A good blood sugar level depends on when you last ate. Fasting (no food for at least 8 hours), a healthy reading is below 100 mg/dL. Two hours after a meal, it should stay below 140 mg/dL. These are the benchmarks for someone without diabetes, but the numbers shift depending on your age, whether you’re pregnant, and whether you’re managing an existing diagnosis.
Fasting Blood Sugar Ranges
A fasting blood sugar test is the most common way to screen for diabetes, and the cutoffs are straightforward:
- Normal: Below 100 mg/dL
- Prediabetes: 100 to 125 mg/dL
- Diabetes: 126 mg/dL or higher on two separate tests
That two-test requirement matters. A single high reading can result from stress, illness, or a poor night of sleep. Diabetes is only diagnosed when elevated fasting glucose shows up consistently. If your result falls in the prediabetes window, your body is already struggling to process sugar efficiently, but the condition is often reversible with changes to diet and activity levels.
After-Meal Blood Sugar Targets
Your blood sugar naturally rises after eating. In a healthy body, it peaks about 60 to 90 minutes after a meal and then drops back down. The key number is where it lands at the two-hour mark: below 140 mg/dL is considered normal for people without diabetes.
If you’re already managing diabetes, the target is more lenient. The CDC sets the post-meal goal at below 180 mg/dL for people with diabetes, measured two hours after the start of the meal. Your care team may personalize this number based on your medications and overall health.
Post-meal spikes above these levels, even when fasting numbers look fine, can be an early sign that your body isn’t producing enough insulin or isn’t using it effectively. This pattern sometimes shows up years before a fasting test catches the problem.
What A1C Tells You
While a finger-stick test captures a single moment, an A1C test reflects your average blood sugar over the previous two to three months. It measures the percentage of your red blood cells that have sugar attached to them, and higher percentages indicate higher average blood sugar.
- Normal: Below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
A1C is useful because it smooths out the day-to-day fluctuations that make single readings unreliable. Someone could have a perfect fasting number on the morning of a test but run high the rest of the time. A1C catches that pattern. It’s also the number most often used to track how well a diabetes treatment plan is working over time.
The Glucose Tolerance Test
If your fasting numbers are borderline, your doctor may order a glucose tolerance test. You drink a sugary solution containing 75 grams of glucose, then have your blood drawn two hours later. The results fall into the same three categories:
- Normal: Below 140 mg/dL at two hours
- Prediabetes (impaired glucose tolerance): 140 to 199 mg/dL
- Diabetes: 200 mg/dL or higher
This test is especially good at catching people whose bodies handle small meals fine but can’t keep up when challenged with a larger sugar load. It’s also the standard screening test during pregnancy.
Blood Sugar Targets During Pregnancy
Pregnancy raises the bar. Because high blood sugar can affect fetal development, the targets are tighter than for the general population. For pregnant women being screened or managed for gestational diabetes, the goals are:
- Fasting: Below 95 mg/dL
- One hour after a meal: Below 140 mg/dL
- Two hours after a meal: Below 120 to 127 mg/dL
Gestational diabetes is diagnosed when two or more glucose measurements from a tolerance test meet or exceed specific thresholds: 95 mg/dL fasting, 180 mg/dL at one hour, 155 mg/dL at two hours, or 140 mg/dL at three hours. Most women who develop gestational diabetes see their blood sugar return to normal after delivery, but the condition does increase the risk of developing type 2 diabetes later in life.
Targets for Children and Teens
For children and adolescents managing type 1 diabetes, international guidelines recommend a before-meal blood sugar between 70 and 144 mg/dL. After meals, the target widens to 70 to 180 mg/dL. The A1C goal is 7% or below for most young people, and 6.5% or below for those using advanced technology like continuous glucose monitors and automated insulin delivery systems, as long as reaching that lower target doesn’t create an undue burden.
For children using continuous monitors, the goal is spending more than 70% of the day in the 70 to 180 mg/dL range. Equally important is minimizing time spent below 70 mg/dL (less than 4% of the day), because low blood sugar poses immediate risks like confusion, shakiness, and loss of consciousness.
Why Targets Differ for Older Adults
Blood sugar targets for people over 65 are often relaxed compared to younger adults, particularly for those managing diabetes. The reason is practical: tighter control requires more aggressive treatment, which raises the risk of dangerously low blood sugar. In older adults, a severe low episode can cause falls, confusion, or cardiac events. For otherwise healthy older adults, standard targets still apply. But for those with multiple chronic conditions or limited life expectancy, providers often aim for an A1C below 8% rather than the standard 7%, prioritizing safety over tight control.
How Accurate Is Your Meter?
Home glucose meters and continuous monitors are useful tools, but they aren’t perfect. FDA standards allow continuous glucose monitors to deviate by up to 15 mg/dL when your blood sugar is below 70, and by up to 15% when it’s between 70 and 180. In practical terms, a reading of 100 mg/dL on your monitor could mean your actual blood sugar is somewhere between 85 and 115.
This margin of error matters most at the boundaries. If your fasting reading is 102 mg/dL, that could genuinely be in the prediabetes range, or it could be a normal reading with a slight upward skew from the device. One reading is a data point. The trend across multiple readings, and especially a lab-drawn A1C, gives you the real picture. If your home numbers are consistently sitting near a threshold, a lab test removes the guesswork.