Hormone replacement therapy is associated with better glycemic control in women with type 2 diabetes: The Northern California Kaiser Permanente Diabetes Registry.

OBJECTIVE: In women with diabetes, the changes that accompany menopause may further diminish glycemic control. Little is known about how hormone replacement therapy (HRT) affects glucose metabolism in diabetes. The aim of this study was to examine whether HbA(1c) levels varied by current HRT among women with type 2 diabetes. RESEARCH DESIGN AND METHODS: In a cohort of 15,435 women with type 2 diabetes who were members of a health maintenance organization, HbA(1c) and HRT were assessed by reviewing records in the health plan's computerized laboratory and pharmacy systems. Sociodemographic and clinical information were collected by survey. RESULTS: The mean age was 64.7 years (SD +/- 8.7). The study cohort comprised 55% non-Hispanic whites, 14% non-Hispanic blacks, 12% Hispanics, 11% Asians, 4% "other" ethnic groups, and 4% with missing ethnicity data. Current HRT was observed in 25% of women. HbA(1c) levels were significantly lower in women currently using HRT than in women not using HRT (age-adjusted mean +/- SE: 7.9 +/- 0.03 vs. 8.5 +/- 0.02, respectively, P = 0.0001). No differences in HbA(1c) level were observed between women using unopposed estrogens and women using opposed estrogens. In a Generalized Estimating Equation model, which took into account patient clustering within physician and adjusted for age, ethnicity, education, obesity, hypoglycemic therapy, diabetes duration, self-monitoring of blood glucose, and exercise, HRT remained significantly and independently associated with decreased HbA(1c) levels (P = 0.0001). CONCLUSIONS: HRT was independently associated with decreased HbA(1c) level. Clinical trials will be necessary to understand whether HRT may improve glycemic control in women with diabetes.