Diffusing capacity for carbon monoxide in children with type 1 diabetes

Abstract

Aims/hypothesis. Few data are available on lung dysfunction in children with diabetes. We studied the association of pulmonary function variables (flows, volumes and alveolar capillary diffusion) with disease-related variables in children with type 1 diabetes mellitus. Methods. We studied 39 children with type 1 diabetes (mean age 10.9±2.6 years, disease duration 3.6±2.4 years, insulin·kg-1·day-1 0.77±0.31) and 30 healthy control children (mean age 10.4±3.0 years). Pulmonary function tests included spirometry, N2 wash-out and the single-breath diffusing capacity for carbon monoxide (DLCO) corrected for the alveolar volume (DLCO/VA). Glycaemic control was assessed on the basis of HbA1c, with HbA1c values of 8% or less considered to indicate good glycaemic control, and HbA 1c values of 8% or more considered to indicate poor control. Results. Children with poor glycaemic control had comparable percentage values for predicted flows and volumes but lower DLCO/VA values than children with good glycaemic control and healthy control children (86.7±12.6 vs 99.8±18.4 and 102.0±15.7; p<0.05). The predicted DLCO/VA percentages correlated with HbA 1c levels (r=-0.39, p=0.013). A multiple regression analysis (stepwise model) controlling for HbA1c levels and other disease-related variables (age of disease onset, disease duration, daily insulin dose/kg, sex) identified HbA1c levels as the sole predictor of DLCO/VA in percent. Conclusions/interpretation. In children with type 1 diabetes, the diffusing capacity diminishes early in childhood and is associated with poor metabolic control. Although low DL CO/VA levels in these children probably reflect pulmonary microangiopathy induced by type 1 diabetes, other factors presumably influencing CO diffusion capacity measurements (e.g. a left shift in HbA1c resulting in high O2 binding and low CO binding) could explain the apparent capillary and alveolar basal membrane dysfunction. © Springer-Verlag 2004.