If you're looking at a blood sugar number — your own or a family member's — and trying to figure out what it means, the short answer is: it depends on which number. A fasting reading of 110 mg/dL means something different from a reading of 110 mg/dL taken an hour after lunch, and neither one is the same thing as the number your doctor might set as your personal daily target. This chart lays out the standard ranges so you can see where a result falls, and it explains why a single number — on its own — isn't enough to diagnose anything.
How Fasting and After-Meal Numbers Differ
Blood sugar isn't a fixed number. It moves throughout the day based on when you last ate, what you ate, and how your body is responding to it. The two most common reference points are:
- Fasting blood sugar — measured after at least 8 hours without food, usually first thing in the morning before breakfast. This is your body's baseline, without any recent meal affecting the number.
- After-meal (postprandial) blood sugar — measured after eating. Blood sugar normally rises after a meal as food is digested, typically peaking within the first hour, then coming back down. Clinical testing after a glucose drink checks the level at the 1-hour and 2-hour marks specifically.
Because these two numbers answer different questions — “what's my baseline?” versus “how do I handle a meal?” — they're read against different reference ranges. A fasting number and an after-meal number taken on the same day will almost never match, and that's expected, not a sign something is wrong.
Blood Sugar Levels Chart
The ranges below come from the Centers for Disease Control and Prevention and apply to non-pregnant adults being tested for prediabetes or type 2 diabetes. All values are in milligrams per deciliter (mg/dL) unless noted, and the A1C test is reported as a percentage.
Fasting Blood Sugar Test
Timing: after an overnight fast, before eating. Purpose: screening/diagnosis.
- Normal: 99 mg/dL or below
- Prediabetes: 100–125 mg/dL
- Diabetes: 126 mg/dL or above
A1C Test
Timing: no fasting required; reflects average blood sugar over 2–3 months. Purpose: screening/diagnosis.
- Normal: below 5.7%
- Prediabetes: 5.7%–6.4%
- Diabetes: 6.5% or above
Oral Glucose Tolerance Test (2-Hour Mark)
Timing: fasting baseline, then blood sugar checked 2 hours after drinking a glucose solution. Purpose: screening/diagnosis.
- Normal: 140 mg/dL or below
- Prediabetes: 140–199 mg/dL
- Diabetes: 200 mg/dL or above
Random Blood Sugar Test
Timing: any time of day, no fasting needed. Purpose: diagnosis when symptoms are present.
- Diabetes: 200 mg/dL or above, when paired with symptoms such as increased thirst or urination
Pregnant people are screened for gestational diabetes using separate thresholds and a different testing schedule, usually between 24 and 28 weeks. Those numbers aren't interchangeable with the chart above — if you're pregnant, your clinician will walk you through the specific cutoffs used for that test.
Diagnostic Ranges vs. Your Personal Target — Don't Merge Them
The ranges in the chart above are diagnostic cutoffs. They're population-level thresholds that a lab or clinician uses to answer one specific question: does this result fall in the range associated with normal glucose metabolism, prediabetes, or diabetes? They were set by looking at large groups of people and the long-term health outcomes connected to certain glucose levels — not any one individual's situation.
A personal blood sugar target is a different kind of number. If you've already been diagnosed with diabetes or prediabetes, your doctor may set day-to-day targets that are tailored to you — based on your age, how long you've had diabetes, the medications you take, your risk of low blood sugar (hypoglycemia), and other health conditions. Two people with the same diagnosis can have different personal targets for good clinical reasons.
This distinction matters because the two numbers get confused often. A diagnostic cutoff (like “126 mg/dL or above = diabetes range on a fasting test”) is not the same thing as a treatment target (like “my doctor wants my fasting number under 130 mg/dL because of my other medications”). Using one in place of the other — for example, assuming a diagnostic cutoff is automatically your personal goal — can lead to unnecessary worry or a false sense of reassurance. If you have a specific target number, it should come from your own clinician, not from a general chart.
A Blood Sugar Log to Bring to Your Clinician
A single blood sugar reading, by itself, doesn't diagnose anything — not even when it falls outside the “normal” range. Diagnosis typically requires a confirmed pattern, often using more than one test or a repeat test on a different day. What's genuinely useful is a short log that captures the context around each reading, so a clinician can see the pattern instead of one isolated number. Here's what to track for each entry:
- Date and time of the test — so patterns by day or time of day are visible.
- Test timing — fasting, 1 hour after a meal, 2 hours after a meal, or random/unplanned. Note it exactly, since the same number means different things depending on timing.
- Food context — what you ate or drank before the reading, and roughly how long before. A high post-meal number after a large or carbohydrate-heavy meal reads differently than the same number after a light snack.
- Medicines taken — any diabetes medication, insulin, or other prescriptions that can affect blood sugar, with the time taken relative to the test.
- Symptoms at the time — such as shakiness, excessive thirst, fatigue, or none at all. Symptom-free readings are still worth logging.
- The question to bring to your clinician — write down what you actually want to ask about that reading (for example: “Is this pattern normal for me, or should my fasting number be lower?”). Having the question ready makes the appointment more useful than describing symptoms from memory.
Keeping even a week or two of entries like this turns a list of numbers into something a clinician can actually use — rather than a single value that's easy to misread in either direction.
Reading the Chart, Then Reading It With Your Doctor
Use the chart above to understand what category a number generally falls into and why fasting and after-meal results are evaluated differently. Use the log to capture the context that a number alone can't show. Neither one replaces an actual diagnosis — that still requires a clinician to review your results, confirm them appropriately, and factor in your personal health history. If a reading concerns you, the next step is a conversation with your doctor, log in hand, not a self-diagnosis based on where one number lands on a chart.
For a closer look at how everyday food choices interact with blood sugar day to day, see our guide on using nutrition to support natural blood sugar health. And if you're checking how a packaged food fits into your overall intake, our breakdown of reading added sugar and fiber on a Nutrition Facts label covers the same three-number approach for a single meal.
Educational Disclaimer
This article is for general educational purposes only and is not medical, nutritional, or dietary advice. It does not replace guidance from a registered dietitian or healthcare provider. Refine Nutrition is an independent educational publication and does not sell, endorse, or recommend specific products. Diagnostic ranges cited above are sourced from the CDC and apply to non-pregnant adults; always confirm current, individualized ranges and targets with your own healthcare provider.
Read next