What are the symptoms of gestational diabetes mellitus?

Most patients have no symptoms. GDM is almost always caught by routine screening, not because anything felt wrong.; When symptoms do show up, they overlap with normal pregnancy: unusual thirst, frequent urination beyond the baseline pregnancy increase, fatigue out of proportion to the trimester.; Recurrent yeast or urinary tract infections during pregnancy can be a sign of elevated glucose.; Blurred vision or a sweet smell on the breath are late signs and warrant same-day evaluation.; Because symptoms are unreliable, the diagnosis depends on getting screened on time. Skipping the 24-28 week glucose test because you feel fine is the most common way GDM gets missed.

What questions should I ask my doctor about gestational diabetes mellitus?

When will I be screened for gestational diabetes during this pregnancy, and what does the two-step process involve?; If I am diagnosed, should I see a maternal-fetal medicine specialist or a dietitian with MNT experience?; What are my blood sugar targets during pregnancy and how do I check them at home?; After delivery, when exactly should I have my postpartum OGTT, and how do I make sure it is scheduled before I leave the hospital?; Given that Black women have the highest risk of converting to type 2 diabetes after GDM, what is our specific plan for monitoring my blood sugar in the years after delivery?; If I have prediabetes at my postpartum test, what lifestyle and medication options are available to me?;

Endocrine / Metabolic Last reviewed: May 22, 2026

Gestational Diabetes Mellitus

Also known as: GDM, pregnancy-related diabetes, diabetes diagnosed during pregnancy

Reviewed by the Black Health editorial team Last reviewed May 2026

8.3%

of US pregnancies (2021 NVSS); rates among Black mothers climbed from 49.0 to 55.7 per 1,000 first live births between 2011 and 2019

Overview

Gestational diabetes mellitus (GDM) affects blood sugar during pregnancy and, if unmanaged, raises the risk of complications for both mother and baby. For Black mothers, the stakes after delivery are especially high: research shows Black women have the lowest rates of postpartum diabetes screening despite carrying the highest risk of converting to type 2 diabetes after GDM. That combination, high risk and low follow-up, is a documented gap in care that this page addresses directly.

How Gestational Diabetes Mellitus affects Black patients

The story you may have heard - that Black women are at the highest risk for gestational diabetes - is not quite what the data show. In a JAMA analysis of US first births from 2011 to 2019, age-standardized GDM rates among non-Hispanic Black mothers rose from 49.0 to 55.7 per 1,000 (Shah et al., JAMA 326:660-669, 2021), running slightly below the rate for non-Hispanic White mothers. What is different - and more dangerous - is what happens after delivery.

Black women with GDM convert to type 2 diabetes faster and more often than any other group in the US. A CDC Preventing Chronic Disease analysis of women with prior GDM found type 2 diabetes had developed in 30.8% of non-Hispanic Black women versus 22.1% of non-Hispanic White women, with Black women carrying a 63% higher hazard for conversion even after adjustment (Shah et al., Prev Chronic Dis 16:E18, 2019). A separate NHANES analysis of women with prior GDM put the burden of any chronic condition - diabetes, hypertension, cardiovascular disease, depression - at 74.4% in Black women versus 58.5% in White women, with 2.4 times the adjusted odds of carrying a chronic diagnosis (Xiang et al., J Womens Health 30:874-881, 2021).

The complications during the pregnancy itself also break harder on Black patients. Compared with non-Hispanic White women with the same diagnosis, Black women with GDM had 1.57 times the odds of preeclampsia and 1.56 times the odds of preterm delivery before 37 weeks, with Black neonates 1.79 times as likely to develop neonatal hypoglycemia (Nguyen et al., Am J Obstet Gynecol 207:322.e1-e6, 2012). These gaps held after controlling for maternal age, education, prenatal care timing, BMI, parity, and chronic hypertension.

