The studies you will read below, some of which are not cited in the AACE guidelines, make a cogent case that post-meal blood sugars of 140 mg/dl (7.8 mmol/L) and higher and fasting blood sugars over 100 mg/dl (5.6 mmol/L) when found in association with those higher than normal post-meal blood sugars, cause both permanent organ damage and the worsening of diabetes. Some of this data also suggests that maintaining an A1c of 5.7% to 6% is much safer for people with diabetes who wish to avoid developng diabetic complications.