Girls who start their menstrual cycles early at a young age -- before the age of 13 -- could be at an increased risk of developing type 2 diabetes and stroke in midlife, finds research.

Starting periods before the average age of 13 were associated with a heightened risk of Type 2 diabetes. This ranged from 32 per cent greater (10 or younger) through 14 per cent greater (age 11) to 29 per cent greater (age 12).

Very early age at the first menstrual cycle -- 10 or younger -- was also associated with a more than doubling in stroke risk among women below the age of 65 with diabetes, after similar adjustments for influential factors.

This risk fell in tandem with increasing age: 81 per cent among those with their first menstrual bleed at the age of 11, to 32 per cent at the age of 12, and to 15 per cent at the age of 14.

This is an observational study, and as such, can't establish causal factors. But," earlier age at [first menstrual cycle] may be one of the early life indicators of the cardiometabolic disease trajectory in women", said corresponding author Sylvia H Ley from Tulane University in the US.

"One potential pathway explanation may be that [such] women are exposed to oestrogen for longer periods, and early [menstruation] has been associated with higher oestrogen levels," Ley added.

Diabetes and its complications are on the rise among young and middle-aged adults, while the age at which women start having periods is falling worldwide, said the researchers.

The study, published online in the journal BMJ Nutrition Prevention & Health, explored the link between the two, with a study on some 17,377 women aged between 20 and 65, all of whom specified the age at which they had had their first menstrual cycle. This was categorised as 10 or younger, 11, 12, 13, 14 and 15 and older.

Of the total, 1,773 (10 per cent) reported a diagnosis of Type 2 diabetes. Of these, 205 (11.5 per cent) reported some type of cardiovascular disease.

The researchers point out that while the observed associations between age at first menstrual cycle and stroke complications weakened slightly after accounting for weight, these remained statistically significant.

"Therefore, adiposity may also play a role in the observed association between early age at [first menstrual cycle] and stroke complications, as higher childhood adiposity is associated with earlier age at [menstruation] and with cardiometabolic diseases later in life," they suggest.