Does low bone mineral density start in post-teenage years in women with type 1 diabetes?

Type 1 diabetes has been associated with decreased bone mineral density (BMD). However, the natural history and etiopathogenesis of osteoporosis in type 1 diabetes are not clear. The aims of this study were to assess BMD in a cohort of young women with type 1 diabetes compared with nondiabetic control subjects and to evaluate the possible association of BMD with diabetes duration, HbA(1c), and biomarkers of bone metabolism.

BMD was measured by dual-energy X-ray absortiometry scan in 39 teenage (age 13-19 years) and 33 post-teenage females (age 20-37 years) with type 1 diabetes and 91 female age-matched control subjects. Serum osteocalcin, IGF-I, IGF binding protein-3 (IGFBP-3), HbA(1c), and urine N-telopeptides were measured.

After adjustment for age and BMI, BMD values were significantly lower at the femoral neck and lateral spine in women with type 1 diabetes older than age 20 years compared with control subjects but not in the case subjects younger than age 20 years, nor at the anterio-posterior spine, wrist, or whole body. No association was found between BMD and diabetes duration or glycemic control. IGF-I, IGFBP-3, osteocalcin, and N-telopeptides were similar in diabetic subjects and control subjects.

This study indicates that women with type 1 diabetes exhibit BMD differences early in life with significant differences already present in the post-teenage years. Lower hip BMD in these young women may explain, in part, the higher incidence of hip fracture experienced in postmenopausal women with type 1 diabetes.