Abstract 555 Poster Session II, Sunday, 5/2 (poster 199)

Women with type 1 Diabetes Mellitus (DM) have a higher incidence of osteoporosis compared to age-matched controls. However, the literature lacks data on the natural history of this disease in type 1 DM. The aim of our study is to assess Bone Mineral Density (BMD) and Bone Mineral Content (BMC) in teenagers with type 1 DM and to correlate these measures with bone markers and current HbA1c. This abstract presents the data in the first 10 patients studied. Caucasian females, receiving insulin via tid injections or CSII, age 13-19 yrs (16.4 ± 1.4), with type 1 DM duration ≥5 yrs (10.2 ± 3.9), and menstrual periods for ≥2 years (3.4 ± 1.6) were recruited from the patients followed at a University based diabetes clinic. BMI >30, any additional chronic illness (unrelated to DM complications) except for autoimmune thyroiditis, history of estroprogestinic intake and pregnancy represented exclusion criteria. BMD (g/cm2) and BMC (g) were determined for the spine (L1-4), femoral neck (FN), wrist (W) and total body (TB) using Dual Energy X-Ray Absorptiometry (Hologic). During the routine visit a urine sample for N-Telopeptides (ELISA) and a serum sample for Osteocalcin (RIA) and IGF-I (IGFBP-blocked RIA) were collected and assayed at the Endocrine Sciences Laboratory. The data were expressed as mean ± SD and correlation coefficients between BMD and BMC and bone markers were examined. The HbA1c value was 8.9 ± 1.7%. The BMC and BMD, respectively, were 61.8 ± 14.1 and 1.02 ± 0.14 (L1-4), 4.6 ± 1.0 and 0.95 ± 0.19 (FN), 12.7 ± 1.7 and 0.54 ± 0.05 (W), 2,273.7 ± 399.5 and 1.12 ± 0.12 (TB). These values are within normal limits compared to North American age specific normative data (Hologic). The mean Osteocalcin level was 18.7 ± 5.7 ng/ml compared to the Tanner 5 female mean value of 49 ± 7 (Endocrine Sciences). The mean N-Telopeptides value was 74.1 ± 35.7 nmol of Bone Collagen Equivalent/mmol Creatinine which is at the lower limit of the gender and age matched normal range (60-429, same ELISA, Bollen et al. 1994). The mean IGF-I value of 273 ± 78 ng/ml is at the lower end of normal (5th%=270ng/ml), as previously shown by us and others. A significant negative correlation was observed between N-Telopeptides level and BMC at L1-4 (r=0.61, p<0.05) or BMD (r=0.66 L1-4, -0.63 FN, -0.72 W, -0.66 TB, p<0.05). HbA1c was positively correlated with bone markers, BMC or BMD (r=0.3-0.5). In conclusion the peak BMD of teenagers with long standing DM in variable degree of metabolic control is within normal limits. While the low N-Telopeptide level does not provide evidence of increased bone reabsorption, the lower mean osteocalcin level may suggest decreased osteoblastic activity. This may be playing a role in the etiopathogenesis of the osteoporosis observed in older patients with type 1 DM, but needs to be interpreted cautiously due to the limited normative data in this population. Data collection is ongoing in patients with DM and our own age matched controls to verify our preliminary findings.