How is gestational diabetes diagnosed?

Gestational diabetes is usually diagnosed between the 24th and 28th week of pregnancy (when insulin resistance usually begins). If you have had gestational diabetes before, or if your doctor is concerned about your risk of developing gestational diabetes, the test may be performed before the 13th week of pregnancy.

To screen for gestational diabetes, you will take a test called the oral glucose tolerance test. You quickly drink a sweetened liquid, which contains 50g of glucose. The body absorbs this glucose rapidly, causing blood sugar levels to rise within 30-60 minutes. A blood sample will be taken from a vein in your arm about 30 minutes after drinking the solution. The blood test measures how the glucose solution was metabolized (processed by the body).

If your test results are not normal, you will have a similar type of diabetes test in which you have to fast (not eat anything) before the test. If this second test shows abnormal results, you have gestational diabetes.

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