As a 64 year old goat fighting this type 2 crud for last 30 years and last 4 getting mess under control I would offer my opinion as follows:
Setting of the body BG level at fasting when gut produces no glucose requires waltz of three main players namely:
Liver, pancreas, and the fat/skeletal muscle cells that absorb glucose under insulin control if there is room and cells not filled to capacity and turning on Insulin resistance.
Simply stated as liver ages, it starts releasing larger and larger low level releases of glucose ( it ages); on top of that the pancreas also ages and probably reduces its basil pulse release as well. Since this is pre diabetes, I would assume the skeletal muscle/fat cells are not completely filled up and the average BG set point starts shifting up as describrd for pre-diabetes.
At this point, carbs control and hearty exercise are capable overcoming the liver small over release and thus stopping the diabetes in its tracks as the extra liver releases are not sufficient to fill completely the local storage sites of the skeletal muscle cells and fat keeping insulin resistance turned off.
As the body ages; the liver gets nastier releasing larger releases ( leaks) of glucose and the pancreas further drops its basil response resulting in the fat/skeletal muscle cells to fill riht up and enforce insulin resistance.
At this stage it takes a heroic effort to cut the glucose pressure, arrest the liver on drugs - and any other meds - possibly a insulin boost - liquid insulin. In addition carbs control and sufficient hearty exercise are still critically needed to ensure that once liver/pancreas monkey shines are arrested - corrected, the carbs control and hearty exercise keep glucose burned off and room in fat/skeletal muscle cells do not stay filled up enforcing insulin resistance.
The big problem here is that once one decides to correct this crap, the external insulin/ pills one has been on must continue till the pancreas and and the skeletal fat muscle cells decide to go back to work and use the body's own insulin as the pancreas goes back to work as well. At that point - unpredictable timing on, the body suddenly now has twice as much working insulin it had a day before.
This needs to be watched /alarmed by a CGMS and protected by patient action against lows and promptly cut back the external pills/insulin injections to correct operating point. At all times one must be under care/approval of plan by your diabetes care doctor. Do NOT TRY this on your own.
This is not puff pastry and wishefull thinking as research papers bearing the ADA label have data and conclusions suggesting this is what is going on.