What Causes Gestational Diabetes? Symptoms, Risks & MD Guide

In my years of clinical practice, I have sat across from many expectant mothers who are surprised, and often distressed, by a diagnosis of gestational diabetes. One of the very first questions they ask is, “What causes gestational diabetes?” There is often a sense of misplaced guilt, as if a specific meal or a skipped workout session triggered the condition.

The reality is that gestational diabetes is a complex metabolic shift driven primarily by the biological demands of pregnancy itself. It is a form of high blood sugar that develops during pregnancy in women who did not previously have diabetes. Understanding what causes gestational diabetes in pregnancy is the first step toward managing it effectively and ensuring a healthy outcome for both mother and baby.

It is important to remember that this condition is common and highly manageable. By identifying why women get diabetes during pregnancy, we can move away from blame and toward proactive care. This guide will walk you through the hormonal, genetic, and lifestyle factors involved in what gestational diabetes is and what causes it.

What Is Gestational Diabetes?

Gestational diabetes mellitus (GDM) occurs when the body cannot properly process carbohydrates for the first time during pregnancy. Unlike type 1 diabetes, which results from an autoimmune response, or type 2 diabetes, which often stems from long-term metabolic issues, GDM specifically relates to the physiological changes that happen during pregnancy.

It typically develops between weeks 24 and 28 of pregnancy. This is the window when the placenta is growing rapidly and producing high levels of hormones. While most women’s bodies can compensate for these changes, others cannot, leading to elevated blood glucose levels.

Statistics show that gestational diabetes affects approximately 6% to 9% of all pregnancies in the United States. In the United Kingdom, the NHS estimates that about 5% of pregnant people develop the condition. However, these rates are not uniform across all populations, highlighting the role of genetics and underlying health.

When we look at gestational diabetes and what causes it, we must look at the pancreas. In a healthy pregnancy, the pancreas produces extra insulin to keep blood sugar stable. In GDM, the pancreas cannot keep up with the increased demand, leading to insulin resistance and high blood sugar.

What Causes Gestational Diabetes in Pregnancy?

To understand what causes gestational diabetes during pregnancy, we have to look at the organ that connects the mother to the baby: the placenta. The placenta is an endocrine powerhouse, churning out hormones necessary for the baby’s growth and development.

However, these very hormones have a secondary, often problematic effect on the mother’s metabolism. They are designed to ensure the baby has enough glucose for fuel, but they do this by making the mother’s cells more resistant to her own insulin.

The Role of Pregnancy Hormones

There is not a single hormone that causes gestational diabetes; rather, it is a cocktail of several hormones working in tandem. As the placenta grows, it releases increasing amounts of these substances into the mother’s bloodstream.

The primary hormones involved in this process include:

Human placental lactogen (hPL): This hormone modifies the mother’s metabolic state to facilitate energy supply to the fetus, often blocking the action of insulin.
Progesterone: While vital for maintaining the pregnancy, high levels can interfere with insulin receptor signaling in the mother’s cells.
Cortisol: Often called the stress hormone, its levels rise during pregnancy and naturally increase insulin resistance.
Placental growth hormone: This hormone helps regulate the baby’s growth but also stimulates the liver to release more glucose.

This hormonal shift creates a state of “physiologic insulin resistance.” This means every pregnant woman experiences some level of resistance. What causes gestational diabetes to occur in some women and not others is the ability of the pancreas to compensate for this resistance.

Why Some Women Develop Gestational Diabetes

In a typical pregnancy, the pancreas detects the rising blood sugar and pumps out two to three times more insulin than usual. This extra insulin overcomes the “blocking” effect of the placental hormones, keeping the mother’s glucose levels in a healthy range.

When we ask what causes you to have gestational diabetes, the answer is often an “insulin gap.” This occurs when the mother’s pancreas is unable to produce that massive extra surge of insulin. The result is that glucose remains in the blood rather than being used by the cells for energy.

This metabolic failure can be due to pre-existing insulin resistance that was present before pregnancy but not yet detectable. Pregnancy simply acts as a “stress test” for the pancreas, revealing an underlying vulnerability in how the body processes carbohydrates and sugar.

