A good fasting blood sugar level for someone without diabetes is 70 to 99 mg/dL. After eating, blood sugar naturally rises but should stay below 140 mg/dL within two hours of a meal. These two numbers give you the clearest snapshot of healthy blood sugar, but the full picture depends on when you’re testing, your age, and whether you’re managing diabetes.
Normal Blood Sugar by Time of Day
Blood sugar isn’t a fixed number. It shifts throughout the day based on what you eat, how active you are, and even your sleep cycle. A healthy range for someone without diabetes breaks down like this:
- Fasting (morning, before eating): 70 to 99 mg/dL
- Two hours after a meal: Less than 140 mg/dL
Some people without diabetes routinely dip to 50 or 60 mg/dL without any symptoms, and that can still be considered normal. The key is whether the number causes problems, not whether it hits a precise target.
In the early morning hours, typically between 3 a.m. and 8 a.m., your body releases cortisol and growth hormone that signal the liver to push out more glucose. This is called the dawn phenomenon, and it’s the reason your fasting reading can be slightly higher if you test right after waking compared to the middle of the night. It happens in everyone, but it’s more noticeable in people with diabetes.
Where Prediabetes and Diabetes Begin
The American Diabetes Association draws clear lines between normal, prediabetes, and diabetes using two main tests: fasting blood glucose and A1C (a measure of your average blood sugar over roughly three months).
- Normal: Fasting glucose below 100 mg/dL, A1C below 5.7%
- Prediabetes: Fasting glucose 100 to 125 mg/dL, A1C 5.7% to 6.4%
- Diabetes: Fasting glucose 126 mg/dL or higher, A1C 6.5% or higher
Prediabetes is the range most people are surprised to learn about. A fasting reading of 105 mg/dL feels close to normal, and you won’t have obvious symptoms, but it signals that your body is already struggling to regulate glucose efficiently. About 80% of people with prediabetes don’t know they have it.
Target Numbers if You Have Diabetes
If you’re managing type 1 or type 2 diabetes, the targets shift upward to balance blood sugar control against the risk of dropping too low. The CDC recommends these general targets for adults with diabetes:
- Before a meal: 80 to 130 mg/dL
- Two hours after starting a meal: Less than 180 mg/dL
These ranges are wider than the numbers for someone without diabetes, and that’s intentional. Tightly controlling blood sugar with medication increases the chance of hypoglycemia (dangerously low blood sugar), which can be more immediately harmful than running slightly high.
What A1C Tells You That a Single Reading Can’t
A finger prick or glucose meter gives you a snapshot of one moment. Your A1C captures the bigger picture by measuring how much glucose has attached to your red blood cells over the previous two to three months. Each percentage point translates to a specific average daily glucose level:
- A1C 5.7%: Estimated average glucose around 117 mg/dL
- A1C 6%: About 126 mg/dL
- A1C 6.5%: About 140 mg/dL
- A1C 7%: About 154 mg/dL
- A1C 8%: About 183 mg/dL
- A1C 9%: About 212 mg/dL
This is why your doctor may not be alarmed by a single high fasting reading but will take an elevated A1C seriously. One bad morning doesn’t define your metabolic health, but a high A1C means your blood sugar has been consistently elevated for weeks or months.
How Age Affects Your Target
For healthy younger and middle-aged adults, the standard ranges above apply. For adults over 65, the targets are often relaxed. The ADA suggests a broader target range of 70 to 180 mg/dL for people older than 65, and some guidelines recommend aiming for blood sugar to be in range at least 50% of the time (compared to a higher threshold for younger adults). The reasoning is straightforward: as you age, the risks of low blood sugar, including falls, confusion, and heart events, can outweigh the long-term benefits of tight control.
When Blood Sugar Gets Dangerous
Below 70 mg/dL is the threshold for hypoglycemia. Early symptoms include shakiness, sweating, a fast heartbeat, and feeling anxious or irritable. As levels drop further, confusion, blurred vision, and loss of consciousness can follow. If you take insulin or certain diabetes medications, this is the number to watch most carefully.
On the high end, blood sugar that stays above 250 to 300 mg/dL can lead to a condition called diabetic ketoacidosis (in type 1 diabetes) or hyperosmolar syndrome (in type 2), both of which are medical emergencies. Persistent readings above 180 mg/dL, even without acute symptoms, cause gradual damage to blood vessels, nerves, kidneys, and eyes over time.
Finger Pricks vs. Continuous Glucose Monitors
If you’re checking your own blood sugar, it helps to know that different devices measure slightly different things. A finger prick meter reads glucose directly from your blood. A continuous glucose monitor (CGM) reads glucose from the fluid surrounding your cells, just beneath the skin. That fluid lags behind your actual blood sugar by 5 to 20 minutes, which matters most when glucose is changing rapidly, like right after a meal or during exercise.
For readings under 100 mg/dL, a CGM should be within 15 mg/dL of a finger prick result. Above 100 mg/dL, expect the CGM to fall within 15% of the meter value. So if your meter reads 180, a CGM showing anywhere from 153 to 207 is performing normally.
Several things can throw off readings from either device. For finger pricks, residue on your hands (even from handling fruit), an insufficient blood drop, or expired test strips can skew results. For CGMs, sleeping on the sensor, the first 24 hours after placing a new sensor, and extreme temperatures can all introduce error. If a reading seems off, washing your hands and retesting with a finger prick is the most reliable way to confirm.
What a “Good” Number Really Means
A single blood sugar reading is useful, but the pattern over time matters far more. Someone whose fasting glucose bounces between 85 and 95 mg/dL with post-meal peaks below 140 has excellent metabolic health. Someone whose fasting numbers creep from 95 to 105 over a few years is heading toward prediabetes, even though each individual reading looks close to normal.
If you’re tracking your own numbers, the most informative readings are fasting (first thing in the morning, before eating) and two hours after your largest meal. Those two data points, repeated over weeks, tell you more than any single test at a doctor’s office. An A1C test every six to twelve months fills in the gaps between daily checks and gives you the clearest measure of whether your blood sugar management is working.