Asymmetric dimethylarginine is associated with parameters of glucose metabolism in Caucasian but not in African women from South Africa

Aim: Ethnic differences in obesity and obesity related disorders prompted us to search for possible contributors. The impact of the novel cardiovascular risk factor asymmetric dimethylarginine (ADMA) has been never determined in the African population. The present observational study aimed to compare ADMA levels between healthy African (102) and Caucasian women (115) from South Africa, and its impact on glucose metabolism. Methods: All participants underwent an oral glucose tolerance test with measurements of glucose, insulin, C-peptide, proinsulin and free fatty acids before and after 30, 60, 90, 120 minutes. Fasting serum ADMA was measured by ELISA assay and obesity was determined by anthropometry. Results: Serum ADMA did not differ between the ethnic groups. After stratification according to ADMA quartiles Caucasian women in the upper quartile had significantly higher body mass index and waist circumference as well as elevated insulin resistance, insulin, C-peptide and proinsulin levels with no differences in serum glucose compared to women in the lowest quartile. There was a significant stronger postchallenge insulin response in Caucasian women of the upper quartile. No differences were found in African women. Conclusions: Despite similar ADMA levels in both ethnic groups ADMA was positively correlated with parameters of glucose metabolism in the Caucasian but not in the African women from South Africa.