The blood sugar level of an adult diabetic should be between 70 and 130 before eating and below 180 after having a meal, as stated by WebMD. If an adult with diabetes is fasting, the blood sugar level should be less than 100. A normal blood sugar level before bedtime for a diabetic adult is between 100 and 140.
It is important for diabetics to properly manage their blood sugar in order to reduce the chance of developing complications that have a negative impact on nerve, kidney and eye health, as advised by WebMD. Diabetics who properly maintain their blood sugar levels also have a smaller chance of having a stroke and face less of a risk of developing heart disease.