Then there is the postpartum gap. ACOG recommends a 75-g oral glucose tolerance test between 4 and 12 weeks after delivery for every patient who had GDM, with rescreening every one to three years for life. National data show that fewer than half of women with GDM complete that postpartum OGTT, and Black women are less likely than White women to receive timely follow-up testing despite carrying the highest conversion risk (Ferrara et al., Diabetes Care; BMJ postpartum A1C study, 2026). The window where prediabetes is reversible - the window where metformin and a real referral matter - is the window Black patients are most often shut out of.

Symptoms

Most patients have no symptoms. GDM is almost always caught by routine screening, not because anything felt wrong.
When symptoms do show up, they overlap with normal pregnancy: unusual thirst, frequent urination beyond the baseline pregnancy increase, fatigue out of proportion to the trimester.
Recurrent yeast or urinary tract infections during pregnancy can be a sign of elevated glucose.
Blurred vision or a sweet smell on the breath are late signs and warrant same-day evaluation.

Because symptoms are unreliable, the diagnosis depends on getting screened on time. Skipping the 24-28 week glucose test because you feel fine is the most common way GDM gets missed.

When to see a doctor

If you are pregnant and have not been offered glucose screening by 28 weeks, call your obstetric provider and ask for it directly. The US Preventive Services Task Force gives screening at or after 24 weeks a Grade B recommendation, meaning insurers are required to cover it without cost-sharing under the Affordable Care Act (USPSTF, August 2021).

Ask for early screening at your first prenatal visit if you have a prior GDM pregnancy, a first-degree relative with type 2 diabetes, a BMI of 30 or higher, polycystic ovary syndrome, a prior baby weighing 9 pounds or more, or hypertension. ACOG's 2024 Clinical Practice Update endorses early screening at the first prenatal visit for high-risk patients to catch undiagnosed pregestational type 2 diabetes (ACOG, Obstet Gynecol 144:e20-e23, July 2024).

After delivery, get on the calendar for postpartum glucose testing between 4 and 12 weeks. If you do not hear from your provider's office, call. The single most important sentence in your postpartum chart is the result of that test.

Screening

The USPSTF recommends screening every pregnant person without known diabetes at or after 24 weeks of gestation, Grade B (USPSTF, August 2021). Two validated approaches are in routine use, and ACOG accepts both.

Two-step approach (used by most US obstetric practices). Step one is a non-fasting 50-g oral glucose challenge with venous glucose measured one hour later. A result at or above the institutional threshold (commonly 130, 135, or 140 mg/dL) triggers step two: a fasting 100-g, three-hour oral glucose tolerance test. Two or more abnormal values diagnose GDM. Carpenter-Coustan thresholds: fasting at or above 95, one-hour at or above 180, two-hour at or above 155, three-hour at or above 140 mg/dL. NDDG thresholds are slightly higher.

One-step approach (IADPSG, endorsed by the WHO and the American Diabetes Association). A single fasting 75-g, two-hour OGTT at 24-28 weeks. One abnormal value diagnoses GDM: fasting at or above 92, one-hour at or above 180, or two-hour at or above 153 mg/dL. The one-step approach catches more cases. The USPSTF, citing comparable maternal and infant outcomes between the two approaches, declined to endorse one over the other.

Early screening for high-risk patients. ACOG's 2024 Clinical Practice Update recommends screening for undiagnosed type 2 diabetes at the first prenatal visit in patients with risk factors (prior GDM, BMI 30 or higher, family history of diabetes, hypertension, prior macrosomic infant). Use a standard non-pregnancy diabetes test: fasting glucose, A1c, or 75-g OGTT.

Postpartum. Every patient with GDM should complete a 75-g, two-hour OGTT between 4 and 12 weeks after delivery, with rescreening every one to three years thereafter. ACOG shortened the lower bound from 6 weeks to 4 weeks in 2024 explicitly to reduce loss to follow-up.

Treatment overview

Lifestyle first. Medical nutrition therapy and physical activity are first-line for every patient. Most clinics work with a registered dietitian on carbohydrate distribution across meals and snacks, with glucose monitoring four times daily (fasting plus one or two hours after each meal). ACOG glycemic targets: fasting under 95 mg/dL, one-hour postprandial under 140, two-hour postprandial under 120 (ACOG Practice Bulletin 190, reaffirmed; ACOG Clinical Practice Update, 2024). Roughly 70-85% of patients achieve target on lifestyle alone.

