A good fasting blood glucose level is below 100 mg/dL. After eating, your blood sugar should return to below 140 mg/dL within two hours. These two numbers are the most practical benchmarks for healthy glucose, and they apply to most non-pregnant adults.
But “good” depends on context: whether you’ve just eaten, whether you’re pregnant, whether you have diabetes, and even your age. Here’s how to interpret the numbers you’re seeing.
Fasting Blood Sugar Ranges
Fasting blood glucose is measured after at least eight hours without eating, typically first thing in the morning. It’s the most common test used to screen for diabetes and prediabetes.
- 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 automatically mean you have either condition. Diagnosis requires a second confirmatory test, because stress, illness, poor sleep, and even dehydration can temporarily push your numbers up. That said, if your fasting glucose consistently lands above 100 mg/dL, something is shifting in how your body handles sugar, and it’s worth paying attention to.
After-Meal Blood Sugar
Your blood sugar naturally rises after eating. In someone without diabetes, it typically peaks about 60 to 90 minutes after a meal, then drops back down. A good two-hour post-meal reading is below 140 mg/dL. If you have diabetes, the general target is below 180 mg/dL two hours after eating.
The size and composition of your meal matters a lot here. A plate of white rice will spike your glucose faster and higher than a meal built around protein, fiber, and fat. If you’re testing at home and notice post-meal numbers regularly creeping above 140, that pattern is more meaningful than any single reading.
A1C: Your Three-Month Average
While a finger-stick reading captures a single moment, the A1C test reflects your average blood sugar over roughly two to three months. It measures the percentage of your red blood cells that have glucose attached to them. 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
In practical terms, a normal A1C (under 5.7%) corresponds to an estimated average glucose between 70 and 126 mg/dL. Most people with diabetes aim for an A1C below 7%, which translates to an average glucose under about 154 mg/dL. Your doctor may set a different target depending on your age, overall health, and risk of low blood sugar episodes.
When Blood Sugar Drops Too Low
Good glucose isn’t just about avoiding highs. Going too low is dangerous, sometimes more immediately so than running high. Blood sugar below 70 mg/dL is considered low (hypoglycemia) and typically causes shakiness, sweating, confusion, or irritability. Below 54 mg/dL is a more serious drop that can impair your ability to think clearly or function normally. Severe hypoglycemia, where you need someone else’s help to recover, is a medical emergency regardless of the exact number on the meter.
Low blood sugar is most common in people taking insulin or certain oral diabetes medications. If you don’t take these, your body is generally very good at preventing dangerous lows on its own.
Why Morning Readings Run High
If you’ve noticed your fasting numbers are higher than expected even when you ate well the night before, you’re not imagining it. Between roughly 3 and 8 a.m., your body releases hormones like cortisol and growth hormone that signal the liver to pump out extra glucose. This is called the dawn phenomenon, and it gives you energy to wake up. In someone without diabetes, insulin kicks in to keep things balanced. If you have diabetes or insulin resistance, that compensating insulin response falls short, and you wake up with elevated numbers.
A large dinner or bedtime snack can also keep blood sugar elevated through the night. On the flip side, skipping dinner or taking too much insulin in the evening can cause your blood sugar to crash overnight, triggering your body to overcompensate by releasing stored glucose. You then wake up with a puzzlingly high reading despite having been low hours earlier. This rebound pattern is called the Somogyi effect.
Targets During Pregnancy
Pregnancy tightens the targets considerably because even mildly elevated blood sugar affects fetal development. For women with gestational diabetes, the recommended levels are:
- Fasting (before meals): 95 mg/dL or lower
- One hour after eating: 140 mg/dL or lower
- Two hours after eating: 120 mg/dL or lower
Women who had type 1 or type 2 diabetes before becoming pregnant have even tighter goals: fasting glucose between 60 and 99 mg/dL, and peak post-meal readings between 100 and 129 mg/dL. These ranges are narrower than standard diabetes targets because the developing baby is sensitive to glucose fluctuations, particularly in the first trimester.
Adjusted Goals for Older Adults
For older adults with diabetes, especially those managing multiple health conditions, a slightly higher target is often safer than an aggressive one. The real danger shifts: low blood sugar in someone over 65 can cause falls, confusion, and heart problems, and the consequences are harder to recover from.
An A1C under 7% remains the goal for healthy, independent older adults with a life expectancy of more than ten years. But for those who are frail, have cognitive decline, or take medications that increase the risk of lows (like insulin), a target A1C up to 8% or even 8.5% is considered appropriate. The priority becomes avoiding dangerous drops rather than chasing perfect numbers.
Continuous Monitors and Time in Range
If you wear a continuous glucose monitor, the most useful metric isn’t any single number. It’s “time in range,” the percentage of the day your glucose stays between 70 and 180 mg/dL. For most people with type 1 or type 2 diabetes, the goal is spending more than 70% of the day in that window, roughly 17 hours out of 24. Older adults or those at high risk for lows have a more relaxed target of 50% or more.
Time in range captures something that fasting glucose and A1C miss: how much your blood sugar swings throughout the day. Two people can have the same A1C, but one might have steady glucose while the other ricochets between 50 and 250 mg/dL. The person with stable readings is in a meaningfully better position, and time in range reveals that difference.
Glucose Ranges for Children
Normal glucose ranges for children are similar to adults but slightly broader, particularly for very young kids. Children under two typically have a normal range of 60 to 100 mg/dL. By school age and beyond, the adult benchmarks (fasting under 100 mg/dL) generally apply. For children with type 1 diabetes, the same 70 to 180 mg/dL time-in-range target used for adults is now the standard recommendation, replacing older pediatric-specific ranges that allowed higher readings.
Hypoglycemia in children is defined at the same threshold as adults: below 70 mg/dL. Young children are less able to recognize or communicate low blood sugar symptoms, which makes consistent monitoring especially important for kids on insulin.