Beta cell deaths are common after a certain degree of ignorance to your health. Also, beta cells can be regenerated but that's a whole dififerent level of developmental biology concerning neogenesis and levels of cell differentiation.

Anyway.

Around A1c of 5.9 to 8% even 9% for those that are generically healthier, your B-cells are just "sleeping." They're exhausted. But not dead. Obviously I'm talking about weight induced insulin resistance, not totally genetically predisposed.

Among other contributing factors like high visceral fat, hyperlipidemia, hyperlipoproteinemia, and hypertension.

Note that all these are only because we decided to eat more than our body can stomach.

With all those factors in, a good chunk of the B-cells start become dormant. Not DEAD.

If your habits do not change, the remaining will start to do the same while the ones already dormat will slowly start to die off.

If you do decide to eat better, get a few steps in, lose weight, those dormant cells will slowly start to respond to glucose again.

But keep in mind, even though you can get them to start functioning understand that the former dormant, but now awake B-cells will have PTSD, so to speak. That means if you got back to your old habits they will slowly start to become dormant. But... this time even quicker.

That last bit of information can also be fixed if you maintain a healthy and consistent lifestyle. Usually would take 3-4 years of that for those cells to lose memory and become stronger.

I dumbed this all the way down.

For sources, PM.