Insulin when lifestyle is not enough. ACOG names insulin as the preferred pharmacologic therapy when nutrition and exercise do not get glucose to goal. It does not cross the placenta in clinically meaningful amounts and has the longest track record in pregnancy. Dosing is individualized: a basal-bolus regimen using long-acting insulin (detemir or NPH) plus rapid-acting insulin (aspart or lispro) at meals is standard.

Metformin and glyburide. Both oral agents cross the placenta. ACOG accepts metformin as a reasonable second-line option when patients decline insulin or cannot use it, while noting that long-term follow-up of children exposed in utero is incomplete and that up to 46% of patients on metformin will still need insulin added. Glyburide is no longer recommended as a first-line oral because it is associated with higher rates of neonatal hypoglycemia and macrosomia than insulin or metformin.

Delivery planning. Patients with well-controlled GDM on lifestyle alone do not need to deliver before 39 weeks. Patients on medication, or with poor control, are typically delivered between 39 and 39 weeks 6 days. Estimated fetal weight at or above 4,500 g is an indication to discuss scheduled cesarean to reduce shoulder dystocia and birth injury.

After delivery. Most pharmacologic therapy is stopped at delivery. The postpartum OGTT at 4-12 weeks is the hinge. If it is normal, rescreen every one to three years and treat lifestyle as long-term type 2 prevention. If it is abnormal, you have prediabetes or new type 2 diabetes, and metformin plus structured lifestyle programs (the CDC National Diabetes Prevention Program is covered by Medicare and most commercial plans) cut conversion to diabetes by more than half.

Questions to ask your doctor

Bring this list to your next appointment.

When will I be screened for gestational diabetes during this pregnancy, and what does the two-step process involve?
If I am diagnosed, should I see a maternal-fetal medicine specialist or a dietitian with MNT experience?
What are my blood sugar targets during pregnancy and how do I check them at home?
After delivery, when exactly should I have my postpartum OGTT, and how do I make sure it is scheduled before I leave the hospital?
Given that Black women have the highest risk of converting to type 2 diabetes after GDM, what is our specific plan for monitoring my blood sugar in the years after delivery?
If I have prediabetes at my postpartum test, what lifestyle and medication options are available to me?

The numbers

Non-Hispanic Black women have a gestational diabetes prevalence of approximately 4.4%, comparable to non-Hispanic white women at 4.2%. GDM does not strike Black mothers more often during pregnancy. What happens after delivery is where the disparity becomes severe. (PMC: Disparities in the Risk of Gestational Diabetes by Race-Ethnicity and Country of Birth, PMC4180530)

Within 8 years of a GDM pregnancy, 1 in 5 Black women will have developed type 2 diabetes, compared to 1 in 7 for Hispanic women and 1 in 20 for non-Hispanic white women. (Columbia University Mailman School of Public Health: Examining Disparities for Developing Diabetes Mellitus Following Gestational Diabetes)

A CDC-linked study found that 30.8% of non-Hispanic Black women who had GDM developed type 2 diabetes, compared to 22.1% of non-Hispanic white women. Black women had a 63% higher hazard of developing type 2 diabetes (HR = 1.63). (PMC: Racial/Ethnic Differences in Diabetes Screening and Hyperglycemia Among US Women After Gestational Diabetes, PMC6824147)

Only 33% of Black women with a prior GDM pregnancy complete the recommended postpartum diabetes screening, compared to 35% of white women, 45% of Hispanic women, and 50% of Asian women. All rates are low. Black women's rate is the lowest in the country. (PMC: Maternal Race/Ethnicity and Postpartum Diabetes Screening, PMC7247031)

Black women born outside the United States face an approximately 80% higher risk of developing GDM compared to US-born Black women, suggesting that nativity and immigration status add further complexity to this picture. (PMC: Disparities in the Risk of Gestational Diabetes by Race-Ethnicity and Country of Birth, PMC4180530)

Across all women with GDM, up to 50% will develop type 2 diabetes within 10 years. For Black women, that trajectory is steeper and faster. (NIDDK: Diabetes Statistics)

What it is

Gestational diabetes is high blood sugar that develops during pregnancy in a woman who did not have diabetes before. During pregnancy, the placenta produces hormones that cause insulin resistance, meaning the body needs more insulin than usual to keep blood sugar normal. When the pancreas cannot keep up, blood sugar rises.

