Effect of Postmenopausal Hormone Therapy on Glucose Regulation in Women With Type 1 or Type 2 Diabetes: A Systematic Review and Meta-analysis

BACKGROUND: Blood glucose regulation in women with diabetes may change during and after menopause, which could be attributed, in part, to decreased estrogen levels.

PURPOSE: To determine the effect of postmenopausal hormone therapy (HT) on HbA1c, fasting glucose, postprandial glucose, and use of glucose-lowering drugs in women with type 1 and women with type 2 diabetes.

DATA SOURCES: We conducted a systematic search of MEDLINE, Embase, Scopus, the Cochrane Library, and the ClinicalTrials.gov registry to identify randomized controlled trials (RCTs).

STUDY SELECTION: We selected RCTs on the effect of HT containing estrogen therapy in postmenopausal women (≥12 months since final menstrual period) with type 1 or type 2 diabetes.

DATA EXTRACTION: Data were extracted for the following outcomes: HbA1c, fasting glucose, postprandial glucose, and use of glucose-lowering medication.

DATA SYNTHESIS: Nineteen RCTs were included (12 parallel-group trials and 7 crossover trials), with a total of 1,412 participants, of whom 4.0% had type 1 diabetes. HT reduced HbA1c (mean difference -0.56% [95% CI -0.80, -0.31], -6.08 mmol/mol [95% CI -8.80, -3.36]) and fasting glucose (mean difference -1.15 mmol/L [95% CI -1.78, -0.51]).

LIMITATIONS: Of included studies, 50% were at high risk of bias.

CONCLUSIONS: When postmenopausal HT is considered for menopausal symptoms in women with type 2 diabetes, HT is expected to have a neutral-to-beneficial impact on glucose regulation. Evidence for the effect of postmenopausal HT in women with type 1 diabetes was limited.