Compounds having the structure are peroxisome proliferator-activated receptor-gamma (PPAR-gamma) selective agonists and as such are useful in the modulation of blood glucose and the increase of insulin sensitivity in mammals. This activity of the piperazine derivatives of the invention make them particularly useful in the treatment of those conditions selected from the group consisting of diabetes, atherosclerosis, hyperglycemia, hyperlipidemia, obesity, syndrome X, insulin resistance, hypertension, heart failure and cardiovascular disease in mammals.