Kaely, those blood sugar levels are very high and it's in the best interest of the patient to keep the post prandial lower.
http://www.phlaunt.com/diabetes/14045621.php This excerpt is from Blood Sugar 101.
A non-diabetic's blood sugar may spike to around 120 after eating especially if the meal is full of carbs like bread and pasta but the blood sugar will recover to around 100 or lower by an hour post prandial.
A diabetic or someone who's insulin resistant will experience greater spikes depending on the measure of carbs in the meal and the amount of food eaten. (Please read the sticky that talks about what affects our blood sugar at the top of our forum.) So, you may see any reading right after you eat (130, 140, 170) - depending on what you eat, the amount you eat and your personal situation, that is, how insulin resistant you are. Also, how long your blood sugar remains elevated depends on these factors. People whose blood sugar spikes like this should be on meds if they can't (or won't) control their blood sugar purely by diet and exercise.
It is not known at what blood sugar levels that organ damage will occur. This varies with individuals. Normally it happens after some period of time of uncontrolled hyperglycemia, but, again, can it happen with levels of 140? Maybe, after a period of time. Neuropathy may start in the feet. Vision can be affected. Heart, kidney, circulation and so on. All may be damaged by elevated blood sugar over some time - but since diabetes affects us differently, no one can state it's at a certain blood sugar level or for an exact period of time.
We do know the levels of non-diabetics before and after they eat, etc. and I think it's in our best interest to try to keep our own blood sugar as near 'normal' as we can. This means: diet, meds and excercise in whatever combination works for us.