@joycelen Think of it as a continuum. Almost everyone with type 2 diabetes started as prediabetic. I was prediabetic for over 10 years before I went over the level it is called diabetes. How serious depends on the number and how you were diagnosed. Fasting blood can vary and is not definitive unless you are constantly over. The A1c is best. On this blood test 5.6 and below is normal and 6.5 and above is diabetic. Between those numbers is called prediabetes. The closer you are to 6.5 the worse it is. The glucose challenge test usually detects prediabetes earlier than other tests. Diabetes is progressive and it tends to get worse as you get older. There are both genetic and environmental factors for the disease. Studies have shown that children of diabetics show signs of muscle insulin resistance in their teens, 30 or more years before they test as prediabetic.

The main environmental factor is weight. Losing fat is the best way to get the blood glucose back to normal. I actually went over to minimal diabetic levels about 5 years end than did serious diet and exercise and that gave me another 5 years. The resistance exercise is required so that you lose fat and not muscle. If you are not very good at diet, there are now very good GLP-1 drugs that will help (Mounjaro/Zepbound or Ozempic/Wegovy) you lose weight. They also help the blood glucose by reducing insulin resistance and stimulating insulin release. Even with these medications you will still need to exercise since your body will lose more muscle than fat without it.

@joycelen
I was in the "prediabetic" state for a while, and I had no idea what the term meant, either, and doctor just kind of shrugged, too.
Then I suddenly had a hideous attack, was hospitalized over the weekend, sent home with insulin, and ... 90 days later I was off insulin, prediabetic again but taking metformin, and 120 days later I was lower than prediabetic - but still taking metformin to keep it that way. My scenario is fairly rare, but there it is.

So to answer your question from what I've learned about it all since, being prediabetic means you should wake up and work on it. Heck, everybody these days should learn more about diet and exercise and even get a blood glucose meter at the local drug store and learn to check you own levels.

So what it means is your diet is doing you harm, mild but steady, and you almost certainly need some more exercise - nothing major, just frequent, mild exercise is very effective.

Get your numbers down, make your doctor happy, and probably prevent any number of complications down the line. And once you understand the dietary side, you'll be amazed at what a bad job you've been getting away with since forever!

In summary: diet and exercise will almost certainly get your numbers below "prediabetic" and that would be a good thing.