Insulin sensitivity is a signifier of overall metabolism which has too many facets for us to comprehend at present. Attempting to manually steer specific hormones is often a fool's errand when we zoom in one domino and ignore the dozen before and after.
Everyone I know who achieved verified improvements in BG did so with permanent dietary upgrades--more nutrients, fewer toxins, and no temporary measures. The body knows how to heal when given the chance.
Lots of: urban hiking, cycling, sprinting
Lots of: fresh meat, seafood, eggs, organs, tubers, starch fruits, vegetables, meat fat, dairy fat, oil fruits
Some: cured meat, dairy protein, sweet fruits, rice, pulses, tree nuts, oil seeds
Minimal: soy, refined proteins, sugar, liquid carbohydrate, grains, refined oils, peanuts