Glycemic control and bone mineral density in children and adolescents with type 1 diabetes

Background/Objective Fracture risk is increased in patients with type 1 diabetes. We aimed to evaluate bone mineral density (BMD) and to identify risk factors associated to lower BMD in Danish children and adolescents with type 1 diabetes. Methods In this cross‐sectional study BMD Z‐score were determined by dual‐energy X‐ray absorptiometry (DXA) from a cohort of otherwise healthy children and adolescents with type 1 diabetes. Puberty Tanner stage, hemoglobin A1c (HbA1c), disease duration, and age at diabetes onset were investigated for associations to DXA results. Results We included 85 patients, 39 girls, 46 boys, with a median (range) age of 13.2 (6‐17) years; disease duration 4.2 (0.4‐15.9) years; HbA1c of the last year 61.8 (41‐106) mmol/mol. Our patients were taller and heavier than the background population. When adjusted for increased height SD and body mass index SD, no overall difference in BMD Z‐score was found. When stratified by sex, boys had significantly increased adjusted mean BMD Z‐score, 0.38 (95% confidence interval [CI]: 0.13;0.62), girls; −0.27 (95% CI: −0.53;0.00). For the whole cohort, a negative correlation between mean latest year HbA1c and BMD Z‐score was found, adjusted ß −0.019 (95%CI: −0.034;−0.004, P = 0.01). Poor glycemic control (HbA1c > 58 mmol/mol [7.5%]) within the latest year was likewise negatively correlated with BMD Z‐score, adjusted ß −0.35 (95%CI: −0.69;−0.014, P = 0.04). Conclusions Our study suggests that elevated blood glucose has a negative effect on the bones already before adulthood in patients with type 1 diabetes, although no signs of osteoporosis were identified by DXA.