Gestational diabetes (GDM, or gestational diabetes mellitus) affects about 2 to 10% of pregnant women in the US every year [1]. Left untreated, GDM can cause serious long-term health complications for both a mom and her baby [2].
For a mom with gestational diabetes, there is a higher risk of:
- High blood pressure during pregnancy, or preeclampsia
- C-section delivery
- Gestational diabetes in future pregnancies, and/or type 2 diabetes later in life
For her baby, there is an increased risk of:
- Stillbirth
- Preterm birth
- Excessive birth weight
- Breathing difficulty
- Low blood sugar, obesity, and type 2 diabetes later in life
Pretty serious things.
Following an effective gestational diabetes meal plan is something you can do to protect against the development of GDM. Or to keep it under control. But there are other factors that are worth looking into. One of them is your microbiome composition.
What is gestational diabetes and who is at risk?
GDM occurs when a mom’s body isn’t able to process sugar efficiently [3]. Most cases of GDM result from dysfunction in the cells that produce insulin, a pancreatic hormone that helps regulate sugar levels [4]. When blood sugar levels are high, the pancreas produces insulin, and insulin signals to cells to take glucose in.
During pregnancy, mom’s hormone levels shift frequently to meet the needs of her growing baby:
- Throughout pregnancy, a cocktail of hormones promotes mild insulin resistance, that is, cells become less sensitive to insulin. This helps with glucose transport from the bloodstream to the placenta.
- In a healthy pregnancy, the cells that produce insulin kick into action and make more of it to prevent high blood sugar.
- In GDM, a mom’s body isn’t able to keep up with the needs of her pregnancy and produce enough insulin to keep her blood sugar in check. Combined with the insulin resistance caused by the cocktail of pregnancy hormones, the mom’s blood sugar increases and GDM can develop.
Gestational diabetes risk factors include:
- Advanced maternal age
- Family history of diabetes
- Being overweight or obese [4]
- Undiagnosed prediabetes [5], [6]
- Polycystic ovary syndrome (PCOS)
However, GDM can affect anyone. Your doctor will do a test to see if you have or are at risk of this condition between the 24th and 28th weeks of your pregnancy.
Some scientists think that this testing may be a little too late - there is evidence suggesting that by the time GDM is diagnosed, there may already be effects on the fetus [7], [8]. The good news is that early actions taken to reduce your risk can have long-term benefits for your health, regardless of whether you develop GDM.
The gut microbiome and gestational diabetes
It’s normal for the gut microbiome to change during pregnancy. This is especially true in the third trimester, when the gut microbiome shifts to a state that resembles that of people who are overweight or have metabolic syndrome [9], [10].
This shift makes it possible to give the baby all the nutrients necessary for healthy growth and development.
But what if your gut microbiome isn't that healthy to begin with? While we can’t say for sure that changes in the gut microbiome lead to GDM and not the other way around, several studies have found differences in the gut microbiome of women with GDM compared to healthy women.
So there's definitely a relationship between your gut microbes and GDM.
Some examples:
- Bacteroides levels are higher in women with GDM during the second and third trimester of pregnancy [11]–[14]. Some species of Bacteroides are friendly while others can contribute to inflammation [15].
- Streptococcus levels are also higher in women with GDM, during the third trimester [11], [12], [16], [17]. Most Streptococcus species are unfriendly.
- Bifidobacterium levels are lower throughout pregnancy [12], [13], [18], [19]. And this could negatively impact your baby’s health because Bifidobacterium — passed from a mom’s gut to her baby during birth — are key during the first months of life. These beneficial bacteria help train your baby’s immune system and keep unfriendly microbes at bay [20].
Gestational diabetes risk factors and the GDM signature
After evaluating published studies on GDM and the gut microbiome, the Tiny Health team of scientists carefully chose a set of bacteria that we use to determine whether your gut microbiome resembles that of women with GDM.
This is what we call a GDM signature.
Detecting such a signature before pregnancy or during the first trimester will allow you to implement changes into your lifestyle that could potentially reduce the risk of GDM.
3 diet tips on what to eat with gestational diabetes
Eating healthy food, in the right amounts and at the right times keeps your blood sugar steady. And it also positively impacts your gut microbiome.
A dietary intervention has been shown to reduce the risk of GDM by 30% [21]. So whether you’re trying to conceive, pregnant, or have been recently diagnosed with GDM, an effective meal plan is key.
That said, there’s no one-fits-all gestational diabetes diet. Which is why it’s important to always seek personalized advice from a healthcare provider.
Let’s dive into some scientific facts that show why what you eat is so important when it comes to GDM.
1. A plant-based diet reduces the risk of GDM
A plant-based diet is defined as one where someone eats mainly from plants, but not exclusively. It doesn't mean you have to ditch all animal-based food completely. In a plant-based diet, you choose more foods from plant sources than animal sources. This includes fruits and vegetables, nuts, seeds, oil, whole grains, legumes, and beans. An example of a plant-based diet is the Mediterranean diet, which emphasizes plant-based foods while also incorporating fish, chicken, eggs, healthy fats, dairy, and occasionally red meat.
