Normal 3 Hour Glucose Test Pregnancy

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How to Prepare for the Test

Eat your regular diet in the days leading up to your test, whether it’s a one-step test or a two-step test. Inquire with your doctor if any of the medications you take have the potential to affect your test results.

The glucose tolerance test rarely has negative effects on most female subjects. The glucose solution is similar to a very sweet soda when consumed. After consuming the glucose solution, some women might experience nausea, perspiration, or lightheadedness. Serious side effects from this test are very uncommon.

This test checks for gestational diabetes. A glucose screening test is typically performed on pregnant women between 24 and 28 weeks of pregnancy. If you have a high level of glucose in your urine during your routine prenatal visits or if you have a high risk for diabetes, the test might be performed earlier.

Women with a low risk of developing diabetes might choose not to have the screening test. To be low-risk, all of these statements must be true:

  • You have never had a test that showed your blood glucose was higher than normal.
  • Your ethnic group has a low risk for diabetes.
  • You do not have any first-degree relatives (parent, sibling, or child) with diabetes.
  • You are younger than 25 years old and have a normal weight.
  • You have not had any bad outcomes during an earlier pregnancy.
  • A blood sugar reading of 140 mg/dL or less is typically considered normal for the glucose screening test (7). 8 mmol/L) 1 hour after drinking the glucose solution. A normal result means you do not have gestational diabetes.

    Note: mmol/L denotes millimoles per liter and mg/dL denotes milligrams per deciliter. There are two ways to determine the blood’s level of glucose.

    If your blood glucose is higher than 140 mg/dL (7. 8 mmol/L), the oral glucose tolerance test follows. This test will show if you have gestational diabetes. About two out of every three women who take this test have gestational diabetes do not have it.

    You do not have gestational diabetes if your glucose level is lower than the abnormal results listed below.

    For a 3-hour 100-gram oral glucose tolerance test, abnormal blood values are:

  • Fasting: greater than 95 mg/dL (5.3 mmol/L)
  • 1 hour: greater than 180 mg/dL (10.0 mmol/L)
  • 2 hour: greater than 155 mg/dL (8.6 mmol/L)
  • 3 hour: greater than 140 mg/dL (7.8 mmol/L)
  • For a 2-hour 75-gram oral glucose tolerance test, abnormal blood values are:

  • Fasting: greater than 92 mg/dL (5.1 mmol/L)
  • 1 hour: greater than 180 mg/dL (10.0 mmol/L)
  • 2 hour: greater than 153 mg/dL (8.5 mmol/L)
  • Your healthcare provider may simply advise you to switch some of the foods you eat if only one of your blood glucose results from the oral glucose tolerance test is higher than normal. After you’ve altered your diet, your doctor might then retest you.

    You have gestational diabetes if more than one of your blood glucose results is higher than normal.

    You might experience some of the symptoms mentioned under the section “How the Test will Feel” “.

    There is little risk involved with having your blood taken. Each person’s veins and arteries are unique, as are the sizes on each side of the body. Some people may be more difficult to draw blood from than others.

    Having blood drawn carries a few minor additional risks, which could include:

  • Excessive bleeding
  • Fainting or feeling lightheaded
  • Multiple punctures to locate veins
  • Hematoma (blood buildup under the skin)
  • Infection (a slight risk any time the skin is broken)
  • American Diabetes Association Professional Practice Committee. 2. Diabetes classification and diagnosis: diabetes medical care standards through 2022 Diabetes Care. 2022;45(Suppl 1):S17-S38. PMID: 34964875 pubmed. ncbi. nlm. nih. gov/34964875/.

    Committee on Practice Bulletins–Obstetrics. Practice Bulletin No. 190: Gestational diabetes mellitus. Obstet Gynecol. 2018;131(2):e49-e64. PMID: 29370047 pubmed. ncbi. nlm. nih. gov/29370047/.

    Landon MB, Catalano PM, Gabbe SG. Diabetes mellitus complicating pregnancy. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbes Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 45.

    Metzger BE. Diabetes mellitus and pregnancy. Among others, eds. Jameson JL, De Groot LJ, de Kretser DM Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 45.

    Moore TR, Hauguel-De Mouzon S, Catalono P. Diabetes in pregnancy. Resnik, Lockwood, Moore, Moore, Greene, Copel, and Silver, editors. Creasy and Resniks Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 59.

    Last reviewed on: 4/19/2022

    Reviewed by: John D. Obstetrics and Gynecology Department, Loma Linda University School of Medicine, Loma Linda, California, Dr. Jacobson Also reviewed by David C. Brenda Conaway, the editorial director, Dugdale, MD, the medical D. A. M. Editorial team.


    Gestational diabetes is most often encountered in late pregnancy. A family history of diabetes, a history of delivering a baby who weighed more than nine pounds, a history of stillbirth or certain birth defects, high blood pressure, obesity, or being older than thirty at the time of delivery were once used as screening criteria for this disease. Nevertheless, screening for gestational diabetes is now done for all pregnant women between 24 and 28 weeks of pregnancy because many women develop the condition without any of these risk factors.

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