Blood Sugar Chart for Adults: Complete Reference

A blood sugar chart for adults puts the most clinically important glucose reference ranges in one place — making it easy to understand what any given glucose reading means and what action, if any, it warrants. Blood glucose is measured in three main contexts — fasting (before eating), post-meal (after eating), and as a long-term average via the A1C test — and each context has its own set of normal, prediabetes, and diabetes thresholds. Knowing which range applies to which measurement, and what the difference between a diagnostic threshold and a management target means, is essential for anyone interpreting their own glucose results or those of a family member. This reference guide compiles all key blood sugar thresholds for adults, organized for practical use. For the physiological explanation of what these numbers mean and why they matter, our guide on what is normal blood sugar provides the full context. For understanding why maintaining glucose within these ranges matters for long-term health, see our guide on why blood sugar matters long-term.

Diagnostic Blood Sugar Ranges: Normal, Prediabetes, and Diabetes

The following table presents the American Diabetes Association diagnostic criteria for normal glucose, prediabetes, and diabetes across all three standard measurement methods.

Test	Normal	Prediabetes	Diabetes
Fasting Plasma Glucose (8+ hrs without food)	Below 100 mg/dL (5.6 mmol/L)	100–125 mg/dL (5.6–6.9 mmol/L)	126 mg/dL or above (7.0 mmol/L) on 2 occasions
2-Hour Post-Glucose Load (OGTT, 75g glucose)	Below 140 mg/dL (7.8 mmol/L)	140–199 mg/dL (7.8–11.0 mmol/L)	200 mg/dL or above (11.1 mmol/L)
A1C (no fasting required)	Below 5.7%	5.7–6.4%	6.5% or above
Random Plasma Glucose (any time, with symptoms)	Typically below 140	—	200 mg/dL or above with classic symptoms

Notes on using this diagnostic chart: A single test result in the diabetes range requires confirmation on a second occasion (unless the person has unambiguous symptoms of hyperglycemia plus a random glucose at or above 200 mg/dL, in which case one test suffices). Prediabetes findings on one test type should ideally be confirmed with the same test or a different test on a separate day. A1C may be less reliable in people with certain hemoglobin variants, hemolytic anemias, or iron deficiency — in these situations, fasting or post-meal glucose testing is preferred. For a detailed explanation of each of these tests, see our dedicated guides on fasting blood sugar, post-meal blood sugar, and the A1C test.

Blood Sugar Management Targets for Adults With Diabetes

For people already diagnosed with diabetes who are actively managing their condition, the target glucose values differ from the diagnostic thresholds above. Management targets are set to balance the benefits of glucose control against the risk of hypoglycemia from treatment.

Measurement	ADA Target (Most Adults)	Notes
Before meals (preprandial)	80–130 mg/dL	Higher than “normal” to allow buffer against hypoglycemia
1–2 hours after meal start (postprandial)	Below 180 mg/dL	Peak target; not a 2-hr diagnostic threshold
Bedtime	80–180 mg/dL	Individualized based on insulin regimen and hypoglycemia risk
A1C	Below 7.0%	Below 6.5% for some; 7.5–8.0% for higher-risk individuals
Time in Range (CGM)	More than 70% of time in 70–180 mg/dL	Supplementary target reflecting glucose variability

These management targets are starting points — they are individualized based on each person’s hypoglycemia risk, life expectancy, comorbidities, patient preference, and resources. People using insulin, particularly intensive regimens, may have more stringent bedtime targets to prevent nocturnal hypoglycemia. For people who are older, have cardiovascular disease, or have significant hypoglycemia risk, more lenient A1C targets (7.5–8.5%) are appropriate per ADA guidance. Home glucose monitoring — described in our guide on home blood sugar monitoring — is the practical tool for tracking whether readings are within these management targets day to day.

Blood Sugar Levels That Require Immediate Action

Beyond the reference ranges above, several glucose thresholds have specific action implications that are important to know regardless of whether diabetes has been diagnosed.

Glucose Level	Clinical Significance	Recommended Action
Below 54 mg/dL	Severe hypoglycemia — dangerous brain glucose deficit	Immediate fast-acting glucose; call 911 if unable to self-treat
54–70 mg/dL	Mild-moderate hypoglycemia — symptomatic low	Treat with 15g fast-acting carbohydrates; recheck in 15 min
70–130 mg/dL (fasting)	Target zone in managed diabetes	Continue current management
140–180 mg/dL (post-meal)	Slightly elevated post-meal glucose	Monitor; consider dietary adjustments
Above 180 mg/dL (post-meal)	Elevated post-meal; above ADA management threshold	Review meal composition and medication with care team
Above 250 mg/dL	Significantly elevated; ketone check indicated in Type 1	Contact diabetes care team; check ketones if Type 1
Above 300 mg/dL	Highly elevated; risk of DKA or HHS with sustained elevation	Same-day contact with care team; watch for nausea/vomiting
Above 400 mg/dL with nausea/vomiting	Possible DKA or HHS emergency	Emergency evaluation (911 or ER)