Risk Factors for Gestational Diabetes

While the causes of gestational diabetes are largely hormonal, certain factors make a woman much more likely to experience that “insulin gap.” In my experience, identifying these risks early allows for earlier screening and more personalized intervention.

Major risk factors for gestational diabetes include:

Obesity: A Body Mass Index (BMI) of 30 or higher significantly increases pre-pregnancy insulin resistance.
Age Over 25: The risk of developing GDM increases as a woman gets older, particularly after the age of 25.
Family History: Having a first-degree relative (parent or sibling) with type 2 diabetes increases your genetic predisposition.
Previous Gestational Diabetes: If you had GDM in a previous pregnancy, you have a 30% to 60% chance of it recurring.
PCOS: Polycystic Ovary Syndrome is inherently linked to insulin resistance, making GDM more likely.

Ethnicity plays a major role in prevalence. Data from the Centers for Disease Control and Prevention (CDC) shows significant disparities in GDM rates among different racial and ethnic groups in the US:

Asian Americans: 12.8%
Hispanic/Latina women: 10.2%
Black/African American women: 9.9%
White/Caucasian women: 7.0%

In the UK, women of South Asian, Black African, and African-Caribbean descent are at a higher risk. These statistics are vital for healthcare providers to ensure that high-risk groups receive the specialized screening they need to stay safe during pregnancy.

Can Food Cause Gestational Diabetes?

A very common misconception is that gestational diabetes is caused by food choices made during the first trimester. I have had patients ask, “Did I get this because I ate too much ice cream last week?” The answer is a definitive no.

Food alone does not cause gestational diabetes; the hormonal environment of the placenta is the primary driver. However, dietary patterns can certainly increase your risk if you already have a predisposition toward insulin resistance.

Diets high in ultra-processed foods, sugary drinks, and refined carbohydrates can put an additional strain on an already struggling pancreas. While these foods don’t “create” the condition, they can push a borderline pancreas over the edge into a GDM diagnosis.

Instead of asking what food causes gestational diabetes, it is considered more helpful to focus on how food can be used to manage it. Nutrition is regarded as the most powerful tool available for stabilizing blood sugar levels once the diagnosis is made, but it is acknowledged that the initial trigger is always biological.

Is Gestational Diabetes Caused by the Father?

This is a question that frequently comes up in counseling: Is gestational diabetes caused by the father? While the father’s DNA contributes to the formation of the placenta, the condition itself is a result of the mother’s metabolic response to that placenta.

Genetics from both parents determines the “aggressiveness” of the placental hormones. In that sense, paternal genes play a role in how much insulin resistance the placenta creates. However, the father’s lifestyle, diet, or weight has no direct impact on whether the mother develops GDM.

If you are a mother asking, “Did I cause my gestational diabetes?” please hear me: you did not. You cannot control how your placenta secretes hormones or how your pancreas responds to the massive physiological shifts of pregnancy.

This condition is a reflection of your body’s current metabolic capacity under extreme stress. It is not a failure of character or a result of “bad” behavior. Focus your energy on the management plan rather than looking for a source of blame.

Early Signs and Symptoms of Gestational Diabetes

One of the most challenging aspects of this condition is that most women have no symptoms at all. This is why universal screening is so important. Often, the symptoms of gestational diabetes are so mild that they are mistaken for regular pregnancy discomforts.

In cases where sugar levels are significantly elevated, you might notice early signs of gestational diabetes, such as the following:

Increased Thirst: Feeling like you can’t get enough water despite drinking frequently.
Frequent Urination: Needing to go more often than the usual pregnancy-induced frequency.
Fatigue: Feeling an overwhelming sense of exhaustion that goes beyond normal pregnancy tiredness.
Blurred Vision: Temporary vision changes caused by high sugar levels affecting the fluid in the eyes.

Because these warning signs of gestational diabetes are so subtle, many women are shocked by their test results. If you do experience these, it doesn’t mean something is permanently wrong, but it does mean your body is struggling to process the glucose in your system.

