Shaky at normal bg levels?

My husband is prediabetic, with low insulin production and doesn’t seem to have insulin resistance. He has been managing his bg through diet and exercise. His levels are usually 110-120. Lately, he’s been feeling shaky and unwell at bg levels of 95-100ish. Is that normal and should he be concerned? Or do anything different? Or should his body just adapt if he persists? Thanks, and stay healthy everyone.