A healthy fasting blood glucose level is 99 mg/dL or below. Two hours after eating, it should stay under 140 mg/dL. These numbers shift depending on whether you’re managing diabetes, pregnant, or older, but those two benchmarks are the standard starting point for most adults.
Normal Blood Glucose Ranges
Blood sugar doesn’t stay at one number all day. It rises after meals and dips during sleep, so the targets depend on when you’re measuring. For people without diabetes, the key thresholds are straightforward:
- Fasting (no food for at least 8 hours): 99 mg/dL or below
- Two hours after a meal: Below 140 mg/dL
If your fasting level lands between 100 and 125 mg/dL, that falls into the prediabetes range. A fasting reading of 126 mg/dL or higher, confirmed on a second test, meets the diagnostic threshold for diabetes. The same pattern applies to post-meal numbers: a two-hour reading between 140 and 199 mg/dL signals prediabetes, while 200 mg/dL or above indicates diabetes.
Targets if You Have Diabetes
If you’re managing Type 1 or Type 2 diabetes, the goal isn’t to match the numbers of someone without diabetes. The CDC recommends these general targets:
- Before a meal: 80 to 130 mg/dL
- Two hours after the start of a meal: Below 180 mg/dL
These ranges are wider than normal because tightly controlling blood sugar with medication increases the risk of dangerous lows. Your specific targets may differ based on your age, how long you’ve had diabetes, and what other health conditions you’re dealing with.
What Your A1C Tells You
While a finger-stick or glucose monitor captures a single moment, an A1C test reflects your average blood sugar over roughly three months. It’s reported as a percentage. Here’s how the categories break down:
- Normal: Below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
You can roughly translate A1C into an average daily glucose number. An A1C of 6% corresponds to an average of about 126 mg/dL. At 7%, the average is around 154 mg/dL. At 8%, it’s roughly 183 mg/dL. The formula behind this conversion is (28.7 × A1C) minus 46.7, which gives you the estimated average glucose in mg/dL. This is useful for connecting a lab result to what you see on your meter day to day.
Blood Sugar Targets During Pregnancy
Pregnancy calls for tighter glucose control because high blood sugar can affect fetal development. The American College of Obstetricians and Gynecologists recommends these goals for pregnant women with diabetes:
- Fasting: Below 95 mg/dL
- One hour after eating: Below 140 mg/dL
- Two hours after eating: Below 120 mg/dL
A1C should stay below 6% during pregnancy. These same targets are often used when screening for and managing gestational diabetes, the type that develops during pregnancy in women who didn’t previously have it.
Adjusted Targets for Older Adults
For older adults with diabetes, the 2025 American Diabetes Association standards set different goals based on overall health. A healthy older adult with few other medical problems can aim for the same general targets as younger adults: fasting glucose of 80 to 130 mg/dL and an A1C below 7.0% to 7.5%.
For someone managing multiple chronic conditions or mild cognitive decline, the fasting target relaxes to 90 to 150 mg/dL, with an A1C goal below 8.0%. For those in poor health or with significant cognitive impairment, the priority shifts away from hitting a specific A1C number entirely. Instead, the focus is on avoiding both dangerously low blood sugar and symptoms of very high blood sugar, with fasting targets of 100 to 180 mg/dL. The reasoning is simple: an aggressive low blood sugar episode can cause falls, confusion, or hospitalization, and those risks outweigh the long-term benefits of tight control in someone with limited life expectancy.
When Blood Sugar Drops Too Low
A reading below 70 mg/dL is considered low blood sugar, or hypoglycemia. This is primarily a concern for people taking insulin or certain diabetes medications, though it can occasionally happen in others. Symptoms tend to come on fast: shakiness, dizziness, hunger, a racing heartbeat, confusion, or irritability. You might also get a headache or find it hard to see or speak clearly.
Very low blood sugar is a medical emergency. If levels keep falling, the brain doesn’t get enough fuel to function normally, which can lead to loss of consciousness or seizures. Low blood sugar during sleep has its own signs, including nightmares, night sweats, and waking up feeling unusually tired or confused. If you check your glucose and it’s below 60 mg/dL, consuming fast-acting sugar (a glass of milk, a few crackers, or glucose tablets) is the standard response.
When Blood Sugar Stays Too High
High blood sugar, or hyperglycemia, often produces no symptoms at all until levels climb above 180 to 200 mg/dL. At that point you might notice increased thirst, frequent urination, blurred vision, or fatigue. A reading above 240 mg/dL, especially with nausea or vomiting, is a situation that requires urgent medical attention because of the risk of a serious complication called diabetic ketoacidosis.
The real danger of high blood sugar, though, is what happens over months and years rather than in a single afternoon. Chronically elevated glucose damages blood vessels and nerves throughout the body. The major long-term consequences include heart disease, kidney damage, nerve pain or numbness in the hands and feet, vision loss from retinal damage, and slow-healing foot wounds that can become severe infections. These complications develop gradually, which is why staying within target ranges consistently matters more than any single reading.
Surprising Things That Affect Your Numbers
Food is the most obvious driver of blood sugar, but plenty of non-food factors push your levels around. Even one night of poor sleep makes your body use insulin less efficiently. Stress of any kind, including something as simple as a sunburn, triggers hormones that raise blood sugar. Dehydration concentrates the glucose in your blood, so your reading can climb just because you haven’t been drinking enough water.
Caffeine affects some people more than others, and it can raise blood sugar even when you drink your coffee black. Skipping breakfast tends to cause higher spikes after lunch and dinner compared to eating a morning meal. There’s also a natural daily rhythm at play: most people experience a hormone surge in the early morning hours (sometimes called the dawn phenomenon) that nudges fasting blood sugar higher than you’d expect. Blood sugar also tends to be harder to control later in the day, so an identical meal at dinner may spike you more than the same meal at lunch.