# Fasting glucose: Your blood sugar after a night without food

> Fasting glucose is your blood sugar after a night without food. Check your result and see what normal, prediabetes and diabetes mean.

- Also called Fasting plasma glucose, FPG and Fasting blood sugar
- Often on a standard checkup
- Fast for at least 8 hours
- Web page: https://picardo.health/guides/biomarkers/fasting-glucose

## The short answer

Fasting glucose is your blood sugar after a night without food. Under 100 mg/dL is normal.[1] It varies from one morning to the next, so a high result needs confirming with a second test.[1][4]

- **A good result:** Under 100 mg/dL.[1]
- **If yours is high:** 100 to 125 is prediabetes, and losing weight and moving more can bring it back to normal. 126 or more, confirmed by a second test, is diabetes. At 250 or more, get advice the same day.[1][2][11]
- **Should you test?** Yes, from age 35 and at least every three years, or younger if you carry extra weight and have another risk factor, such as diabetes in a parent, brother or sister.[1]

## What is a normal fasting glucose level?

Labcorp’s range runs from 70 to 99 mg/dL.[3] The American Diabetes Association uses the same upper line, and the same cutoffs at every adult age:[1]

Have you been diagnosed with diabetes?

### No, or not sure

| Result (mg/dL) | What it means |
| --- | --- |
| Under 55 | Very low: how do you feel now? |
| 55 to 69 | Below the lab’s range |
| 70 to 99 | Normal fasting glucose |
| 100 to 125 | Prediabetes: higher than normal, and worth acting on |
| 126 to 249 | In the diabetes range |
| 250 or more | Very high: get advice today |

### Yes, I have diabetes

| Result (mg/dL) | What it means |
| --- | --- |
| Under 54 | Very low for someone with diabetes |
| 54 to 69 | Low for someone with diabetes |
| 70 to 130 | Around the usual goal |
| 131 to 249 | Above the usual goal |
| 250 or more | Very high: get advice today |

The normal, prediabetes and diabetes lines are for diagnosing people who don’t have diabetes, and they don’t apply in pregnancy.[1] If you have diabetes, your result is read against your treatment goal instead.[10] If you feel shaky, sweaty or confused right now, have 15 grams of fast sugar, such as half a cup of juice, before reading on.[12]

### Very low: how do you feel now?

**Range:** Under 55 mg/dL without diabetes.

Your report shows your blood sugar when the sample was taken, not now. In someone without diabetes, a low result matters when it comes with symptoms that ease once you eat, such as shakiness, sweating, a racing heart or confusion. Below 55 with symptoms like these, the Endocrine Society recommends looking for a cause.[7] Without symptoms, it may be a sample that waited too long before testing: blood cells keep using up sugar in the tube.[1]

**How worried to be:** If you feel shaky, sweaty or confused now, treat it now: have 15 grams of fast sugar, such as half a cup of juice or regular soda, wait 15 minutes, and have more if you still feel low.[12] If someone is too confused to swallow safely or passes out, call 911.[10] If you had symptoms at the time, talk to a clinician within a day or two.[7]

**What to do next:**

1. If you take any medicine that lowers blood sugar, including insulin or a sulfonylurea such as glipizide, choose “Yes” above and call your clinician today. These medicines are the most common cause of very low blood sugar.[7][10]
2. Note whether you felt unwell at the time of the draw, and tell your clinician.
3. Don’t fast again to retest until you’ve talked to a clinician, especially if you had symptoms. If a cause needs looking for, they’ll arrange the right test.[7]

### Below the lab’s range

**Range:** 55 to 69 mg/dL.

Labcorp’s range starts at 70.[3] Without symptoms, a result just under it is usually not a problem. Healthy people, especially women, can run a little lower after a long fast.[7] A sample that waited too long before testing also reads low.[1]

**How worried to be:** Not a worry on its own if you felt fine.

**What to do next:**

1. If you had shakiness, sweating or confusion that eased when you ate, see a clinician.[7] If you feel like that now, have 15 grams of fast sugar, such as half a cup of juice.[12]
2. If you take a medicine that lowers blood sugar, choose “Yes” above.
3. Otherwise, no action is needed. Retest with your next checkup.

