A good blood sugar reading depends on when you last ate and whether you’re managing diabetes, but for most healthy adults, the target is below 100 mg/dL when fasting and below 140 mg/dL two hours after a meal. These numbers shift if you have diabetes, are pregnant, or are older, so understanding the full picture helps you make sense of any reading you get.
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 people without diabetes, a normal fasting reading is 99 mg/dL or below. Once you cross into the 100 to 125 mg/dL range, that’s considered prediabetes. A fasting level of 126 mg/dL or higher on two separate tests meets the diagnostic threshold for type 2 diabetes.
These cutoffs matter because the jump from normal to prediabetes is where your body starts losing its ability to process sugar efficiently. Roughly 1 in 3 American adults falls into the prediabetes range, and most don’t know it. A single fasting test can flag the problem years before full diabetes develops.
Blood Sugar After Eating
Your blood sugar naturally rises after a meal, peaks around one hour later, and then gradually drops back down. For someone without diabetes, a reading taken two hours after eating should be below 140 mg/dL. If it’s consistently above that, it may signal that your body isn’t clearing sugar from the bloodstream the way it should.
The size and composition of your meal affects the peak. A plate of white rice will spike your blood sugar faster and higher than a meal built around protein, fiber, and healthy fats. This is why two people with identical fasting numbers can have very different post-meal patterns.
Targets if You Have Diabetes
If you’ve been diagnosed with diabetes, the goalposts are wider. The CDC recommends aiming for 80 to 130 mg/dL before meals and less than 180 mg/dL two hours after starting a meal. These ranges reflect the reality that tighter control increases the risk of blood sugar dropping too low, which can be dangerous.
Your specific targets may differ based on your age, how long you’ve had diabetes, and what medications you take. For adults 65 and older, guidelines generally recommend more lenient targets to reduce the chance of hypoglycemia, which is especially risky in older adults because it can cause falls, confusion, and heart problems. In hospital or nursing home settings, the recommended fasting range for older adults with diabetes is 100 to 140 mg/dL, with post-meal readings of 140 to 180 mg/dL.
Blood Sugar During Pregnancy
Pregnancy tightens the acceptable ranges significantly because high blood sugar affects fetal development. The American College of Obstetricians and Gynecologists recommends these targets for pregnant women managing diabetes:
- Fasting: below 95 mg/dL
- One hour after eating: below 140 mg/dL
- Two hours after eating: below 120 mg/dL
These tighter windows apply whether you had diabetes before pregnancy or developed gestational diabetes during it. Most women check their blood sugar four or more times a day to stay within range.
What A1C Tells You
While a finger stick or glucose monitor gives you a snapshot, an A1C test shows 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. A normal A1C is below 5.7%. Between 5.7% and 6.4% indicates prediabetes, and 6.5% or higher means diabetes.
To translate A1C into daily numbers: an A1C of 7% corresponds to an average blood sugar of about 154 mg/dL, while an A1C of 9% corresponds to roughly 212 mg/dL. For most people managing diabetes, an A1C of 7% or below is a common goal, though your target may be higher or lower depending on your situation.
When Blood Sugar Gets Dangerously Low or High
Blood sugar below 70 mg/dL is considered low, a condition called hypoglycemia. Symptoms include shakiness, sweating, confusion, and irritability. This is most common in people taking insulin or certain diabetes medications, and it requires quick treatment with fast-acting sugar like juice or glucose tablets.
On the high end, readings above 240 mg/dL are a warning sign. At that level, the body may start producing ketones, acidic byproducts that can build up in the blood and become life-threatening. If your reading is 240 mg/dL or above, checking for ketones with a urine test kit is an important next step.
Why Morning Readings Can Run High
If you notice your blood sugar is higher when you wake up than when you went to bed, you’re not alone. This is usually caused by the dawn phenomenon: between roughly 3 and 8 a.m., your body releases hormones like cortisol and growth hormone that signal your liver to push out more glucose. This natural surge gives you energy to wake up. In people without diabetes, insulin rises to match it. In people with diabetes, insulin can’t keep pace, leaving morning readings elevated.
A less common cause is the Somogyi effect, where blood sugar drops too low overnight (from skipping dinner or taking too much insulin in the evening) and the body overcompensates by flooding the bloodstream with glucose. The result looks the same on your morning reading, but the cause and fix are different. Checking your blood sugar at 2 or 3 a.m. for a few nights can help you and your care team figure out which pattern is at play.
Time in Range for Continuous Monitors
If you use a continuous glucose monitor, “time in range” is becoming just as important as any single reading. This metric tracks what percentage of the day your blood sugar stays between 70 and 180 mg/dL. The general recommendation is to spend at least 70% of your day in this range, which works out to about 17 hours out of 24. This gives a much richer picture than isolated finger sticks because it captures the highs, lows, and everything in between across your entire day and night.