Isotopic test of capillary permeability to albumin in diabetic patients: Effects of hypertension, microangiopathy, and duration of diabetes

Abstract

Capillary permeability to albumin (CPA) was studied by performing an isotopic noninvasive test with venous compression on 87 nonselected diabetics with no edema, no cardiac failure, and no peripheral vascular disease. Excessive albumin retention (AR ≥ 8%) ten minutes after removal of the compression was found in 27 patients (31%). The radioactivity disappearance curve was then analyzed using the Fast Fourier Transform (FFT). An abnormal isotopic CPA test was thus found in at least 45 out of the 87 patients. The prevalence of an abnormal test was not different in type 1 and type 2 diabetics. We studied the independent effects of hypertension, presence of specific clinical signs of microangiopathy (retinopathy and/or significant proteinuria), and duration of diabetes. Among diabetics free of specific clinical signs of microangiopathy, the prevalence of an AR ≥8% was significantly higher in those with hypertension ( 11 19 ) than in those with normal blood pressure ( 2 28 ) and in nondiabetic hypertensive patients ( 0 16 ). Among normotensive diabetics, the prevalence of an abnormal test was higher, but not significantly, in patients with specific clinical signs of microangiopathy ( 8 11 ) than in those free of them ( 7 18 ). Seven normotensive diabetics without specific clinical signs of microangiopathy had an abnormal test; five of them had had diabetes for more than five years. The prevalence of diabetes of more than five years duration was significantly higher in patients with an abnormal test ( 35 45 ) than in normotensive diabetics free of specific clinical signs of microangiopathy with a normal test ( 4 11 ). These results show (1) the high prevalence of an abnormal CPA in a nonselected diabetic population, (2) the major independent roles of hypertension, microangiopathy, and duration of diabetes in this abnormality, and (3) with the FFT, evidence of a late abnormal phenomenon in the radioactivity disappearance curve, which may be due to a deficient lymphatic wash-out of albumin preceding overt albumin retention.