I'll explain a bit about pre-diabetes, with some help from some websites to fill the gaps in my understanding
Prediabetes is basically when your sugars are high, but not high enough to be considered diabetes. So your sugars are above the normal range, consistently, but not high enough to trigger all the other symptoms of diabetes and don't need treatment to manage just yet.
Lou mentioned A1C, which is a test they do to check these levels. Its basically a test for your hemoglobulin. When i was looking up how to interpret the results etc I stumbled on something interesting from the American Diabetes Association:
Now we all know Lou was diagnosed diabetic less than one year ago, but from the selfies etc it doesn't look like there has been much weight loss. That and he is still on insulin, which is pretty bad on its own as type 2 diabetes shouldn't have to be treated with insulin- that means he is really, badly diabetic to the point where it has effected his pancreas. Type 2 does not usually do this, only when it is left untreated. Getting down to pre-diabetic levels in this short amount of time, given the background we know about Lou's diabetic "journey" (if you will), would be extremely impressive, bordering on impossible. He has liver problems as well, which could very likely be advanced complications of NAFLD (Non-Alcoholic Fatty Liver Disease), and if so, point to not a lot of weight loss.
Here are the 'levels' btw