Each month, the average woman’s body prepares for pregnancy. Ovaries release an egg, if pregnancy doesn’t occur, the lining of the uterus sheds, and hormone levels rise and fall. The average menstrual cycle is 28 days long, but anything between 21 and 45 days is considered normal. Bleeding for 2 – 8 days is average and normal.
… typing the words “average” and “normal” over and over again feels weird, because women with diabetes know we’re coming into this whole arrangement outside the range of “average” or “normal” when it comes to pancreatic function.
Admittedly, I didn’t know a lot about the phases of the menstrual cycle until I was trying to get pregnant with my second child. I understood the basic mechanics, but it wasn’t until I was tracking ovulation and fertility potential on a spreadsheet that I saw data on how my period influenced my blood sugar control. Essentially, I saw that my blood sugars had predictable and irritating fluctuations around certain points in the menstrual cycle, adding a new variable to diabetes management.
The two main hormones that regulate the menstrual cycle are estrogen and progesterone. Estrogen causes the lining of the uterus to thicken in preparation for a potential pregnancy, in addition to helping regulate bone and vaginal health. Progesterone helps maintain the lining of the uterus during pregnancy, and both of these hormones affect insulin resistance and/or sensitivity, contributing to the roller coaster of blood sugars that many women experience during their cycle. Add these hormonal influences to the long list of things that can influence blood sugars!
Endocrinologist Jennifer Shine Dyer offered some clinician perspective: “Both highs or lows can be seen 1 week before the menstrual cycle, depends on the woman. This is due to increased or decreased insulin sensitivity and progesterone seems to be the main player here. Very few studies have been done to really look into the causes but H.I. Cramer was the first researcher to notice fluctuations in blood sugar due to menstruation. His findings were published in the Canadian Medical Association Journal in 1942. He found that 38% of the women reported that menstruation had changed their diabetes control. 70% of those women reported deterioration of control by experiencing hyperglycemia. 30% experienced hypoglycemia and improved control. Studies also show increased insulin sensitivity or no effect in women as well.”
And after talking with several women about how their periods affect diabetes, I saw some themes in these anecdotal experiences:
“This [the menstrual cycle] is a HUGE and under-examined area of influence on BG patterns. My own BG starts going up a few days before my period, and I literally start craving chocolate.”
“I definitely go high consistently/have insulin resistance the week before [my period]. Once it starts, everything levels out.”
“I can predict the start of my period from the terrifying low that always happens the night before. Lows so severe that my husband has had to call the paramedics three times, even though I cut my nighttime insulin in half the week before, trying to catch them. And then highs for the 3rd, 4th and 5th days. Really huge blood glucose swings.”
“I am very insulin resistant the week before. I am so not insulin resistant during. Makes me nuts.”
Researcher Sheri Colberg-Ochs had perspectives as researcher and a woman with type 1 diabetes to share. “in the research world, it’s pretty well established that if you’re studying insulin action as an outcome in women subjects, you have to try to study them at the same time of their cycle. Hormonal elevations from ovulation until the period starts raise insulin resistance. There’s lots of variations in hormone levels from one woman to the next, though. Being perimenopausal is also very challenging as levels of some hormones are higher and others lower. My control was easiest during my three pregnancies, even though my total insulin needs were higher. They didn’t fluctuate by the month, more by the trimester as they rose over time.”
Looking to make your period less of a diabetes hassle? There are some things that might help:
Track your cycle every month. This will help you identify monthly trends, giving you some data to take proactive moves (like setting a basal rate profile on your insulin pump for the week of your cycle, etc.) Be patient in pursuit of patterns, as it may take a few months to see them emerge. There are a lot of period tracking apps available.
Consider using a continuous glucose monitor to help track your monthly trends. This data, mapped against the data from your monthly cycles, can help drill down on blood sugar trends and give you the information you need to make medication changes, etc. (Definitely talk to your clinician before making any changes, though!)
Talk with your clinician about your options. Some women with diabetes opt to employ hormonal birth control methods, like the pill or an IUD, to help regulate their cycle and help predict fluctuations on a monthly basis.
Practice self-care. Getting enough sleep, eating well, and exercising regularly help in every aspect of your physical and mental health.