More menstrual cycles, sex hormones, and breastfeeding are tied to lowered risk of developing T2D, but the new info is no reason to avoid the pill.
Findings in a recent research suggests that women who take birth control pills are at an elevated risk for developing type 2 diabetes (T2D), even after controlling for weight, family history of type 2 diabetes, blood pressure, and smoking.
The findings, presented at the European Association for the Study of Diabetes (EASD) in Barcelona, Spain, on September 16, 2019, also demonstrated that women who go through puberty and menopause later have a lower risk of developing type 2 diabetes.
These discoveries support earlier research on the protective value of longer exposure to one’s own sex hormones, says Stephanie S. Faubion, MD, the medical director of the North American Menopause Society and the director of the Mayo Clinic Center for Women’s Health in Rochester, Minnesota. Dr. Faubion was not involved in this research. “These results may help clinicians identify women with greater risk for diabetes in whom more aggressive lifestyle modification may be needed,” says Dr. Faubion.
The study, set to be published in the journal Diabetologia, looked at 83,799 French women from the E3N prospective cohort study who were followed between 1992 and 2014. Through the use of computer modeling, scientists were able to adjust for type 2 diabetes risk factors such as smoking, age, physical activity, family history, blood pressure, education level, and socioeconomic status in order to find out how different hormonal factors impact a woman’s risk of developing type 2 diabetes.
Who Has a Lower Risk for Developing Type 2 Diabetes?
There were several factors that were linked with a lower risk of developing T2D, including:
- Longer duration of exposure to sex hormones This is the number of years between when a woman first starts her period and when she goes through menopause. Women who menstruated for over 38 years compared with under 31 years had a 34 percent decreased risk of developing type 2 diabetes.
- Breastfeeding Women who ever breastfed in their lifetime had a 10 percent reduced risk of developing T2D compared with women who never breastfed.
- Beginning menstruation at a later age Women who began puberty at age 14 and older versus under 12 years had a 12 percent lower T2D risk.
More menstrual cycles Women who had more than 470 menstrual cycles versus under 390 had a 25 percent lower risk of developing T2D.
Later menopause Women who reached menopause at age 52 and older had a 30 percent lower T2D risk compared with women who experienced menopause at age 47 or earlier.
“These findings are consistent with those of the Women’s Health Initiative (WHI) trials, which suggested reduced risk of diabetes in women using menopausal hormone therapy,” says Faubion. In that large-scale long-term study, researchers found that women taking estrogen plus progestin reduced their risk for developing T2D by 14 to 19 percent.
How Could Estrogen Reduce Diabetes Risk in Women?
There are different theories on why estrogen might help reduce the risk of diabetes, says Sopio Tatulashvili, MD, an endocrinologist at Avicenne Hospital, Bobigny, France, and the lead author of the research. Pancreatic islet cells, important in regulating insulin secretion and glucose metabolism, contain estrogen receptors. It is hypothesized that when estradiol (a form of estrogen) interacts with those receptors it can help with the survival and stability of islet cells and in stimulating insulin synthesis, which aids glucose metabolism. This could make developing diabetes less likely, says Dr. Tatulashvili.
Estrogen also seems to increase insulin sensitivity and our muscles’ ability to efficiently metabolize glucose, which would also make the progression to diabetes less likely, she adds.
Estrogen Provides Protective Health Effects
It’s not surprising that women who have less exposure to their own sex hormones have an increased risk of developing type 2 diabetes, says Faubion. “We see this same effect with other chronic diseases, especially if estrogen is lost early as in the case of early or premature menopause,” says Faubion. Research has established a clear link to early loss of hormones (early or premature menopause-ovaries removed early) and accelerated aging and development of chronic diseases, including increased risk for heart disease, osteoporosis, dementia and even early death, says Faubion, who coauthored research on the potential long-term health consequences of early menopause.
A study published in Diabetologia in October 2017 found that women who had natural menopause at an earlier age (age 44 or younger) were at a higher risk for developing type 2 diabetes.
Birth Control Pills Linked to Increased Risk of Type 2 Diabetes
The study also discovered that the use of birth control pills at least once was associated with a 33 percent increased risk of developing type 2 diabetes compared with women who had never used them. “Risk induced by oral contraceptives could lead to personalized advice for young women at risk of developing T2D, such as those with a family history of diabetes, those who are overweight or obese, or those with polycystic ovary syndrome,” said the authors.
New Results Are No Reason to Avoid Birth Control Pills
It’s not clear why birth control pills could increase risk, but it may potentially relate to the progestogen component of the oral contraceptive pill (OCP), and so risk may vary based on type of progestogen found in the OCP, says Faubion. “In any event, women should not alter their decision-making regarding their contraceptive method based on these results,” she added.
Extensive Research Is Needed to Understand the Pill and Diabetes Link
Tatulashvili agrees there is no clear explanation why contraceptive pill use is associated with higher risk of type 2 diabetes. Another hypothesis is that birth control pills can lead to higher than normal estradiol levels, which could cause insulin resistance in the liver or a reduction in the efficiency of glucose use and transport in muscle cells, says Tatulashvili.
“Further research is needed on the influence of each type and exposure of contraceptive agents before translating these findings into clinical practice and prevention strategies,” says Tatulashvili.