Maintaining normal blood sugar levels is very important to your overall health. When blood sugar – or blood glucose – levels drop too low it can cause fatigue, lethargy, and difficulty concentrating (1). This is known as hypoglycemia. High blood sugar levels, or hyperglycemia, can result in similar side effects but over time can lead to insulin resistance and type 2 diabetes.
What is Normal Blood Sugar?
Blood sugar levels are measured in milligrams per deciliter (mg/dl) in the United States.
The following numbers are for those that have not been diagnosed with diabetes (2):
Normal fasting blood sugar levels (measurements taken before the first meal of the day) should be 100 mg/dl or less. A blood sugar range of 70-99 mg/dl before meals is considered normal. Two hours after eating, blood sugar levels should be less than 140 mg/dl.
For diabetics, normal blood sugar levels are as follows (3):
If you find your numbers are consistently outside this range, you may wish to speak with your physician to get yourself checked out. Consistently high glucose levels are generally associated with insulin resistance (pre-diabetes) or type 2 diabetes. If your numbers are all over the place (too high and too low), that may be a sign of type 1 diabetes. (4)
Blood sugar spikes are normally associated with diabetes, but the truth is that anyone can experience high glucose levels after consuming a high carbohydrate meal (5). For most people, your body responds by releasing insulin to turn the glucose into energy (6). Individuals with type 1 diabetes are unable to produce insulin, while those with type 2 diabetes are resistant to the insulin produced. Both of these conditions result in hyperglycemia.
Hyperglycemia occurs when blood sugar remains high over time (not just a short-lived spike after a meal). Causes of hyperglycemia include illness, infection, stress, certain medications, or not taking enough insulin.
On the other hand, symptoms of hyperglycemia include fatigue, nausea, vomiting, dry mouth, and increased thirst. Hyperglycemia is confirmed by a blood test if the glucose level measures over 240 mg/dl.