Jacob KJ, et al. - In prefrail and frail older women enrolled in this double-blinded placebo-controlled study, researchers assessed the changes in insulin sensitivity (IS) in relation to leucine supplementation and resistance training (RT). Via Fried criteria, 19 nondiabetic prefrail (1–2 criteria) and frail (≥ 3 criteria) older women were assigned to an intervention for 3-months, including RT 3 times weekly with a protein-optimized diet of 1.2 g·kg⁻¹·d⁻¹ and 7.5 g·d⁻¹ of L-leucine supplementation vs placebo L-alanine. In nondiabetic prefrail and frail older women, IS remained uninfluenced by RT and leucine supplementation. Thus, leucine supplementation did not impact IS under these conditions.