Diffusing capacity for carbon monoxide in children with type 1 diabetes.
OBJECTIVE
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, N(2) wash-out and the single-breath diffusing capacity for carbon monoxide (DL(CO)) corrected for the alveolar volume (DL(CO)/V(A)). Glycaemic control was assessed on the basis of HbA(1)c, with HbA(1)c values of 8% or less considered to indicate good glycaemic control, and HbA(1)c 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 DL(CO)/V(A) 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 DL(CO)/V(A) percentages correlated with HbA(1)c levels (r=-0.39, p=0.013). A multiple regression analysis (stepwise model) controlling for HbA(1)c levels and other disease-related variables (age of disease onset, disease duration, daily insulin dose/kg, sex) identified HbA(1)c levels as the sole predictor of DL(CO)/V(A) in percent.


CONCLUSIONS
In children with type 1 diabetes, the diffusing capacity diminishes early in childhood and is associated with poor metabolic control. Although low DL(CO)/V(A) 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 HbA(1)c resulting in high O(2) binding and low CO binding) could explain the apparent capillary and alveolar basal membrane dysfunction.
Villa
M P
MP
Department of Paediatrics, Sant'Andrea Hospital, II Faculty of Medicine, University La Sapienza, Via di Grottarossa, 1035-1039, 00189 Rome, Italy. mariapia.villa@uniroma1.it
Montesano
M
M
Barreto
M
M
Pagani
J
J
Stegagno
M
M
Multari
G
G
Ronchetti
R
R
D000293:Adolescent; D002248:Carbon Monoxide / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology; D004058:Diffusion; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D012016:Reference Values; D012129:Respiratory Function Tests
D002248:Carbon Monoxide; D006442:Glycated Hemoglobin