Gestational Diabetes Test: How It Is Diagnosed

Because symptoms are rare, a gestational diabetes test is a standard part of prenatal care. In the US, this usually happens between 24 and 28 weeks, but it may occur earlier if you have significant risk factors.

Screening Test: The Glucose Challenge Test

This is the first step. You will drink a syrupy liquid containing a specific amount of glucose. One hour later, your blood is drawn to see how your body handled the sugar. You do not need to fast for this specific test.

Diagnostic Test: Oral Glucose Tolerance Test (OGTT)

If your screening results are high, you will take the OGTT. This requires fasting overnight. Your blood is drawn, then you drink a high-sugar solution, and your blood is drawn again at one-, two-, and sometimes three-hour intervals.

In the UK, the NHS typically uses the OGTT directly for women who have at least one risk factor. Understanding these tests is crucial because a diagnosis allows us to intervene before high sugar levels can affect the baby’s growth.

How Gestational Diabetes Affects Pregnancy

A diagnosis of GDM is taken seriously because of how gestational diabetes affects pregnancy and the developing fetus. When the mother has high blood sugar, that extra glucose crosses the placenta to the baby.

The baby’s pancreas must then produce extra insulin to handle the sugar. Since insulin is a growth hormone, this can lead to several complications:

Large Birth Weight (Macrosomia): Extra sugar makes the baby grow too large, which can lead to birth injuries or the need for a C-section.
Preterm Birth: High sugar levels can trigger early labor or lead to a medical recommendation for early delivery.
Low Blood Sugar (Hypoglycemia) After Birth: Once the baby is born and the sugar supply is cut off, their high insulin levels can cause their own sugar to drop dangerously low.
Respiratory Distress: Babies of mothers with GDM are at a higher risk of breathing difficulties at birth.

Regarding the most serious concerns, what causes stillbirth with gestational diabetes is usually chronic, untreated high blood sugar that affects placental function and oxygen delivery. However, it is vital to know that with modern management, the risk of stillbirth is not significantly higher than in a normal pregnancy.

Gestational Diabetes Diet and Treatment

Once diagnosed, the goal of gestational diabetes treatment is to keep blood sugar levels equal to those of a woman without the condition. For most women, this can be achieved through lifestyle changes alone.

The Gestational Diabetes Diet

A gestational diabetes diet is not about deprivation; it is about balance. You need to eat enough to fuel the baby while avoiding large sugar spikes.

Complex Carbohydrates: Swap white bread and rice for brown rice, quinoa, and whole grains.
Lean Protein: Include chicken, fish, tofu, or beans with every meal to slow sugar absorption.
High Fiber: Aim for plenty of non-starchy vegetables like spinach, broccoli, and peppers.
Small, Frequent Meals: Eating five to six small meals a day prevents the pancreas from being overwhelmed.

Exercise and Activity

Physical activity makes your cells more sensitive to insulin. A simple 15-minute walk after meals can significantly lower your post-meal glucose readings. Prenatal yoga and swimming are also excellent, low-impact ways to stay active.

Medication and Insulin

If diet and exercise aren’t enough, we use medication. About 10% to 20% of women with GDM will need insulin. Insulin is the “gold standard” because it does not cross the placenta, making it very safe for the baby.

In some cases, oral medications like metformin may be used, though insulin is often preferred for its precision. Using medication is not a failure; it is simply a way to provide your body with the extra help it needs during this high-demand period.

How to Prevent Gestational Diabetes

Many women ask, “Can I prevent gestational diabetes?” The answer is that you can significantly reduce your risk, but you cannot always prevent it, especially if you have a strong genetic predisposition.

If you are asking how to avoid gestational diabetes while pregnant, the best strategy is early intervention. Starting pregnancy at a healthy weight and maintaining a consistent exercise routine can help keep your insulin receptors active.

Focus on how to avoid gestational diabetes by:

Attending all prenatal checkups to catch rising sugar levels early.
Focusing on whole foods rather than processed “pregnancy cravings.”
Staying hydrated, as dehydration can cause sugar concentrations to rise.

