How high does my blood sugar level need to be for damage to occur?

The American Diabetes Association (ADA) recommends an A1C below 7.4, equivalent to a blood sugar level of 166, which is too high. Damage from high blood sugar begins above 100. A study shows that fasting blood glucose between 110 and 125 can destroy 40% of pancreatic beta cells, leading to less insulin and more damage. The ideal A1C is under 5%. To improve your levels, consider reducing refined carbs and sugar, and try intermittent fasting, which may help reverse damage if addressed early.