Gestational diabetes is largely preventable through a combination of diet, exercise, weight management, and sleep habits. About 79 out of every 1,000 U.S. births involved gestational diabetes in 2024, a rate that has climbed 36% since 2016 and continues rising across every racial and ethnic group. The good news: lifestyle changes started early in pregnancy, or even before conception, can meaningfully lower your risk.
Start Before Pregnancy if You Can
Your pre-pregnancy weight is one of the strongest predictors of gestational diabetes risk. An Australian population study found that women who reduced their BMI between pregnancies had a 36% lower risk of developing gestational diabetes in their next pregnancy compared to women whose weight stayed the same. You don’t need to hit a perfect number. Even a modest reduction in body weight before conceiving shifts the odds in your favor.
If you’re planning a pregnancy, this is the single most impactful window for prevention. Losing 5 to 10% of your body weight through sustainable changes (not crash dieting) can improve how your body handles insulin before the metabolic demands of pregnancy even begin.
Follow a Mediterranean-Style Eating Pattern
The specific diet with the most evidence behind it for gestational diabetes prevention is the Mediterranean diet: heavy on vegetables, fruits, whole grains, legumes, nuts, olive oil, and fish, with limited processed foods and added sugars. Randomized controlled trials show that women who closely follow this pattern during pregnancy reduce their risk of gestational diabetes by roughly 25 to 28%. One trial that added extra-virgin olive oil and pistachios to the Mediterranean framework found a similar reduction.
What makes this pattern effective isn’t any single food. It’s the overall combination of fiber, healthy fats, and complex carbohydrates that slows the release of sugar into your bloodstream. Practically, this looks like building meals around vegetables and whole grains, using olive oil as your primary cooking fat, snacking on nuts instead of refined carbs, and eating fish a couple of times a week. You don’t need to follow a rigid meal plan. The closer you get to this pattern overall, the more benefit you get.
One consistent finding: higher adherence to this eating style also reduces the risk of gaining too much weight during pregnancy, which is itself a risk factor for gestational diabetes.
How Much Weight to Gain During Pregnancy
Gaining too much weight during pregnancy increases your body’s resistance to insulin, which is the core mechanism behind gestational diabetes. The CDC publishes weight gain ranges based on your pre-pregnancy BMI:
- Underweight (BMI under 18.5): 28 to 40 pounds
- Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds
- Overweight (BMI 25.0 to 29.9): 15 to 25 pounds
- Obese (BMI 30.0 to 39.9): 11 to 20 pounds
These ranges exist because the right amount of weight gain depends on where you started. If your BMI is in the overweight or obese range before pregnancy, staying toward the lower end of your recommended range can significantly reduce metabolic strain. Your provider can help you track this at routine visits.
Move Your Body Most Days
Physical activity helps your muscles absorb blood sugar without needing as much insulin, which directly counteracts the insulin resistance that builds during pregnancy. The American Diabetes Association notes that diet, exercise, and lifestyle counseling can reduce gestational diabetes risk, particularly when started in the first trimester or early in the second.
Walking is the simplest, best-studied option. A 20-minute walk after meals helps lower the blood sugar spike that follows eating. Aim for some form of moderate activity most days of the week. Swimming, stationary cycling, prenatal yoga, and light strength training all count. The key is consistency rather than intensity. You’re not training for performance. You’re keeping your blood sugar regulation system working efficiently throughout the day.
If you were sedentary before pregnancy, start with 10 to 15 minutes of walking after your largest meal and build from there. If you were already active, you can generally continue your routine with modifications as your pregnancy progresses.
Sleep Matters More Than You Think
Sleep duration has a surprisingly strong link to gestational diabetes risk, and it works in both directions. Pregnant women who sleep fewer than seven hours a night face a significantly higher chance of developing the condition. One large study of over 12,000 women found that sleeping under seven hours in mid-pregnancy increased the risk by 21%. Another meta-analysis found that women sleeping fewer than six to seven hours had a 70% higher risk compared to those getting adequate rest.
Sleeping too much also appears problematic. Women sleeping nine or more hours per night showed a 61% increased risk in one analysis. The sweet spot, consistently across studies, is seven to nine hours per night.
This connection likely involves how sleep deprivation disrupts hormones that regulate blood sugar and appetite. If you’re struggling with sleep during pregnancy (which is common), focus on what you can control: a consistent bedtime, limiting fluids close to bed to reduce nighttime bathroom trips, and sleeping on your side with a pillow between your knees for comfort.
Vitamin D and Gestational Diabetes Risk
Low vitamin D levels during pregnancy are associated with a higher risk of gestational diabetes, particularly when combined with other risk factors. One study found that pregnant women who smoked and had very low vitamin D levels (below 30 nmol/L) had nearly four times the odds of developing the condition compared to nonsmokers with adequate levels.
Many pregnant women are deficient without knowing it, especially those who live in northern climates, have darker skin, or spend limited time outdoors. Your prenatal care typically includes checking vitamin D status, and most prenatal vitamins contain some. If your levels are low, your provider may recommend additional supplementation. Getting regular sunlight exposure and eating vitamin D-rich foods like fatty fish, fortified milk, and eggs can also help.
A Supplement Worth Knowing About
Myo-inositol, a compound naturally found in fruits, beans, grains, and nuts, has shown strong results in clinical trials for preventing gestational diabetes in high-risk women. Taken at 2 grams twice daily throughout pregnancy, it reduced the incidence of gestational diabetes by 65 to 87% in some studies. In women specifically at risk due to a family history of type 2 diabetes, the same dose reduced incidence by about 40%.
Myo-inositol works by improving how your cells respond to insulin. It’s generally considered safe during pregnancy and is available as an over-the-counter supplement, but it’s worth discussing with your provider before starting, especially since the evidence is strongest for women who are already at elevated risk (due to family history, polycystic ovary syndrome, or obesity).
What Doesn’t Work
Not every intervention lives up to its promise. A meta-analysis of 11 randomized trials found that metformin, a common blood sugar medication sometimes prescribed to high-risk pregnant women, does not reduce the risk of gestational diabetes in women with obesity, polycystic ovary syndrome, or preexisting insulin resistance. This is worth knowing because it underscores that lifestyle changes remain the primary prevention tool, not medication.
Who Faces the Highest Risk
Gestational diabetes rates vary substantially by race and ethnicity. In 2024, American Indian and Alaska Native women had the highest rate at 137 per 1,000 births, followed by Asian women at 131 per 1,000 and Native Hawaiian/Pacific Islander women at 126 per 1,000. Hispanic women had a rate of 85 per 1,000, White women 71, and Black women 67. Other risk factors include being over 25, having a family history of type 2 diabetes, having had gestational diabetes in a previous pregnancy, and carrying excess weight.
If you fall into a higher-risk group, the lifestyle strategies above become even more important, and early screening (often in the first trimester rather than the standard 24 to 28 weeks) may be recommended. Prevention strategies are most effective when they begin early, ideally in the first trimester or before conception.