A healthy blood sugar level on an empty stomach falls between 70 and 99 mg/dL. After eating, it should stay below 140 mg/dL when measured two hours later. These numbers shift depending on whether you’re fasting, pregnant, managing diabetes, or over 65, so knowing which target applies to you matters.
Normal Fasting Blood Sugar
Fasting blood sugar is measured after you haven’t eaten for at least eight hours, typically first thing in the morning. For someone without diabetes, a normal fasting reading is 70 to 99 mg/dL. Some people naturally run a bit lower, and readings between 50 and 70 mg/dL can still be normal if you feel fine and have no symptoms like shakiness or confusion.
Once your fasting level hits 100 mg/dL or above, it crosses into a different category. A fasting reading of 100 to 125 mg/dL falls in the prediabetes range. At 126 mg/dL or higher on two separate tests, the result meets the threshold for a diabetes diagnosis.
Blood Sugar After Eating
Your blood sugar naturally rises after a meal, peaking somewhere around one to two hours later. For people without diabetes, it should come back down to less than 140 mg/dL by the two-hour mark. If you’re eating a balanced meal, most people won’t notice this rise at all because the body releases insulin quickly to bring levels back to baseline.
A two-hour post-meal reading between 140 and 199 mg/dL suggests prediabetes when measured during a formal glucose tolerance test. A result of 200 mg/dL or higher points to diabetes. If you’re checking at home with a glucose meter, testing about two hours after your first bite gives you the most useful comparison to these standard ranges.
The A1C Test: Your Three-Month Average
While a finger prick captures a single moment, the A1C test reflects your average blood sugar over the past two to three months. It measures the percentage of your red blood cells that have sugar attached to them, giving a broader picture of how your body handles glucose day to day.
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
Your doctor may order an A1C alongside a fasting glucose test. The two results don’t always line up perfectly because they measure different things: one is a snapshot, the other a long-term trend. A borderline result on either test usually leads to repeat testing to confirm.
Targets If You Have Diabetes
If you’ve already been diagnosed with diabetes, your targets are slightly wider than the ranges for someone without it. The CDC recommends most adults with diabetes aim for 80 to 130 mg/dL before meals and less than 180 mg/dL two hours after eating. These targets balance keeping blood sugar controlled while reducing the risk of it dropping too low.
Your personal target may differ. Factors like how long you’ve had diabetes, what medications you take, and whether you experience episodes of low blood sugar all influence where your care team sets the range. The numbers above are a starting point, not a rigid rule.
Targets During Pregnancy
Pregnancy tightens the window considerably. Both the American Diabetes Association and the American College of Obstetricians and Gynecologists recommend that pregnant individuals with gestational diabetes keep fasting blood sugar below 95 mg/dL, one-hour post-meal readings below 140 mg/dL, and two-hour post-meal readings below 120 mg/dL. These stricter targets exist because elevated blood sugar during pregnancy increases the risk of the baby growing larger than normal, which can complicate delivery.
How Targets Change for Older Adults
For adults 65 and older with diabetes, guidelines emphasize avoiding low blood sugar over hitting aggressive targets. Low blood sugar (hypoglycemia) is particularly dangerous for older adults because it raises the risk of falls, confusion, and heart complications. For this reason, the Endocrine Society recommends that glucose goals be more lenient and tailored to overall health rather than following one-size-fits-all numbers.
For older adults in hospitals or nursing facilities, recommended fasting targets are 100 to 140 mg/dL, with post-meal readings of 140 to 180 mg/dL. Outside of those settings, individual goals depend on factors like cognitive function, other health conditions, and what medications are being used. Someone who is otherwise healthy at 68 will have different targets than someone at 82 with memory concerns.
When Blood Sugar Gets Dangerously High
A reading above 240 mg/dL combined with symptoms like nausea, vomiting, fruity-smelling breath, or extreme thirst signals a potentially dangerous situation. At that level, the body may start breaking down fat for fuel and producing toxic byproducts called ketones, which can make the blood dangerously acidic. This is a medical emergency, particularly for people with type 1 diabetes, though it can happen with type 2 as well.
Persistent readings above 180 mg/dL, even without dramatic symptoms, cause damage over time. Elevated blood sugar gradually harms blood vessels and nerves, contributing to complications in the eyes, kidneys, feet, and heart. You won’t necessarily feel different at 200 mg/dL compared to 130 mg/dL on any given day, which is exactly why regular testing matters.
What Affects Your Reading
Blood sugar isn’t static. It fluctuates throughout the day based on what you eat, how active you are, how well you slept, and even your stress level. A high-carbohydrate meal will spike it faster and higher than a meal built around protein, fat, and fiber. Exercise lowers it, sometimes for hours afterward. Illness, poor sleep, and stress hormones push it up.
Timing also matters when you test. A reading taken 30 minutes after eating will almost always be higher than one taken two hours later, even in a perfectly healthy person. If you’re monitoring at home, consistency in when you test gives you the most useful trend. Testing at the same time relative to meals (say, always two hours after dinner) creates a pattern you can actually learn from, rather than a confusing set of numbers that jump around.
Medications, caffeine, and alcohol also influence readings. Caffeine can raise blood sugar slightly in some people. Alcohol can lower it unpredictably, especially on an empty stomach. If a reading surprises you, consider what happened in the hours before you tested rather than reacting to a single number in isolation.