Gestational diabetes: definition, causes, treatment

Pregnant women's bodies undergo profound changes during this nine-month period and they can sometimes develop gestational diabetes [1,2].

According to the most recent (2019) IDF (International Diabetes Federation) estimates, it affects approximately 13% of future mothers worldwide [3].

How do you recognize it? What diet should you be following?

Definition and diagnosis

The definition of gestational diabetes is quite simple: it is chronic hyperglycaemia first diagnosed during pregnancy in a woman with no previous history of diabetes [1,2,4].

Gestational diabetes usually resolves immediately after the baby is born [2,5], but a woman who develops it during pregnancy is more likely to develop type 2 diabetes later on [1,2,4,5].

Although it usually appears at the end of the second trimester, gestational diabetes can occur at any time during pregnancy [2,4].

The International Association of the Diabetes and Pregnancy Study Groups (IADPSG) therefore recommends that pregnant women:

• perform an early pregnancy screening test during the first prenatal visit [1].
• perform additional screening at 24-28 weeks of pregnancy if no previous diabetes has been diagnosed[1].

Effective management of gestational diabetes is recommended to avoid macrosomia (a much larger than average baby), giving birth by caesarean section, and other complications during the final phase of pregnancy and birth [1,5]

What causes gestational diabetes?

During pregnancy, a woman's body undergoes a series of considerable changes in metabolism, one of which is resistance to insulin that can then lead to the appearance of gestational diabetes [2].

Starting in the sixth month of pregnancy, a series of hormones secreted by the placenta will increase resistance to insulin [1,2,6].

Other factors such as weight gain and a decrease in physical activity also contribute to insulin resistance [2].

But why do some women develop gestational diabetes and not others?

The important thing to know here is that during pregnancy, the number of β cells in the pancreas increases to prevent insulin resistance [1]. If this increment does not occur, gestational diabetes will set in [1,2,7].

The risk factors associated with gestational diabetes are well known:

• history of gestational diabetes; 
• overweight and obesity of the mother;
• family history of diabetes or insulin resistance;
• the future mother is in the older age group;
• a previous birth with a baby weighing more than 4kg;
• presence of ovarian cysts;
• multiple prior abortions or stillborn babies with no clear medical explanation;
• history of hypertension [1,2,5,7]

Treatment and diet

Future mums with gestational diabetes are advised to monitor their blood glucose levels frequently while following a simple health and dietary plan, including a balanced diet and doing regular physical exercise suited to pregnant women [2,7].

The goal of this therapy is to support healthy development of the foetus and the well-being of the mother whilst achieving normal blood glucose levels [2].

Changes in eating habits are, above all, focused on managing carbohydrate intake to reduce risks of postprandial hyperglycaemia (a spike in the blood glucose levels after eating a meal) and reduce the exposure of high glucose levels to the baby [6].

The main recommendations are:

• carbohydrates representing between 35 % and 45 % of total calories [2];
• spreading the intake of carbohydrates over three meals and two to four light snacks [2];
• increasing the proportion of fiber-rich foods [1,6].

If the changes in diet do not have the desired effect on gestational diabetes, medication or insulin therapy may be prescribed [1,2].

Keeping an eye on your blood glucose levels and following a healthy, balanced diet are the key to successfully managing your gestational diabetes and having an enjoyable, fulfilling pregnancy.