A good blood sugar level for most adults is below 100 mg/dL when fasting (before eating) and below 140 mg/dL after meals. These are the numbers that indicate your body is processing glucose normally. But “good” changes depending on your situation: whether you’re managing diabetes, pregnant, or older with other health conditions. Here’s what the numbers mean and how to read yours.
Normal Blood Sugar Without Diabetes
If you don’t have diabetes, your body keeps blood sugar in a tight range without much effort. A normal fasting blood sugar, measured after at least eight hours without eating, is 99 mg/dL or below. After a meal, glucose peaks about 60 minutes after you start eating, rarely exceeds 140 mg/dL, and returns to pre-meal levels within two to three hours.
Those two numbers, fasting and post-meal, are the ones most people encounter on lab work or a home glucose meter. If your fasting level falls between 100 and 125 mg/dL, that’s classified as prediabetes. At 126 mg/dL or higher on two separate tests, the diagnosis shifts to type 2 diabetes.
What the Diagnostic Cutoffs Look Like
Doctors use three main tests to assess blood sugar status. Each has its own thresholds for normal, prediabetes, and diabetes:
- Fasting blood glucose: Normal is below 100 mg/dL. Prediabetes is 100 to 125 mg/dL. Diabetes is 126 mg/dL or higher.
- A1C (a blood test reflecting your average over 2 to 3 months): Normal is below 5.7%. Prediabetes is 5.7% to 6.4%. Diabetes is 6.5% or higher.
- Oral glucose tolerance test (measured 2 hours after drinking a sugary solution): Normal is below 140 mg/dL. Prediabetes is 140 to 199 mg/dL. Diabetes is 200 mg/dL or higher.
A random blood sugar of 200 mg/dL or higher, taken at any time of day regardless of meals, also qualifies as a diabetes diagnosis when symptoms are present.
A1C and What It Tells You
A1C measures the percentage of your red blood cells that have glucose attached to them. Because red blood cells live about three months, this test captures your average blood sugar over that window rather than a single snapshot. An A1C of 5% corresponds to an estimated average glucose of about 97 mg/dL. At 6%, that average jumps to roughly 126 mg/dL. By 7%, you’re looking at an average around 154 mg/dL.
For most nonpregnant adults with diabetes, the American Diabetes Association recommends an A1C below 7%. Some people can safely aim lower, closer to the normal range, if they can do so without frequent drops in blood sugar. Others, particularly older adults or those with other serious health conditions, may have a higher target. The number isn’t one-size-fits-all.
Targets If You Have Diabetes
Living with type 1 or type 2 diabetes means your targets are broader than those for someone without the condition. The general goals for most nonpregnant adults with diabetes are a fasting (pre-meal) glucose of 80 to 130 mg/dL and a peak after-meal reading below 180 mg/dL. These numbers aim to prevent long-term complications while keeping the risk of dangerously low blood sugar manageable.
If you wear a continuous glucose monitor (CGM), the key metric is “time in range,” meaning how much of the day your glucose stays between 70 and 180 mg/dL. The goal for most adults is to spend more than 70% of the day in that window, which works out to roughly 17 hours. Time spent below 70 mg/dL should stay under 4% of the day (less than 1 hour), and time below 54 mg/dL should be under 1% (less than 15 minutes). Time above 250 mg/dL should remain under 5%.
When Blood Sugar Drops Too Low
Good blood sugar isn’t just about avoiding highs. Going too low is its own problem, and it can happen quickly. Blood sugar below 70 mg/dL is considered mild hypoglycemia. You might feel shaky, sweaty, lightheaded, or irritable. Below 54 mg/dL is more serious and can cause confusion, blurred vision, or difficulty speaking. Severe hypoglycemia, at any glucose level, means you need someone else’s help to recover because your mental or physical function is impaired.
Hypoglycemia mostly affects people taking insulin or certain diabetes medications, but it can occasionally occur in people without diabetes after prolonged fasting or intense exercise.
Blood Sugar Targets During Pregnancy
Pregnancy tightens the targets significantly because even mildly elevated glucose can affect fetal development. For women with gestational diabetes or pre-existing diabetes, the goals are a fasting glucose below 95 mg/dL, a one-hour post-meal reading below 140 mg/dL, and a two-hour post-meal reading below 120 mg/dL. Women with type 1 or type 2 diabetes also have a lower limit of 70 mg/dL for fasting glucose to avoid hypoglycemia.
These tighter ranges often require more frequent monitoring, sometimes four or more times a day, to catch patterns early.
How Targets Shift for Older Adults
Blood sugar goals relax as people age, especially when other health conditions, cognitive changes, or fall risk enter the picture. A healthy older adult with few other medical issues generally aims for an A1C below 7.5% and a fasting or post-meal glucose of 80 to 130 mg/dL. For someone managing multiple chronic conditions or mild cognitive impairment, the A1C target loosens to below 8%, with glucose goals of 90 to 150 mg/dL. Older adults in poor health or long-term care may aim for an A1C below 8.5% and fasting glucose of 100 to 180 mg/dL.
The reasoning is straightforward: tight blood sugar control carries a real risk of hypoglycemia, and a sudden low in an older adult can trigger a fall, a fracture, or a cardiac event. At a certain point, avoiding lows matters more than chasing perfect numbers.
Why Morning Readings Can Be Higher
If you’ve ever checked your blood sugar first thing in the morning and found it higher than expected, despite not eating overnight, the likely explanation is the dawn phenomenon. Between roughly 4 a.m. and 8 a.m., your body releases hormones that signal your liver to push glucose into the bloodstream, preparing you for the day ahead. In people without diabetes, insulin rises to match. In people with diabetes, that compensation doesn’t happen fully, and fasting readings can creep up.
This doesn’t mean something went wrong overnight. It’s a normal hormonal pattern that becomes visible when insulin production or response is impaired. Eating a balanced evening snack, adjusting medication timing, or shifting exercise to the evening can sometimes help smooth out those morning numbers.
Putting the Numbers Together
A single blood sugar reading is a snapshot. What matters more is the pattern over time. A fasting reading of 105 mg/dL once doesn’t mean prediabetes, but seeing it consistently does. Similarly, a post-meal spike to 160 mg/dL after a large carb-heavy meal is different from regularly landing above 180 mg/dL. If you’re tracking your numbers, pay attention to trends over days and weeks rather than any single reading. Your A1C, which averages everything together over months, is the best single number for understanding where you stand long-term.