Glucose gets converted to Glucose-6-Phosphate (G6P) through Glucokinase; and G6P is subsequently oxidized to form ATP. This process inhibits the ATP-sensitive potassium ion channels of the cell causing the Potassium ion channel to close and not function anymore.
Binding of insulin to the α-subunit results in a conformational change in the membrane-bound glycoprotein, which activates tyrosine kinase domains on each β-subunit.