Prediabetes is a condition in which your blood glucose levels are higher than normal, but not so high as to they would be if you have diabetes.
Prediabetes is diagnosed if you have a blood glucose of:
- 6.1 to 6.9 without having consumed calories for at least the preceding 8 hours. (If your blood glucose is 7.0 or higher in the fasting state then you have diabetes, not prediabetes.*)
- 7.8 to 11.0 at the two hour stage of a what is called a glucose tolerance test. (If your blood glucose is 11.1 or higher at the two hour mark of the glucose tolerance test then you have diabetes, not prediabetes.*)
Prediabetes is not "borderline diabetes." Indeed, there is no such thing as borderline diabetes. One can no more have borderline diabetes than one can be borderline pregnant...as with pregnancy, you either is or you ain't.
Having prediabetes means you are at enormous risk of later developing type 2 diabetes. There's a big 'but' here, though. And here it is: You can do something to lower this risk! If you follow a very healthy lifestyle with healthy eating, regular exercise (at least 150 minutes per week with you exercising most days of the week), and weight control, you can drastically reduce your risk of developing type 2 diabetes. There are also medications available to reduce your risk (such as metformin, acarbose, and rosiglitazone), but as any doctor worth his salt will tell you, medications to treat prediabetes are always second rate treatment compared to lifestyle therapy (and thus should generally be used only if lifestyle therapy, alas, isn't happening and isn't going to happen).
(*A diagnosis of diabetes typically requires a second, confirmatory blood test be done on another day with this second blood test again being elevated.)