INS and Impaired glucose tolerance: In contrast to the impact of insulin on total peripheral resistance and cardiac output in response to glucose ingestion in normal glucose tolerance, it is suggested that in a state of impaired glucose tolerance, which is characterized by elevated resting insulin and sympathetic neural activity (Rowe et al., 1981), an additional surge in insulin will further raise sympathetic nerve activity and, therefore, impact on total peripheral resistance (Ferrannini et al., 1997).