Ethnic and gender differences regarding the insulin–blood pressure relationship

Ageing is associated with increased insulin and C-peptide levels. Due to a lack of data, our first aim was to establish whether this also holds true for Africans from South Africa. Our second aim was to determine whether an association between insulin/C-peptide levels and blood pressure exist within an African and Caucasian population with increasing age, as well as to establish gender differences. African men and women (N = 260) and Caucasian men and women (N = 369) were recruited and stratified into age groups (18–35 years, 36–45 years and >45 years). ANCOVAs and partial correlations were performed. Results showed opposing changes in insulin/C-peptide levels of African and Caucasian men with increasing age. Insulin/C-peptide tended to decrease in African men, whereas insulin tended to increase and C-peptide increased significantly (p = 0.03) in Caucasian men. Despite similar obesity levels, the oldest African women had significantly lower insulin (p < 0.01) and C-peptide (p < 0.01) levels compared to their Caucasian counterparts. In conclusion, insulin/C-peptide levels tended to decrease in the African population with increasing age. Despite significantly lower levels of insulin, blood pressure levels of African men seems to be affected more detrimentally compared to their Caucasian counterparts, leaving them more vulnerable for the development of cardiovascular diseases.