A normal fasting blood sugar level is below 100 mg/dL (5.6 mmol/L), and a normal reading two hours after eating is below 140 mg/dL (7.8 mmol/L). These are the benchmarks used to distinguish healthy blood sugar from prediabetes and diabetes, though the numbers shift during pregnancy, childhood, and depending on how your blood sugar is being measured.
Fasting Blood Sugar Ranges
Fasting blood sugar is measured after at least eight hours without food, typically first thing in the morning. A result under 100 mg/dL is considered normal. Between 100 and 125 mg/dL falls into the prediabetes range, meaning your body is starting to struggle with blood sugar regulation but hasn’t crossed into diabetes territory. A fasting level of 126 mg/dL or higher, confirmed on two separate tests, meets the diagnostic threshold for diabetes.
These cutoffs aren’t arbitrary. They’re based on the point at which the risk of complications, particularly damage to small blood vessels in the eyes and kidneys, starts climbing meaningfully.
Blood Sugar After Meals
Your blood sugar naturally rises after eating and peaks roughly one to two hours later. In a healthy person, that peak stays below 140 mg/dL (7.8 mmol/L) at the two-hour mark. A reading between 140 and 199 mg/dL two hours after eating suggests prediabetes, and anything at or above 200 mg/dL points to diabetes.
Continuous glucose monitors have given researchers a much clearer picture of what happens between meals in people without diabetes. A 2024 study in The Journal of Clinical Endocrinology & Metabolism tracked glucose around the clock in over 500 healthy adults and found their average blood sugar was about 114.5 mg/dL. They spent roughly 87% of the day in the 70 to 140 mg/dL range. That means even people with perfectly normal metabolic health spend about three hours a day above 140 mg/dL, usually right after meals. Seeing an occasional spike on a glucose monitor doesn’t automatically signal a problem.
A1C: The Bigger Picture
While a finger stick or fasting test captures a single moment, A1C reflects your average blood sugar over the previous two to three months. It measures the percentage of your red blood cells that have glucose attached to them. According to the American Diabetes Association’s 2025 Standards of Care, the ranges break down like this:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
A1C is useful because it smooths out the daily fluctuations that can make individual readings confusing. A single high fasting number could reflect a bad night of sleep or stress, but an elevated A1C means your blood sugar has been running high consistently. Conditions like anemia or recent blood loss can skew A1C results, so your doctor may rely on other tests if those apply to you.
Different Targets During Pregnancy
Pregnancy changes how the body processes sugar, and the thresholds for concern are tighter than for the general population. For women being monitored for gestational diabetes, the recommended targets are a fasting blood sugar below 95 mg/dL, a one-hour post-meal reading below 140 mg/dL, and a two-hour post-meal reading below 120 mg/dL. Post-meal timing starts from the beginning of the meal, not the end.
These stricter numbers exist because even modestly elevated blood sugar during pregnancy can affect fetal growth and increase the risk of complications during delivery. Most pregnant women are screened with a glucose tolerance test between weeks 24 and 28.
Blood Sugar Ranges for Children
Children, especially young ones, have slightly wider acceptable ranges than adults because their eating patterns are less predictable and the risks of blood sugar dropping too low are more immediate. General pediatric targets look like this:
- Under 5 years: 80 to 200 mg/dL
- Ages 5 to 11: 70 to 180 mg/dL
- Ages 12 and up: 70 to 150 mg/dL
These ranges are primarily used for children who are already monitoring their blood sugar due to type 1 diabetes. Healthy children without diabetes rarely need routine blood sugar testing.
How Your Body Keeps Blood Sugar Stable
Blood sugar regulation is a constant balancing act between two hormones produced by the pancreas. When you eat and blood sugar rises, the pancreas releases insulin, which moves glucose out of the bloodstream and into cells where it’s used for energy. When blood sugar drops too low, such as between meals or overnight, the pancreas releases glucagon instead. Glucagon signals the liver to convert its stored glucose back into a usable form and release it into the blood. It also prompts the body to make new glucose from other sources, like proteins.
These two hormones counterbalance each other continuously. In a healthy system, this keeps blood sugar within a remarkably narrow range all day and night. Prediabetes and type 2 diabetes develop when cells gradually stop responding to insulin as efficiently, forcing the pancreas to produce more and more of it until it can no longer keep up.
What Can Throw Off a Reading
If you’re testing at home with a finger-stick meter, several things can affect accuracy. Residue on your hands, especially from food or fruit, can artificially inflate a reading. Wash and dry your hands thoroughly with soap and water before testing. Hand sanitizer or alcohol wipes can also interfere if the skin isn’t completely dry before you prick it.
Dehydration tends to concentrate the sugar in a smaller volume of blood, pushing readings higher than they’d otherwise be. Anemia, or a low red blood cell count, can also distort results. Temperature matters too: test strips stored in humid or very warm environments degrade and become less reliable. Keep your meter and strips at room temperature in their sealed container.
Testing from sites other than the fingertip, like the forearm or palm, can lag behind actual blood sugar levels when glucose is changing quickly, such as right after a meal or during exercise. Fingertip samples are the most reliable for real-time accuracy.