Chart selection
Match the chart to the question—not only the number
An A1C percentage, fasting plasma glucose, pre-meal meter value, after-meal reading, and estimated average glucose may all appear in a diabetes record. They do not answer the same question. Before opening a chart, copy the name of the metric, its unit, the time it was measured, and whether it came from a laboratory, meter, or CGM.
Use the A1C Conversion Chart when the goal is translation. It takes a laboratory A1C percentage and shows the population-based estimated average glucose, or eAG. Use the A1C Levels Chart when the goal is understanding the standard screening ranges and the difference between a diagnostic threshold and an individual goal. Use the Blood Sugar Chart when interpreting a glucose value with a known testing condition or meal timing.
A chart is a reference, not a substitute for the original report. Keep the date, source, and unit with any number you copy. If a clinician gave you a personal target, that written target takes priority over a general public table.
Quick comparison of the three charts
| Chart | Input/source | Main answer | Does not provide |
|---|---|---|---|
| A1C Conversion | A1C (%) | Estimated average glucose | Diagnosis or personal goal |
| A1C Levels | Laboratory A1C | Screening category and context | Current glucose or daily pattern |
| Blood Sugar | Timed glucose value | Screening cutoffs or common targets | Long-term A1C or medication dose |
Screening thresholds are not treatment targets
Screening thresholds classify laboratory results in people being evaluated for prediabetes or diabetes. For A1C, below 5.7% is generally the normal range, 5.7%–6.4% is the prediabetes range, and 6.5% or higher is the diabetes range. Fasting plasma glucose and the two-hour oral glucose tolerance test have their own diagnostic cutoffs.
A treatment target answers a different question after diagnosis: what range balances benefit, low-glucose safety, side effects, treatment effort, other health conditions, and personal priorities? For many nonpregnant adults with diabetes, current ADA examples include 80–130 mg/dL before meals and below 180 mg/dL at peak after a meal. Those values are not universal.
A treated A1C below the diagnostic threshold does not by itself erase a diabetes diagnosis. It may reflect successful management. Conversely, a home meter result in a typical treatment range is not proof that a person without a diagnosis has normal fasting laboratory glucose.
Units that look similar can mean different things
US laboratories generally report A1C as a percentage and glucose in milligrams per deciliter, abbreviated mg/dL. Many countries report HbA1c in IFCC mmol/mol and glucose in mmol/L. The shared “mmol” wording causes frequent mistakes, but mmol/mol HbA1c and mmol/L glucose are not interchangeable.
For glucose, divide mg/dL by approximately 18.018 to obtain mmol/L. That conversion does not apply to A1C percentage. HbA1c percentage uses the NGSP-to-IFCC master equation to produce mmol/mol. The A1C unit converter shows both concepts side by side.
Do not remove the unit when writing or sharing a result. “7” could mean 7% A1C, 7 mmol/L glucose, or an unrelated value. “126” could be mg/dL fasting glucose or 126 mmol/mol HbA1c. The number alone is unsafe shorthand.
Timing gives a glucose reading its meaning
A diagnostic fasting plasma glucose is collected after a defined fast, usually in the morning, and analyzed by a laboratory. A home pre-meal check may be taken before breakfast, lunch, or dinner and can still reflect the previous meal, medication, activity, illness, or stress. Those readings can have different purposes even though neither immediately follows food.
For after-meal monitoring, note when the meal began. Current ADA targets commonly refer to peak postprandial glucose assessed one to two hours after the beginning of the meal. A value at 60 minutes should not be compared casually with a two-hour threshold. Meal size and composition, digestion, activity, insulin timing, and individual physiology all influence the curve.
Bedtime also lacks one universal “normal” value for every person with diabetes. The appropriate range depends on the treatment plan, recent food and exercise, medications, overnight-low risk, and monitoring setup. Use the personal instructions from your care team.
When a chart should not guide the next action
Do not use a reference table to change insulin or another medication. Dose decisions require the prescribed plan, current glucose direction, meals, activity, kidney function, previous lows, and other information a static chart cannot know.
Glucose below 70 mg/dL is a common low-glucose alert threshold, but severe symptoms, unconsciousness, seizure, or inability to swallow require emergency action—not more chart reading. Follow your hypoglycemia plan, use glucagon when prescribed and appropriate, and contact emergency services for a severe event.
Very high glucose with vomiting, trouble breathing, confusion, dehydration, or ketone concerns also needs urgent clinical guidance. A chart cannot evaluate diabetic ketoacidosis or another acute illness.
Why laboratory and device values may not line up
A1C reflects glucose exposure through glycated hemoglobin, while a meter captures selected capillary readings and a CGM estimates glucose in interstitial fluid throughout the day. A sparse meter log can miss after-meal or overnight patterns. CGM data can have gaps or cover an unusual period. Recent changes may appear quickly in device data while A1C still reflects earlier weeks.
Red-blood-cell biology can alter the relationship between A1C and glucose. Anemia, kidney disease, pregnancy, recent blood loss, transfusion, erythropoietin therapy, and some hemoglobin variants may matter. Meter technique, strip storage, unwashed hands, temperature, sample size, and device limitations can affect an individual glucose reading.
When values conflict, preserve both originals, document their dates and units, review data coverage and testing technique, and ask a clinician to evaluate the pattern. Do not force agreement by selectively choosing the chart that produces the preferred answer.
A practical way to save or print a reference
Add your purpose
Write whether the page is being used for conversion, screening education, or a personal treatment discussion.
Keep the source date
Guidance changes. Record the page review date and verify current instructions during future appointments.
Circle the unit
Mark %, mg/dL, mmol/L, or mmol/mol so a printed number cannot be separated from its measurement.
Add personal targets separately
A clinician-provided range should be clearly labeled as personal rather than printed over a general population threshold.
Record measurement timing
For glucose, note fasting, before meal, one hour after meal, two hours after meal, bedtime, or symptoms.
Bring the original report
A chart annotation cannot replace laboratory method, reference information, test date, and other details on the report.
For an exact interactive result instead of a lookup table, visit the A1C and glucose calculators.
Chart questions
Which chart should I use for an A1C result?
Use the A1C Conversion Chart to find estimated average glucose. Use the A1C Levels Chart to understand screening categories and why treatment goals are individualized.
Is an A1C conversion chart a diagnostic chart?
No. It translates A1C into an estimated average glucose. Diagnostic thresholds are a separate issue and generally require appropriate laboratory testing and confirmation.
Are fasting and before-meal glucose the same?
Not necessarily. Diagnostic fasting plasma glucose follows a defined fast and laboratory method. A home pre-meal check can occur before any meal and is used for monitoring.
Why are there two glucose units?
US reports and meters usually use mg/dL. Many other countries use mmol/L. For glucose, divide mg/dL by about 18.018 to obtain mmol/L.
Are the ranges suitable during pregnancy?
No general adult chart should replace pregnancy-specific testing and goals. Pregnancy has distinct screening methods, targets, and safety considerations.
Can I print a chart and use it as my treatment plan?
A chart can be a discussion aid, but your written plan should come from your care team and include personal targets, low-glucose treatment, medication instructions, and escalation steps.
Sources and review date
Screening thresholds and test context: NIDDK Diabetes Tests & Diagnosis. Typical adult management targets: ADA Standards of Care in Diabetes—2026. A1C/eAG conversion: ADAG study. Reviewed August 15, 2026. Each chart page includes its own scope and limitations.