Blood sugar levels are constantly changing throughout the day and night. Just a fact.

And you are correct that different people have different baselines all within normal range when there is NO disease process. It is a matter of body metabolism.

Peripheral neuropathy is NOT limited to diabetics but it is always one of the first things checked when PN symptoms appear to rule that out.

There are some NEW lab tests out just recently regarding blood sugar levels. I was just reading about one a few days ago.

A CGM is a good method for seeing what your blood sugar does every few minutes over several days, usually 4 to 7 days. Many doctors are reluctant to have a patient wear the device for a short duration due to cost and is usually reserved for use in a diabetic for which medication is not working and a better record is needed than one with a regular meter and lab testing. (CGM is a continuous glucose monitor)

These devices are primarily used by type 1 diabetics on an insulin pump. They wear them all the time.

I have seen CGM's used on a one time temporary basis with type 2 diabetics to aid in determining the proper medication regimen.

Fast and slow carbs act differently upon some people as you mentioned.

Also, just one bite of rice will skyrocket blood sugar levels in some yet the same person can handle other starches better, like potato or pasta.

Blood sugar is NOT a one size fits all for sure. Some baselines are in the 70's, some the 80's and others the 90's without any disease process.

Fasting blood sugar levels can change also just with movement of the clock. I can do a fasting blood sugar level at 6 AM, continue fasting completely, no food or even water, and do another fasting blood sugar level at 9 AM and it may be 30 points higher. (But, I AM a diabetic.)

Blood sugar levels are very complex and what is normal for one person may not be normal for another. Levels change all day and night for everyone, not just diabetics. When the body does not make the proper adjustments to these changes is when one is declared diabetic.