I would be surprised if this happens.... looking at the numerous threads on these forums where people report their FBG, with various levels of chat, anything close to 4.5 is pretty rare.
For myself I had a bit of surgery last autumn which knocked my FBG levels, +6.5, which was way above my "target", 5.2. Over time it came down and when I was more or less happy with the output it went bonkers over one month and climbed to 6.2, weekly mean. I dropped the carbs, two days a week did a 24 hr fast, other five days 14 hr fast and my FBG came down rapidly to 5.4, weekly mean.... and that's where I am at the moment...
I reckon my control is fine for me but I won't be getting anywhere near 4.5 any time soon.....