Increased transcapillary escape rate of albumin in microalbuminuric type II diabetic patients.
OBJECTIVE
To evaluate microvascular permeability by the transcapillary escape rate of albumin (TERalb) in type II diabetic patients with normo- and microalbuminuria.


METHODS
The TERalb has been measured following intravenous injection of 125I-labeled human serum albumin in 32 normotensive type II diabetic patients and 9 healthy control subjects matched for sex and age. Type II diabetic subjects were grouped in normoalbuminuric, albumin excretion rate (AER) < 20 micrograms/min (n = 18), and microalbuminuric, AER 20-200 micrograms/min (n = 14) categories.


RESULTS
In type II diabetic patients, no differences were noted between normo- and microalbuminuric groups for known diabetes duration (8.3 +/- 5.9 vs. 11.7 +/- 8.0 years), blood pressure (BP) (129/76 +/- 16/8 vs. 131/76 +/- 14/5 mmHg), current metabolic control (HbA1c: 8.0 +/- 1.4 vs. 8.5 +/- 1.6%), and serum lipids. However, previous 2-year mean HbA1c levels were significantly higher in microalbuminuric patients (8.7 +/- 1.45 vs. 7.6 +/- 1.29%; P < 0.05). The TERalb was similar in control subjects and normoalbuminuric patients (5.16 +/- 1.09 vs. 5.71 +/- 1.66 %/h) and significantly higher in the microalbuminuric group (8.98 +/- 1.35 %/h; P < 0.0001). The increased leak of albumin was not explained by differences in diabetes duration, BP, or metabolic control at the time of investigation and was independently related to the presence of microalbuminuria (r = 0.63, percent explained variance approximately 40) and mean "historical" HbA1c (multiple r = 0.705; total explained variance approximately 50%).


CONCLUSIONS
Type II diabetic patients with microalbuminuria show an increased TERalb, i.e., a widespread microvascular damage that may be important in the pathogenesis of long-term complications. Our findings may contribute to the explanation of why albuminuria seems to be an independent cardiovascular risk factor in type II diabetes.
Nannipieri
M
M
Chair of Metabolic Diseases, University of Pisa, Italy.
Rizzo
L
L
Rapuano
A
A
Pilo
A
A
Penno
G
G
Navalesi
R
R
D000419:Albuminuria / Q000209:etiology / Q000378:metabolism*; D000704:Analysis of Variance; D002199:Capillary Permeability / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000378:metabolism*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D012709:Serum Albumin / Q000378:metabolism*; D011795:Surveys and Questionnaires
D007457:Iodine Radioisotopes; D012709:Serum Albumin