We tested apolipoprotein E genotypes in 79 patients with hyperlipidemic diabetes, 44 patients with cerebrovascular accident and acute myocardial infaction, and normal subjects with normolipidemia. We distinguished four different apolipoprotein E genotypes by polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis (PAGE) and determined genotypes and allele frequencies. 1) The frequencies of apo E genotype E3/E4 was higher in the patients with hyperlipidemic diabetes (20.2%) than in the normal subjects with normolipidemia(4.1%) (0.01