### Normal fasting glucose

**Range:** 70 to 99 mg/dL.

Your blood sugar is in the normal range after fasting.[1] Risk of diabetes doesn’t start suddenly at 100. It rises gradually through the upper part of the normal range.[1]

**How worried to be:** Nothing to worry about.

**What to do next:**

1. Retest at least every three years from age 35, or sooner if you gain weight or have other risk factors.[1]
2. If you’ve never had HbA1c checked, add it. It shows your three-month average, which fasting glucose can miss.[1]

[Test HbA1c, $4.00](https://app.picardo.health/labs/order?tests=001453&ref=guide-fasting-glucose)

### Prediabetes: higher than normal, and worth acting on

**Range:** 100 to 125 mg/dL.

Your fasting blood sugar is higher than normal but below the diabetes range. The American Diabetes Association calls this impaired fasting glucose, a form of prediabetes.[1] The closer you are to 125, the higher your risk of type 2 diabetes.[1] Most prevention trials enrolled people whose glucose tolerance test was abnormal, so the evidence is less direct if fasting glucose is your only high number.[1]

**How worried to be:** Not urgent, but worth acting on over the next few months.

**What to do next:**

1. Check HbA1c too. It shows whether your three-month average is raised as well.[1]
2. If you have weight to lose, aim to lose at least 5% to 7%: 10 to 14 pounds if you weigh 200.[2]
3. Build up to 150 minutes a week of brisk activity, such as walking.[2]
4. Retest at least once a year.[1]

[Test HbA1c and insulin, $10.50](https://app.picardo.health/labs/order?tests=001453,004333&ref=guide-fasting-glucose) Fast for at least 8 hours first.

### In the diabetes range

**Range:** 126 to 249 mg/dL.

A fasting glucose of 126 or more on two tests, or alongside an HbA1c of 6.5% or more, means diabetes.[1] Unless you also have classic symptoms, such as heavy thirst, one result on its own isn’t a diagnosis: check you fasted for at least 8 hours.[1]

**How worried to be:** See a clinician in the next week or two. Go sooner if you’re very thirsty, passing a lot of urine or losing weight without trying.[1]

**What to do next:**

1. Confirm it with HbA1c, or a second fasting glucose on another day.[1]
2. Book a clinician visit to plan treatment. Losing weight and staying active still help.[1]

[Test HbA1c and fasting glucose, $7.25](https://app.picardo.health/labs/order?tests=001453,001032&ref=guide-fasting-glucose) Fast for at least 8 hours first.

### Very high: get advice today

**Range:** 250 mg/dL or higher.

Blood sugar this high needs attention within hours or days, not weeks. At 250 or more, the CDC advises people with diabetes to check for ketones, a sign of diabetic ketoacidosis (DKA), a medical emergency.[11] Very high blood sugar with heavy thirst, passing a lot of urine and weight loss can be new diabetes, including type 1.[1] Above 600 can mean a hyperglycemic hyperosmolar state, a crisis that can happen even without ketones.[10]

**How worried to be:** Contact a clinician today. Call 911 or go to an emergency department now if you’re vomiting and can’t keep fluids down, your breath smells fruity, you’re breathing fast or deep, you have belly pain, you feel very drowsy or confused, or your blood sugar stays at 300 or more.[11] A result over 600 needs emergency care now.[10]

**What to do next:**

1. If you have a glucose meter or ketone strips, check now, and tell your clinician the numbers.[11]
2. Don’t wait for a second lab test before getting advice. Your clinician will confirm the diagnosis and start treatment.[1]

### Very low for someone with diabetes

**Range:** Under 54 mg/dL with diabetes.

Under 54 is what the American Diabetes Association calls level 2 hypoglycemia, low enough to be dangerous.[10] Your report shows your level when the sample was taken, not now. A low reading after an overnight fast often means a medicine dose needs changing, especially insulin or a sulfonylurea such as glipizide.[10]

**How worried to be:** If you feel shaky, sweaty or confused now, treat it now: have 15 grams of fast sugar, such as half a cup of juice, recheck in 15 minutes, and repeat if you’re still under 70.[12] If someone is too confused to swallow safely or passes out, use glucagon if you have it and call 911.[10] Either way, call your clinician today.

**What to do next:**

1. Tell your clinician about this result today, even if you feel fine now, so they can review your medicines.[10]
2. Ask how to take your diabetes medicines before your next fasting blood test.

