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

OBJECTIVE - Type I diabetes has been associated with decreased bone mineral density (BMD). However, the natural history and etiopathogenesis of osteoporosis in type I diabetes are not clear. The aims of this study were to assess BMD in a cohort of young women with type I diabetes compared with nondiabetic control subjects and to evaluate the possible association of BMD with diabetes duration, HbA(1c), and biomarkers of bone metabolism. RESEARCH DESIGN AND METHODS - 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 I 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. RESULTS - After adjustment for age and BMI, BMD values were significantly lower at the femoral neck and lateral spine in women with type I diabetes older than age 20 years compared with control subjects but not in the case subjects younger than age 20 years, nor at the anterioposterior 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. CONCLUSIONS - This study indicates that women With type I 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 I diabetes.