What is a normal adult blood sugar level?

The normal blood sugar level in an adult who has fasted for 8 to 10 hours is between 70 to 99 mg/dl, according to Lab Tests Online. In an adult who has eaten 2 hours ago, the normal blood sugar level should be less than 140 mg/dl.

If the fasting blood sugar is less than 70 mg/dl, this is known as hypoglycemia. This condition can cause palpitations, sweating, tremors, anxiety, confusion, blurred vision, coma and even death.

If the fasting blood glucose is greater than 126 mg/dl, the person likely has diabetes mellitus, a condition of high blood sugar levels. A fasting blood sugar level between 100 to 125 mg/dl indicates pre-diabetes, which increases the risk of developing diabetes.