What is the normal blood sugar range for a healthy adult?

The normal blood sugar range for a healthy adult is anything below 140mg within one to two hours after a meal, according to WebMD. Less than 100mg after fasting for 8 hours, 70 to 130mg before a meal, and 100 to 140mg at bedtime are all normal blood sugar ranges.

Adults with higher than normal blood glucose levels, but not diabetic levels, are considered to have prediabetes, explains WebMD. Adults with prediabetes are five to six times more likely to develop diabetes in their lifetime. Diet and exercise are strongly recommended to combat the progression of prediabetes and diabetes. Medications are used for diabetes, which cannot be controlled with diet and exercise.