The haptoglobin 2-2 genotype is associated with carotid atherosclerosis in 64-year old women with established diabetes

BackgroundHaptoglobin polymorphism generates three common human genotypes: Hp1-1, Hp2-1 and Hp2-2. Among subjects with diabetes, Hp2-2 is associated with an elevated risk to develop cardiovascular disease. The impact of haptoglobin genotype on subclinical carotid atherosclerosis is not known. We hypothesized that Hp2-2 was associated with increased occurrence of carotid atherosclerosis in subjects with diabetes.MethodsWe studied a population-based sample of 64-year old women with diabetes (n = 226), either established diabetes known before study entry (n = 116) or new diabetes detected at study screening (n = 110). Haptoglobin genotype was determined by PCR. Carotid atherosclerosis was assessed by ultrasound imaging.ResultsIn the entire diabetes cohort, no differences were observed in carotid intima-media thickness (IMT) or plaque prevalence between the genotype groups. However, among those with established diabetes, Hp2-2 was associated with higher plaque prevalence and larger carotid IMT compared with the Hp2-1 and Hp1-1 genotypes. Common cardiovascular risk factors did not differ between the genotype groups.ConclusionsThe Hp2-2 genotype was associated with increased occurrence of subclinical carotid atherosclerosis in 64-year old women with established diabetes. This association was not explained by traditional risk factors for cardiovascular disease. These results extend previous observations that Hp2-2 is associated with clinical cardiovascular disease in diabetes.