Use the right table
A glucose target is not a diagnostic cutoff
The first chart supports day-to-day management after diabetes has been diagnosed. The second summarizes laboratory thresholds used to screen for prediabetes or diabetes in nonpregnant adults. Mixing the two creates confusing conclusions. A pre-meal target of 80–130 mg/dL does not mean every fasting laboratory value within that interval is normal for someone being screened.
Likewise, a home reading cannot establish a diagnosis. Laboratory plasma glucose and capillary meter glucose use different sample and testing conditions. If repeated home readings are outside the expected range, record the time, food, medication, activity, and symptoms, then contact a clinician for appropriate assessment.
A1C answers another question by reflecting longer-term glucose exposure. It cannot show today’s current level. Compare longer-term values with our A1C levels guide, or use the A1C-to-eAG chart to understand estimated average glucose.
Timing changes the meaning of a glucose number
A fasting laboratory glucose follows an overnight fast of at least eight hours. A pre-meal home reading may happen before lunch or dinner and can be influenced by the prior meal, activity, medication, stress, or illness. Although both occur before food, they are not automatically the same type of measurement.
For after-meal monitoring, start the clock when the meal begins. Current ADA guidance expresses the target as peak postprandial glucose, generally assessed one to two hours after the start of the meal. Testing at 60 minutes and testing at 120 minutes can produce different numbers because digestion, meal composition, insulin timing, and individual physiology affect when glucose peaks.
A bedtime value has no single universal target for every adult. The appropriate range depends on the treatment plan, recent food and activity, medication, overnight-low risk, and whether a CGM alert or follow-up check is planned. That is why this page does not present a generic “normal bedtime” number as though it applied to everyone.
Before testing
Wash and fully dry hands. Confirm strips match the meter and are stored correctly.
At the reading
Record time, relation to the meal, medication or insulin, activity, and symptoms.
After testing
Repeat an unexpected result according to device instructions and use your safety plan when needed.
Why personal targets can be different
Targets should support better health without creating unacceptable hypoglycemia or treatment burden. A clinician considers diabetes type and duration, pregnancy, age, cardiovascular or kidney disease, cognitive and functional status, medications, low-glucose awareness, work and driving risks, access to food and supplies, and the person’s priorities.
Targets may be adjusted during acute illness, after surgery, with steroid treatment, when medication changes, or when recurrent lows occur. Children, pregnancy, older adults with complex health, and people with severe hypoglycemia risk require population-specific guidance. Do not copy another person’s range even if their diagnosis or medication sounds similar.
When an A1C goal is not met despite pre-meal readings being in range, a clinician may pay closer attention to after-meal glucose. The solution is not always more medication; data completeness, meal timing, dose timing, and hypoglycemia also need review.
Low blood sugar needs a safety plan
Glucose below 70 mg/dL is the common alert threshold for hypoglycemia. Symptoms may include shaking, sweating, hunger, confusion, weakness, dizziness, or a fast heartbeat, but some people have few warning signs. Follow the plan prescribed by your diabetes team.
CDC guidance describes the 15-15 rule for many alert people who can swallow safely: take 15 grams of fast-acting carbohydrate, wait 15 minutes, and recheck; repeat if still below 70 mg/dL. Young children may need less, and an individualized plan takes priority. Fatty or high-fiber foods may act too slowly for initial treatment.
A person who is unconscious, having a seizure, unable to swallow, or otherwise unable to self-treat has a medical emergency. Do not give food or drink by mouth. Use glucagon if available and you are trained to do so, and call emergency services. Recurrent lows require prompt review even when they can be treated at home.
Meter and CGM results have limitations
A blood glucose meter analyzes a small capillary blood sample. Accuracy depends on the device, compatible strips, storage, temperature, sample size, technique, and substances or medical conditions listed in the device instructions. Even a small amount of food or sugar on a finger can distort a result, so FDA guidance recommends washing and drying hands before testing.
Do not use expired, damaged, previously owned, or unauthorized strips. If a reading does not match how you feel, wash and dry your hands and repeat according to the manufacturer’s instructions. Use a fingertip rather than an alternate site when glucose is changing rapidly or low glucose is suspected. A control-solution check or comparison with a laboratory result may help assess performance.
A CGM measures glucose in fluid between cells rather than directly in blood, so the display can lag during rapid change. Compression, sensor placement, warm-up, medication interference for a specific model, and data gaps can matter. Follow device instructions about when to confirm with a meter, especially when symptoms disagree with the sensor.
Patterns matter more than an isolated number
One unexpected reading can result from technique, timing, food, activity, stress, illness, or medication. Repeated readings at the same time of day reveal more. A useful log includes date, time, meal relationship, food when relevant, medication or insulin timing, activity, symptoms, sleep disruption, and illness.
Look for recurring questions rather than diagnosing yourself: Are morning values consistently above the agreed range? Do lows follow exercise? Are after-meal readings high after a particular meal? Does the CGM show overnight patterns that finger-sticks miss? Bring those observations to the clinician who can weigh safety and treatment options.
If you use CGM, averages should be accompanied by Time in Range, time below range, data coverage, and daily patterns. Our Time in Range calculator and guide explains how percentages translate into hours per day.
Blood sugar chart questions
What is a normal fasting blood sugar?
For laboratory screening in a nonpregnant adult, fasting plasma glucose of 99 mg/dL or below is in the normal range. A home meter result is useful for monitoring but does not replace diagnostic laboratory testing.
What are typical blood sugar targets for adults with diabetes?
For many nonpregnant adults, current ADA guidance lists 80–130 mg/dL before meals and below 180 mg/dL at peak after a meal. Personal goals may be higher or lower.
When does the clock start for an after-meal reading?
The ADA postprandial target is generally assessed 1–2 hours after the beginning of the meal, not after the last bite. Follow the specific timing in your care plan.
Is blood sugar below 70 mg/dL low?
Yes. Below 70 mg/dL is the common alert threshold for hypoglycemia. Follow your prescribed treatment plan; severe symptoms or inability to self-treat require emergency help.
Can a glucose meter diagnose diabetes?
No. Diagnosis requires an appropriate laboratory blood test. Meter readings can identify a concerning pattern or urgent problem, but they are not interchangeable with diagnostic plasma glucose.
Why is my CGM different from my finger-stick?
CGM measures glucose in interstitial fluid while a meter uses capillary blood. Timing lag, rapidly changing glucose, pressure on the sensor, technique, strip condition, and device performance can contribute.
Sources and review date
Management targets: ADA Standards of Care in Diabetes—2026. Laboratory thresholds: NIDDK Diabetes Tests & Diagnosis. Low-glucose response: CDC hypoglycemia guidance. Meter technique: FDA Blood Glucose Monitoring Devices. Reviewed August 15, 2026. Educational information only.