Fasting Blood Glucose 118 mg/dL: What Does It Mean?
A fasting blood glucose of 118 mg/dL (6.6 mmol/L) sits in the band the American Diabetes Association calls impaired fasting glucose, which runs from 100 to 125 mg/dL (5.6 to 6.9 mmol/L) and is often called the prediabetes range. It is in the upper part of that band, below the 126 mg/dL (7.0 mmol/L) level that sits in the diabetes range, but not far below it. This is one reading from one morning, so it is a reason to get a proper appointment and probably a repeat test, not a reason to conclude anything about yourself today.
118 mg/dL is the same as about 6.6 mmol/L. The prediabetes band of 100 to 125 mg/dL is written as 5.6 to 6.9 mmol/L, and the 126 mg/dL cut-off is 7.0 mmol/L. Labs in the United States, India and some other countries report in mg/dL, while the UK, Canada, Australia, China and much of Europe use mmol/L. To convert, divide mg/dL by 18 (118 divided by 18 is 6.6) or multiply mmol/L by 18. The two numbers mean exactly the same thing.
What this test measures
A fasting blood glucose test shows how much sugar is in your blood after roughly 8 hours or more without food. Your body normally keeps this level steady overnight using insulin, a hormone that moves sugar out of the blood and into cells so they can use it as fuel. When the body produces less insulin than it needs, or the cells stop responding to it as well as they used to, sugar leaves the blood more slowly and the morning number rises. Because that change happens gradually and quietly, a fasting reading above the normal band is often noticed long before a person feels anything different.
Where 118 mg/dL (6.6 mmol/L) sits
Under the American Diabetes Association (ADA) Standards of Care, fasting glucose falls into three bands: 70 to 99 mg/dL (3.9 to 5.5 mmol/L) normal; 100 to 125 mg/dL (5.6 to 6.9 mmol/L) impaired fasting glucose, widely known as the prediabetes range; and 126 mg/dL (7.0 mmol/L) or higher on two separate occasions, which is in the diabetes range. At 118 mg/dL (6.6 mmol/L) your result sits toward the top of that middle band, roughly 8 points below the diabetes cut-off. Being near a line is not the same as crossing it, and where a number sits on a chart is not a diagnosis. Only a doctor who can see your history, your symptoms and your other results can interpret it. If you are pregnant or might be, these cut-offs do not apply. Pregnancy uses different, lower thresholds and screening is usually done with a glucose tolerance test rather than a single fasting sample. Ask your maternity team.
What to do next
- Arrange an appointment with a doctor reasonably soon rather than waiting for your next routine check. A number in the upper part of this band is worth reviewing properly, even though it is not an emergency.
- Take the complete lab report, not a photo of one line, along with any earlier glucose or HbA1c results you have. Seeing whether the number is stable, rising or falling changes how a doctor reads it.
- Write down how long you fasted, whether you were unwell, sleeping badly or unusually stressed, and anything you drank other than water before the test. All of these can lift a reading and your doctor will want to know.
- Make a list of every medicine and health condition you have, and take it with you. Several conditions and medicines affect blood sugar. Do not stop or adjust anything you already take on your own; that decision belongs to your doctor.
- Ask what happens next: whether the fasting test will be repeated, whether HbA1c or a glucose tolerance test would add anything, and when you should be re-checked. Having a clear plan is more useful than trying to interpret one number by yourself.
Common questions
Is 118 mg/dL close to diabetes?
118 mg/dL (6.6 mmol/L) is about 8 points below the ADA's 126 mg/dL (7.0 mmol/L) cut-off, so it is in the upper part of the prediabetes band rather than in the diabetes band. Being near a line is not the same as being over it, and single readings move around by several points from day to day. That closeness is a good reason to see a doctor, not a reason to assume the worst.
Does 118 mg/dL mean I have diabetes?
No, this page cannot tell you that and one number cannot either. 118 mg/dL sits below the level the ADA places in the diabetes range, and even results above that level require confirmation on a second occasion before anyone draws a conclusion. Diagnosis is a judgement made by a doctor who sees your whole picture, including repeat tests.
Should I be scared by this result?
Fear is an understandable first reaction, but this number does not describe an emergency. It sits above the normal band, which is a signal to get it checked properly and repeated. Many people first learn about their glucose from a result like this, and the sensible response is a booked appointment rather than panic or dismissal.
What if my next test comes back over 126 mg/dL?
That is exactly what repeat testing is for, and it is a question to put to your doctor rather than something to rehearse alone. The ADA asks for a result of 126 mg/dL (7.0 mmol/L) or above on two separate occasions before it is treated as sitting in the diabetes range, so even then a single reading would not settle it. Whatever the next number shows, your doctor decides what it means and what follows.
Can stress, a cold or bad sleep raise a fasting result?
Yes. Illness and infection, poor or short sleep, significant stress, a very late or heavy meal the night before, and not fasting the full 8 hours can all push a reading up. Labs also differ slightly from one another. None of this means your result should be ignored, but it does explain why doctors weigh a repeat test so heavily.
I feel completely fine. How can my sugar be this high?
Feeling well is normal at this level. Blood sugar in this band usually produces no symptoms you would notice, which is the whole reason the test exists. Feeling fine is genuinely good news, but it is not evidence that the number should be set aside.
How often should I be re-tested?
There is no one interval that suits everyone. It depends on how high the reading is, what your other results show, and your age, family history and general health. Ask your doctor to tell you the plan and to put a date on it, so you are not left guessing.
Is a finger-prick reading the same as this lab number?
Not exactly. Home meters and laboratory blood samples are measured differently and can disagree by a noticeable margin, so a meter reading is not a substitute for the lab result on your report. If you already use a meter, take its readings to your appointment, but let the doctor decide how much weight they carry.