A good blood sugar range for most healthy adults is under 100 mg/dL when fasting and under 140 mg/dL two hours after eating. Those two numbers are the benchmarks doctors use to define normal glucose metabolism. If you already have diabetes, your targets are different, and if you’re pregnant, they’re tighter still. Here’s how to make sense of all the numbers.
Normal Blood Sugar for Healthy Adults
If you don’t have diabetes, your body keeps blood sugar in a remarkably narrow band. A normal fasting level, measured after at least eight hours without food, is below 100 mg/dL (5.6 mmol/L). After a meal, blood sugar rises as your body absorbs carbohydrates, then insulin brings it back down. Two hours after eating, a healthy reading is below 140 mg/dL.
In practice, most people without diabetes hover between roughly 70 and 100 mg/dL throughout the fasting period, with brief spikes after meals that rarely exceed 140. If your numbers consistently fall in this window, your blood sugar regulation is working as it should.
Where Prediabetes and Diabetes Begin
The American Diabetes Association draws clear diagnostic lines. Prediabetes is diagnosed when fasting blood sugar lands between 100 and 125 mg/dL, or when A1C (a measure of your average blood sugar over roughly three months) falls between 5.7% and 6.4%. These numbers mean your body is starting to struggle with glucose regulation but hasn’t crossed into diabetes territory yet.
Diabetes is diagnosed at a fasting blood sugar of 126 mg/dL or higher, or an A1C of 6.5% or above. These thresholds aren’t arbitrary. They correspond to the glucose levels where the risk of complications to your eyes, kidneys, and nerves begins to climb significantly. A single elevated reading isn’t enough for a diagnosis; your doctor will typically confirm with a repeat test.
Targets if You Have Diabetes
Once you have a diabetes diagnosis, the goal shifts from “normal” to “well-managed.” The ADA recommends these targets for most nonpregnant adults with diabetes:
- Before meals: 80 to 130 mg/dL
- One to two hours after starting a meal: below 180 mg/dL
- A1C: below 7%, which translates to an estimated average glucose of about 154 mg/dL
These targets are looser than the “normal” range for a reason. Pushing blood sugar too aggressively toward non-diabetic levels can increase the risk of dangerous lows, especially if you take insulin. That tradeoff matters more as you get older or if you have other health conditions. For older adults or people with a long history of diabetes, doctors often set slightly higher targets to prioritize safety over tight control. Your specific numbers should reflect your age, how long you’ve had diabetes, and whether you’ve experienced episodes of low blood sugar.
What A1C Tells You That a Single Reading Can’t
A finger stick or fasting blood draw captures one moment. A1C captures the bigger picture by reflecting your average blood sugar over the previous two to three months. The conversion is straightforward: an A1C of 6% corresponds to an average glucose of about 126 mg/dL, 7% maps to 154 mg/dL, 8% to 183 mg/dL, and 9% to 212 mg/dL. Each half-point increase in A1C adds roughly 14 mg/dL to your estimated average.
This is useful because blood sugar swings throughout the day. You could have a perfect fasting number in the morning but run high after every dinner. A1C catches that pattern even when individual readings look fine.
Blood Sugar Targets During Pregnancy
Pregnancy tightens the acceptable range considerably. The American College of Obstetricians and Gynecologists recommends these goals for pregnant women managing diabetes:
- Fasting: below 95 mg/dL
- One hour after eating: below 140 mg/dL
- Two hours after eating: below 120 mg/dL
These stricter numbers reflect the fact that elevated blood sugar during pregnancy affects the baby’s growth and increases the risk of complications during delivery. Frequent monitoring, often four or more checks per day, is standard for pregnant women with gestational or pre-existing diabetes.
Using a Continuous Glucose Monitor
If you wear a continuous glucose monitor (CGM), you’ll encounter a metric called Time in Range, or TIR. For most adults with Type 1 or Type 2 diabetes, the target range is 70 to 180 mg/dL, and the goal is to spend at least 70% of the day within that window. That works out to roughly 17 hours out of every 24.
TIR is helpful because it captures variability. Two people can have the same A1C, but one might achieve it with steady, moderate glucose levels while the other swings wildly between highs and lows. A high TIR percentage means your blood sugar stays more stable throughout the day, which is associated with better outcomes and fewer symptoms.
When Blood Sugar Drops Too Low
Low blood sugar (hypoglycemia) is the flip side of good glucose control, and it’s mainly a concern for people who take insulin or certain diabetes medications. The ADA classifies it in levels:
- Level 1: between 54 and 69 mg/dL. You may feel shaky, sweaty, or hungry. This can usually be corrected by eating a fast-acting carbohydrate.
- Level 2: below 54 mg/dL. This is clinically significant and requires immediate treatment.
- Level 3: a severe event where you need someone else’s help to recover, regardless of what the number reads.
If you’re exercising and your blood sugar drops to 70 mg/dL or lower, or you feel shaky, weak, dizzy, or confused, stop the activity and treat the low. For people on insulin, checking blood sugar every 30 minutes during exercise can help you spot a downward trend before it becomes dangerous.
Quick Reference by Situation
- Healthy adult, fasting: below 100 mg/dL
- Healthy adult, 2 hours after eating: below 140 mg/dL
- Prediabetes, fasting: 100 to 125 mg/dL
- Diabetes diagnosis, fasting: 126 mg/dL or higher
- Diabetes management, before meals: 80 to 130 mg/dL
- Diabetes management, after meals: below 180 mg/dL
- Pregnancy, fasting: below 95 mg/dL
- CGM target range: 70 to 180 mg/dL, at least 70% of the day
- Low blood sugar alert: below 70 mg/dL