In a review of the health records of more than 15,000 women with type 2 diabetes, researchers from the Northern California Kaiser Permanente Diabetes Registry found that those taking hormones had significantly lower HbA1c levels than those who did not.

The difference in HbA1c levels was about a half of one percentage point (mean of 7.9 vs 8.5). While that may not seem like much, the report’s authors pointed out that such a decrease translates roughly into a 10% reduction for any complications of diabetes, an 18% reduction for microvascular complications such as retinopathy and peripheral vascular disease, and a 7% reduction in heart attack.

Overall, about one-quarter of the women were on hormone replacement therapy. The findings did not differ among women taking estrogen only and those on a combined estrogen-progesterone regimen. The lower HbA1c levels were independent of age, ethnicity, education, body mass index, type of hypoglycemic therapy, duration of diabetes, blood glucose self-monitoring practice, or exercise.

Additional research will be needed to verify this effect and also to determine in what way(s) hormone replacement therapy affects glucose control.

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