OBJECTIVE-The effect of hormone replacement therapy on the risk of myo
cardial infarction in diabetic women has not been well studied. We con
ducted a case-control study of postmenopausal estrogen use and risk of
incident myocardial infarction (MI) in pharmacologically treated diab
etic women enrolled at Group Health Cooperative of Puget Sound, a larg
e health maintenance organization in the state of Washington. RESEARCH
DESIGN AND METHODS-Case subjects (n = 212) were all postmenopausal wo
men with treated diabetes who sustained an incident fatal or nonfatal
MI between July 1986 and December 1994. Control subjects (n = 122) wer
e treated diabetic women drawn from a stratified random sample of post
menopausal women without prior MI. Computerized pharmacy data and medi
cal records were used to measure use of estrogens. Cardiovascular risk
factors recorded from medical records, computerized pharmacy and labo
ratory data, and telephone interviews were used as adjustment variable
s. RESULTS-In this study, 8.5% of case and 13.9% of control subjects w
ere current users of estrogens. The relative risk (RR) of MI for curre
nt estrogen users was 0.51 (95% CI 0.22-1.15) relative to never users,
adjusted for age, study year, weight, angina, and duration of treated
diabetes. Among current estrogen users, risk of MI tended to decline
with each additional year of estrogen use (adjusted RR = 0.78, 95% CI
0.56-1.08). Of those studied, 45.3% of case and 37.7% of control subje
cts were past users of estrogens (adjusted RR = 1.22, 95% CI 0.71-2.09
). CONCLUSIONS-This study suggests that use of postmenopausal estrogen
s does not increase risk of MI in diabetic women and that sustained us
e may be of benefit.