These action thresholds apply most directly to people who are already monitoring glucose — either because they have diabetes or because they are screening for it. For people who discover a reading in the concerning range without a prior diabetes diagnosis, the appropriate response is medical evaluation within 24–72 hours for readings in the 250–300 range (with same-day evaluation if symptoms are present), or same-day emergency evaluation for readings above 400 mg/dL accompanied by nausea, vomiting, or altered consciousness. Our guide on when blood sugar symptoms need medical attention provides a comprehensive framework for determining urgency based on symptoms and glucose level together.

Blood Sugar Ranges by Situation and Context

The same glucose value can mean different things depending on the context in which it is measured. The following provides a practical summary of how to interpret readings in different situations.

Morning fasting readings: Compare to the fasting diagnostic range above. A consistent pattern above 100 mg/dL on multiple mornings warrants medical evaluation. Isolated elevated readings during illness, after stress, or after poor sleep are expected and do not warrant immediate concern — patterns matter more than single readings.

Post-meal readings (1–2 hours after eating): Compare to the post-meal ranges. Readings consistently above 140 mg/dL at the two-hour mark indicate impaired glucose tolerance. Readings above 180 mg/dL indicate a post-meal glucose pattern that exceeds even the diabetes management target. For context on what drives post-meal glucose and how to reduce it, our guide on post-meal blood sugar explained covers meal composition, food order, and activity timing strategies.

Random readings (taken without timing relative to meals): A random glucose at or above 200 mg/dL on multiple occasions suggests diabetes, particularly when accompanied by symptoms. Random readings between 140 and 200 mg/dL are harder to interpret without context — the same reading could be normal post-meal or abnormally elevated fasting. Recording the timing relative to meals makes random readings more interpretable.

Bedtime readings: For people managing diabetes with insulin, bedtime glucose is a critical safety reading — too low at bedtime predicts risk of nocturnal hypoglycemia. The typical bedtime target is 90–150 mg/dL for people using bedtime insulin, adjusted based on individual hypoglycemia risk and insulin type. For people not on insulin, bedtime glucose has less immediate safety relevance but can track overnight glucose trends when combined with morning fasting readings. The resources in our guides on what diabetes is, what prediabetes is, and diabetes risk factors provide the context needed to interpret glucose readings in light of personal medical history and risk factors. The diagnostic ranges in this chart, combined with the management targets and action thresholds, provide the complete practical reference for understanding what any adult’s blood sugar reading means and what to do with that information.

Understanding the Difference Between Diagnostic and Management Ranges

One of the most common points of confusion when reading blood sugar charts is the difference between diagnostic thresholds (used to identify whether someone has a glucose problem) and management targets (used to guide treatment in someone already diagnosed). These two sets of numbers serve different purposes and should not be conflated.

The diagnostic thresholds — fasting glucose above 126 mg/dL for diabetes, above 100 mg/dL for prediabetes; A1C above 6.5% for diabetes, 5.7–6.4% for prediabetes — are the values at which the medical evidence shows that the risks associated with elevated blood glucose become clinically significant enough to warrant a diagnostic label and treatment discussion. These numbers were chosen based on the glucose levels at which retinopathy (diabetic eye disease) begins to appear in population studies, and on epidemiological data showing where cardiovascular and metabolic risk rises substantially above baseline. They represent population-level thresholds, not precise individual cutoffs — the risk of complications does not jump sharply at 126 mg/dL fasting and is zero below it; rather, risk rises on a continuum and these thresholds represent where clinical action is clearly warranted based on the overall risk-benefit picture.

The management targets — 80–130 mg/dL before meals, below 180 mg/dL post-meal, A1C below 7.0% — are set for people already diagnosed with diabetes who are using medications that carry hypoglycemia risk. The preprandial target of 80–130 mg/dL, rather than the diagnostic threshold of “below 100 mg/dL,” reflects the practical reality that targeting fasting glucose below 100 mg/dL in someone using insulin would require doses that cause dangerous overnight hypoglycemia in many people — the management target provides a clinically useful window that achieves meaningful control without unacceptable risk of lows. This difference explains why someone with diabetes might have a “normal” fasting glucose reading (say, 95 mg/dL) and still have an A1C above their management target — because the A1C reflects averages including post-meal peaks that the fasting reading alone does not capture. Understanding these nuances makes blood sugar charts more useful as practical tools rather than simple pass-fail scorecards. For context on what glucose levels mean in terms of symptom likelihood, our guide on early signs of high blood sugar connects specific glucose ranges to the symptoms they are likely to produce. For understanding what prediabetes means in terms of risk and action urgency, our guide on what prediabetes is provides the full context.