### Low for someone with diabetes

**Range:** 54 to 69 mg/dL with diabetes.

Under 70 is level 1 hypoglycemia, the level the American Diabetes Association uses as an alert to treat it and to look at why.[10] It’s most likely if you take insulin or a sulfonylurea.[10]

**How worried to be:** If you feel low now, have 15 grams of fast sugar and recheck in 15 minutes.[12] Not an emergency if you feel well, but tell your clinician within a few days.

**What to do next:**

1. Tell your clinician, especially if lows happen often or without warning. Your medicines or goal may need adjusting.[10]
2. Ask how to take your diabetes medicines before your next fasting blood test.

### Around the usual goal

**Range:** 70 to 130 mg/dL with diabetes.

The American Diabetes Association’s usual goal before meals is 80 to 130 mg/dL. Readings in the 70s are below that goal but aren’t low blood sugar.[10] Your clinician may set a different goal for you.[10]

**How worried to be:** Nothing to worry about from this number.

**What to do next:**

1. Keep checking HbA1c as your clinician advises. It shows your three-month average.[10]
2. If you often see readings in the 70s and take insulin or a sulfonylurea, mention it at your next visit.[10]

### Above the usual goal

**Range:** 131 to 249 mg/dL with diabetes.

This is above the American Diabetes Association’s usual before-meal goal of 80 to 130.[10] One reading can be pushed up by illness, stress, a steroid medicine or not fasting for the full 8 hours.[1] Your HbA1c says more about how your treatment is working.[10]

**How worried to be:** Not urgent on its own. Worth raising at your next visit, and sooner if your readings stay this high.

**What to do next:**

1. If you’re unwell, check your blood sugar more often and follow your sick-day plan.[11]
2. Bring your readings and your HbA1c to your next visit to review your treatment.[10]

[Test HbA1c, $4.00](https://app.picardo.health/labs/order?tests=001453&ref=guide-fasting-glucose)

## What is fasting glucose?

> Think of fasting glucose as your blood sugar at rest. After a meal it rises and falls; after a night without food, it should settle back under 100.

It’s measured after at least 8 hours with no calories; water is fine.[1] It’s one of three tests used to diagnose prediabetes and diabetes, each with its own cutoffs:[1]

|  | Normal | Prediabetes | Diabetes |
| --- | --- | --- | --- |
| Fasting glucose | Under 100 mg/dL | 100 to 125 mg/dL | 126 mg/dL or more |
| HbA1c | Under 5.7% | 5.7% to 6.4% | 6.5% or more |
| 2-hour glucose tolerance test | Under 140 mg/dL | 140 to 199 mg/dL | 200 mg/dL or more |

Cutoffs from the American Diabetes Association. Unless blood sugar is clearly very high with symptoms, diabetes needs two abnormal results, either two different tests or the same test repeated.[1]

The World Health Organization starts impaired fasting glucose at 110 mg/dL rather than 100, so a result of 100 to 109 counts as prediabetes in the US but not under WHO criteria.[1]

## Why can one fasting glucose result be misleading?

Your fasting glucose shifts from one morning to the next. In a study of 8,315 adults without diabetes who wore glucose monitors for about a week, a person’s fasting level typically varied by about 7.5 mg/dL from day to day. Of those with a normal first reading, 40% had a reading in the prediabetes range on a later morning.[4]

Things that can push a single result up or down:[1]

- Not fasting for the full 8 hours
- Recent exercise, illness or acute stress
- The time of day, since glucose varies through the day
- Steroid medicines, which raise blood sugar
- A sample that waited too long before testing, which reads falsely low

That’s why a diagnosis needs two abnormal results, and why clinicians repeat a result close to the diabetes cutoff in 3 to 6 months.[1]

## Can high fasting glucose go back to normal?

It can. In the Diabetes Prevention Program, people who got their blood sugar back to normal, even once, had a lower risk of diabetes later, whatever treatment they were on.[2]

It may protect the heart too. In US and Chinese prevention trials followed for 20 to 30 years, people whose prediabetes went into remission had about half the risk of dying from cardiovascular disease or being admitted for heart failure.[5] These were analyses after the fact, not trials of remission itself, so they show a link rather than proof.

