Your cells have receptors which insulin binds to. There are different things that factor into diabetes. One is that, due to genetics, you don’t have as many open receptors available, so there is a genetic component that can factor into all of this. The second thing is that if you are overweight, for whatever reason, fat particles can block the insulin receptors. Either one or both of these together can make your pancreas work harder to regulate your sugar. If you overstress and kill some of the cells in your pancreas, they don’t grow back. Voila, you now can’t produce enough insulin and you have type II diabetes (compared to type I diabetes which is where the cells in your pancreas can’t produce enough insulin to start with).
That article seems to be a big load of hooey. Obviously genetics can be an important factor. If you don’t have as many insulin receptors to start with you are much more prone to diabetes. However, just fat alone can block the insulin receptors and overstress your pancreas. So you can overeat yourself into type II diabetes.
There is a point to be made, and that is that if you have type II diabetes it is possible that you didn’t overeat yourself into it. It’s also possible that you did, though, and that’s where the article is flat out wrong.
Losing weight gets rid of the fat that blocks your insulin receptors, so if you lose weight and follow a strict diabetic diet (count carbs) you can significantly help to regulate your blood sugar, and if the cells in your pancreas haven’t been too badly damaged, it’s possible for you to be “cured” (not needing diabetic medications). It’s not really a cure though since the cells in your pancreas will never grow back. It’s probably better to say it is managed rather than cured.
If there is too much damage to your pancreas though, you will probably be stuck on diabetic meds for the rest of your life.
ETA: Also, it is important to note that if you do lose weight, you free up the fat from your insulin receptors, and even if you do have to be on diabetic meds, you ease the load on your pancreas and stop yourself from doing even more damage to it. If your pancreas gets worse, it can be much more difficult, even with meds, to keep your blood sugar properly regulated.
(IANAD, but I have diet and exercise managed (not “cured”) type II diabetes)