Lung functions in poorly controlled type 1 Saudi diabetic children and adolescents.

I have 3 comments on the interesting study by Al-Saadi et al1 on the lung functions in poorly controlled type 1 Saudi diabetic children and adolescents. First, diabetic microangiopathy targets the lung as it does other organs. Even though respiratory dysfunction in most patients with diabetes mellitus (DM) is subclinical and rarely the presenting complaint, there are several reasons why pulmonary assessment is important: 1. Pulmonary function testing noninvasively quantifies physiological reserves in a large microvascular bed that is not clinically devastated by DM. 2. Subclinical loss of pulmonary reserves becomes overtly debilitating under conditions of stress, such as with aging, chronic hypoxia due to lung disease or high altitude exposure, or volume overload secondary to cardiac and renal failure. 3. Unlike myocardial or skeletal muscle function, pulmonary indices are largely independent of physical fitness. 4. Interpretation of pulmonary function indices is not complicated by secondary sequelae of diabetic end-organ failure or prior therapy. Lung function could provide useful measures of the progression of systemic microangiopathy. 5. Chronic use of inhaled insulin may affect long-term pulmonary function, while preexisting pulmonary dysfunction might alter the absorption and bioavailability of inhaled insulin.2 Second, Al-Saadi et al1 stated that pulmonary function in children with type 1 diabetes mellitus (T1DM) showed significant lower mean values of actual lung function parameters, namely forced vital capacity (FVC), peak expiratory flow, and maximum mid expiratory flow rate compared to their predicted values. However, there was no significant reduction in the actual forced expiratory volume in the first second (FEV1), and FEV1/FVC% compared to their predicted values. It is well-known that normal lung function tends to be population-specific. According to my knowledge, no normal reference spirometric values for Saudi children and adolescents are present. Though Al-Saadi et al1 did not address prediction equations applied in their study, it seems that they referred to equations specific for the Caucasian population. Recently, normal reference spirometric values for Omani children and adolescents3 have been constructed that could be considered for use in neighboring Arab countries, including Saudi Arabia. Applying these references might alter the data addressed by Al-Saadi et al.1 Third, interestingly, Al-Saadi et al’s study1 supports the view that the lung is functionally involved in children with T1DM early on in the course of the disease.4 It, therefore, seems justifiable to regularly assess pulmonary functions in children with T1DM for early detection of any dysfunction. Portable spirometers could provide measurements that are highly comparable to those obtained from “gold standard” laboratory spirometers and high quality tracings could be achieved both at home and in the office setting. They could provide all curve waveforms that could be stored and available for visual inspection.5,6 Accordingly, it might be recommended to provide every T1DM child with a portable spirometer with the purpose of regularly monitoring pulmonary functions at home.