Gestational diabetes

Gestational diabetes affects 3-20% of pregnant women. It is defined as high blood sugar, or hyperglycemia, that occurs during pregnancy in a woman who did not previously have diabetes. It usually occurs towards the end of the 6th month of pregnancy. In most cases, it disappears after delivery, but the mother is then at risk of developing type 2 diabetes in the following years.

The cause

The placenta produces hormones that are very helpful for a healthy pregnancy, but they interfere with the work of insulin. Insulin is a hormone that helps lower blood sugar levels.

In some pregnant women, the body cannot produce enough insulin to compensate for the effect of these hormones. This causes sugar to build up in the blood and raises blood sugar levels.

The symptoms

Generally, pregnant women do not have obvious symptoms of diabetes. However, occasionally, symptoms may appear:

• Unusual fatigue;
• Exaggerated thirst;
• Increased volume and frequency of urination;
• Headaches.

These symptoms can easily go unnoticed because they are very common during pregnancy.

Women at risk

Several factors increase the risk of developing gestational diabetes:

• Being 35 years old or older;
• Having a body mass index (BMI) equal to or greater than 30 before pregnancy or gaining weight beyond the recommended range during the first two trimesters of pregnancy;
• Have an immediate family member living with type 2 diabetes;
• Having multiple pregnancies;
• Having previously given birth to a baby weighing more than 4 kg (9 lbs);
• Have developed gestational diabetes in a previous pregnancy;
• Have had abnormally high blood glucose values in the past, either a diagnosis of impaired glucose tolerance or pre-diabetes;
• Be of Native American, Latin American, Asian, Arab, or African descent;
• Taking a cortisone medication regularly;
• Have polycystic ovary syndrome;
• Have acanthosis nigricans, which is a brownish discoloration of the skin on the neck and under the arms.

Screening

a screening test for gestational diabetes for all pregnant women between the 24th and 28th week of pregnancy is mandatory.

The recommended method of testing for diabetes is to measure blood glucose 1 hour after ingesting a liquid containing 50 g of glucose.

• If the result is less than 7.8 mmol/L, the test is normal.
• If the result is between 7.8 and 11.0 mmol/L, an oral glucose tolerance test (HGPO) should be done to clarify the result.
• If the result is greater than 11.0 mmo/L, gestational diabetes is present.

The HGPO test consists of the ingestion of a sugary liquid containing 75 g of glucose. Three blood samples are taken: fasting, 1 hour after the ingestion of the sweetened liquid, and 2 hours after the ingestion of the sweetened liquid. The diagnosis of diabetes is made if any of the values is equal to or greater than:

• 5.3 mmol/L fasting
• 10.6 mmol/L 1 hour after the ingestion of the sweetened liquid
• 9.0 mmol/L 2 hours after ingestion of the sweetened liquid

Some centers perform the HGPO test as a first step. In this case, the following target values apply for diagnosis:

• 5.1 mmol/L fasting
• 10.0 mmol/L 1 hour after ingestion of sugar liquid
• 8.5 mmol/L 2 hours after ingestion of sugar-containing fluid.

Possible risks

For the mother :

• Excess amniotic fluid, increasing the risk of preterm delivery;
• Cesarean delivery or more difficult vaginal delivery (due to the weight of the baby, among other things);
• Pregnancy hypertension or pre-eclampsia (high blood pressure and swelling)
• Remaining diabetic after delivery or developing long-term type 2 diabetes (20-50% risk within 5-10 years of pregnancy);

For the baby :

• Higher than normal birth weight (more than 4 kg or 9 lbs);
• Hypoglycemia, that is, at birth;
• Blockage of the shoulders during delivery;
• Obesity and glucose intolerance in early adulthood (especially if birth weight is greater than 4 kg or 9 lbs);
• Jaundice, lack of calcium in the blood, or breathing difficulty at birth.

Proper management of gestational diabetes can greatly reduce the risk of complications for both mother and baby.

Treatment

Generally, a healthy diet that takes into account the portion size and distribution of carbohydrates (sugars), as well as a healthy lifestyle (stress management, adequate sleep, and physical activity), are sufficient to manage gestational diabetes.

If blood sugar levels remain too high, the doctor will prescribe insulin injections or, in some cases, oral antihyperglycemic drugs. Insulin is completely safe during pregnancy.

Blood glucose targets for most pregnant women :

• Fasting: <5.3 mmol/L
• 1 hour after a meal: <7.8 mmol/L
• 2 hours after a meal: <6.7 mmol/L

Target values for gestational diabetes are lower than for other types of diabetes.

After pregnancy

Women who have had gestational diabetes are 13 times more likely to develop

to develop type 2 diabetes in the following years than those who have not had gestational diabetes. Therefore, it is recommended to do the following:

• Have blood drawn between 6 weeks and 6 months postpartum to screen for prediabetes or type 2 diabetes;
• Maintain a healthy lifestyle to reduce the risk of developing type 2 diabetes or delay its onset.
• Breastfeed as much as possible immediately after birth and for the first four months.

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