INTERVIEW – Nearly one woman in ten declares diabetes during her pregnancy. This gestational diabetes cannot be treated like the others.
- Gestational diabetes occurs only in pregnant women, usually towards the end of the 2nd trimester.
- Screening is recommended for all women between 24 and 28 weeks of amenorrhea. Those at risk should benefit from this screening from the start of pregnancy.
- The main risk factors are: pregnancy after 35 years, a BMI greater than 25, a personal history of gestational diabetes, a family history of type 2 diabetes, or a history of fetal macrosomia.
Every year, about 8% of pregnant women develop gestational diabetes. On paper, the rules are clear. The High Authority for Health (HAS), author of recommendations for good practice, details the path of patients. Diabetes must be systematically treated, giving priority to improving lifestyle. End of debate? Not quite.
In the cabinets, the hour is with the hesitation. Because if insulin is undeniably effective, doctors are considering the use of oral antidiabetics, which are not currently recommended. Back to the debate with Professor Anne Vambergue, diabetologist at the Lille CHRU (North). She moderated the discussions on this subject at the Congress of the French-speaking Diabetes Society, which is being held in Lille from March 28 to 31.
How is gestational diabetes managed?
Professor Anne Vambergue: From the moment the diagnosis is made, management constitutes the cornerstone of the treatment, since it makes it possible to reduce maternal and fetal morbidity. Treatment begins with hygiene and dietary measures, therefore nutritional education associated with appropriate physical activity.
At the same time, we start self-monitoring of blood sugar in the morning on an empty stomach, before meals and two hours after meals. The goal is to achieve a fasting blood glucose level below 0.92, and below 1.20 within two hours after the meal. If after 7-10 days, despite this, we do not achieve the goals, treatment with insulin therapy should be offered. The insulin is then adapted according to the glycemic profiles.
Why do we talk about the use of oral antidiabetics?
Professor Anne Vambergue: A number of women have fear of injection, and the need to educate them has been raised. For medico-economic reasons, oral antidiabetics would also be cheaper than insulin therapy. In addition, there is a possible risk of hypoglycaemia, although the risks are known to be low. It is therefore mainly to improve acceptance by the patient.
What does the literature say?
Professor Anne Vambergue: There was a period, from 2000 to 2010, when the literature suggested that sulfonamides allowed the same control as insulin, without any increased risk for the child at birth. This suggested that the treatment could be used during pregnancy. In parallel, studies have assessed the impact of the use of metformin, which acts more on insulin resistance. Again, a first study published in 2008 showed that there was no increased risk in using it, apart from a small risk of prematurity. But in 30 to 50% of cases, metformin alone was not enough to control this diabetes. It was therefore sometimes necessary to introduce insulin therapy at a later stage.
What are the reasons for not prescribing them?
Professor Anne Vambergue: These are the official recommendations. In addition, from 2010, studies have shown, with larger numbers, a possible increased risk of fetal macrosomia – therefore large babies at birth – and neonatal hypoglycaemia for pregnancies on sulfonamides.
The other element is that we knew that metformin crosses the placenta, which was less certain for sulfonamides. By redoing an analysis of the studies which have been interested in it, it is clear that the methodologies are old, the assay sensitivities less good. More recent data have confirmed placental passage of metformin and sulfonamides.
Are the alleged effects on the fetus serious?
Professor Anne Vambergue: Literature shows that macrosomia increases the risk of later obesity and diabetes. But not much is known about the risk of neonatal hypoglycemia and its impact. In fact, for metformin like sulfonamides, no study has looked at the future of the child after birth.
These long-term studies are extremely important to assess the risk of obesity, diabetes or neurosensory. The answer is therefore that currently, oral antidiabetics cannot be used during pregnancy. A study has just been completed in France, which compares the maternal-fetal morbidity of women on insulin therapy and on sulfonamides. We look forward to these results.
The effects of gestational diabetes have been proven…
Professor Anne Vambergue: Yes, there too, it would seem that there is an increased risk of overweight and obesity, even abnormalities in glucose tolerance in adulthood. All this confirms to us that the intrauterine environment is extremely important. It is the concept of metabolic programming which shows that during pregnancy there may be periods of vulnerability with epigenetic modifications, which will have consequences for subsequent generations.
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