29 November 2002
Aim: To analyze whether bone mineral density (BMD) and bone resorption status are influenced by long-term metabolic control and duration of disease in adolescents with long-standing type 1 diabetes mellitus. Methods: Twenty-seven adolescents (age 13.1 ± 1.7 years, duration of diabetes 6.9 ± 3.0 years) were studied. The BMD, expressed as z score, was measured at the lumbar spine (L1–L4) using dual-energy X-ray absorptiometry, while the urinary excretion of total deoxypiridinoline (Dpyd), a marker of bone resorption, was measured by immunoassay and was corrected by creatinine (Cr). Linear and multivariate correlations between lumbar BMD z score or Dpyd/Cr excretion and age and disease variables [short-term (Hb A<sub>1clatest</sub>) or long-term (Hb A<sub>1cwholeduration</sub>) metabolic control, duration, ‘diabetes impact index’ (mean Hb A<sub>1cwholeduration</sub> x duration of disease in months)] were sought. Results: In diabetic subjects the mean BMD z score was –0.44 ± (SD) 1.02 (95% CI: –0.03; –0.84), and the Dpyd/Cr excretion was not increased. A negative correlation was found between lumbar BMD z score and age (r –0.59; p = 0.001), duration (r –0.39; p = 0.04), and the diabetes impact index (r –0.4; p = 0.04). The Dpyd/Cr ratio correlated negatively with age (r –0.40; p = 0.04) and positively with height velocity (r 0.42; p = 0.04). By using multiple linear regression, age showed a significant inverse correlation with lumbar BMD z score (β = –0.39; p = 0.0005). A negative correlation was found between lumbar BMD z score and Hb A<sub>1cwholeduration</sub> (β = –0.40; p = 0.02) or diabetes impact index (β = –0.001; p = 0.01). Conclusions: Poor metabolic control may expose adolescents with long-standing type 1 diabetes to the risk of developing osteopenia in adult age. Optimization of metabolic control in growing diabetic children may prevent osteoporosis in later life.