Disclosed are the preparation and pharmaceutical use of novel noncyclic 1,3-dicarbonyl compounds of formula I, wherein ring A, ring B, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, X, Y, Z, Q, Ar and n are as defined in the specification. These compounds, as peroxisome proliferator-activated receptor (PPAR) dual agonists for both RXR/PPARgamma and RXR/PPARalpha heterodimers, are useful in the treatment and/or prevention of type 2 diabetes and associated metabolic syndrome such as hypertension, obesity, insulin resistance, hyperlipidemia, hyperglycemia, hypercholesterolemia, atherosclerosis, coronary artery disease, and other cardiovascular disorders.