Objective: To assess the influence of several variables on serum laminin-P1 (Lam-P1) and to evaluate its usefulness as a serum marker of diabetic microangiopathy.
Material and methods: We determined Lam-P1 by serum radioimmunoassay in 121 controls and 176 diabetic patients, 58 type 1 (insulin dependent) and 118 type (non-insulin dependent), grouped according to retinal status and urinary albumin excretion. The variables evaluated were: age, gender, body mass index, blood pressure, consumption of tobacco and alcohol, type of diabetes, duration of disease, fasting blood glucose, HbA1, cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides and apolipoproteins (A1, B). Imprecision for laminin determination was: 3.6% intrassay; 5.8% interassay.
Statistics: Student's t-test, ANOVA, ANCOVA, and multiple regression analysis.
Results: In diabetic patients Lam-P1 was higher than in controls (X = 1.63 +/- S.D. 0.36 vs. X = 1.40 +/- S.D. 0.18 U ml-1; P < 0.001) and only correlated with age (P = 0.002). Lam-P1 was higher in diabetics with proliferative retinopathy than in patients with non-proliferative retinopathy and without retinopathy (X = 2.17 +/- S.D. 0.49 U ml-1 vs. X = 1.71 +/- S.D. 0.22 U ml-1 vs. X = 1.47 +/- S.D. 0.26 U ml-1; P < 0.001). Patients with macroalbuminuria presented higher serum Lam-P1 than patients with micro or normoalbuminuria (X = 2.39 +/- S.D. 0.53 U ml-1 vs. X = 1.78 +/- S.D. 0.23 U ml-1 vs. X = 1.51 +/- S.D. 0.29 U ml-1; P < 0.001). These differences remained significative when patients were age-adjusted.
Conclusions: Lam-P1 could be useful as an index of diabetic microangiopathy but patient's age should be considered.