that weight was disproportionately lower than BMD. There were no significant linear correlations between metabolic control and L-2-L-4 BMD. When L-2-L-4 BMD was adjusted for differences in body weight, spinal BMD values in children with IDDM were not lower than in control subjects. These findings indicate that in children with IDDM, as in previously studied nondiabetic youths, body weight and spinal BMD are highly correlated; although BMD is reduced in some children with diabetes, the reduction parallels reductions in growth, and may simply reflect a normal response of the skeleton to a lower weight-bearing load.