The Pharmaceutical Journal
Vol 270 No 7231 p41
11 January 2003

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Risk of developing diabetes reduced in women with heart disease taking HRT

Women with coronary heart disease who take hormone replacement therapy (HRT) have a substantially reduced risk of developing diabetes, a large randomised controlled trial has shown.

The findings come from the heart and estrogen/progestin replacement study (HERS), which randomised 2,763 postmenopausal women with heart disease to receive HRT or placebo for four years. The active therapy used in the trial was 0.625mg conjugated oestrogen plus 2.5mg medroxyprogesterone acetate. Although the main study end point was prevention of further coronary events, and the incidence of diabetes was not specified as a secondary outcome, blood glucose levels were selected as a possible variable that might influence the effects of HRT on coronary heart disease.

Fasting blood glucose levels were measured at baseline and at the end of the trial. New cases of diabetes were defined as either a fasting glucose level of 6.9mmol/L at year one or the end of the trial, self-reported new diabetes or the presence of any complication directly related to diabetes.

At the start of the study 718 women had diabetes, 218 had impaired glucose tolerance and 1,811 women were normoglycaemic. Fasting glucose levels rose among women assigned to placebo but did not change among women receiving HRT. Overall, the incidence of diabetes was 6.2 per cent in the 1,380 women assigned to HRT compared with 9.5 per cent in the 1,383 women assigned to placebo, a 35 per cent reduction in the relative risk of diabetes (P=0.006).

However, the researchers say that although the observation may provide important clues about the metabolic effects of HRT, the risks and benefits of hormone therapy must be considered for each individual before deciding whether or not the therapy is warranted for prevention of diabetes. "Postmenopausal women at high risk for incident diabetes, such as those with impaired fasting glucose, may benefit from HRT," write the researchers. But they add that this benefit must be weighed against the increase in venous thromboembolism, the early risk of coronary events after starting HRT, and the increased risk of breast cancer associated with long-term use (Annals of Internal Medicine 2003;138:1).