How to Improve Blood Sugar Control During Your Period

Written by Ginger Jeanne Vieira

Contrary to the basic explanation we all received in the 8th grade, your hormones are changing every single day of the month, and you can bet those hormones impact your sensitivity to insulin, too.

Trying to determine when the hormones of your menstrual cycle impact your blood sugars and how to adjust your insulin doses—in an effort to keep your blood sugars in your goal range—feels nearly impossible to predict. And for each woman, that entire process and reaction can be slightly different, so there isn’t a “one size fits all” plan.

To give guidance about how to make diabetes management less stressful during that “time” of the month (or, more accurately, the whole month),OnTrack Diabetes reached out to Jennifer Smith, RD, CDE from (And Jenny should know since she’s lived with type 1 diabetes for over 30 years!)

The Fab Four: Hormones and Your Blood Sugar Levels

“Every month,” explains Smith, “the body cycles through hormones that are meant to essentially prepare the body for pregnancy.”

There are three phases that your body cycles through the follicular, the ovulatory and the luteal phase.

“The four hormones that regulate your menstrual cycle are estrogen, progesterone, Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH). And to a very small extent, testosterone production is a factor here, too,” explains Smith.

Each of these hormones will impact your blood sugars and sensitivity to insulin differently as their production levels fluctuate throughout the entire month-long cycle. Here’s how it breaks down:

"During the week before the first day of your period, estrogen and progesterone levels are peaking,” says Smith. “This would be days 21 through 28 of a typical 28-day cycle.”

As these hormones peak in production, your blood sugars become more resistant to your “normal” insulin doses, particularly your background or basal rate insulin. While the increase of progesterone and estrogen are gradual, it can seem like there is actually one day right before your period begins during which your blood sugar spikes dramatically.

Progesterone is also the constantly-increasing hormone during pregnancy that causes insulin needs to persistently rise throughout the last two trimesters.

Preparing for Insulin Resistance During Your Cycle

Considering your hormone levels are in a constant state of flux, don’t let your frustration or confusion get the best of you. Balancing your blood sugars around the hormones of your menstrual cycle is not an easy task, especially considering that not every cycle is the exact same number of days.

Here are a few steps to help you control fluctuating blood sugars around those pesky fluctuating hormone levels:

  1. “Track your period for 3 months using a period app or even an ovulation kit, to determine when you’re likely ovulating and how many days your cycle usually is,” advises Smith. If you’ve never studied your own cycle before—even aside from its impact on your blood sugars—that’s the best place to start. Most women don’t have a need to track when they ovulate and how many days their cycle is until, or if, they begin pursuing pregnancy. Tracking your cycle for a few months can help you know when those days of stubborn high blood sugars are really the result of hormones, not your sudden inability to accurately count carbs. Some good apps to try—One Drop, mySugr, and Clue.
  2. “Watch your blood sugar for two months to establish a pattern and identify just how much your blood sugar rises during the two phases of your cycle that cause insulin resistance,” suggests Smith. Again, you’ll notice insulin resistance and higher blood sugar levels around the time you ovulate and in the days right before your period is expected to begin.
  3. “Experiment with adjusting your insulin doses with the help of your CDE or endocrinologist,” adds Smith. “Most women find they need a 25 to 40% increase in their background insulin during the days before their period starts and around the time they ovulate, whether you’re using a pump or injections.” Generally, she explains, women notice that their fasting blood sugar levels being creeping up and staying up. Some women may notice they need to slightly increase the insulin doses they take for meals, too.

“These are starting places,” explains Smith. It’s important to track for a few months first before making any major changes in your insulin doses. Be patient, try to identify a pattern, and if all else fails, do the best you can while remembering that no one does diabetes management perfectly.