Relation of apolipoprotein (a) phenotypes to diabetic retinopathy in elderly type 2 diabetes

The aim of this study was to clarify the relationship between apolipoprotein (a) (apo (a) ) phenotypes and diabetic retinopathy in elderly type 2 diabetes. Serum Lp (a) concentrations and apo (a) phenotypes were analyzed in 250 diabetic patients aged 60 to 88 years old. Apo (a) phenotypes were classified into 7 subtypes (F, B, S1, S2, S3, S4, O (Null) ) by the method SDS electrophoresis with Western blotting. Patients were divided into two groups according to their apo (a) phenotypes:a low molecular weight (LMW) Lp (a) group, and a high molecular weight (HML) Lp (a) group. Patients were classified as having one of 4 types of diabetic retinopathy: no retinopathy (R0), simple retinopathy (R1), pre-proliferative retinopathy (R2), and proliferative retinopathy (R3). There was a significant association between serum Lp (a) levels and severity of diabetic retinopathy (p<0.001). A gradual trend toward increasing serum Lp (a) levels was observed across the groups (from R0 to R3). A significantly greater percentage of LMW Lp (a) was observed in the R1, R2, and R3 groups than in the R0 group (42.9% (p<0.001), 27.0% (p<0.01), and 27.3% (p<0.05) vs. 10.4%). Multiple logistic regression analysis revealed that duration of diabetes and LMW Lp (a) are independent risk factors for diabetic retinopathy. These results provide significant evidence that LMW Lp (a) contributes to an increased risk of diabetic retinopathy in elderly type 2 diabetes.