Getting periods before the age of 13 is linked to a heightened risk of developing type 2 diabetes later in life, a new study has found.

The study, published in the journal BMJ Nutrition Prevention & Health, also suggests that girls who start menstruation before the age of 10 or younger are at an increased risk of having a stroke before the age of 65.

The first menstrual cycle, or menarche, typically occurs between 10 and 16 years of age. The average age of menarche has declined across the world in recent years owing to factors such as obesity, endocrine-disrupting chemicals in the environment and nutritional status. Studies also indicate a significant rise in diabetes cases among young and middle-aged adults in the U.S.

In the latest study, researchers decided to investigate if there is any link between the age of menarche and diabetes risk. The study was based on the National Health and Nutrition Examination Survey (NHANES) 1999–2018, which included responses from 17,377 women aged between 20 and 65.

Based on the age of their first menstruation, they were categorized as 10 or younger, 11, 12, 13, 14, 15 and older. Among the participants, 1,773 (10%) had a diagnosis of type 2 diabetes and 205 (11.5%) of them reported some type of cardiovascular disease.

"Starting periods before the average age of 13 was associated with a heightened risk of type 2 diabetes, after accounting for a range of potentially influential factors, including age, race/ethnicity, education, motherhood, menopausal status, and family history of diabetes, smoking, physical activity, alcohol consumption, and weight (BMI). This ranged from 32% greater (10 or younger) through 14% greater (age 11) to 29% greater (age 12)," the researchers said in the news release.

In women with diabetes, early menstruation was associated with an increased risk of stroke. The results didn't indicate a heightened risk of cardiovascular disease in general after researchers looked at the same set of potentially influential factors.

When the age of first menstruation was very early (before the age of 10), the risk of stroke was double in those below the age of 65 with diabetes. With the increase in age of menarche, the researchers noted a decrease in risk. While the risk of stroke was 81% among those who started menstruation at the age of 11, it decreased to 32% in women who had their first menstruation by the age of 12 and 15% in those who had menarche at the age of 14.

Since the study is observational, it does not identify causal factors behind the link. Researchers, however, believe it has something to do with the increase in the duration of estrogen exposure in people with early menstruation.

"Earlier age at [first menstrual cycle] may be one of the early life indicators of the cardiometabolic disease trajectory in women. One potential pathway explanation may be that [such] women are exposed to estrogen for longer periods of time, and early [menstruation] has been associated with higher estrogen levels," the researchers explained.

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