KatCarney

Insulin resistance in PCOS may be more common in Mexican Americans than whites. (Separate Screening Values Needed?).

OB/GYN News, July 1, 2002, by Sherry Boschert

LOS ANGELES -- Insulin resistance in women with polycystic ovary syndrome was more common and more severe in Mexican Americans than whites in a retrospective study of 102 patients.

If larger studies confirm these findings, results of insulin resistance screening tests in women with suspected polycystic ovary syndrome (PCOS) may need to be interpreted based on the patient's ethnicity, Dr. Robert P. Kauffman said at the annual meeting of the Society for Gynecologic Investigation.

PCOS, the most frequent cause of anovulatory infertility, is characterized by hyperandrogenism and insulin resistance in most cases. The investigators compared serum insulin, glucose, testosterone, and dehydroepiandrosterone levels in 19 control women who had normal ovulatory cycles and 83 women who were evaluated for possible PCOS. All women had normal glucose tolerance and no other endocrine disorders. Screening results came from fasting serum samples taken in the early proliferative phase, followed by an oral glucose load and blood samples drawn 1, 2, and 3 hours later.

Forty women were diagnosed with PCOS and insulin resistance. A total of 34 had PCOS without insulin resistance, and 9 had irregular menstrual cydes but no PCOS or other endocrine disorder, he said in a poster presentation at the meeting.

Sixty-five of the study participants were white, and 37 were Mexican American.

Women with insulin resistance had a significantly higher mean body mass index; higher scores on two indicators of insulin resistance, fasting insulin values and the homeostasis model assessment (HOMA); and lower mean glucose/insulin/ratios, a third indicator of insulin resistance.

In the women with PCOS, insulin resistance was found in 73% of Mexican Americans and 44% of whites. In patients with PCOS and insulin resistance, the Mexican Americans had higher mean fasting insulin values, compared with their white counterparts (35 [micro]U/mL vs. 26 [micro]U/ mL), as well as higher HOMA results (9 vs. 6) and lower glucose/insulin ratios (3 vs. 5). In all groups, Mexican American women had a higher mean body mass index. Previous studies have shown that the severity of insulin resistance is proportional to the severity of obesity.

After adjusting for body mass index in women with PCOS and insulin resistance, however, Mexican Americans still had higher mean fasting insulin levels, higher HOMA results, and lower glucose/insulin ratios, compared with whites, at least in women with a body mass index of at least 24. The ethnic differences disappeared in thinner women.

An analysis of the entire cohort suggests that PCOS-related insulin resistance might be defined as a fasting insulin value higher than 20 [micro]U/mL in white women and higher than 23 [micro]U/mL in Mexican American women, Dr. Kauffman said.

Alternatively, a HOMA greater than 3.8 or a glucose/insulin ratio less than 7.2 might be reasonable cutoffs to detect insulin resistance in whites. In Mexican Americans, more appropriate cutoffs may be a HOMA higher than 4.6 or a glucose/insulin ratio under 4.

Physicians should not adopt these ethnicity-specific values, however, until larger studies are done to confirm the findings, Dr. Kauffman cautioned.

COPYRIGHT 2002 International Medical News Group in association with The Gale Group and LookSmart.
COPYRIGHT 2002 Gale Group

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