Guide to gestational diabetes in pregnancy: tests and therapies

Gestational diabetes is a form of diabetes that develops in the second half of pregnancy and resolves in most cases after delivery

Gestational diabetes should not be confused with diabetes manifest in pregnancy , a form of the disease that is already present before pregnancy and requires much more rigorous and complex care and attention.

Gestational diabetes in Italy has a prevalence of about 7% of pregnancies.

Gestational diabetes diagnosis

Screening for gestational diabetes is not done for all pregnant women but only for those most at risk.

All pregnant women with at least one of the following risk factors should perform an oral glucose challenge (OGTT) with 75 mg of glucose between weeks 24 and 28 of pregnancy:

• family history of diabetes in first-degree relatives (parents, siblings);
• fetal macrosomia in previous pregnancies;
• sovrappeso (BMI 25-30 kg/m ² );
• age ≥ 35 years;
• high-risk ethnicities (South Asia, Middle East, Caribbean).

All women who present at least one of the following factors, i.e. at high risk, should perform an OGTT with 75 g of glucose between the 16th and 18th week of pregnancy:

• obesity (BMI ≥30 kg/m ² );
• previous gestational diabetes;
• fasting blood sugar 100-125mg/dl, in early pregnancy or in the past.

The miniload of glucose (with 50 g) which was used as the first screening in past years, has now fallen into disuse. In fact, if the result was positive, it was also necessary to do the traditional load of 75 g of glucose, therefore double examination, double shopping, double nausea.

What is the OGTT and how is it interpreted?

For the oral glucose load it is necessary to go to the fasting laboratory for analysis. A venipuncture is performed to measure blood glucose before starting the test. Immediately afterwards the patient should drink a glass with 75 g of sugar dissolved in 300 cc of water.

The strong sweet taste commonly causes nausea. We remain fasting for another two hours, without being able to smoke or drink. A venipuncture is done at one hour and at two hours. Afterwards you can go to breakfast.

Tempo	Venous plasma glucose (mg/dl)
0	92
1 no	180
2 ore	153

The table shows the blood glucose limit values ​​during the test . If even just one of these values ​​is higher, the test is diagnostic for gestational diabetes. If the fasting blood glucose value is high, the laboratory may decide to interrupt the test since it is no longer necessary.

Therapy and diet

If the OGTT values ​​are altered, even slightly, the expectant mother must be immediately referred to the competent Antidiabetic Center to receive a treatment plan appropriate to her clinical picture.

Prescribing personalized nutritional treatment is the first step to take and is often sufficient to bring glycemic values ​​back to normal. A balanced diet rich in fiber and aimed at limiting the intake of simple sugars.

Apart from sweets, fruit juices and other sugary drinks, did you know that certain types of fruit are very rich in sugar and therefore should be limited? Oranges, tangerines, figs, persimmons, bananas, grapes, melons and pineapples.

Some advice from our dietician when there is nausea with gestational diabetes .

The diabetologist also provides for an occasional check of blood sugar at home, teaching the patient how to use the portable glucometer and prescribing what is needed. This leads to better results and increases awareness of your blood sugar levels. In fact, mild hyperglycemia does not cause any disturbance and can be underestimated .

The diet in gestational diabetes should not lead to a reduction in maternal weight which could be harmful to the fetus, but simply to reduce blood sugar levels and not gain excessive weight.

Insulin use

In the event that the diet and light physical activity do not lead to the desired result, it may be necessary to add insulin injection therapy for a short time . A single dose of long-acting insulin covering the whole day is almost always sufficient.

Oral hypoglycaemic drugs (much more convenient than injected insulin!) are not yet used in clinical practice because there is a lack of data on their safety in pregnancy. In many experimental studies, however, they are giving excellent results, giving hope for their future use.

Untreated gestational diabetes, what are the consequences?

The most frequent complications of untreated gestational diabetes are:

• preterm birth;
• fetal macrosomia (birth weight >4kg);
• hypoglycemia, hyperbilirubinemia, hypocalcaemia and breathing problems of the baby at birth.

Furthermore, mothers with gestational diabetes have a greater risk of developing diabetes mellitus in older age , so the correct treatment in pregnancy aimed at weight control and a healthy and balanced diet can reduce this risk.

Diabetes mellitus

Diabetes mellitus is a disease that leads to a reduced use by the cells of glucose due to a lack/ineffectiveness of the hormone insulin produced by the pancreas.

It therefore causes hyperglycemia (excessive blood sugar level) which in the long run seriously damages the heart, blood vessels, eyes, kidneys and nervous system.