A large study of approximately 15,000 women found that adherence to a plant-based diet reduced the risk of developing GDM by 30% [22]. Another study with pregnant women in their second or third trimester found that those consuming a plant-based diet with dairy and eggs had a lower risk of GDM than those with a very high consumption of red or white meats [23]. The Mediterranean diet has also been shown to reduce the risk of GDM [24]–[27].
Recommended actions:
- Fill half of your plate with vegetables at lunch and dinner. Also try to incorporate plant-based foods into your other meals, such as fruit for dessert and nuts for a snack.
- Eating a diverse range of plant-based foods is great for your gut microbiome [28], [29], so aim to include at least 30 different plant-based foods per week.
2. The type of protein you eat matters
Observational studies have found that women with a high consumption of red meat tend to have a higher risk of GDM. It has to be noted though, that not all studies make a distinction between the consumption of unprocessed (e.g. ground beef and sirloin) and processed meats (meat that is salted, cured, smoked, or dried) [30]–[33]. What’s more, processed meats on their own seem to greatly contribute to the risk of GDM [31], [32].
Also, we don't know whether women from these studies were eating conventional grain-fed, grass-fed, or organic red meats.
Studies have found that how meat is raised affects nutritional composition. Compared to grain-fed, grass-fed is typically lower in total and saturated fat, while higher in omega-3 fatty acids [34]. Processed meats are often very high in salt and contain many preservatives [35].
Since animal foods are important sources of protein, iron, and other nutrients, it’s important to include these in your diet while pregnant. In order to fulfill your protein needs while keeping potential risks to a minimum, try doing the following:
Recommended actions:
- When it comes to animal protein, go for variety: chicken, turkey, fish, eggs, beef, pork, etc.
- When possible, shop for organic, well-raised meats. Apart from having a better nutritional profile, organic meats are also free from hormones and antibiotics.
- Try eating less processed meats like ham, salami, and bacon. For example, you can switch the ham in a sandwich for delicious sliced roasted chicken.
3. Choose your carbs wisely
The conventional approach to manage GDM is to reduce carbohydrate intake. But studies haven’t agreed on the benefits of this practice.
Studies on pregnant women with GDM have found that a diet high in complex carbohydrates and low in fat, is similar to or better than a diet low in complex carbohydrates and high in fat, because both can successfully keep sugar levels under control [36], [37]. And this also positively impacted the levels of beneficial Bifidobacterium adolescentis [38].
As a good rule of thumb, try to limit carbs with high glycemic index such as sugary drinks, high-sugar fruits, white bread, and potatoes. Instead, choose complex carbs with low glycemic index like whole-grains, legumes, non starchy vegetables (e.g. kale, asparagus, tomatoes), and fruits that are low in sugar (e.g. berries, watermelon, peaches).
The order in which you eat your carbs may also influence your blood sugar levels.
For example, one study with folks who had been diagnosed with type 2 diabetes found that eating protein and vegetables before carbs can lead to lower post-meal glucose and insulin levels [39]. Which is a good thing. When eating out, this means you want to pass on free table appetizers, like breadsticks, chips with salsa, or popcorn.
Recommended actions:
- Choose complex carbohydrates over simple carbohydrates.
- Eat your proteins and vegetables before your carbs
Bottom line, what you eat matters. And while we can give you some broad ideas of a gestational diabetes diet plan that protects against GDM, it’s always important to get advice from a licensed nutritionist before implementing any major dietary changes.
Are there other ways to prevent or manage GDM?
As it turns out, staying active through pregnancy can reduce gestational weight gain. Physical activity has been shown to reduce the risk of GDM by 40% [21].
Exercise lowers blood sugar and makes you more sensitive to insulin. Clinical trials have shown that regular physical activity improves blood glucose levels during pregnancy and postpartum [40]–[43].
What about probiotics and supplements? Here are some facts:
- Probiotics. The effectiveness of probiotics in managing or preventing GDM is not conclusive. A meta-analysis that looked at six clinical trials concluded that the effects of probiotics on reducing the risk of GDM were not clear [44]. When it comes to managing GDM, results also vary among studies [45], [46]. A meta-analysis that looked at 11 clinical trials concluded that the use of Lactobacillus probiotics in pregnant women with GDM were effective in controlling blood sugar levels [47]. But differences between the individual studies and the fact that most of them were conducted in Iran made the results difficult to generalize. On the other hand, a probiotic containing Akkermansia muciniphila has been shown to improve glucose control in individuals with type 2 diabetes [48]. But this hasn’t been studied for GDM. Conclusion: the evidence is not enough to recommend probiotics for GDM, so if you choose to take one, we recommend asking your provider first.
- Myo-inositol: Myo-inositol (MI) is a sugar alcohol naturally present in foods like fruits, beans, grains, and nuts [49]. Two meta-analyses concluded that for some women daily supplementation with 4 grams of MI significantly reduced the risk of GDM and the need of insulin treatment [50], [51]. That said, the overall quality of the studies was not very high.
- Vitamin D. Vitamin D is one of the main supplements prescribed during pregnancy. Being deficient in this vitamin has been found to increase the risk of GDM by 26% [52]. Daily doses higher than 2,000 IU seem to significantly reduce the risk of GDM [53], [54].
As always, before starting a new supplement, make sure to ask your healthcare provider first.
