Spirometry and diffusion studies in patients with type-2 diabetes mellitus and their association with microvascular complications.

Background. Diabetes is a systemic disease with-well known complications involving eyes, kidneys and nerves. The presence of an extensive pulmonary microvascular circulation and abundant connective tissue raises the possibility that lung may also be a target organ in diabetes. Methods. A total of 45 subjects were included in the study. All patients were evaluated for diabetic microangiopathies: nephropathy (by 24-hour protein excretion), retinopathy (by direct ophthalmoscopy) and neuropathy (by clinical examination). The patients were divided into following three groups: Group A: patients with type-2 diabetes mellitus (DM) with evidence of microangiopathy (n=15); Group B: patients with type-2 DM without any evidence of microangiopathy (n=15); Group C: non-diabetic subjects (n=15) as controls. Glycosylated haemoglobin (HbA1C) was measured as an indicator of glycemic control. Spirometry and single-breath diffusion capacity for carbon-monoxide (DLCO) were performed on all patients using Elite Series Body Plethysmograph machine. Results. A significant reduction of diffusion capacity corrected for alveolar volume (%DL/VA) was observed in group A (p<0.001), as compared to the other groups. There were no differences among the three groups for other pulmonary functions. There was a significant correlation between DL/VA percent predicted and albuminuria (r= -0.975, p<0.001), and DL/VA percent predicted and the retinopathy (r = -0.550, p< 0.05). Conclusion. This study shows a mild reduction in diffusing capacity in patients with type-2 DM with microangiopathy.