Respiratory responses of diabetics to hypoxia, hypercapnia, and exercise.
The respiratory responses of 52 diabetics and 65 non-diabetic controls to hypoxia, hypercapnia, and exercise were studied. Twenty five per cent of the diabetics had evidence of impaired sensitivity to hypoxia or decreased ventilatory response to hypercapnia, while 7% of the diabetics who performed the exercise tests had an abnormal pattern of respiration during exercise; 33% of the diabetics who performed all three tests of respiratory reflex action had at least one abnormal test response. There was no correlation between the presence of an abnormal respiratory response and the presence of clinical diabetic complications. Abnormal respiratory reflexes could not be predicted from the results of the "routine" pulmonary function tests. The possibility that the abnormal respiratory responses were due to autonomic neuropathy is discussed.