Glucose testing is a standard part of prenatal care, and for women pregnant after 35, understanding this screening process can help reduce anxiety and support more informed conversations with a healthcare provider. Gestational diabetes—high blood sugar that develops during pregnancy—is more common with increasing maternal age, which is one reason glucose screening is a routine part of antenatal care for all pregnant women and a topic worth understanding in more depth for older mothers.
According to the American College of Obstetricians and Gynecologists (ACOG), gestational diabetes affects between 6–9% of pregnancies in the United States. While the condition requires management, it is also highly manageable with appropriate medical guidance, and the majority of women with gestational diabetes go on to have healthy pregnancies and deliveries.
Why Glucose Screening Matters After 35
Age is one of several risk factors associated with gestational diabetes. Other factors include a family history of type 2 diabetes, previous gestational diabetes, a BMI above 25, certain ethnic backgrounds, and a prior baby weighing more than 9 pounds. Having one or more of these risk factors does not mean gestational diabetes will develop, but it underscores why routine screening is valuable.
Unmanaged gestational diabetes can affect both maternal and foetal health, including increasing the risk of large-for-gestational-age babies, birth complications, and a higher likelihood of caesarean delivery. It is also associated with an increased risk of developing type 2 diabetes later in life for the mother. Early identification through screening enables timely management that significantly reduces these risks.
How Glucose Screening Works
The One-Hour Glucose Challenge Test
The initial screening test is typically the one-hour glucose challenge test (GCT), performed between 24 and 28 weeks of pregnancy. You drink a glucose solution, and your blood glucose is measured one hour later. This test does not require fasting beforehand. A result above a defined threshold (typically 130–140 mg/dL, depending on the laboratory) indicates a need for further testing—it does not diagnose gestational diabetes on its own.
The Three-Hour Glucose Tolerance Test
If the one-hour test result is elevated, a three-hour glucose tolerance test (GTT) is performed. This test requires fasting overnight and involves multiple blood draws over three hours after drinking a higher-concentration glucose solution. Gestational diabetes is diagnosed if two or more of the four readings (fasting, one-hour, two-hour, three-hour) exceed defined thresholds. Some practices use the two-hour GTT as an alternative approach; your provider can explain which protocol they use.
Alternative Screening for High-Risk Pregnancies
Women with multiple risk factors or a history of gestational diabetes may be offered earlier screening—sometimes in the first trimester—in addition to the standard 24–28 week test. This is worth discussing at your first prenatal appointment if it applies to you. Our article on prenatal testing after 35 covers the broader landscape of antenatal screening in more detail.
Managing Gestational Diabetes If Diagnosed
A diagnosis of gestational diabetes does not automatically mean medication is required. Many women manage gestational diabetes effectively through dietary adjustments and regular physical activity alone. Blood glucose monitoring at home is typically part of management, allowing you and your healthcare team to track how your levels respond to meals and activity.
For women whose blood sugar does not respond adequately to lifestyle measures, medication—most commonly insulin or metformin—may be recommended. Both options have established safety profiles in pregnancy when used as directed. Management plans are tailored to individual needs, and regular contact with your obstetric team is a key part of ensuring both maternal and foetal wellbeing throughout the pregnancy.
After Pregnancy: Postpartum Glucose Monitoring
Gestational diabetes typically resolves after delivery as pregnancy hormones normalise, but it is associated with an increased lifetime risk of developing type 2 diabetes. ACOG recommends postpartum glucose testing at 4–12 weeks after delivery and at regular intervals thereafter. Women with a history of gestational diabetes are advised to maintain awareness of their glucose health long term. This follow-up is an important but sometimes overlooked part of care after a gestational diabetes diagnosis.
Frequently Asked Questions
Does age alone increase gestational diabetes risk significantly?
Age over 35 is associated with a modestly higher risk of gestational diabetes compared to younger pregnant women, but it is one of several risk factors rather than a standalone determinant. Many women over 35 do not develop gestational diabetes, and standard screening catches cases that do occur, enabling management that supports healthy outcomes.
What should I eat before the glucose challenge test?
The one-hour glucose challenge test typically does not require fasting, though some providers suggest avoiding high-sugar foods or drinks in the hour or two before the test. Your healthcare provider will give you specific preparation instructions. The three-hour test does require overnight fasting, and your provider will explain the protocol in advance.
Does gestational diabetes mean I’ll have diabetes after pregnancy?
Gestational diabetes usually resolves after delivery, but it does increase the lifetime risk of type 2 diabetes—research suggests approximately 50% of women with gestational diabetes may develop type 2 diabetes within 5–10 years. Regular postpartum glucose monitoring and lifestyle awareness are recommended as part of long-term health management after a gestational diabetes diagnosis.
Can gestational diabetes be prevented?
There is no guaranteed way to prevent gestational diabetes, but a healthy weight before pregnancy, regular physical activity, and a balanced diet are associated with lower risk in some research. Discussing your individual risk factors with your healthcare provider before and during pregnancy can inform a personalised approach to monitoring and lifestyle.
Key Takeaways
- Glucose screening is a standard part of prenatal care; the one-hour challenge test is typically performed at 24–28 weeks and does not require fasting.
- Age over 35 is one of several risk factors for gestational diabetes, but the majority of older pregnant women do not develop the condition.
- A positive initial screening result requires follow-up testing—it does not diagnose gestational diabetes on its own.
- Many cases of gestational diabetes are managed effectively through dietary adjustments and blood glucose monitoring, without requiring medication.
- Postpartum glucose testing is recommended after a gestational diabetes diagnosis, given the increased long-term risk of type 2 diabetes.
Medical Disclaimer
This content is for informational purposes only and does not constitute medical advice. Individual health situations vary significantly. Always consult a qualified healthcare provider before making decisions related to your health, fertility, or pregnancy.
About the Author
Emily Carter is a women’s health writer focused on fertility, pregnancy after 35, and sleep changes in midlife. She writes research-informed, non-alarmist content to help women navigate reproductive and hormonal transitions with clarity and confidence.