Recurrent miscarriage tied to insulin resistance: Check fasting insulin levels

OB/GYN News, Jan 15, 2002 by Kate Johnson

ORLANDO, FLA. -- Women who have had at least two miscarriages are more than twice as likely to have insulin resistance as those without recurrent pregnancy loss, according to results of a study of 172 women.

"The women in my study had normal fasting glucose levels, and that's what most physicians use to test for diabetes. But if you looked at their fasting insulin, it was greatly elevated in those who had insulin resistance. So you need to test both," Dr. LaTasha Barker said in an interview during the annual meeting of the American Society for Reproductive Medicine.

Insulin resistance is commonly found in women with polycystic ovarian syndrome (PCOS) and has been associated with the classic PCOS characteristics, including obesity, hirsutism, anovulation, and infertility. In Dr. Barker's study, which was presented in poster form at the meeting, more than half of the women with insulin resistance had no signs or symptoms of the disorder other than RPL.

"About 60% of patients didn't fit the classical picture, so regardless of how they look, everyone should be tested for insulin resistance if they have recurrent pregnancy loss," said Dr. Barker, a senior resident at the University of Tennessee Health Science Center, Memphis.

The study included 74 consecutive nonpregnant, nondiabetic women between the ages of 22 and 46 who presented for evaluation of RPL. The women underwent a complete RPL evaluation, including karyotyping of both partners; uterine cavity evaluation; evaluation of TSH, prolactin, midluteal progesterone, lupus anticoagulant, and antiphospholipid antibodies; and cervical cultures for Chlamydia, Mycoplasma, and Ureaplasma species.

The women were matched by age, race, and body mass index to 74 control patients who were fertile, had borne at least one live infant, had no history of RPL, and were not diabetic or currently pregnant.

Insulin resistance was defined as a fasting insulin level of at least 20 [micro]U / mL and/or a fasting glucose to insulin ratio of less than 4.5.

Among the 74 women with RPL, 27% had insulin resistance, compared with 9.5% in the control group, for an odds ratio of 3.55.

The next step will be to see whether treating insulin resistance will decrease pregnancy loss in these patients.

"We've started treating all our insulin-resistant patients with metformin during the first trimester of their pregnancies, to see if we can improve the outcome," she said, noting that this strategy has already been shown to improve fertility in PCOS patients.