One caveat: most prevention trials enrolled people whose glucose tolerance test was abnormal. There’s less evidence for people whose only high number is fasting glucose.[1]

## How to lower fasting glucose

- **A structured lifestyle program:** Aim to lose at least 5% to 7% of your weight and get 150 minutes a week of activity. In the Diabetes Prevention Program, a program like this cut the risk of diabetes by 58% over three years.[2] How much it helps: a lot. How sure we are: very sure.
- **Losing extra weight:** In the same trial, each kilogram lost was linked to a 16% lower risk of diabetes over about three years.[2] How much it helps: a lot. How sure we are: very sure.
- **GLP-1 and related weight-loss drugs:** In people with obesity and prediabetes, new diabetes over three years was 1.3% on tirzepatide and 13.3% on placebo. Seventeen weeks after stopping, it was 2.4% against 13.7%.[6] The ADA says only metformin has long-term evidence as a drug taken just to prevent diabetes, but advises considering these for weight loss if you have overweight or obesity.[2] How much it helps: a lot. How sure we are: very sure.
- **Metformin:** Worth considering at high risk. The ADA names people aged 25 to 59 with a BMI of 35 or more, higher fasting glucose (such as 110 or more) and higher HbA1c (such as 6.0% or more), and women who had diabetes in pregnancy.[2] How much it helps: some. How sure we are: very sure.

Weight loss matters most: the more you lose, the more your blood sugar improves.[2]

## Should you wear a glucose monitor if you don’t have diabetes?

More and more people without diabetes wear continuous glucose monitors to see how food and exercise affect them.[9] They can’t diagnose anything: the American Diabetes Association says there isn’t enough evidence to use them to screen for or diagnose prediabetes or diabetes.[1]

Short rises after meals are normal. In healthy children and adults without obesity wearing a monitor, glucose stayed between 70 and 140 mg/dL about 96% of the time, and above 140 for about 30 minutes a day.[8]

In a 2026 review of 23 studies, wearing one improved blood sugar in people with prediabetes, but not in people whose glucose was already normal, and it didn’t change weight on its own.[9]

## Who should get a fasting glucose test?

- Every adult from age 35, at least every three years.[1]
- Anyone younger with extra weight and another risk factor, such as diabetes in a parent or sibling, high blood pressure or polycystic ovary syndrome.[1]
- Everyone with prediabetes, every year.[1]

Fasting glucose is often tested with HbA1c. If both come back in the diabetes range, that’s enough to confirm it.[1]

## How to get a fasting glucose test, and what it costs

A fasting glucose test costs $3.25 through Picardo. The Heart Health panel adds 16 more tests from the same visit for $150.90.

- **Recommended:** [the Heart Health panel, $150.90](https://app.picardo.health/labs/order?panels=heart-health&ref=guide-fasting-glucose). 17 tests, fast for 12 hours first. Fasting glucose is one morning. The panel adds HbA1c for your three-month average and insulin for a rough read on insulin resistance, plus ApoB, Lp(a), uric acid, and kidney and liver tests. [What’s in it](https://picardo.health/guides/panels/heart-health.md).
- [Fasting glucose on its own, $3.25](https://app.picardo.health/labs/order?tests=001032&ref=guide-fasting-glucose). Labcorp 001032, fast for at least 8 hours.

Every order comes with:

- Results in 2 to 3 days, in the app
- Physician follow-up if you want one
- Free Labcorp draw, or $75 at home
- No other fees. HSA and FSA eligible.

It’s also part of the [Base Core Annual – Men](https://picardo.health/labs/panels/base-core-men), [Base Core Annual – Women](https://picardo.health/labs/panels/base-core-women), [Brain Health Screening](https://picardo.health/labs/panels/brain-health), [Pregnancy](https://picardo.health/labs/panels/pregnancy), [Postpartum](https://picardo.health/labs/panels/postpartum), [Fertility](https://picardo.health/labs/panels/fertility), [Thyroid & Autoimmunity](https://picardo.health/labs/panels/thyroid-autoimmunity) and [Celiac / GI](https://picardo.health/labs/panels/celiac-gi) panels, if you want a wider checkup.

Already have a result? [Ask Picardo about it](https://app.picardo.health/auth).

