A good fasting blood sugar for most adults is below 100 mg/dL. After eating, blood sugar typically rises but should stay under 140 mg/dL in a healthy person within two hours. These numbers shift depending on whether you’re managing diabetes, pregnant, or checking a child’s levels, so the full picture matters.
Normal, Prediabetes, and Diabetes Ranges
Blood sugar is categorized into three tiers based on a fasting test, meaning you haven’t eaten for at least eight hours. The American Diabetes Association defines them this way:
- Normal: below 100 mg/dL
- Prediabetes: 100 to 125 mg/dL
- Diabetes: 126 mg/dL or higher
A single reading in the prediabetes or diabetes range doesn’t lock in a diagnosis. The test is usually repeated on a separate day to confirm. Your doctor may also order a glucose tolerance test, where you drink a sugary liquid and have blood drawn two hours later. On that test, normal is below 140 mg/dL, prediabetes falls between 140 and 199, and 200 or higher indicates diabetes.
Blood Sugar After Meals
Food sends blood sugar upward, peaking roughly 60 to 90 minutes after you start eating. In a person without diabetes, levels usually return to their pre-meal baseline within two to three hours. If you’re monitoring at home, the general target is below 140 mg/dL at the two-hour mark.
For people already living with diabetes, the CDC recommends keeping post-meal readings below 180 mg/dL two hours after eating. That ceiling is higher because tighter targets can increase the risk of blood sugar dropping too low, especially for those on insulin. Your individual target may be stricter or more relaxed depending on your health history and medications.
What A1C Tells You
A1C (also written HbA1c) reflects your average blood sugar over roughly three months. It’s reported as a percentage, and each point translates to a concrete daily average. An A1C of 6% corresponds to an average blood sugar of about 126 mg/dL. At 7%, that average climbs to 154 mg/dL. By 9%, the daily average sits around 212 mg/dL.
The diagnostic cutoffs mirror the fasting test tiers:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
Most people with diabetes aim for an A1C below 7%, which keeps the average blood sugar under about 154 mg/dL. That target is associated with fewer long-term complications affecting the eyes, kidneys, and nerves. Some people, particularly those with a long history of diabetes, a high risk of low blood sugar episodes, or other serious health conditions, may be given a more relaxed target closer to 8%.
Time in Range for CGM Users
If you wear a continuous glucose monitor, you’ll see a metric called Time in Range (TIR). This is the percentage of the day your blood sugar stays between 70 and 180 mg/dL. For most adults with Type 1 or Type 2 diabetes, the goal is to spend at least 70% of the day in that window. That works out to roughly 17 hours.
The remaining targets help flag dangerous extremes. You want less than 4% of readings between 54 and 69 mg/dL (mildly low), less than 1% below 54 mg/dL (dangerously low), less than 25% between 181 and 250 mg/dL (moderately high), and less than 5% above 250 mg/dL (very high). These percentages give a more complete picture than a single fasting number because they capture how stable your blood sugar stays throughout the day, including overnight and after meals.
Targets During Pregnancy
Pregnancy tightens the acceptable ranges significantly. Both the American College of Obstetricians and Gynecologists and the American Diabetes Association recommend a fasting blood sugar below 95 mg/dL for women with gestational diabetes. One hour after the start of a meal, the target is below 140 mg/dL. If checking at two hours instead, the goal drops to below 120 mg/dL.
These tighter numbers exist because elevated blood sugar during pregnancy can affect the baby’s growth and increase the risk of delivery complications. Most women with gestational diabetes check their blood sugar four times a day: once fasting in the morning and once after each main meal.
Ranges for Children
Children, particularly young ones, have slightly wider target ranges because their eating patterns are unpredictable and low blood sugar episodes can be harder to recognize. Target ranges by age, used in pediatric diabetes care:
- 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
As children get older and more capable of recognizing and communicating symptoms of low blood sugar, the window narrows to match adult targets.
Why Targets Vary From Person to Person
There’s no single “good” range that applies to everyone. The American Diabetes Association lists several factors that shift the target: how long you’ve had diabetes, your age and life expectancy, whether you have cardiovascular disease or other complications, and whether you’ve experienced hypoglycemia unawareness (the inability to feel when blood sugar drops too low). Someone who frequently has dangerous lows may need a higher floor, while a newly diagnosed 35-year-old with no complications might aim for tighter control.
What stays consistent across all groups is the direction. Keeping blood sugar as close to the normal range as is safely achievable reduces the risk of damage to blood vessels, nerves, and organs over time. The specific numbers are simply calibrated to balance that benefit against the real-world risk of going too low.
How to Read Your Results
If you’re testing at home with a finger-stick meter, keep in mind that home glucometers are allowed a margin of error of about 15%. A reading of 105 mg/dL could mean your actual level is anywhere from roughly 89 to 121. One elevated reading after a large meal or a stressful day doesn’t necessarily signal a problem. Patterns matter more than individual numbers.
Track your readings across several days, noting the time and what you ate. Fasting numbers consistently above 100 mg/dL or post-meal numbers regularly above 140 mg/dL (or 180 if you have diabetes) are worth discussing with a healthcare provider. Bringing a log of your readings, rather than recalling a few numbers from memory, makes those conversations far more productive.