A good fasting blood glucose level is 99 mg/dL or below. After eating, glucose naturally rises but should stay under 140 mg/dL in a healthy body. These numbers shift depending on whether you’re managing diabetes, pregnant, or using a continuous glucose monitor, so the full picture involves several different benchmarks worth knowing.
Normal Glucose Ranges Without Diabetes
For people without diabetes, a normal fasting blood glucose (measured after at least eight hours without eating) is below 100 mg/dL (5.6 mmol/L). This is the most common test used in routine checkups, and it gives a snapshot of how well your body handles glucose overnight when no food is coming in.
After a meal, blood sugar rises as your body digests carbohydrates. In a healthy person, it typically peaks around one hour after eating and returns close to baseline within two to three hours. A reading under 140 mg/dL two hours after a meal is generally considered normal.
Your body keeps glucose in this narrow window through two hormones made by the pancreas. Insulin lowers blood sugar by moving glucose out of the blood and into cells, where it’s used for energy. Glucagon does the opposite: when levels dip too low, it signals the liver to release stored glucose back into the bloodstream. These two hormones continuously counterbalance each other, acting like a thermostat that keeps your blood sugar stable throughout the day.
Prediabetes and Diabetes Thresholds
The line between “normal” and “concerning” is defined by specific cutoffs from the American Diabetes Association. Understanding where you fall helps you know whether your numbers call for lifestyle changes or closer monitoring.
- Normal: Fasting glucose below 100 mg/dL, A1C below 5.7%
- Prediabetes: Fasting glucose 100 to 125 mg/dL, A1C 5.7% to 6.4%
- Diabetes: Fasting glucose 126 mg/dL or higher, A1C 6.5% or higher
A1C is a blood test that reflects your average blood sugar over the previous two to three months rather than a single moment. It’s useful because it captures the bigger picture, including the post-meal spikes and overnight dips that a single fasting test would miss. A fasting glucose reading in the prediabetes range doesn’t mean you have diabetes, but it does mean your body is having a harder time keeping glucose in check.
Targets for People Managing Diabetes
If you’ve been diagnosed with type 1 or type 2 diabetes, the goal isn’t necessarily to match the ranges of someone without diabetes. Instead, the CDC recommends these general targets:
- Before a meal: 80 to 130 mg/dL
- Two hours after starting a meal: Below 180 mg/dL
These targets are deliberately wider than the non-diabetic range. Pushing too aggressively toward “normal” numbers can increase the risk of blood sugar dropping dangerously low, especially for people using insulin. Your specific targets may differ based on your age, how long you’ve had diabetes, and what other health conditions you have.
How Low Is Too Low
Blood sugar below 70 mg/dL is considered low, or hypoglycemic. At this level you may feel shaky, sweaty, dizzy, or suddenly hungry. It’s important to treat it quickly with fast-acting carbohydrates (like juice or glucose tablets) to prevent it from falling further.
Severe hypoglycemia occurs when blood sugar drops so low that you can’t treat it yourself. You may lose consciousness or become unable to eat or drink. This is more common in people taking insulin or certain diabetes medications, and it’s one reason glucose targets for diabetes aren’t set as tightly as those for people without the condition.
Glucose Targets During Pregnancy
Pregnancy tightens the acceptable range because high blood sugar affects fetal development. For women with gestational diabetes, the American Diabetes Association recommends:
- Before a meal: 95 mg/dL or less
- One hour after a meal: 140 mg/dL or less
- Two hours after a meal: 120 mg/dL or less
Notice that the pre-meal target is lower than for non-pregnant adults with diabetes (95 versus 130), and the post-meal window is measured at one hour as well as two. These tighter goals reflect how sensitive fetal growth is to sustained high glucose, particularly in the second and third trimesters.
Time in Range for CGM Users
If you use a continuous glucose monitor, you’re getting readings every few minutes rather than a handful of finger sticks per day. That volume of data introduced a newer metric called “time in range,” or TIR, which measures the percentage of the day your glucose stays between 70 and 180 mg/dL.
An international consensus panel set these benchmarks for most adults with type 1 or type 2 diabetes:
- Time in range (70 to 180 mg/dL): More than 70% of the day, roughly 17 hours
- Time below range (under 70 mg/dL): Less than 4% of the day, under 1 hour
- Time above range (over 180 mg/dL): Less than 25% of the day, under 6 hours
- Time significantly above range (over 250 mg/dL): Less than 5%, under about 1 hour
For older adults or those at higher risk of hypoglycemia, the goals are more relaxed: at least 50% of the day in range (12 hours), with less than 1% below 70 mg/dL. The priority for this group shifts toward avoiding dangerous lows rather than minimizing highs.
Time in range is gaining ground as a practical way to evaluate glucose control because it captures the full daily pattern. Two people can have the same A1C but very different glucose swings. Someone spending 80% of their day in range with gentle fluctuations is in a different situation than someone bouncing between 50 and 250 mg/dL throughout the day, even if the averages come out the same.
Why Targets Vary by Age and Health
Glucose targets aren’t one-size-fits-all. Healthy older adults don’t necessarily need looser targets, but those with limited life expectancy or multiple health conditions often do, because the risks of aggressive treatment (particularly hypoglycemia) can outweigh the long-term benefits of tight control. For young children with diabetes, simplified targets may be used initially to reduce the burden on families and build confidence before tightening goals over time.
As a general guideline, diabetes experts suggest that nonpregnant adults with diabetes aim for at least 70% of their blood sugar readings to fall within their target range. For older adults or people prone to lows, 50% is a more realistic and still meaningful goal. These percentages apply whether you’re checking with finger sticks or wearing a continuous monitor.