Pulmonary functions in patients with type 2 diabetes mellitus & correlation with anthropometry & microvascular...

The purpose of this study was to evaluate pulmonary functions including respiratory muscle strength in patients with type 2 diabetes mellitus (T2DM) and to determine their correlations with anthropometric profile, glycaemic control, and microangiopathic diabetic complications.

Twenty nine patients with T2DM and 11 healthy control subjects were divided into the following three groups; (i) T2DM patients with any or a combination of microangiopathy(ies) (retinopathy, nephropathy, and peripheral neuropathy) (group 1, n=12); (ii) T2DM patients without any complications (group 2, n = 17); and (iii) a healthy control group (group 3, n=11). All patients were assessed with anthropometry, glycosylated haemoglobin (HbA1C), and lipid profile. Pulmonary functions were measured by spirometry. Pulmonary diffusion capacity for carbon monoxide (DLco) was measured by the steady state method. The presence of diabetic nephropathy was determined by 24 h protein excretion.

A significant reduction of DLco was observed in group 1 (P<0.001), as compared to the other groups. There were no differences among the three groups for other pulmonary functions; forced vital capacity, forced expired volume in one second, peak expiratory flow rate, and maximal static inspiratory and expiratory pressures. Significant correlations were observed between DLco and the following parameters in group 1; HbA1c (r=0.62, P<0.05), total cholesterol level (r = -0.44, P<0.05) and creatinine clearance (r=0.42, P<0.05).

The present study shows that the impairment of pulmonary diffusion capacity for carbon monoxide was common in T2DM Asian Indian patients having microangiopathy. Pathophysiologically, it could be related to glycaemic control or dyslipidaemia. Correlation of % BF with DLCo needs to be explored further.