It causes many other metabolic problems.
First of all, insulin resistance is the beginning of glucose intolerance. If glucose metabolism is impaired, there will be many problems in daily life of someone. Obviously some of those will be related to energy production.
If someone have insulin resistant, we can say that they will have fatigue and brain fog problems. Eventually, they way that our brain cells metabolize glucose is similar to how our muscle cells metabolize glucose.
I suggest watching Thomas DeLauer's channel: