Non-diabetic's pancreases stay at around 100.
When you read the research paper summaries for these numbers you usually get the 85 to 110 range. You need to also consider that the majority of research is aimed toward type 2 (unfortunately), because higher number of people. If you read the entire report you'll see the 85 number comes from fasting levels, pre dawn phenomenum, of non-diabetics.
I always hated Biology (no black and white answers only shades of gray of multiple answers), but you have to think about it to get an understanding of how complex the machinery of the body is.
In non-diabetics the pancreases releases insulin and glucagon to keep the blood sugar at 100. The insulin (beta) is transported to the blood stream via fat cells and the glucagon (alpha) is transported through the liver. Keeping levels constant at 100.
Insulin coats the surface of the cell which allows glucose to penetrate the surface membrane and be converted to energy.
Cells have short life spans. They replicate, replacing dying cells, while we sleep. The organs are not at their maximum efficency during this time, because the energy is being used to replace the cells (heart beat and breathing slows, temperature drops, etc) .
Once this regeneration activity is completed the pancrease (in non-diabetics) releases glucagon and insulin to "wake" the body up by giving energy.
The 85 fasting numbers for non-diabetics comes from this fasting level.