What is Normal Blood Sugar?
Normal Fasting Blood Sugar
A truly normal fasting blood sugar (which is also the blood sugar a normal person will see right before a meal) is between 70 mg/dl (3.9 mmol/L) and 92 mg/dl (5.0 mmol/L) .
Doctors consider any fasting blood sugar between 70 mg/dl (3.9 mg/dl) and 100 mg/dl (5.5 mmol/L) to be normal. But several studies suggest that people whose fasting blood sugar is over 92 mg/dl (5.1 mmol/L) are more likely to be diagnosed with diabetes over the next decade.
What is an Abnormally Low Blood Sugar?
Blood sugars under 70 mg/dl (3.9 mmol/L) are considered to be hypoglycemic. However, if you are not on insulin or a drug that causes your pancreas to secrete insulin, a blood sugar slightly below this range, while it might be uncomfortable, is not dangerous unless there is evidence that it is continuing to drop.
The dangerous levels of low blood sugar–the hypos that require a visit to the ER–are those in the 40 mg/dl (2.2 mmol/L) range and lower. At those levels unconsciousness and brain damage can occur.
Post-Meal Blood Sugar (Postprandial)
Independent of what they eat, the blood sugar of a truly normal person is under 120 mg/dl (6.6 mmol/L) one or two hours after a meal.
Most normal people are under 100 mg/dl (5.5 mmol/L) two hours after eating.