For a healthy adult without diabetes, the ideal fasting glucose level is below 100 mg/dL (5.6 mmol/L). After eating, blood sugar naturally rises but should drop back below 140 mg/dL within two hours. These numbers serve as the baseline, but “ideal” shifts depending on whether you’re managing diabetes, pregnant, or monitoring glucose continuously throughout the day.
Fasting Blood Sugar Targets
Fasting blood sugar is measured after at least eight hours without food, typically first thing in the morning. Below 100 mg/dL is considered normal. Once fasting glucose consistently lands between 100 and 125 mg/dL, it falls into the prediabetes range, signaling that your body is starting to struggle with blood sugar regulation. A fasting reading of 126 mg/dL or higher on two separate tests meets the diagnostic threshold for diabetes.
If you’re already managing diabetes, the target is slightly wider. The American Diabetes Association’s 2026 Standards of Care recommend a pre-meal glucose of 80 to 130 mg/dL for most nonpregnant adults. That range accounts for the reality that tighter control increases the risk of blood sugar dropping too low, which carries its own dangers.
After-Meal Glucose Levels
Blood sugar peaks roughly 60 to 90 minutes after you start eating. In someone without diabetes, it rarely exceeds 140 mg/dL before settling back down. For people with diabetes, the widely used clinical target is below 180 mg/dL two hours after a meal. That number might seem high compared to healthy levels, but it balances effective blood sugar control against the risk of hypoglycemia from aggressive treatment.
What you eat matters enormously. Refined carbohydrates and sugary drinks cause sharp spikes, while meals with fiber, protein, and fat produce a slower, more gradual rise. A post-meal walk, even just 10 to 15 minutes, can meaningfully blunt the spike by helping your muscles pull glucose from the bloodstream.
A1C: The Bigger Picture
A single blood sugar reading is a snapshot. Your A1C (also written HbA1c) gives you the longer view, reflecting your average blood sugar over the previous two to three months. It works by measuring how much sugar has attached to your red blood cells.
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or above
For most adults managing diabetes, an A1C below 7% is the standard goal. Some people with otherwise good health and a low risk of blood sugar crashes may aim tighter, below 6.5%. Others, particularly older adults dealing with multiple health conditions or cognitive decline, may be better served by a less aggressive target where the risks of tight control outweigh the benefits.
Continuous Glucose Monitors and Time in Range
Continuous glucose monitors (CGMs) have changed how many people think about blood sugar. Instead of checking a few times a day with finger sticks, a small sensor tracks glucose levels every few minutes. This produces a stream of data that introduces a newer metric: time in range.
The target range for most people is 70 to 180 mg/dL. The goal is to spend at least 70% of the day within that window, roughly 17 out of 24 hours. Equally important is minimizing time below range. Glucose under 70 mg/dL is considered level 1 hypoglycemia, and below 54 mg/dL is level 2, a more serious drop that needs immediate attention. Current guidelines recommend spending less than 4% of the day below 70, and less than 1% below 54.
On the high end, spending less than 25% of the day above 180 mg/dL and less than 5% above 250 mg/dL are the benchmarks. Another useful CGM metric is glucose variability, measured as the coefficient of variation. Keeping that at 36% or below indicates relatively stable blood sugar without large swings throughout the day. Big swings, even if your average looks fine, can signal room for improvement in how you’re eating or timing your meals.
Glucose Targets During Pregnancy
Pregnancy tightens the targets considerably. Elevated blood sugar during pregnancy increases the risk of preeclampsia, preterm delivery, and the baby growing too large for safe delivery. For women with gestational diabetes, the fasting glucose threshold is around 92 mg/dL, and some evidence suggests that readings consistently above that level in the first trimester predict higher rates of complications.
After meals, one hour post-meal glucose below 140 mg/dL appears to strike the best balance. Research comparing different targets found that aiming for below 140 at one hour significantly reduced the chance of an oversized baby without increasing preterm delivery risk. Pushing for a more aggressive target of below 120 mg/dL at one hour actually increased preterm birth rates without meaningful improvement in other outcomes. The A1C goal during pregnancy is typically around 6%, tighter than the standard 7% target for nonpregnant adults.
When Levels Get Dangerous
Low blood sugar tends to cause symptoms faster than high blood sugar. Below 70 mg/dL, you may notice shakiness, sweating, confusion, or a racing heartbeat. Below 54 mg/dL, the situation becomes more urgent, and severe drops can cause seizures or loss of consciousness. People taking insulin or certain diabetes medications face the highest risk of lows, particularly overnight or after exercise.
High blood sugar builds damage more slowly but causes more harm over time. Persistent readings above 180 mg/dL contribute to long-term complications affecting the eyes, kidneys, nerves, and cardiovascular system. Glucose above 240 mg/dL warrants prompt medical attention, especially if you’re feeling symptoms like excessive thirst, frequent urination, or blurred vision. At very high levels (above 250), your body may start breaking down fat for fuel in a way that produces dangerous acids in the blood, a condition called diabetic ketoacidosis.
Exercise and Blood Sugar
Physical activity generally lowers blood sugar by increasing how much glucose your muscles absorb. For people managing diabetes, checking levels after a workout is useful. A post-exercise reading around 90 mg/dL is a reasonable target. Keep in mind that intense bursts of exercise, like sprints or high-intensity interval training, can temporarily raise blood sugar due to stress hormones. This is normal and typically resolves within an hour or two.
The more consistent your exercise routine, the more predictable your blood sugar response becomes. Over weeks and months, regular physical activity improves your body’s sensitivity to insulin, which tends to lower fasting glucose and A1C independent of any changes to diet or medication.