Young women with type 1 diabetes have lower bone mineral density that persists over time

OBJECTIVE - Individuals with type 1 diabetes have decreased bone mineral density (BMD), yet the natural history and pathogenesis of osteopenia are unclear. We have previously shown that women with type I diabetes (aged 13-35 years) have lower BMD than community age-matched nondiabetic control subjects. We here report 2-year follow-up BMD data in this cohort to determine the natural history of BMD in young women with and without diabetes. RESEARCH DESIGN AND METHODS - BMD was measured by dual-energy X-ray absorptiometry at baseline and 2 years later in 63 women with type I diabetes and in 85 age-matched community control subjects. A1C, IGF-1, IGF binding protein-3, serum osteocalcin, and urine N-teleopeptide were measured at follow-up. RESULTS - After adjusting forage, BMI, and oral contraceptive use, BMD at year 2 continued to be lower in women >= 20 years of age with type I diabetes compared with control subjects at the total hip, femoral neck, and whole body. Lower BMD values were observed in cases <20 years of age compared with control subjects; however, the differences were not statistically significant. Lower BMD did not correlate with diabetes control, growth factors, or metabolic bone markers. CONCLUSIONS - This study confirms our previous findings that young women with type I diabetes have lower BMD than control subjects and that these differences persist over time, particularly in women >= 20 years of age. Persistence of low BMD as well as failure to accrue bone density after age 20 years may contribute to the increased incidence of osteoporotic hip fractures seen in postmenopausal women with type I diabetes.