A fasting blood sugar below 100 mg/dL is considered normal for adults without diabetes. That single number is the most common benchmark, but “good” blood sugar depends on when you last ate, whether you have diabetes, your age, and whether you’re pregnant. Here’s how to interpret the numbers across every common scenario.
Normal Fasting Blood Sugar
Fasting blood sugar is measured after at least eight hours without eating, typically first thing in the morning. For a healthy adult, the normal range is below 100 mg/dL (5.6 mmol/L). 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 on two separate tests indicates diabetes.
These thresholds aren’t arbitrary cutoffs. They reflect the point at which your body starts having measurable trouble processing sugar, and the risk of complications begins to climb. A fasting level in the low-to-mid 80s is common in healthy adults, though anything under 100 is perfectly fine.
Blood Sugar After Eating
Your blood sugar naturally rises after a meal, peaking about 60 to 90 minutes later and then gradually dropping. In someone without diabetes, post-meal blood sugar rarely exceeds 140 mg/dL and returns to baseline within a couple of hours. For people managing diabetes, the general target is below 180 mg/dL two hours after starting a meal, with a pre-meal target of 80 to 130 mg/dL.
These post-meal numbers matter because consistently high spikes, even if your fasting levels look fine, can signal early insulin resistance. If you’re monitoring at home, checking two hours after your first bite gives you the most useful reading.
What Your A1C Tells You
While a finger-stick reading captures a single moment, the A1C test reflects your average blood sugar over the past two to three months. It’s reported as a percentage. Normal is below 5.7%, prediabetes falls between 5.7% and 6.4%, and 6.5% or above indicates diabetes.
Each percentage point translates to a meaningful difference in daily blood sugar levels:
- A1C of 5%: average blood sugar around 97 mg/dL
- A1C of 6%: average around 126 mg/dL
- A1C of 7%: average around 154 mg/dL
- A1C of 8%: average around 183 mg/dL
For most adults with diabetes, keeping A1C below 7% is the standard goal. That corresponds to an average blood sugar of roughly 154 mg/dL, a level that significantly reduces the risk of complications affecting the eyes, kidneys, and nerves.
When Blood Sugar Is Too Low
Good blood sugar isn’t just about avoiding highs. A reading below 70 mg/dL is considered low, and below 54 mg/dL is classified as severely low. Symptoms include shakiness, sweating, confusion, and irritability. Severe episodes can cause seizures or loss of consciousness.
Low blood sugar is most common in people taking insulin or certain oral diabetes medications. If you don’t take these medications, true hypoglycemia is rare. Feeling lightheaded before lunch isn’t the same thing as a clinically low reading.
Targets During Pregnancy
Pregnancy tightens the window for good blood sugar considerably. Whether you had diabetes before becoming pregnant or develop gestational diabetes, the targets are stricter than standard adult goals because even moderately elevated blood sugar can affect fetal development.
The recommended targets during pregnancy are a fasting level below 95 mg/dL, below 140 mg/dL one hour after eating, and below 120 mg/dL at the two-hour mark. The A1C goal drops to below 6%, which is lower than the usual 7% target, partly because red blood cell turnover increases during pregnancy and naturally shifts A1C readings downward.
How Targets Change With Age
Blood sugar goals aren’t one-size-fits-all, especially at the extremes of age. For children and adolescents with diabetes, the 2025 American Diabetes Association guidelines now recommend an A1C below 6.5%, tighter than previous recommendations. The reasoning is that younger bodies tolerate tighter control well and benefit from decades of lower blood sugar levels.
Older adults get more flexibility. A healthy older person with few other medical conditions can aim for an A1C below 7% to 7.5%. But for someone who is frail, has multiple chronic conditions, or is at high risk for dangerous low blood sugar episodes, a target of below 8% is often more appropriate. The priority shifts from perfect numbers to avoiding the immediate danger of hypoglycemia, which can cause falls, confusion, and hospitalizations in older adults.
Time in Range: A Newer Way to Measure
If you use a continuous glucose monitor (a small sensor worn on your skin that tracks blood sugar around the clock), you’ll encounter a metric called “time in range.” Instead of focusing on individual readings, this tells you what percentage of the day your blood sugar stays within a target zone.
For most adults with Type 1 or Type 2 diabetes, the goal is spending at least 70% of the day between 70 and 180 mg/dL. That works out to roughly 17 hours a day in range. For people at higher risk for low blood sugar, the goal relaxes to at least 50%. During pregnancy with Type 1 diabetes, the target range narrows to 63 to 140 mg/dL, with at least 70% of readings falling within that window.
Time in range is useful because it captures the full picture of daily fluctuations. Two people can have the same A1C but very different day-to-day patterns. One might have stable readings hovering around 150 mg/dL, while the other swings between 60 and 250 mg/dL. Time in range reveals those swings in a way that a single average number cannot.
Quick Reference: Blood Sugar Targets at a Glance
- Normal fasting (no diabetes): below 100 mg/dL
- Prediabetes fasting: 100 to 125 mg/dL
- Diabetes fasting: 126 mg/dL or higher
- Before meals (with diabetes): 80 to 130 mg/dL
- Two hours after eating (with diabetes): below 180 mg/dL
- A1C, normal: below 5.7%
- A1C, prediabetes: 5.7% to 6.4%
- A1C, diabetes diagnosis: 6.5% or above
- A1C goal for most adults with diabetes: below 7%
- Low blood sugar: below 70 mg/dL
- Severely low blood sugar: below 54 mg/dL