Background: Spirometry assessed pulmonary function has been shown to be mildly reduced in type 1 diabetes (t1d) and while this reduction appears to be chronic it doesn’t appear to be progressive. This suggests that functional reduction may not be a microvascular complication of t1d despite the enormous capillary bed in the lungs. CT imaging of the lungs of people with t1d evaluated for pulmonary function is essentially unexplored. We examined CT imaging of participants with and without t1d to explore lung morphology as it relates to t1d.
Methods: The CACTI study conducted CT imaging of the chest as well as pulmonary function testing via spirometry (PFT) . Imaging included the majority of the lungs but does not include the apexes or bases. These lung fields were assessed in a systematic way by a single clinician for incident and these observations were text mined in order to capture the most frequently observed morphologies. PFT results are reported as % predicted values for forced expiratory volume 1 second (FEV1%p) and Forced Vital Capacity (FVC%p) .
Results: 525 CT scans (2t1d, 316 control) were matched to PFT and compared for each of the most common morphologies (nodules (66) , calcified nodes (25) , emphysema (19) , atelectasis (28) , ground glass (13) , airway thickening (34) and granulomatous disease (28) were the most frequently observed) . Participants with t1d had lower FEV1%p (85.9%p vs. 94.4%p, p <0.0001) , lower FVC (87%p vs. 95.5%p, p<0.0001) , were equally likely to be current and former cigarette smokers (28% vs. 27%, p=0,6) , significantly less likely to have calcified nodes (1.6% vs. 4.2%, p=0.03) or granulomatous disease (1.8% vs. 4.6%, p=0.02) but were not different on any of the other incidental findings on CT.
Conclusions: People with t1d have reduced pulmonary function but CT scans of the central lungs do not show morphological changes that may explain this reduction.
G.L.Kinney: None. R.B.Conway: None. K.Young: None. Y.Li: Employee; Vertex Pharmaceuticals Incorporated. J.K.Snell-bergeon: Stock/Shareholder; GlaxoSmithKline plc.