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What can help prevent gestational diabetes?

Created: ; Next update: 2020.

Some women can prevent gestational diabetes (diabetes in pregnancy) by getting enough exercise and changing their diet. But there is no evidence that this also prevents complications during pregnancy and childbirth.

Women’s metabolism changes in pregnancy. This can cause their blood sugar levels to increase temporarily. If certain levels are exceeded, the woman is considered to have gestational diabetes. Risk factors include being very overweight, having relatives with diabetes, and having had diabetes in a previous pregnancy.

When can changing your diet prevent gestational diabetes?

Women are generally advised to eat a balanced diet during pregnancy. This means making sure you have a varied diet rather than eating a lot of the same type of food, so the baby gets all the nutrients it needs. Most women can simply trust their appetite and don’t need to follow a special diet.

According to the research done so far, the only women who benefit from dietary changes are those who are overweight or obese. They can lower their risk of gestational diabetes by changing their diet with the help of a nutritional therapist.  The dietary changes can reduce their blood sugar levels and help them put on less weight in pregnancy. In women who have a normal weight, dietary changes do not have a preventive effect.   

Research has shown the following for women who are overweight (BMI > 25) or obese (BMI > 30):

  • If they didn’t change their diet, 16 out of 100 women were diagnosed with gestational diabetes.
  • If they did change their diet, 6 out of 100 women were diagnosed with gestational diabetes.

But it wasn’t clear from the studies whether making dietary changes also affects the child’s birth weight, lowers the risk of complications during childbirth, or helps reduce the need for C-sections.

What type of dietary changes can help prevent gestational diabetes?

Because carbohydrates increase your blood sugar levels, eating too many carbohydrates can make you gain weight. For this reason, people are usually advised to cut down on carbohydrates (“carbs”) while making sure they still get enough fiber, and generally eat a balanced diet otherwise. Other common advice includes eating three not-too-big main meals and two to three smaller meals per day.

The exact dietary changes to be made will depend on things like how much the woman weighs and how much exercise she gets. Getting special advice from a nutritional therapist can help to avoid adverse effects. Pregnant women need to make sure they get enough calories and important nutrients, which is why they shouldn’t go on a low-calorie diet, for instance.

Can dietary supplements help?

It is sometimes claimed that dietary supplements – omega 3 fatty acids (fish oil), for instance – can help prevent gestational diabetes. When omega 3 fatty acids were tested in studies, no preventive effect was found. Other products, such as probiotics and the vitamin-like substance myo-inositol, have hardly been studied.

Does getting more exercise help?

A number of studies have looked into whether getting more movement from the start of pregnancy can help prevent gestational diabetes. They found that women who exercise more are actually less likely to develop gestational diabetes. More specifically:

  • 5 out of 100 women who didn't get much movement were diagnosed with gestational diabetes,
  • compared to 3 out of 100 women who exercised more.

Sports and exercise also lowered the likelihood of needing a Cesarean section:

  • 22 out of 100 women who didn't get much movement had a Cesarean,
  • compared to 18 out of 100 women who exercised more.

Getting more exercise didn't increase the risk of the baby being born too early (preterm birth). It isn't clear whether, or how, higher levels of physical activity affect the risk of complications during birth. 

Doing at least 30 minutes of a strenuous activity on about three to four days per week is often enough to lower blood sugar levels. Suitable types of exercise include swimming, cycling and brisk walking. Sports such as martial arts, skiing and football are too risky for pregnant women, though. Women with a greater risk of preterm birth are usually advised to avoid sports altogether. It's best to talk to your gynecologist about which types of exercise are suitable for you.


  • Bain E, Crane M, Tieu J, Han S, Crowther CA, Middleton P. Diet and exercise interventions for preventing gestational diabetes mellitus. Cochrane Database Syst Rev 2015; (4): CD010443. [PubMed: 25864059]
  • Chen B, Ji X, Zhang L, Hou Z, Li C, Tong Y. Fish Oil Supplementation does not Reduce Risks of Gestational Diabetes Mellitus, Pregnancy-Induced Hypertension, or Pre-Eclampsia: A Meta-Analysis of Randomized Controlled Trials. Med Sci Monit 2015; 21: 2322-2330. [PMC free article: PMC4544354] [PubMed: 26256041]
  • Di Mascio D, Magro-Malosso ER, Saccone G, Marhefka GD, Berghella V. Exercise during pregnancy in normal-weight women and risk of preterm birth: a systematic review and meta-analysis of randomized controlled trials. Am J Obstet Gynecol 2016; 215(5): 561-571. [PubMed: 27319364]
  • Rogozinska E, Chamillard M, Hitman GA, Khan KS, Thangaratinam S. Nutritional manipulation for the primary prevention of gestational diabetes mellitus: a meta-analysis of randomised studies. PLoS ONE 2015; 10(2): e0115526. [PMC free article: PMC4342242] [PubMed: 25719363]
  • Sanabria-Martinez G, Garcia-Hermoso A, Poyatos-Leon R, Alvarez-Bueno C, Sanchez-Lopez M, Martinez-Vizcaino V. Effectiveness of physical activity interventions on preventing gestational diabetes mellitus and excessive maternal weight gain: a meta-analysis. BJOG 2015; 122(9): 1167-1174. [PubMed: 26036300]
  • Tieu J, Shepherd E, Middleton P, Crowther CA. Dietary advice interventions in pregnancy for preventing gestational diabetes mellitus. Cochrane Database Syst Rev 2017; (1): CD006674. [PMC free article: PMC6464792] [PubMed: 28046205]
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    Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

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