Insulin resistance
When cells respond less to insulin, so the body needs more of it to keep glucose in check.
In insulin resistance, muscle, fat, and liver cells don't take up glucose as readily in response to insulin. The pancreas compensates by making more, and glucose can creep up when it can't keep pace.
It's a central feature of prediabetes and type 2 diabetes, and it's strongly influenced by activity, sleep, and body composition.