The 1-Hour Glucose Test in Pregnancy: Cut-offs and What Happens Next
The 1-hour glucose test is a screen: you drink 50 grams of glucose, and a blood sample an hour later is compared with a cut-off of 130, 135 or 140 mg/dL, depending on your clinic. A value at or above the cut-off usually means a 3-hour test follows. It does not by itself mean you have gestational diabetes.
What happens
- You drink a 50-gram glucose drink. It is sweet and you drink it within a few minutes. ACOG describes this as a non-fasting test.
- You wait one hour. Most clinics ask you to sit and not eat or drink anything else.
- One blood sample is taken at the 1-hour mark and sent to a lab.
The NIDDK says testing is done between 24 and 28 weeks of pregnancy. The CDC gives the same window.
The cut-offs
| Cut-off used by the clinic | mg/dL | mmol/L |
|---|---|---|
| Lower | 130 | 7.2 |
| Middle | 135 | 7.5 |
| Higher | 140 | 7.8 |
ACOG accepts any of the three. A lower cut-off sends more people on to the 3-hour test, and a higher one fewer. A value at or above the clinic’s cut-off means the next step is the 3-hour glucose test.
See which cut-offs a value reaches
Nothing you type is stored or sent. This compares with published numbers; it is not a diagnosis.
How to prepare
- Ask your clinic whether to eat normally beforehand and whether to avoid anything. The official sources do not require fasting for this screen, but clinics differ.
- Plan to stay for the hour, and bring something to read.
- Tell the clinic about any medicine you take. Do not stop or change anything without asking.
- If the drink makes you feel unwell, tell the staff. Do not eat or drink anything else until the sample is taken unless they say so.
If the result is at or above the cut-off
You will usually be offered the 3-hour test with a 100 gram drink. That test, not this one, is used to diagnose. See the glucose tolerance test page for how the 75 gram and 100 gram versions differ. Write down any readings you take at home in the gestational diabetes log and share them with your care team.
Some clinics skip the two-step approach and use a single 75 gram, 2-hour test instead. ADA lists both approaches.
Frequently asked questions
Do I need to fast for the 1-hour glucose test?
No. ACOG describes the 50-gram glucose challenge as a non-fasting test, and ADA lists the first step of the two-step approach as a 50 g non-fasting load. Follow the instructions from your own clinic, because some give extra directions about what to eat beforehand.
What is a passing score?
There is no single pass mark. ACOG accepts three cut-offs for the 1-hour value: 130, 135 or 140 mg/dL (7.2, 7.5 or 7.8 mmol/L). Your clinic chooses one. A value at or above it usually leads to the 3-hour test, not to a diagnosis.
Does a high 1-hour result mean I have gestational diabetes?
No. The 1-hour test is a screen. Most official guidance uses it to decide who needs the longer 3-hour test, which is the one used to diagnose.
When is the test done?
The NIDDK and CDC both say testing happens between 24 and 28 weeks of pregnancy. People with higher risk may be tested earlier; your care team decides.
Can I take it at home?
No. The test is done at a clinic or lab with a measured 50 gram drink and a venous blood draw. Home meter readings are not used for the screen.
Information only, not medical advice. Your care team may set different targets for you, and only a lab test ordered by a clinician can diagnose diabetes or prediabetes. See our medical disclaimer.
Sources
- ADA Standards of Care in Diabetes—2026, Section 2: Diagnosis and Classification
- ACOG Practice Bulletin 190: Gestational Diabetes Mellitus (2018; cut-offs as quoted in ADA Standards 2026, Section 2)
- NIDDK: Gestational Diabetes (reviewed May 2017)
- ADA Standards of Care in Diabetes—2026, Section 15: Management of Diabetes in Pregnancy
Last reviewed: by the Diabetes Blogs editorial team. Information only, not medical advice.
