You have to have what's called an A1C level. It's a measurement of basically the amount of sugar in your blood over a period of time. It has to be above or below a certain threshold, and once it's above a certain threshold you will probably be diagnosed with what's called pre-diabetes. In other words, your ability to manufacture insulin is impaired to lower the amount of sugar in your blood, and as that sugar builds up you incur things like heart attacks, stroke, kidney failure, and diabetic-related blindness. Those are the major complications.
It's critically important. You must lower your level of blood glucose, because those complications can start in people, not just with diabetes but with pre-diabetes as well.