Hi,
It's difficult to quantify exactly what the results will be but according to the American Diabetes Association, every one percentage point drop in HbA1c levels (e.g., from nine to eight percent) can lead to a 35 percent drop in the risk of diabetes-related complications.
Aiming for less than 6.5% is the way to go in my opinion.
Have a look on here especially at the retinopathy threads and you will see that members there can go through terrible things because of the damage to their eyes - if you really take care of your blood sugars you will in all likelihood avoid those complications, if you don't you will in all likelihood end up with them.
The trouble with diabetic complications is once you've passed a 'tipping point' you can't go back and undo them whatever control you have, so we all need to ensure we don't get to that stage.
When I was 19 I didn't really think about what I'd be doing when I was in my 40's - it seemed to be so far away as to be irrelevant but time and the tide is forever moving on and one day you'll get to that ripe old age and if you've spend the last 20 years of your life making an enemy of your future you'll be stuck and wishing you'd gone about things differently. Luckily for me I never went too far off the wall; but with each year that passes I realise the need to tighten up as much as possible on the control.
So, well done for deciding to look at this now; everything is possible for you; but it's a marathon not a sprint.
Best
Dillinger