The levels up to 100 are considered normal sugar levels, and levels between 100 and 126 are considered pre-diabetes. Most people who have had a blood glucose level over 500mg are considered to be into uncontrolled diabetis. When the blood glucose level gets over 500mg, generally, the cause is uncontrolled diabetes. The effects of having a consistent high blood glucose level can be devastating on the body which can cause complications such as heart disease and stroke, blindness, hypertension, diabetic neuropathy, nerve damage, depression, complications with feet, kidney disease and limb amputation.