Systemic thickening of capillary endothelial basement membrane underlies the chronic complications of human diabetic microangiopathy. Since (99)mTc-DTPA aerosol scintigraphy is a sensitive, non-invasive test of membrane permeability, we decided to study the effect of diabetes on the permeability of lung epithelium in diabetic patients using this test. Fifty (NIDDM) patients, aged 40-70 years, with or without complications, and who were non-smokers, were subjected to evaluation using Tc-99m-DTPA aerosol. At the same time, pulmonary function tests, including carbon monoxide diffusion capacity, were done. Normal non-smoking subjects with no history of cardio-respiratory disease, who underwent Tc-99m-DTPA and pulmonary function tests, served as controls. The risk factors which included age, sex, degree of control and presence of complications were noted. Twenty-nine (58%) of the patients had abnormal Tc-99m-DTPA clearance. Thirty-four percent of the patients with complications and 24% of those without complications had abnormal clearance. Complications recorded included retinopathy, neuropathy and nephropathy. Fifty-five percent of patients with abnormal Tc-99m-DTPA had suffered from diabetes for longer than 10 years. Sixty-two percent of patients with poor glycaemic control had abnormal Tc-99m-DTPA. Diffusion capacity was not significantly affected in patients with complicated diabetes. Our preliminary results suggest that Tc-99m-DTPA is a potentially sensitive test in assessing the degree of lung affection in diabetic patients. No significant correlation exists between diffusion capacity and Tc-99m-DTPA. The risk factors did not affect the Tc-99m-DTPA clearance, probably due to the small sample size.
