This work does not prove that endometriosis causes diabetes. But they raise an important question: could this disease have consequences well beyond the reproductive sphere?
A disease known to hurt, but whose consequences could extend beyond the pelvis
For women living with endometriosis, daily life can already be heavy. Chronic pelvic pain, particularly difficult periods, fatigue, difficulty conceiving… The disease is linked to the presence, outside the uterus, of tissues similar to that which normally lines its wall. It concerns approximately one in ten women of childbearing age.
But could endometriosis also affect metabolic health? This is the question asked by the team of Maggie Fuzak Nunziato and Anna Z. Pollack, from the George Mason College of Public Health. To answer this, the researchers used the Utah Population Database, a large American medical database.
In total, 2,939,364 women were followed between 1996 and 2021of which 99,978 had been diagnosed with endometriosis. According to the researchers, this is the largest study carried out to date to examine the link between this disease and type 2 diabetes.
The result immediately attracts attention: after taking into account in particular age, body mass index and demographic factors, women with endometriosis presented a 46% higher risk of developing type 2 diabetes than the others.
For Maggie Fuzak Nunziato, this observation requires us to look at endometriosis differently.
“Previous studies largely assessed endometriosis as a single disease and generally reported little or no overall association with type 2 diabetes. Our findings add to a growing understanding that endometriosis may affect more than just reproductive health.“.
The most surprising result concerns the women we least expected
The 46% figure only tells part of the story, however. Because by refining their analyses, the researchers found that the link varied greatly depending on the profile of the patients and the form of endometriosis.
The association was notably stronger in premenopausal women under 50with an excess risk of 55%. It was also particularly marked in women whose BMI was less than 30 kg/m²: their relative risk was more than doubled (x 2.39)compared to 1.74 in women with obesity. In other words, the observed signal is not only carried by factors traditionally associated with type 2 diabetes, such as being overweight.
The same phenomenon appears when gestational diabetes is taken into account. The risk remained close to two, whether or not there was a history of diabetes during pregnancy:
1.99 without history and 2.05 with.
This discovery is all the more interesting since previous studies had not found such a clear link. Work carried out in particular in the Nurses’ Health Study II and the French E3N cohort reported much weaker associations, around +9%.
Why such a difference? Part of the answer may lie in how we view endometriosis. Because not all forms of the disease seem associated with the same level of risk.
Not all endometriosis appears to present the same risk
Researchers have thus distinguished several forms of endometriosis. The association with type 2 diabetes ranged from
1.34 for adenomyosis to 1.67 for superficial endometriosis.
The signal was even greater for certain extra-pelvic locations, with a risk that could be multiplied by 2.47 to 2.67.
This difference could be an important avenue for understanding what is happening biologically. The researchers particularly mention the hypothesis of a chronic inflammation
linked to endometriosis lesions. Previous work has indeed shown higher levels of certain inflammatory markers, such as interleukin 6 (IL-6) or C-reactive protein, in certain patients.
The hypothesis is that this persistent inflammation could, at least in part, disrupt sensitivity to insulin, this hormone essential for blood sugar control.
But the authors remain cautious. The study is observational: it highlights an association, not a cause and effect relationship. Other factors, notably certain hormonal treatments which could not be precisely measured, could also be involved.
A way to better anticipate diabetes, without creating new concerns
So, should we now consider endometriosis as a risk factor for type 2 diabetes? Not yet. The results must be confirmed by other research, and the authors highlight several limitations, including the use of diagnostic codes which do not always allow endometriosis to be perfectly characterized. In women whose diagnosis had been confirmed by laparoscopy, the association was more moderate, with an excess risk of +31%.
However, this study opens an interesting avenue. She suggests that monitoring a woman with endometriosis could, ultimately, not be limited to her gynecological symptoms or her fertility. More careful metabolic monitoring could be considered in certain patients, particularly those presenting the forms most associated with risk.
The issue is essential: it is not a question of adding additional worry to women who already live with an often painful illnessbut to better understand its possible consequences in order to be able, tomorrow, to prevent certain complications sooner.