A normal fasting blood sugar level is below 100 mg/dL (5.6 mmol/L). That’s the number most people are looking for, but “right” depends on when you last ate, whether you’re pregnant, your age, and whether you’re managing diabetes. Here’s a full breakdown of what the numbers mean in every context that matters.
Fasting Blood Sugar: The Baseline Number
Fasting blood sugar is measured after at least eight hours without food, typically first thing in the morning. For a healthy adult, a reading below 100 mg/dL is normal. Between 100 and 125 mg/dL is considered prediabetes, a warning zone where your body is starting to lose its ability to regulate glucose efficiently. A fasting reading of 126 mg/dL or higher, confirmed on two separate tests, meets the threshold for a diabetes diagnosis.
These cutoffs aren’t arbitrary. They reflect the point at which the risk of complications, particularly damage to blood vessels, the kidneys, and the eyes, begins to climb meaningfully. If your fasting number consistently lands in the prediabetes range, that’s not a diagnosis you’re stuck with. It’s a signal that dietary changes and increased physical activity can still shift the trajectory.
Blood Sugar After Eating
Your blood sugar naturally rises after a meal, peaks around 60 to 90 minutes later, and then gradually returns toward baseline. In a person without diabetes, that post-meal peak rarely exceeds 140 mg/dL, and the level typically drops back below 120 mg/dL within two hours. If your blood sugar is still above 140 mg/dL two hours after eating, that’s a sign your body may not be processing glucose efficiently.
What you eat matters enormously here. A meal heavy in refined carbohydrates (white bread, sugary drinks, white rice) will spike your blood sugar faster and higher than a meal built around protein, fiber, and healthy fats. The total amount of carbohydrate in the meal is the single biggest factor determining how high your post-meal glucose climbs.
Blood Sugar Targets During Pregnancy
Pregnant women are held to tighter targets because high blood sugar during pregnancy can affect fetal development and increase the risk of complications during delivery. The American College of Obstetricians and Gynecologists recommends these goals for women with gestational diabetes or pre-existing diabetes during pregnancy:
- Fasting: below 95 mg/dL
- One hour after eating: below 140 mg/dL
- Two hours after eating: below 120 mg/dL
Notice the fasting target is five points lower than the standard adult cutoff. That tighter window exists because even mildly elevated glucose crosses the placenta and can cause the baby to grow larger than normal, increasing the likelihood of delivery complications. Most women with gestational diabetes can reach these targets through dietary changes alone, though some need medication.
Targets for Children With Type 1 Diabetes
Children managing Type 1 diabetes have slightly wider acceptable ranges to account for the unpredictability of activity levels, eating patterns, and the heightened risk of low blood sugar episodes. UC Davis Children’s Hospital lists starting blood glucose goals of 71 to 180 mg/dL during the daytime and 101 to 200 mg/dL at bedtime, with an A1c goal of 7% for most children. The bedtime range is deliberately higher because blood sugar can drop overnight while a child sleeps and can’t recognize or respond to symptoms.
Readings between 71 and 80 mg/dL are technically safe, but if the trend is downward, treatment with fast-acting carbohydrates is recommended before the level drops to 70 or below.
Relaxed Targets for Older Adults
Adults over 65, especially those managing multiple chronic conditions or cognitive decline, often have more lenient blood sugar goals. The Endocrine Society recommends that diabetes regimens for older adults be designed specifically to minimize low blood sugar episodes, which can cause falls, confusion, and hospitalizations in this age group.
For older adults in hospitals or nursing homes, the recommended fasting target is 100 to 140 mg/dL, and the post-meal target is 140 to 180 mg/dL. These are noticeably higher than standard adult goals. The reasoning is straightforward: in an older person with limited life expectancy or multiple health issues, the immediate danger of a severe low blood sugar episode outweighs the long-term risks of slightly elevated glucose.
When Blood Sugar Drops Too Low
Low blood sugar, or hypoglycemia, is classified in three levels of severity. Level 1 (mild) is a reading between 54 and 69 mg/dL. You might feel shaky, sweaty, or irritable. Level 2 (moderate) is anything below 54 mg/dL, where confusion, blurred vision, and difficulty concentrating become more likely. Level 3 (severe) is defined not by a specific number but by the need for someone else to help you, because your mental or physical state has deteriorated to the point where you can’t treat yourself.
Low blood sugar is most common in people taking insulin or certain oral diabetes medications. If you don’t take these medications, hypoglycemia is uncommon. The standard treatment for a mild or moderate low is 15 grams of fast-acting carbohydrate (four glucose tablets, half a cup of juice, or a tablespoon of honey), followed by rechecking your level after 15 minutes.
What Your A1c Tells You
While a finger-stick reading captures a single moment, the A1c test reflects your average blood sugar over the previous two to three months. It measures the percentage of hemoglobin in your red blood cells that has glucose attached to it. For someone without diabetes, a normal A1c is below 5.7%. Between 5.7% and 6.4% indicates prediabetes, and 6.5% or higher indicates diabetes.
You can translate an A1c percentage into an estimated average glucose using the formula: (28.7 × A1c) minus 46.7. Here’s what that looks like in practice:
- A1c of 6%: average blood sugar of about 126 mg/dL
- A1c of 7%: average blood sugar of about 154 mg/dL
- A1c of 8%: average blood sugar of about 183 mg/dL
- A1c of 9%: average blood sugar of about 212 mg/dL
For most adults managing diabetes, the general target A1c is below 7%, though your specific goal may be higher or lower depending on your age, how long you’ve had diabetes, and what medications you’re taking.
Time in Range: A Newer Way to Measure
If you use a continuous glucose monitor (CGM), the sensor on your arm or abdomen takes a reading every few minutes throughout the day and night. This produces a metric called “time in range,” which measures the percentage of the day your blood sugar stays within your target zone, typically 70 to 180 mg/dL.
The general recommendation is to spend at least 70% of the day in range, which translates to roughly 17 out of 24 hours. This metric captures something A1c can’t: the difference between someone whose blood sugar is stable at 150 mg/dL all day and someone who swings wildly between 50 and 250 mg/dL. Both could have similar A1c results, but the person with stable readings has far fewer dangerous lows and damaging highs. Your personal target may differ based on your specific situation.
Factors That Affect Your Reading’s Accuracy
Even a perfectly functioning glucose meter can give misleading results under certain conditions. Dehydration or anemia (a low red blood cell count) can throw off the accuracy of a finger-stick reading. Substances on your skin, including residue from food, lotion, or hand sanitizer, can contaminate the blood sample. Always wash your hands with soap and water before testing. If you use an alcohol wipe, let the site dry completely before pricking.
Temperature matters too. Extreme heat or cold can degrade test strips and affect the meter’s electronics, so store your supplies at room temperature. Testing on alternate sites like the forearm is sometimes less accurate than fingertip testing, particularly when your blood sugar is changing rapidly, such as right after a meal or during exercise. If a non-fingertip reading seems off, retest with a fingertip sample.