Even with the best efforts, some women will still develop GDM. If this happens to you, remember that the most important thing is how you manage it after diagnosis, not whether you could have “stopped” it from happening.

Does Gestational Diabetes Go Away After Pregnancy?

One of the best pieces of news is that for the vast majority of women, does gestational diabetes go away immediately after delivery? Once the placenta is delivered, the source of the insulin-blocking hormones is gone, and blood sugar levels usually return to normal within hours.

However, your journey doesn’t end there. Having GDM is a significant indicator of future health. Women who have had gestational diabetes have a 50% higher risk of developing type 2 diabetes later in life.

Postpartum care should include a follow-up glucose test 6 to 12 weeks after delivery. It is also recommended to maintain a healthy weight and stay active in the years following your pregnancy to mitigate the long-term risk of type 2 diabetes.

Can You Have a Healthy Baby With Gestational Diabetes?

I want to offer a resounding “yes” to the question: Can I have a healthy baby with gestational diabetes? While the diagnosis sounds scary, the medical community has become incredibly adept at managing this condition.

The key to a healthy baby is compliance with your care plan. By monitoring your blood sugar, following your gestational diabetes diet, and staying active, you are doing the hard work to protect your baby.

Most women with GDM go on to have completely normal deliveries and healthy, thriving infants. The diagnosis is simply a signal that your body needs a little extra attention and care for a few months.

What Happens If You Have Gestational Diabetes?

If your test comes back positive, here is the care pathway you can expect. First, you will likely be referred to a registered dietitian or a diabetes educator who will teach you how to use a glucose monitor.

You will begin testing your sugar four times a day: once when you wake up and one hour after each main meal. You will keep a log of these numbers and your food intake. Your medical team will review these logs weekly to see if any adjustments are needed.

If your numbers remain high despite diet changes, your doctor will discuss medication options. You may also have more frequent ultrasounds to monitor the baby’s growth and amniotic fluid levels. Toward the end of the pregnancy, your doctor will plan the timing of your delivery to ensure the safest possible birth.

Frequently Asked Questions

What Causes Gestational Diabetes?

Gestational diabetes is caused by placental hormones that create insulin resistance in the mother. If the pancreas cannot produce enough extra insulin to overcome this resistance, blood sugar levels rise.

Why Do Women Get Diabetes During Pregnancy?

Women get diabetes during pregnancy because the metabolic demands of the fetus and the placenta outpace the mother’s ability to produce insulin. It is often a result of underlying insulin resistance and genetic factors.

Is Gestational Diabetes Dangerous?

It can be dangerous if left untreated, leading to high birth weight and delivery complications. However, when managed with diet, exercise, or medication, most pregnancies are healthy and successful.

How to Avoid Gestational Diabetes While Pregnant?

To reduce your risk, focus on a balanced diet rich in whole foods, stay physically active with daily walking, and maintain a healthy weight gain according to your doctor’s recommendations.

Does Gestational Diabetes Go Away?

Yes, in most cases, gestational diabetes resolves as soon as the baby and placenta are delivered. However, it does increase the risk of developing type 2 diabetes in the future.

Conclusion

A gestational diabetes diagnosis can feel like a heavy weight during an already emotional time. However, understanding that it is primarily a hormonal response to the placenta can provide peace of mind. You did not cause this, but you do have the power to manage it through consistent care and lifestyle adjustments.

By staying diligent with your glucose monitoring and balanced nutrition, you are providing the best environment for your baby to thrive. Most women find that the habits they build during this period lead to a healthier lifestyle long after the baby arrives. It is a temporary metabolic hurdle, not a permanent label.

Remember, this is just one short chapter in your journey to motherhood. With the right medical team and a proactive approach, you can look forward to a safe delivery and a healthy future for both you and your little one. Stay focused on the goal, and take it one meal at a time.

What Causes Gestational Diabetes? Symptoms, Risk Factors, Prevention & Treatment