The impact of dysglycaemia on bone mineral accrual in young people with cystic fibrosis

Summary Objective The effect of dysglycaemia on bone mineral density ( BMD ) has not been studied in young people with CF . We examined factors associated with BMD in a tertiary paediatric CF clinic. Design Retrospective, clinic‐based study at The C hildren's H ospital at W estmead, S ydney. Patients Young people with CF aged ≤18 years. Measurements Bone mineral density was measured by dual‐energy X ‐ray absorptiometry; main outcome measures were total body ( TB ), lumbar spine ( LS ) and femoral neck ( FN ) BMD and bone mineral content ( BMC ), and LS volumetric BMD (v BMD ), reported as z scores for height. Dysglycaemia, based on oral glucose tolerance test, was defined as CF ‐related diabetes ( CFRD ) or impaired glucose tolerance ( IGT ). Results Overall, 14 of 81 (17%) had CFRD , 6 (7%) IGT and 61 (76%) normal glucose tolerance ( NGT ). Mean age was 14·9 ± 2·4 years and mean height z score −0·68 ± 1·39. Osteopenic ( z score ≤−2) TB , LS or FN BMD was present in 30 of 81 (37%), BMC in 42 (52%) and v BMD in 10 (5%). Across the three groups, there were differences in LS v BMD ( CFRD , −0·67 ± 0·76; IGT , −0·52 ± 0·76; NGT , −0·05 ± 1·39; P = 0·04), LS BMD ( P  <   0·01), LS BMC ( P  =   0·01) and TB BMD ( P  =   0·01). In multivariate linear regression, LS BMC was associated with dysglycaemia (β = 0·56; 95% CI , 0·00–1·13; P  =   0·05) and approached significance for FEV 1 (β = 0·01; 95% CI , 0·00–0·02; P  =   0·06). Conclusions Dysglycaemia is associated with reduced bone mass accrual in youth with CF , in addition to recognized factors such as abnormal lung function, poor nutritional status and disease severity. Bone health assessment is essential in youth with CF .