(The pancreas still works, just the beta cells that make insulin and amylin are “mostly completely dead most of the time” although it looks like beta cells regenerate in small amounts constantly, but get taken out by the immune system on a cyclic basis). Perhaps a prediabetic or highly insulin resistant individual would actually see a significant reduction in daily insulin needs from walking 10 minutes right after each meal, because such a person has a tendency to super-secrete (not under secrete) insulin in response to food, especially carbs, because their blood sugar levels rise higher after meals. As a result they end up overexposed to insulin, and then often have rebound hypoglycemia 2-5 hours after eating (if they wait that long). That’s why they do better on lower carb diets, because it blunts the oversecretion from the initial insulin spike. Exercise would do the same thing, but not by making the cells more insulin sensitive like metformin does, but by speeding up the circulation of insulin after a meal, and slowing down gastric emptying. So in effect, the act of reducing a post meal spike from say 160 to 120 will reduce the oversecretion by reducing the dysfunctional signal for insulin and this will reduce daily insulin exposure which will lead to long term improvement in insulin sensitivity. So it is a good point that blood sugar spike CAUSE OVEREXPOSURE in insulin dysfunctional prediabetics and so blunting the spike can result in long term resensitization. Not to mention that high blood sugars kill beta cells in pre type II diabetics and high insulin output burns out the pancreas and also may cause a secondary autoimmune response. It looks like type II diabetes ends with an autoimmune response just like type I. The body gets so exposed to insulin, and the pancreas gets damaged from high blood sugar and this triggers the immune system to see the pancreas as a foreign body. Usually by age 20 or so though, the pancreas is so large that it takes decades to totally destroy it and destruction may be thwarted.
A healthy person lifting weights. Well, non insulin resistant type 1 diabetics are often very active, and many lift weights. Activity after a meal does have a great effect on preventing the blood sugar spike, but these people are not insulin resistant, and so they don’t have a tendancy to hypersecrete insulin in response to food. Type I diabetic MAY over inject insulin for food, and then have to eat more to prevent a low blood sugar. Point here is just that yes reducing a post meal spike from maybe 125 to 110 3 times a day is going to improve health and lower A1C, but not in the way that metformin does by making cells more sensitive to insulin, but by making the insulin effect match the rise in blood sugar better-circulate faster and slow down the rise in blood sugar from the food. 3 10 minute walks would only lower daily insulin needs by about 4-7% if they ate the same, and not much at all if they ate more to match the exercise needs-at least for the day, but I think that doing so regularly-excercising when carbs are more available-would upregulate muscles glucose burning enzymes and may have long term benefits that way.
I am not downplaying the benefits of 10 minute walks after (ore even right before) meals as they have tremendous health benefits, but they don’t work like metformin does, by making the cells much more sensitive to insulin. They just let your insulin do a better job of keeping blood sugar down. I am all for them, but they don’t work the same way that metformin does. I’ve read articles that say that certain foods like full fat dairy improve insulin sensitivity, while in fact what they do is reduce blood sugar spikes by slowing down the entry of glucose into the bloodstream. I don’t like it when a decrease in blood sugar gets interpreted as a decrease in insulin resistance. Pasta for example produces much smaller blood sugar spikes than rice because the gluten surrounds the starch and makes it very slow to digest. The GI of pasta is in the 30s while rice is in the 90s, but in non-insulin resistant individuals, wheat causes 150-200% as much insulin exposure as rice because it triggers glucagon and cortisol and even some adrenaline while sitting in the gut simply by a reflex that it causes in the intestines. Even pure fiber causes an INCREASE in insulin release. Leucine can lower blood sugar by stimulating insulin release in a non-diabetic, but it can raise blood sugar if it robs the insulin from working on blood sugar if the leucine is consumed with a lot of carbs. FAT increases daily insulin needs significantly if it is simply added to meals. Doubling the fat content of meals will increase the insulin needed to manage the carbs to 200-300% of the level with low fat, but it slows down the rise and so it reduces post meal spikes dramatically by giving time for the pancreas to deal with the needs. This is not to say that replacing carbs with fat will require more insulin. If calories stay constant and carbs are replaced with fat, insulin needs go down, but not in proportion to the decrease in carbs. If muscles are loading with fat, and burning fat and are trying to move free fatty acids from outside to inside then it reduces the rate that they can remove glucose. Sorry to ramble, but point is that things that reduce blood sugar do not necessarily improve insulin sensitivity. They are often just as likely to cause good blood sugar by stimulating GREATER release of insulin faster than the food can raise blood sugar, but all in all, I think you may be right about prediabetics because they have a hypersecretion dysfunction, and I think that 3 10 minute walks around meals (before or after) can greatly improve health, but not primarily by making you more insulin sensitive in an acute way.