As the number of new COVID-19 cases in the United States has steadily declined since peaking in January of this year, and 2.5 million people across the nation are being vaccinated daily, it feels like there is light at the end of the tunnel of this long pandemic. Nevertheless, over the last two weeks rates have been slowly climbing in about half of the country, and over 50,000 new cases are still being diagnosed every day.

Since COVID-19 first emerged over a year ago, we have learned so much about the virus, including who is most at risk and what pre-existing conditions increase the chance of severe illness in those who catch it. Diabetes is one of these conditions: adults with Type 2 diabetes have a higher risk of becoming severely ill from the virus. This news is of particular relevance to menopausal women given that rates of Type 2 diabetes increase in women after menopause.

The connection between diabetes, menopause, and hormone therapy is not commonly known. While rates of Type 2 diabetes in women do increase after menopause, multiple studies over the last 30 years have shown a strong correlation between the use of hormone therapies and lower incidences of Type 2 diabetes in menopausal women.

In one of these earliest of these, a cohort of over 21,000 American women aged 30-55 and free of diabetes, heart disease, and cancer were followed for 12 years. Those who were on hormone therapy developed Type 2 diabetes at a rate 20% lower than those who were not.

A more recent French study looked at the association between adult-onset diabetes and the use of hormone therapy in 63,624 postmenopausal women, monitored over 15 years. In this study, interestingly enough, women on hormone therapy also experienced a reduction in incidence of diabetes of 20%.

The mechanisms by which estrogen influences diabetes are not fully understood, but they are thought to involve regulation and metabolism of glucose. Diabetic women who take hormone therapy had their fasting glucose reduced by over 11%. Studies suggest that mechanisms involving controlling weight gain—as well as others that are independent of weight—are involved.

According to Dr. Franck Mauvais-Jarvis, director of the Tulane Diabetes Research Program at Tulane University: “One of the most important [of these mechanisms] is a decrease in abdominal fat, which improves insulin resistance and systemic inflammation...Estrogen has also been found to increase insulin clearance and sensitivity [and] increase glucose disposal.” The multi-modal influence of estrogen on metabolic processes that are impaired in people with diabetes deserves a closer look, and many researchers are doing just that.