Insulin Resistance Is Increased by Transdermal Estrogen Therapy in Postmenopausal Women with Cardiac Syndrome X

Estrogen has been reported to have both short- and long-term effects on the cardiovascular system. However, it remains to be examined how short-term transdermal estrogen therapy (TET) affects insulin sensitivity (SI) in patients with cardiac syndrome X (CSX), who are characterized by elevated insulin resistance. SI was assessed in a randomized, double-blind, placebo-controlled crossover study by minimal model analysis in seven postmenopausal women with CSX treated by TET. SI decreased by 32 ± 8.3%, from 5.94 ± 1.14 at baseline to 3.61 ± 0.40 [(10–4 × min–1)/(µU/ml)] during TET (p = 0.03). Time to the onset of symptoms increased from 414.2 ± 51.0 s at baseline to 450.0 ± 53.2 s (p = 0.04). We conclude that TET increases SI in postmenopausal women with CSX. This effect is unrelated to the beneficial anti-ischemic effects on exercise duration.