ND did not improve glucose metabolism compared with control diet , but the AR C17 :0 / C21 :0 ratio was inversely associated with fasting insulin concentrations ( P = 0.002 ) and positively associated with the insulin sensitivity indices Matsuda ISI ( P = 0.026 ) and disposition index ( P = 0.022 ) in pooled analyses at 18/24 weeks , even after adjustment for confounders .