How to Use a Blood Sugar Chart With a Home Glucose Meter

The most practical application of a blood sugar chart for adults is as a reference tool when interpreting home glucose meter readings. Understanding what each reading means — whether it is reassuring, worth monitoring, or concerning enough to contact a healthcare provider — requires matching the reading to the right reference range for the context in which it was taken.

Step 1: Record the timing. Write down (or enter into a glucose tracking app) each reading alongside the time it was taken and its timing relative to the last meal — “fasting,” “1 hour after breakfast,” “before dinner,” “2 hours after lunch,” and so on. The same glucose value of 150 mg/dL has very different implications at two hours after a meal (slightly above target but not alarming) versus in the fasting state (significantly above both the normal and prediabetes thresholds).

Step 2: Compare to the appropriate range. Use the diagnostic table above for fasting readings taken in the morning before breakfast, and the post-meal reference range for readings taken 1–2 hours after a meal. For random readings taken at other times, interpret with caution — these do not have standardized reference ranges except at the very high end (above 200 mg/dL with symptoms suggests diabetes).

Step 3: Look for patterns across multiple days. A single reading above range is not a diagnosis — it could reflect an unusual meal, illness, stress, or testing technique variation. A consistent pattern of elevated fasting readings (above 100 mg/dL on most mornings over two to three weeks) or post-meal readings (above 140 mg/dL at two hours after most meals) is clinically meaningful and warrants medical evaluation. Most glucose tracking apps allow you to view graphs of readings over time, making patterns visible that are hard to identify from a list of individual numbers. Our guide on home blood sugar monitoring covers how to set up a tracking routine and how to communicate your readings data to a healthcare provider most effectively.

Step 4: Note any symptoms alongside readings. Glucose values make more sense when paired with how you felt at the time. A reading of 65 mg/dL that coincided with shaking, sweating, and anxiety confirms symptomatic hypoglycemia; a reading of 65 mg/dL with no symptoms suggests either the meter is reading slightly low or you have some degree of hypoglycemia unawareness. A reading of 220 mg/dL with intense thirst and fatigue suggests symptomatic hyperglycemia; 220 mg/dL without symptoms in someone with known diabetes may represent a predictable post-meal spike that their management plan expects. Recording both the number and the associated feeling makes the data more complete and the clinical conversation more productive. Our guide on when blood sugar symptoms need medical attention provides the framework for deciding when a reading-plus-symptom combination requires prompt action versus monitoring.

Blood Sugar Ranges During Pregnancy

Pregnancy introduces distinct blood sugar ranges that are more stringent than general adult standards, because elevated glucose during pregnancy — even at levels below the diabetes diagnostic threshold — can affect fetal development and pregnancy outcomes. Gestational diabetes mellitus (GDM) is diagnosed using different criteria than type 2 diabetes, and the management targets during pregnancy are correspondingly tighter.

The ADA-recommended blood glucose targets for pregnant women with diabetes or gestational diabetes are:

• Fasting and pre-meal: Below 95 mg/dL (significantly tighter than the general adult preprandial target of 80–130 mg/dL)
• One hour after meals: Below 140 mg/dL
• Two hours after meals: Below 120 mg/dL
• A1C (in established diabetes in pregnancy): 6.0–6.5% is the general target, individualized based on hypoglycemia risk

These tighter pregnancy targets reflect the fact that the developing fetus is highly sensitive to maternal glucose levels — elevated glucose crosses the placenta, stimulates fetal insulin production, and drives fetal overgrowth (macrosomia), which increases the risk of delivery complications, neonatal hypoglycemia, and long-term metabolic risk in the child. The postpartum period also requires attention: while gestational diabetes typically resolves after delivery, women who had GDM have a substantially higher risk of developing Type 2 diabetes within 10 years — making postpartum glucose testing and ongoing screening important parts of post-pregnancy health care. For anyone with prediabetes or diabetes who is planning a pregnancy, our guides on what diabetes is, diabetes risk factors, and the comprehensive blood sugar ranges in this article provide the foundational reference for the glucose management conversations that should happen with an obstetric and diabetes care team well before conception when possible. The combination of this chart with regular glucose monitoring using a home meter as described in our home blood sugar monitoring guide provides the practical infrastructure for maintaining the tight glucose control that optimal pregnancy outcomes require.

