Blood Sugar 187 mg/dl — Too High? Fasting & After Eating
Where 187 mg/dl sits — adjust to your situation
187 mg/dl as a fasting reading
Diabetes range
A fasting reading of 126 mg/dl or higher falls into the diabetes range. Diagnosis requires a repeat test on another day — take this result to your doctor.
Fasting = no food for at least 8 hours, typically first thing in the morning. More on fasting readings.
187 mg/dl after eating
Prediabetes range
Between 140 and 199 mg/dl two hours after a meal suggests impaired glucose tolerance, the post-meal form of prediabetes.
Guidelines measure 2 hours after the start of a meal. More on post-meal readings.
A 187 after a forgotten or late dose
One of the most common reasons for a reading of 187 in someone with treated diabetes is simple: a dose was missed, taken late, or taken at the wrong time relative to a meal. Life gets in the way. A busy morning, travel, a change of routine or an empty pill bottle can all leave a gap. The good news is that this kind of high usually has an obvious cause and an obvious fix.
How a missed dose shows up on the meter
Different medicines leave different footprints:
- Mealtime insulin taken late or forgotten often leads to a sharp rise one to two hours after the meal, sometimes well past 187.
- Long-acting (basal) insulin missed for a day tends to raise readings across the whole day, including the next morning’s fasting value.
- Tablets such as metformin work more gradually, so one missed dose may cause only a modest rise, while several missed days add up.
- Weekly injections have their own rules for late doses, written in the leaflet and best confirmed with your pharmacist.
If your log shows a high like 187 and you realise a dose was missed, write that down next to the number. It saves your care team from looking for a problem that is not there.
Why doubling up is risky
The natural urge after a missed dose is to take two the next time. For many diabetes medicines this is a bad idea. A double dose of insulin or of certain tablets such as sulfonylureas can cause a low several hours later, which is more dangerous in the short term than a day of higher readings. Each medicine has its own rule for what to do when a dose is forgotten. Ask your pharmacist or doctor now, while nothing is wrong, and write the answer on a card you keep with your supplies.
The other kind of rebound high
Not every rebound comes from a skipped dose. A high reading like 187 can also follow a low that was treated with too much sugar. When glucose drops, the urge to eat everything in sight is strong. Fifteen grams of fast carbohydrate, such as glucose tablets or half a cup of juice, followed by a recheck after 15 minutes, is the usual approach. Eating far more than that often swings the next reading well above target.
Hormones can add to the swing: after a low, the body releases stress hormones that tell the liver to release stored glucose, which may push numbers higher still.
Making doses easier to remember
Practical habits beat good intentions. Weekly pill organisers, phone alarms tied to meals, keeping medicine next to something you do every day such as the coffee maker, and refilling prescriptions before the last week all help. Some insulin pens record the time of the last dose. If cost is behind skipped doses, tell your doctor: there are often cheaper options. The what affects blood sugar page lists other everyday causes of highs.
Measured right after exercise?
There is no official range for readings taken during or just after a workout, so the two classifications above do not apply to them. How exercise moves blood sugar.
How 187 mg/dl compares to a typical day
Typical day without diabetes; your reading is the horizontal line — above anything a typical day produces, even right after meals.
What to do with a reading of 187 mg/dl
Book a doctor's appointment to confirm with a lab test (fasting glucose or A1C). If you are already diagnosed, this reading belongs in your log for your care team.
What actually moves the number: How to lower blood sugar, Foods that steady your glucose and Exercise and blood sugar.
Save this reading
Stored only in your browser on this device. See the privacy policy for what analytics records when you allow it. Build a history you can chart, print for your doctor, or export.
Questions about 187 mg/dl
Is 187 mg/dl blood sugar normal?
It depends on when you measured. Fasting, 187 mg/dl is diabetes range (normal fasting range: 70–99 mg/dl). Two hours after a meal it is prediabetes range (normal post-meal range: 70–139 mg/dl).
What is 187 mg/dl in mmol/L?
187 mg/dl equals 10.4 mmol/L. Divide mg/dl by 18 to convert (used in the UK, Canada, Australia and most of Europe).
Does one reading of 187 mg/dl mean I have diabetes?
No single home reading is a diagnosis. Guidelines require a second abnormal lab result, either a different test from the same blood draw or a repeat on another day (fasting glucose, an oral tolerance test, or A1C). But a reading like this is exactly the reason those tests exist — take it to your doctor.
How accurate is a home reading of 187 mg/dl?
Home meters are allowed an error of ±15 mg/dl below 100 mg/dl and ±15 % from 100 up (ISO 15197), so a displayed 187 can correspond to a true value anywhere from 159 to 215 mg/dl. Fasting, the entire window stays inside the diabetes range band — this classification is robust even to meter error. After a meal, the window touches the 200 mg/dl boundary.
What A1C would 187 mg/dl correspond to?
If 187 mg/dl were your average glucose over three months, it would work out to an A1C of about 8.1 % — at or above the 6.5 % diabetes threshold. A single reading is not an average — but the conversion shows what this level would mean as a habit. How the two measures relate: A1C and blood sugar.
I forgot my evening tablet and woke up at 187. Should I take it now?
It depends on the medicine and how long until your next dose. For some, taking the missed dose late is fine; for others it should be skipped. Check the leaflet or call your pharmacist. Do not take two doses together unless you have been told this is safe for that specific medicine.
Are there apps that remind me about doses?
Yes. Many phone apps, smart pill caps and connected insulin pens can remind you and record when a dose was taken. A basic alarm on your phone also works. Choose whatever fits your routine; the best reminder is the one you will not switch off.
BloodSugarEasy — blood sugar reading report
Reading: 187 mg/dl (10.4 mmol/L)
Fasting classification: Diabetes range · After-meal classification: Prediabetes range
Reference: ADA criteria, reviewed 2026-11-03 · https://bloodsugareasy.com/blood-sugar-187/
Printed: