Diabetes Care, Vol 18, Issue 12 1577-1581, Copyright © 1995 by American Diabetes Association
Fibrinolysis and diabetic retinopathy in NIDDM
MW Mansfield and PJ Grant
Division of Medicine, University of Leeds, U.K. michaelm@pathology.leeds.ac.uk
OBJECTIVE: By contributing to a prothrombotic state, increased levels of
plasminogen activator inhibitor-1 (PAI-1) may be involved in the
pathogenesis of the vascular complications of non-insulin-dependent
diabetes mellitus (NIDDM). The objective of this study was to compare
levels of components of the fibrinolytic system in NIDDM subjects with and
without retinopathy. RESEARCH DESIGN AND METHODS: A total of 135 Caucasian
NIDDM subjects treated with oral therapy or diet alone were classified by
the presence or absence of retinopathy, and fasting blood samples were
taken for assay of PAI-1 antigen and activity, tissue plasminogen activator
(t-PA), t-PA complexed with PAI-1, euglobulin clot lysis time (a measure of
overall fibrinolytic activity), glucose, HbA1c, cholesterol, triglyceride,
and insulin levels. RESULTS: Subjects with retinopathy had a longer disease
duration than those without (9 vs. 5 years, P < 0.0001) and had lower
levels of PAI-1 (PAI-1 antigen) (geometric mean and 95% confidence
interval), 13.9 (10.4-18.6) vs. 24.1 (21.2-27.4) ng/ml (P < 0.0005);
t-PA antigen, 9.6 (8.6-10.7) vs. 11.5 (10.8-12.3) ng/ml (P < 0.01);
t-PA--PAI-1 complexes, 6.2 (5.2-7.2) vs. 7.8 (6.8-8.8) ng/ml (P < 0.05);
and insulin, 11.5 (9.3-14.3) vs. 19.5 (17.0-22.3) mU/l (P < 0.0005).
Euglobulin clot lysis time was shorter in the subjects with retinopathy,
273 (238-312) vs. 327 (303-352) min. When entered into a logistic
regression model, disease duration, PAI-1 antigen, and HbA1c remained as
significant independent associates of the presence of retinopathy.
CONCLUSIONS: These results do not support the hypothesis that impaired
fibrinolysis due to elevated PAI-1 is associated with the development of
retinopathy because fibrinolysis is indeed enhanced and PAI-1 lower in
subjects with retinopathy.