Most women are screened between 24 and 28 weeks of pregnancy using the oral glucose tolerance test (OGTT). A one-hour glucose challenge test is often done first; if the result is elevated, the full OGTT (a two or three-hour test after fasting) confirms diagnosis.

GDM usually resolves after delivery. The baby no longer needs the placenta's hormones, insulin resistance drops, and blood sugar returns to normal. But the underlying predisposition, a pancreas that struggled to compensate under demand, does not disappear. That is why postpartum monitoring matters.

Why it is different for Black mothers

The postpartum conversion risk is the central issue. GDM is, in many ways, a stress test that reveals pre-existing metabolic vulnerability. Black women appear to have a physiological profile that makes conversion from GDM to type 2 diabetes faster and more likely. Researchers have documented that social and structural factors at the time of delivery explain about 27% of the increased risk, meaning biology and circumstances both contribute. (Columbia University Mailman School of Public Health)

Postpartum screening falls apart for Black mothers specifically. The recommended test is a 75-gram OGTT at 4 to 12 weeks postpartum, followed by testing every 1 to 3 years thereafter. Research consistently shows Black women are least likely to complete this follow-up. Two factors drive this: practical barriers in the postpartum period (childcare, time off work, insurance gaps) and documented medical mistrust rooted in real historical and ongoing experiences of racism in healthcare settings. Research has found that perceived racism in healthcare is a significant predictor of reduced postpartum follow-up among Black mothers. (PMC: Maternal Race/Ethnicity and Postpartum Diabetes Screening, PMC7247031)

Black maternal health and GDM intersect. Black women in the United States already face maternal mortality rates that are approximately 2.6 times higher than white women. GDM, if unmanaged, increases risks of preeclampsia, cesarean delivery, large-for-gestational-age babies, and hypoglycemia in the newborn. The combination of elevated GDM complications during pregnancy and high postpartum conversion risk makes comprehensive management during and after pregnancy non-negotiable for this population.

Socioeconomic and structural barriers compound risk. Food insecurity, limited access to fresh produce, high-stress living environments, and reduced access to specialists all make it harder to prevent GDM from becoming type 2 diabetes. These are not choices; they are conditions produced by documented structural inequities.

Treatment, plainly

During pregnancy: The first line of treatment is medical nutrition therapy (MNT), meaning a carbohydrate-controlled diet designed to keep blood sugar in a target range. Most women manage GDM with diet and physical activity alone. When lifestyle changes are not enough, insulin is the preferred medication because it does not cross the placenta. Metformin and glyburide are sometimes used but carry specific limitations. Blood sugar is monitored daily with a home glucometer.

Targets during pregnancy (per ADA and ACOG):

Fasting blood glucose: less than 95 mg/dL
One-hour postmeal: less than 140 mg/dL
Two-hour postmeal: less than 120 mg/dL

During labor and delivery: Blood sugar is monitored closely. If insulin was required during pregnancy, the clinical team manages dosing. The baby's blood sugar is checked after birth since maternal hyperglycemia causes fetal hyperinsulinism, and the newborn may experience a blood sugar drop.

After delivery: The glucose-lowering medication is usually stopped. The critical step is the 4 to 12-week postpartum OGTT to confirm that blood sugar has normalized. If it has, repeat testing every 1 to 3 years is recommended. If prediabetes is found, lifestyle intervention reduces the risk of full diabetes by up to 58%.

How to find care

Sources

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Medical disclaimer

This content is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about a medical condition. If you are experiencing a medical emergency, call 911 or your local emergency number immediately.

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