Evaluation of Lung Epithelial Permeability in Patients with Type 2 Diabetes Mellitus using 99mTc-DTPA Aerosol Scintigraphy / 대한내분비학회지

ABSTRACT

BACKGROUND: Diabetes mellitus is often accompanied by complicated microangiopathy, such as, retinopathy, nephropathy, peripheral neuropathy, cardiovascular autonomic neuropathy or macroangiopathy, as well as by coronary artery disease and cerebrovascular disease. However, there have been few reports concerning the pulmonary involvement of diabetes. Recently, capillary basement membrane thickening, nonenzymatic glycosylation of tissue proteins, abnormalities of endothelial cells and increased damage by free radicals were reported as the underlying basis for the reduced lung permeability. 99mTc-DTPA aerosol scintigraphy is a noninvasive, accurate method, which evaluates the permeability of lung epithelial membranes. The clearance rate of 99mTc-DTPA in lungs may correlate inversely with the lung's epithelial permeability. We investigated the relationship between microangiopathies and the lung epithelial permeability in patients with diabetes using 99mTc-DTPA aerosol scintigraphy. METHODS: The study group comprised of 33 patients with type 2 diabetes mellitus, with no clinical evidence of past or present respiratory disease. The patients were divided into two groups in relation to the complications. Group 1 16 patients with more than one of the complications of retinopathy, nephropathy, cardiovascular autonomic neuropathy and/or peripheral neuropathy, and comprised of 3 males and 13 females, with a mean age of 52.9 +/- 9.6 years. Group 2 17 patients with no complications, and comprised of 5 males and 12 females with a mean age of 52.8 +/- 11.5 years. Group 3 as a control group, comprised of 11 healthy people 4 males 4 and 7 females with a mean age of 44.2 +/- 12.5 years. 99m-Tc-DTPA aerosol scintigraphy was performed in the subjects by inhalation of 30 mCi 99mTc-DTPA aerosol and oxygen (9 l/min) using an aero-vent jet nebulizer as the lung delivery system. To evaluate the diabetic complications, CAN (Cardiovascular Autonomic Neuropathy), and NCV (Nerve Conduction Velocity) tests for peripheral neuropathy, fundoscopy for retinopathy and 24 hours urine microalbumin for nephropathy were performed. RESULTS: The mean durations of diabetes in Groups 1 and 2 were 11.1 +/- 4.7 years and 3.8 +/- 2.1 years, respectively (p<0.05). The mean clearance rates of 99mTc-DTPA were found to be 72.1 +/- 19.5min, 52.6 +/- 19.7 min, and 47.1 +/- 10.9 min for Groups 1, 2, and 3, respectively. The mean clearance rate of Group 1 was significantly longer than for Groups 2 and 3 (p<0.05). In other words, the pulmonary epithelial permeability was reduced in diabetic patients with complications compared to the patients without complication and/or the normal controls. Significant positive correlation was found between the pulmonary clearance rate of 99mTc-DTPA, and peripheral neuropathy and cardiovascular autonomic neuropathy (p<0.05). Conclusions: The lungs may be a target organ for diabetes, and impaired pulmonary epithelial permeability seems to be closely related to other diabetic microangiopathies. Therefore, we recommend that 99mTc-DTPA aerosol scintigraphy be used as a technique for assessing lung injury in diabetic patients.