Blood Sugar Ranges for Older Adults

Older adults with diabetes — typically defined as those aged 65 and above — frequently have different blood sugar target ranges than the general adult standards presented above, reflecting the distinct risk-benefit balance that applies to this population. The American Geriatrics Society and the ADA jointly recommend less stringent glycemic targets for many older adults with diabetes because the risks of hypoglycemia are substantially greater in this population while the long-term benefits of very tight glucose control are smaller (given the shorter time horizon over which complications develop).

For healthy older adults with long life expectancy and no significant functional impairment, the standard A1C target of below 7.5% (slightly more lenient than the below 7.0% target for most younger adults) is appropriate. For older adults with moderate complexity (multiple chronic conditions, cognitive impairment, or functional limitations), the A1C target is typically 7.5–8.0%. For those with very advanced disease, limited life expectancy, or significant frailty, A1C targets of 8.0–8.5% or even less stringent targets are appropriate, prioritizing avoidance of hypoglycemia and symptom management over long-term complication prevention that they will not survive to experience.

The reasons that hypoglycemia carries disproportionate risk in older adults include: impaired counter-regulatory hormone responses (lower adrenaline and glucagon responses to low blood glucose, reducing both the warning symptoms and the physiological correction); greater cognitive vulnerability (the developing brain tolerates glucose deficiency better than the aging brain); increased fall risk from hypoglycemia-associated weakness, dizziness, and confusion; and greater cardiovascular vulnerability to the arrhythmias and blood pressure changes that severe hypoglycemia can trigger. These risks mean that a fasting glucose of 90 mg/dL in an 80-year-old on sulfonylurea or insulin carries greater risk than the same reading in a 45-year-old — a nuance that standard blood sugar charts do not always capture but that is critical for safe glucose management in the elderly. For a comprehensive understanding of how blood sugar elevation drives long-term consequences that the blood sugar chart must be understood against, our guide on why blood sugar matters long-term covers the full evidence base. And for anyone whose blood sugar readings from a home meter consistently fall in ranges that concern them — or that differ unexpectedly from their clinical A1C results — our guide on home blood sugar monitoring covers how to ensure readings are accurate and how to identify when discrepancies between home readings and A1C warrant discussion with a healthcare provider. The blood sugar chart in this guide is the map; consistent, accurate home monitoring is the navigation system that tells you where you are on that map at any given moment — and the combination of both, applied consistently over time, provides the clearest possible picture of blood glucose health across the full adult lifespan.

Frequently Asked Questions About Blood Sugar Ranges

What is a dangerous blood sugar level? Below 54 mg/dL is clinically severe hypoglycemia requiring immediate treatment. Above 300 mg/dL warrants same-day contact with a healthcare provider. Above 400 mg/dL with nausea, vomiting, or altered consciousness warrants emergency evaluation. See our detailed guide on when blood sugar symptoms need medical attention for the complete urgency framework.

Is 130 mg/dL a good blood sugar level? It depends on when it was taken. Fasting, 130 mg/dL is above the diabetes diagnostic threshold (126+ mg/dL) and would typically warrant confirmation and medical evaluation. Two hours after a meal, 130 mg/dL is well within the normal range (below 140 mg/dL). As a pre-meal management target for someone with diabetes, 130 mg/dL is at the upper limit of the ADA target (80–130 mg/dL). Timing context determines whether any given value is reassuring or concerning.

What blood sugar level indicates prediabetes? Fasting glucose of 100–125 mg/dL, two-hour post-glucose-load glucose of 140–199 mg/dL, or A1C of 5.7–6.4% — on confirmed testing — indicates prediabetes. Any one of these three tests, when in the prediabetes range, is sufficient for the classification, though confirmation is recommended. See our guide on what prediabetes is for what to do if your results fall in this range.

Can blood sugar be too low without diabetes? True fasting hypoglycemia in a person not taking diabetes medications is uncommon and warrants medical evaluation for causes such as insulinoma, adrenal insufficiency, or liver disease. Reactive hypoglycemia (low blood glucose one to three hours after eating) is more common in people with early insulin resistance and does not necessarily indicate diabetes, but does suggest metabolic dysfunction worth investigating. A fasting glucose below 70 mg/dL in a non-medicated person should always be evaluated by a healthcare provider. For the full blood sugar context — including what values indicate risk of developing diabetes over time, how to use the A1C test to track trends, and what the fasting blood sugar and post-meal blood sugar measures reveal about different aspects of glucose regulation — the other guides in this series provide the detailed explanation behind the numbers in this reference chart.

Sources: American Diabetes Association. Standards of Medical Care in Diabetes — 2024. Diabetes Care. 2024;47(Suppl 1):S20–S42. • American Diabetes Association. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes — 2024. Diabetes Care. 2024;47(Suppl 1):S111–S125. • National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes Tests and Diagnosis. NIDDK; 2023.