When we are fasting, out blood sugar is created by the liver in a process called gluconeogenesis. The liver is taking fat and turning it into glucose.
A lot of the tissue in your body will become physiologically insulin resistant (as opposed to pathologically insulin-resistant); which means that when a lot of your tissue (muscles, organs) are burning fat for fuel they don’t need glucose - so glucose stays in the bloodstream longer for things like red blood cells and the brain to use.
It’s not clear if this level of blood sugar in the blood stream is good or bad, in consideration of the context (the body is burning fat for fuel).
But a little bit of insulin can put the brakes on gluconeogenesis. Often times, when you are keto or fasting, you’ll find that eating sometimes LOWERS your blood glucose.
Maybe a few bites of lean meat; or a little dextrose in some coffee, will be enough to raise insulin just enough to stop gluconeogenesis.