Serum Alpha-1-Protease Inhibitor Activity and Pulmonary Function in Young Insulin-Dependent Diabetic Subjects

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Abstract
Abnormalities of lung function have previously been described in patients with impaired .alpha.1-protease inhibitor (.alpha.1-PI) function and more recently in insulin-dependent diabetic subjects. This study was undertaken to test the hypothesis that impaired .alpha.1-PI activity may be implicated in the pathogenesis of lung function abnormalities in young insulin-dependent diabetic patients. Twelve young (16.23 .+-. 4.51 years), non-smoking insulin-dependent diabetic subjects and 12 reference subjects were evaluated in respect to lung mechanics, absolute serum .alpha.1-PI levels and the functional ability of .alpha.1-PI to inhibit elastase. Results of the ventilatory mechanics showed that the mean value for the volume-independent index of lung elasticity Kst(L) was significantly greater in the diabetic gorup (0.149 .+-. 0.05 vs. 0.116 .+-. 0.03; p < 0.05). The absolute serum .alpha.1-PI levels in the insulin-dependent diabetic subjects was significantly lower than in reference subjects (1.74 .+-. 0.11 vs. 2.06 .+-. 0.09 g/l; p < 0.05). While the specific .alpha.1-PI activity of the diabetic sera showed no significant difference from that of the reference sera, the total .alpha.1-PI inhibitory activity in the diabetic sera was significantly lower than reference values (201.9 .+-. 9.7 vs. 246.9 .+-. 13.5 U/L; p < 0.02). Although these findings indicate impairment of both ventilatory mechanics and .alpha.1-PI activity in the insulin-dependent diabetic subjects, the pathogenesis of these findings and their functional implications are at present unknown.