Postmenopausal Hormone Therapy and Blood Sugar

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The summary below is from the full report titled "Glycemic Effects of Postmenopausal Hormone Therapy: The Heart and Estrogen/progestin Replacement Study. A Randomized, Double-Blind, Placebo-Controlled Trial." It is in the 7 January 2003 issue of Annals of Internal Medicine (volume 138, pages 1-9). The authors are AM Kanaya, D Herrington, E Vittinghoff, F Lin, D Grady, V Bittner, JA Cauley, and E Barrett-Connor.

What is the problem and what is known about it so far?

After menopause, the ovaries stop making the hormones estrogen and progesterone. For some women, the decrease in hormone levels causes hot flashes and other uncomfortable symptoms. Postmenopausal hormone therapy consists of taking estrogen with or without progesterone to reduce the uncomfortable symptoms of menopause. A recent study showed that postmenopausal hormone therapy also reduces colorectal cancer and osteoporosis but increases heart attack, stroke, and breast cancer. Ongoing studies are examining other risks and benefits of hormone therapy. Some previous studies suggest that women taking hormone replacement therapy have better blood sugar levels than women not taking it. Blood sugar is important in postmenopausal women because of its relationship to type 2 diabetes. Type 2 diabetes is a common disease that interferes with the body's ability to use and store energy from food and leads to high blood sugar levels. Over time, high blood sugar levels can lead to blindness, kidney failure, nerve damage, and possibly heart disease.

Why did the researchers do this particular study?

To see whether postmenopausal hormone therapy reduces blood sugar levels and incidence of type 2 diabetes.

Who was studied?

2763 women with heart disease who were participating in a study of hormone therapy and heart disease.

How was the study done?

The researchers assigned the study participants to take either hormone therapy or placebo pills that looked exactly like the hormones but contained no active ingredients. The researchers measured fasting blood sugar levels in women at the start of the study, after 1 year, and at the end of the study (an average of 4 years for most women). They compared the numbers of women who developed high blood sugar levels or diabetes in each of the groups. The researchers excluded women who already had diabetes or high blood sugar levels at the beginning of the study.

What did the researchers find?

Blood sugar levels increased in the women taking placebo but did not change in the women taking hormone therapy. Of the women taking hormones, 6.2% developed diabetes compared with 9.5% taking placebo. The researchers estimated that one case of diabetes could be prevented for every 30 women who take hormone replacement therapy for 4 years.

What were the limitations of the study?

The women in this study all had heart disease, and the hormones prescribed were 0.625 mg of conjugated estrogen plus 2.5 mg of medroxyprogesterone acetate. The results might not apply to women without heart disease or to those taking other hormone preparations.

What are the implications of the study?

The decision about whether to take postmenopausal hormone therapy depends on each woman's personal preferences and risks. This study suggests that preventing diabetes might be one of the few benefits of postmenopausal hormone therapy.