A normal fasting blood sugar is 99 mg/dL or below. That single number is the benchmark most people are looking for, but blood sugar isn’t just one measurement. It shifts throughout the day, rising after meals and dropping during sleep, so understanding what’s normal means knowing the right number for the right moment.
Normal Fasting Blood Sugar
Fasting blood sugar is measured after at least eight hours without eating, typically first thing in the morning. A reading under 100 mg/dL (5.6 mmol/L) is considered normal. This is the most common test used in routine checkups because it gives a clean baseline without the influence of a recent meal.
Once fasting levels creep into the 100 to 125 mg/dL range, that’s classified as prediabetes. A fasting reading of 126 mg/dL or higher, confirmed on a second test, meets the diagnostic threshold for diabetes.
Blood Sugar After Eating
Your blood sugar naturally rises after a meal and typically peaks one to two hours later. For people without diabetes, that peak generally stays below 140 mg/dL and settles back toward baseline within a few hours. You won’t usually see this number on a standard lab report because most routine tests are done fasting, but it matters if you’re monitoring at home or wearing a continuous glucose monitor.
For people managing diabetes, guidelines set the post-meal target at under 180 mg/dL, measured one to two hours after the start of a meal. That’s notably higher than the non-diabetic range because tighter control in some individuals can increase the risk of blood sugar dropping too low.
A1c: The Bigger Picture
While a finger stick or fasting test 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. The higher your blood sugar has been running, the higher the percentage.
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
To put those percentages in concrete terms, the American Diabetes Association uses a conversion formula: multiply the A1c by 28.7, then subtract 46.7. An A1c of 6% translates to an estimated average glucose of about 126 mg/dL. At 7%, it’s roughly 154 mg/dL. By the time A1c reaches 10%, average glucose is around 240 mg/dL.
Targets for People With Diabetes
If you’ve already been diagnosed, your targets are different from the “normal” ranges used for screening. The 2026 Standards of Care from the American Diabetes Association recommend these goals for most nonpregnant adults:
- A1c: below 7%
- Before meals: 80 to 130 mg/dL
- After meals (1 to 2 hours): below 180 mg/dL
Some people can safely aim lower. An A1c under 6.5% may be appropriate if you can reach it without frequent low blood sugar episodes. Others, particularly older adults or those prone to dangerous lows, do better with a more relaxed target. The right goal depends on your overall health, the medications you’re on, and how well you recognize the symptoms of low blood sugar.
If you use a continuous glucose monitor, the key metric is “time in range,” which tracks what percentage of the day your glucose stays between 70 and 180 mg/dL. The recommended goal is above 70% of the day spent in that window, with less than 4% of the day below 70 mg/dL.
What Low Blood Sugar Feels Like
Blood sugar below 70 mg/dL is considered low, a condition called hypoglycemia. Below 54 mg/dL is severe. Low blood sugar is most common in people taking insulin or certain diabetes medications, but it can occasionally happen in people without diabetes after prolonged fasting or intense exercise.
Early symptoms include a fast heartbeat, shaking, sweating, sudden hunger, dizziness, and feeling anxious or irritable. As levels drop further, you may feel weak, have trouble seeing clearly, become confused, or have difficulty walking. Seizures can occur in severe cases. Eating or drinking something with fast-acting sugar, like juice or glucose tablets, is the standard immediate response.
What High Blood Sugar Feels Like
High blood sugar, or hyperglycemia, often develops gradually and can go unnoticed for a while. The classic symptoms are increased thirst, frequent urination, and fatigue. These tend to appear as blood sugar climbs well above 180 mg/dL and persists there.
At readings above 240 mg/dL, the risk of a dangerous complication called diabetic ketoacidosis increases, particularly in people with type 1 diabetes. At that level, checking for ketones in your urine is important. Sustained high blood sugar over months and years is what drives long-term complications affecting the eyes, kidneys, nerves, and heart.
Targets During Pregnancy
Pregnancy changes the equation significantly. Blood sugar standards are tighter because elevated glucose affects fetal development. Screening for gestational diabetes typically happens between 24 and 28 weeks of pregnancy using a glucose tolerance test.
During the initial one-hour screening, a result below 140 mg/dL is generally considered normal. A reading of 190 mg/dL or higher points directly to gestational diabetes. Results between those two values lead to a follow-up three-hour test, which has its own set of cutoffs: fasting should be 95 mg/dL or lower, one hour below 180 mg/dL, two hours below 155 mg/dL, and three hours below 140 mg/dL. Two or more elevated values on the three-hour test confirm the diagnosis.
How Targets Shift With Age
For children and adolescents with diabetes, the A1c goal is the same as for most adults: below 7%. A more relaxed target of 7.5% or even 8% may be appropriate for young children who can’t yet recognize or communicate symptoms of low blood sugar, or for kids without access to advanced monitoring technology.
At the other end of the age spectrum, older adults face a different calculus. Healthy older adults generally aim for the same targets as younger adults, with an A1c below 7% to 7.5%. But for those dealing with multiple chronic conditions, cognitive decline, frailty, or limited life expectancy, most guidelines relax the target to 8% or even 8.5%. The reasoning is practical: low blood sugar is particularly dangerous in older adults because it increases the risk of falls, fractures, confusion, and cardiovascular events. For someone who is frail, an overly aggressive blood sugar target can cause more harm than the high blood sugar it’s trying to prevent.
Continuous glucose monitoring data supports this individualized approach. For older adults with complex health conditions, spending at least 50% of the day in the 70 to 180 mg/dL range, with less than 1% of the day below 70 mg/dL, is a reasonable goal that prioritizes safety.
Quick Reference: Blood Sugar Ranges
- Normal fasting: under 100 mg/dL
- Prediabetes fasting: 100 to 125 mg/dL
- Diabetes fasting: 126 mg/dL or higher
- Normal after meals (non-diabetic): under 140 mg/dL
- Diabetes target after meals: under 180 mg/dL
- Low blood sugar: below 70 mg/dL
- Severe low blood sugar: below 54 mg/dL
- Normal A1c: below 5.7%
- Diabetes A1c target: below 7% for most adults