A normal fasting blood sugar level is below 100 mg/dL (5.6 mmol/L). That single number is the most common benchmark, but “normal” actually depends on when you last ate, whether you’re pregnant, and whether you already have diabetes. Here’s a complete breakdown of what your sugar level should be in every common scenario.
Normal Fasting Blood Sugar
Fasting blood sugar is measured after at least 8 hours without eating, typically first thing in the morning. For a healthy adult without diabetes, the targets look like this:
- Normal: below 100 mg/dL (5.6 mmol/L)
- Prediabetes: 100 to 125 mg/dL (5.6 to 6.9 mmol/L)
- Diabetes: 126 mg/dL (7.0 mmol/L) or higher
If your fasting number lands in the prediabetes range, it means your body is starting to have trouble processing sugar efficiently, but you haven’t crossed the threshold into diabetes. That 100 to 125 mg/dL window is where lifestyle changes like diet and exercise can make the biggest difference.
Blood Sugar After Eating
Your blood sugar naturally rises after a meal. In people without diabetes, it peaks about 60 minutes after eating, rarely goes above 140 mg/dL, and returns to pre-meal levels within two to three hours. If you’re checking your own levels, the two-hour mark is the standard time to test after a meal.
A two-hour post-meal reading below 140 mg/dL is considered normal. A reading between 140 and 199 mg/dL falls into the prediabetes range, and 200 mg/dL or higher points toward diabetes. These post-meal numbers matter because some people have normal fasting levels but spike too high after eating, a pattern that can go undetected without targeted testing.
A1C: Your 3-Month Average
While a finger-stick glucose reading captures a single moment, an A1C test reflects your average blood sugar over the past two to three months. It’s reported as a percentage:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
To put those percentages in practical terms: an A1C of 6% corresponds to an average blood sugar of about 126 mg/dL. At 7%, the average is roughly 154 mg/dL. By 9%, you’re looking at an average around 212 mg/dL. The higher the A1C, the greater the risk of complications affecting your eyes, kidneys, and nerves.
A1C is useful because it’s not thrown off by one good or bad day. You don’t need to fast for it, and it gives your doctor a broader picture of how well your body is managing sugar over time.
Targets If You Already Have Diabetes
If you’ve been diagnosed with diabetes, the goal isn’t necessarily to hit the same numbers as someone without it. The CDC recommends these general targets for adults managing diabetes:
- Before a meal: 80 to 130 mg/dL
- Two hours after starting a meal: below 180 mg/dL
These ranges are wider than “normal” because pushing blood sugar too low can be just as dangerous as letting it run too high. The target your doctor sets for you may be tighter or looser depending on your age, how long you’ve had diabetes, and what other health conditions you’re managing. Older adults and people with a history of severe low blood sugar episodes are often given more relaxed targets to avoid dangerous drops.
Blood Sugar Targets During Pregnancy
Pregnant women are held to stricter standards because high blood sugar poses risks to both mother and baby. Whether you have gestational diabetes or entered pregnancy with an existing diagnosis, the American College of Obstetricians and Gynecologists recommends:
- Fasting: below 95 mg/dL
- One hour after eating: below 140 mg/dL
- Two hours after eating: below 120 mg/dL
Notice the fasting cutoff is 95 mg/dL rather than the usual 100. That tighter window reflects how sensitive fetal development is to glucose levels. Most pregnant women check their blood sugar several times a day to stay within these ranges.
Blood Sugar Ranges for Children
Children with diabetes have slightly different targets than adults, largely because younger kids are less able to recognize or communicate symptoms of low blood sugar. General pediatric ranges are:
- Under 5 years: 80 to 200 mg/dL, with an A1C goal below 8.5%
- Ages 5 to 11: 70 to 180 mg/dL, A1C below 8.0%
- Ages 12 and up: 70 to 150 mg/dL, A1C below 7.5%
The wider range for toddlers exists because a severe low blood sugar episode in a very young child carries more risk than in a teenager who can grab a juice box on their own.
When Blood Sugar Drops Too Low
Blood sugar below 70 mg/dL is considered low, a condition called hypoglycemia. Below 54 mg/dL is classified as severe and can cause you to pass out. Low blood sugar is most common in people taking insulin or certain diabetes medications, but it can also happen after intense exercise, skipping meals, or drinking alcohol on an empty stomach.
Early signs include shakiness, sweating, a fast heartbeat, and feeling irritable or confused. The standard response is to eat or drink 15 grams of fast-acting sugar (about 4 glucose tablets or half a cup of juice), wait 15 minutes, and recheck. If you’re regularly dipping below 70 mg/dL, your medication or eating pattern likely needs adjusting.
When Blood Sugar Is Dangerously High
On the other end, blood sugar that stays above 240 mg/dL is a warning sign, especially if you’re also seeing ketones in your urine. Ketones build up when your body can’t use glucose for energy and starts breaking down fat instead. This can spiral into a life-threatening condition that requires emergency treatment.
Blood sugar above 600 mg/dL represents a different kind of emergency, one where the blood becomes extremely concentrated and thick. This is more common in older adults with type 2 diabetes and can develop over days with symptoms like extreme thirst, frequent urination, confusion, and weakness. Both of these situations require immediate medical attention.
Converting Between Units
If you’re reading glucose numbers from another country or using a meter with unfamiliar units, the two systems you’ll encounter are mg/dL (used in the U.S.) and mmol/L (used in most other countries). The conversion is straightforward: divide mg/dL by 18 to get mmol/L, or multiply mmol/L by 18 to get mg/dL. So a reading of 100 mg/dL equals about 5.6 mmol/L, and 140 mg/dL equals about 7.8 mmol/L.