NEW YORK (Reuters Health) - New research shows that diabetes is associated with reduced estrogen levels in women, which may explain why the "female advantage," reducing their risk of chronic kidney disease compared with men, does not extend to diabetic women.

Dr. Christine Maric of Georgetown University's Center for the Study of Sex Differences in Health, Aging and Disease, Washington, DC, explains: "Until they reach menopause, women in general rarely get kidney disease. Once they reach menopause, they start getting kidney disease and catch up to men in incidence."

"Our research," Maric told Reuters Health, "suggests that diabetic women, even premenopausal diabetic women, get just as much kidney disease as men."

What is it about diabetes that predisposes women to develop kidney disease at levels generally associated with their male counterparts? "The most logical reason is estrogen," Maric said.

In female diabetic rats, "we found that their sex hormone levels, in particular estradiol, were very low," Maric said. "We have just started to get some human data and this seems to be the case in type 1 and type 2 diabetic women as well. Diabetic women have very low estradiol levels similar to what a non-diabetic woman would have when she reached menopause."

Maric's study, which she presented at an American Physiological Society-sponsored meeting held this month in Austin, Texas, also shows that estrogen and estrogen-like supplements protect the kidney.

"When we replaced physiological levels of estradiol in female diabetic rats to mimic a woman's cycle with troughs and peaks in estradiol, we completely prevented the kidney disease from developing," she told said.

The situation is somewhat different in male mice. According to Maric, the absence of the male sex hormone testosterone fuels a more rapid progression of kidney disease when diabetes is present. However, in diabetic male rats, "when you replace testosterone it accelerates the disease very quickly," Maric said.

"The biggest surprise has been the finding that sex hormones - normally thought to control only the reproductive function - are involved in controlling processes in non-reproductive organs, including the kidney," Maric pointed out. "Moving forward, we need to look more deeply into understanding how sex hormones affect organ function in each gender."

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