Insulin directly increases Na⁺/K⁺-ATPase activity in skeletal muscle, which enhances the transmembrane sodium gradient and subsequently potentiates SLC6A8-mediated creatine transport.

Study: Effect of insulin upon membrane‐bound (Na+ + K+)‐ATPase extracted from frog skeletal muscle.

The study shows insulin boosts a key cellular pump in muscle that helps move sodium and potassium, which supports the idea that it could help cells take in more creatine.

Study: Role of Serine/Threonine Protein Phosphatases in Insulin Regulation of Na+/K+-ATPase Activity in Cultured Rat Skeletal Muscle Cells*

The study shows insulin turns on a molecular pump in muscle cells that moves sodium and potassium, which could help bring more creatine into the cells. This supports the idea that insulin helps muscles take up creatine.

Study: ERK1/2 Mediates Insulin Stimulation of Na,K-ATPase by Phosphorylation of the α-Subunit in Human Skeletal Muscle Cells*

The study shows that insulin boosts a key cellular pump in muscle cells that helps move sodium and potassium, which creates conditions that should help creatine get into cells more effectively.

Study: Regulatory effect of insulin on the structure, function and metabolism of Na+/K+-ATPase (Review)

The study shows insulin helps boost a cellular pump in muscle that moves sodium and potassium, which matches part of the claim, but it doesn’t test how this affects creatine getting into cells.