Having a long or irregular menstrual cycle may indicate that younger women are at greater risk for nonalcoholic fatty liver disease (NAFLD) — a common form of liver disease that is also linked to diabetes — according to a new study published in the Journal of Clinical Endocrinology & Metabolism.
Research in recent years has indicated that menstrual cycles in women may be related to metabolic health in a number of ways, including diabetes and its complications. Women with irregular menstrual cycles are more likely to develop both type 2 diabetes and heart disease over the course of several decades, according to one recent study. Among teenage girls with type 2 diabetes, a striking proportion — about one in five — has polycystic ovary syndrome (PCOS), a hormonal disorder marked by enlarged ovaries and unpleasant to painful symptoms related to menstrual periods. And in women with PCOS who don’t have diabetes, taking contraceptive pills to treat their PCOS is linked not just to symptom relief, but also to a lower risk of developing type 2 diabetes.
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NAFLD has also gained attention in recent years, since research indicates that the condition — marked by excess liver fat, which can lead to reduced liver function and is linked to poor health outcomes — is widespread in people with type 2 diabetes and too often goes undiagnosed and untreated. While some risk factors for NAFLD — like a family history of diabetes — can’t be controlled, there are steps that many people can take to reduce their risk for NAFLD or even reverse the condition, including following a healthy diet, drinking coffee, and undergoing bariatric (weight-loss) surgery.
For the latest study, researchers looked at menstrual cycle lengths in 51,118 women under age 40 who underwent routine health examinations and didn’t have NAFLD at the beginning of the study period. The researchers defined a long or irregular menstrual cycle as lasting 40 days or longer, or being too irregular to even estimate. As part of their regular health exams, the participants underwent abdominal ultrasound imaging to look for signs of NAFLD. At the beginning of the study period, 27.7% of participants had a long or irregular menstrual cycle. During a median follow-up period of 4.4 years, 8.9% of participants developed NAFLD.
Long, irregular menstrual cycles linked to increased NAFLD risk
As part of their analysis, the researchers tried to control for differences other than menstrual cycle length that could potentially affect both menstrual cycles and the risk for NAFLD. They did this by looking at differences between women with long or irregular menstrual cycles, and those who had a cycle length of 26-30 days, across a number of areas — including age, body-mass index (BMI, a measure of body eight that takes height into account), and insulin resistance. After adjusting for these differences, the researchers found that compared with women whose menstrual cycle lasted 26-30 days, those with a long or irregular cycle were 22% more likely to develop NAFLD.
When the researchers looked at the risk for developing NAFLD during specific windows of time during the follow-up period — rather than across the entire follow-up period — the link between menstrual cycles and NAFLD risk got even stronger. Compared with participants who had a menstrual cycle lasting 26-30 days, those with a cycle lasting 31-39 days were 27% more likely to develop NAFLD at any given point in time. And those with an irregular menstrual cycle or one lasting 40 days or longer were 49% more likely to develop NAFLD, as noted in an article on the study at MedPage Today.
It’s important to note that the differences in risk for NAFLD couldn’t be explained by factors that are widely known to contribute to NAFLD — such as obesity and insulin resistance — because the researchers controlled for these differences. So even in people with the same BMI or the same level of measured insulin resistance, having a longer or more irregular menstrual cycle is linked to the risk for NAFLD.
The researchers noted that some women with longer or irregular menstrual cycles may have PCOS, but that absent any other troubling symptoms, it’s more feasible to screen women for NAFLD risk based on the length of their menstrual cycles, rather than based on a diagnosis of PCOS — since menstrual cycles are more easily measured and reported. “Women with long or irregular menstrual cycles may benefit from lifestyle modification advice to reduce the risk of NAFLD and associated cardiometabolic diseases,” the researchers concluded.
Want to learn more about diabetes and the menstrual cycle? Read “Diabetes and Your Period.”