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 1 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 1 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 for age, BMI, and oral contraceptive use, BMD at year 2 continued to be lower in women ≥20 years of age with type 1 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 1 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 1 diabetes.Type 1 diabetes is an autoimmune disorder resulting in loss of pancreatic insulin-producing β-cells that presents in childhood or early adulthood. Along with increased risk of complications including retinopathy, nephropathy, neuropathy, and cardiovascular events, adults with type 1 diabetes have decreased bone mineral density (BMD) compared with control subjects (1,2). In fact, osteoporosis is the most significant metabolic bone disease in individuals with diabetes (3). Patients with diabetes are at risk for osteoporosis and its complications, including hip fracture (4,5).Recent studies demonstrate that diabetes is associated with alterations in bone health in children and adolescents. Prepubertal and pubertal patients with type 1 diabetes (aged <15 years) have decreased bone mass measured both by duel-energy X-ray absorptiometry (DEXA) scan and quantitative ultrasound (6–8). These observations suggest that adverse effects on bone health may occur early after the diabetes diagnosis. Understanding the natural history of BMD changes in young adults with type 1 diabetes may elucidate how the disease progresses and provide opportunities for prevention of significant bone loss and, presumably, fracture.We demonstrated previously that premenopausal women (aged 20–35 years) with type 1 diabetes have lower BMD at the femoral neck and lateral spine than nondiabetic control subjects (7). This difference was not associated with diabetes duration, metabolic control, or biochemical markers of bone formation, a finding supported by previous work (9,10). Few studies have followed young women longitudinally to assess whether bone mineral acquisition or turnover play a role in the natural history of low BMD in diabetes. The aim of this study was to address the natural history of bone metabolism in type 1 diabetes by performing a follow-up DEXA 2 years after baseline enrollment to determine whether differences persist over time.