Dynamic diffusion lung capacity of carbon monoxide (DLCO) as a predictor of pulmonary microangiopathy and its association with extra pulmonary microangiopathy in patients with type II diabetes mellitus.

BACKGROUND AND AIM

Lung as a target end organ for microvascular disease often remains underdiagnosed. This study aims to assess occurrence of pulmonary microangiopathy among Type 2 diabetes mellitus (T2DM) using dynamic diffusion lung capacity of carbon monoxide (DLCO).

METHODS

A total of 120 participants aged >18 years were enrolled in this study. Group 1 comprised T2DM with microangiopathy (n = 40), group 2 include T2DM without microangiopathy (n = 40), group 3 were healthy controls (n = 40). Individuals with underlying lung disease, smoking history, heart failure, urinary tract infection, macrovascular complications of diabetes, microalbuminuria due to other causes were excluded from the study. Using electronic spirometry, Forced Expiratory Volume in first second (FEV1), Forced Vital Capacity (FVC) was measured and FEV1/FVC ratio calculated. DLCO (%predicted) using single breath method was measured in sitting position followed by supine position and delta DLCO was calculated. DLCO measured was compared between the three groups.

RESULTS

DLCO (median [IQR]) in sitting (78 [70-82.75]) and supine position (70 [62-84]) among group one was significantly decreased when compared to other two groups (p value < 0.001, p value < 0.001 respectively). Delta DLCO (median, [IQR]) among patients with diabetic microangiopathy (-6 [-8 to -2]) was significant on comparison with group two (4[2,6]) and control group (5[4,6]) (p < 0.001). Negative delta DLCO reflecting pulmonary microangiopathy was significantly associated with extrapulmonary microangiopathy (p value = 0.027).

CONCLUSION

Postural variation in DLCO is a useful non-invasive test for identifying pulmonary microangiopathy among T2DM patients. Presence of pulmonary microangiopathy has significant association with diabetic nephropathy and retinopathy.