## Questions people ask

### Is a fasting glucose of 100 bad?

It’s the bottom of the prediabetes range.[1] It’s an early warning, not diabetes. Because fasting glucose varies from day to day, check it again along with HbA1c before you draw conclusions.[1][4]

### What counts as fasting for a glucose test?

No calories for at least 8 hours; water is fine.[1] Labcorp asks for a morning draw after an overnight fast.[3]

### Why is my fasting glucose high when my HbA1c is normal?

The two measure different things. Fasting glucose is one morning; HbA1c is a three-month average. Not fasting long enough, a recent illness, acute stress or a steroid medicine can push up a single result.[1] When the two disagree, clinicians repeat the one that came out abnormal.[1]

### Should my fasting glucose be lower than 90?

No. There’s no guideline target below 100 for people without diabetes, though risk rises gradually through the upper part of the normal range.[1] In a study of adults aged 40 to 70 without diabetes, the average fasting level on a glucose monitor was about 96 mg/dL.[4]

### Can a glucose monitor replace a fasting glucose test?

Not for diagnosis. The American Diabetes Association says there isn’t enough evidence to use one to screen for or diagnose prediabetes or diabetes.[1] There are no agreed cutoffs for diagnosing diabetes from monitor readings.[4]

## Often checked alongside

- [HbA1c](https://picardo.health/guides/biomarkers/hba1c.md): Average blood sugar over three months
- [Fasting insulin](https://picardo.health/guides/biomarkers/fasting-insulin.md): An early sign of insulin resistance
- [HOMA-IR](https://picardo.health/guides/biomarkers/homa-ir.md): An insulin resistance score from glucose and insulin
- [Triglycerides](https://picardo.health/guides/biomarkers/triglycerides.md): Blood fats that rise with sugar and alcohol

## Test details

- **Labcorp test:** Glucose, 001032
- **LOINC:** 2345-7
- **Sample:** Blood
- **Fasting:** No calories for at least 8 hours; water is fine[1][3]
- **Typical lab range:** 70 to 99 mg/dL[3]
- **Units:** mg/dL in the US. For mmol/L, divide by 18.

## Sources

1. American Diabetes Association Professional Practice Committee for Diabetes. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S27–S49. https://doi.org/10.2337/dc26-S002
2. American Diabetes Association Professional Practice Committee for Diabetes. 3. Prevention or delay of diabetes and associated comorbidities: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S50–S60. https://doi.org/10.2337/dc26-S003
3. Labcorp. Glucose, test 001032. Labcorp test menu. Accessed October 28, 2026. https://www.labcorp.com/tests/001032/glucose
4. Shilo S, Keshet A, Rossman H, et al. Continuous glucose monitoring and intrapersonal variability in fasting glucose. Nat Med. 2024;30(5):1424–1431. https://doi.org/10.1038/s41591-024-02908-9
5. Vazquez Arreola E, Gong Q, Hanson RL, et al. Prediabetes remission and cardiovascular morbidity and mortality: post-hoc analyses from the Diabetes Prevention Program Outcome study and the DaQing Diabetes Prevention Outcome study. Lancet Diabetes Endocrinol. 2026;14(2):137–148. https://doi.org/10.1016/S2213-8587(25)00295-5
6. Jastreboff AM, le Roux CW, Stefanski A, et al. Tirzepatide for obesity treatment and diabetes prevention. N Engl J Med. 2025;392(10):958–971. https://doi.org/10.1056/NEJMoa2410819
7. Cryer PE, Axelrod L, Grossman AB, et al. Evaluation and management of adult hypoglycemic disorders: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2009;94(3):709–728. https://doi.org/10.1210/jc.2008-1410
8. Shah VN, DuBose SN, Li Z, et al. Continuous glucose monitoring profiles in healthy nondiabetic participants: a multicenter prospective study. J Clin Endocrinol Metab. 2019;104(10):4356–4364. https://doi.org/10.1210/jc.2018-02763
9. Liao X, Li Y, Tang S, et al. Continuous glucose monitoring in non-diabetic populations: a systematic review of observational and interventional studies with meta-analysis. Eur J Med Res. 2026;31(1):397. https://doi.org/10.1186/s40001-026-03920-0
10. American Diabetes Association Professional Practice Committee for Diabetes. 6. Glycemic goals, hypoglycemia and hyperglycemic crises: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S132–S149. https://doi.org/10.2337/dc26-S006
11. Centers for Disease Control and Prevention. Diabetic ketoacidosis. Updated May 15, 2024. Accessed November 3, 2026. https://www.cdc.gov/diabetes/about/diabetic-ketoacidosis.html
12. American Diabetes Association. Signs, symptoms and treatment for hypoglycemia (low blood glucose). Accessed November 3, 2026. https://diabetes.org/living-with-diabetes/hypoglycemia-low-blood-glucose/symptoms-treatment

Updated 2026-11-03. This is general health information, not medical advice: talk to your clinician about your results and before changing any treatment.