Blood sugar converter — mg/dL to mmol/L and back, with ADA ranges

How to use the blood sugar converter

1. Enter your Glucose reading.
2. Choose the Unit it is in: mg/dL, mmol/L, g/L or µmol/L.
3. Under When was it measured?, choose Fasting (8+ hours without food), 2 hours after a 75 g glucose drink (OGTT), or Random / any time.
4. Read the converted value and the Category, then see the reading in all four units in the table.

What it does and when to use it

Glucose meters, lab reports and articles use different units. One report may say 5.5 mmol/L while a meter says 99 mg/dL, and some lab reports use g/L. This converter turns any of those into the others, so you can compare results, follow advice written in another unit, or log readings consistently.

It also places the reading in the American Diabetes Association’s ranges for the type of test:

Any reading below 70 mg/dL is labelled low. The ADA’s guidance covers more than these cut-offs, including the A1C test, which this converter does not handle.

Related health tools include the blood pressure classifier, the BMI calculator and the protein intake calculator.

How it works

Every reading is first turned into mg/dL:

• mmol/L × 18.0182
• g/L × 100
• µmol/L ÷ 1,000 × 18.0182

Then mmol/L = mg/dL ÷ 18.0182, g/L = mg/dL ÷ 100 and µmol/L = mmol/L × 1,000. The category check uses the mg/dL value and the test type you chose. A converted value that falls between the printed bands, such as 125.6 mg/dL fasting, stays in the lower band, because the diabetes range starts at 126 mg/dL fasting (200 mg/dL for the OGTT).

Worked examples

These figures come from the converter’s own function.

90 mg/dL, fasting. In mmol/L: 4.99 mmol/L. Category: Normal fasting range (below 100 mg/dL). The table also shows 0.9 g/L and 4994.9 µmol/L.

7 mmol/L, fasting. In mg/dL: 126.13 mg/dL. Category: Diabetes range (fasting 126 mg/dL or higher).

1.1 g/L, fasting. 110 mg/dL, in the prediabetes range (fasting 100–125 mg/dL).

9.5 mmol/L, two hours into an OGTT. 171.17 mg/dL, in the prediabetes range for the 2-hour test (140–199 mg/dL).

Limits and tips

• Pick the right test type. A reading of 150 mg/dL after a meal means something different from 150 mg/dL fasting.
• Home meters are not lab tests. Meter readings are useful for tracking, but diagnosis relies on laboratory measurements.
• Readings near a boundary deserve a repeat test rather than a conclusion either way.
• Low readings need action. If you have diabetes and a low reading with symptoms, follow the plan your care team has given you.
• Talk to a doctor about any result that worries you. Values stay in your browser.