Hormones and Your Blood Sugar Levels

The body cycles through hormones designed to essentially get the body ready for pregnancy once a month, according to Smith. Your body goes through three phases: the follicular phase, the ovulatory phase, and the luteal phase.

Oestrogen, progesterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH) are the four hormones that control your menstrual cycle, according to Smith. “Testosterone production is a factor here, too, to a very small extent.”

As the amounts of these hormones’ production vary over the course of the full month-long cycle, each will have a unique effect on your blood sugar levels and sensitivity to insulin. The breakdown is as follows:

Days 1-10: Relatively Smooth Sailing

The first day of your cycle begins on the first day of your period. While some women may experience higher blood sugars and insulin resistance on this day, your insulin sensitivity should return to “normal” for the remainder of your period. The few days following your period are generally insignificant as well in terms of blood sugar challenges.

Days 11-14: Erratic Blood Sugars Typical

The “ovulatory phase” is the first part of your cycle where you may notice higher blood sugars and insulin resistance, Smith explains. As your body prepares to release an egg (ovulate), your levels of LH, FSH, and estrogen all rise, causing a brief but notable spike in blood sugars.

“This phase is generally noticed in blood sugar levels for no more than two or three days at most,” says Smith.

Days 15-20: You Can Relax Now, but Not for Long

During this part of your cycle, your LH and FSH levels drop quickly back to normal levels. Estrogen will decrease rapidly as well, but as you approach the next phase of your cycle both estrogen and, especially, progesterone levels begin to rise, setting the stage for…

Days 21-28 of Your Cycle: High Blood Sugar Territory

The time of your cycle that you’re probably noticing significant and lasting insulin resistance and higher blood sugar is during the three to seven days leading up to the start of your next period.

“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 increases 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.

It’s worth noting that progesterone is also the constantly increasing hormone during pregnancy that causes insulin needs to persistently rise throughout the last two trimesters.

How Else Does Diabetes Affect Your Menstrual Cycle?

Along with big shifts in blood sugar, diabetes can affect your cycle in other ways. Both type 1 and type 2 diabetes are linked to irregularities in the menstrual cycle. Having diabetes can affect the age at which you first get your period and the age at which you experience menopause. People who have type 1 diabetes experience menopause earlier.

Type 1 and type 2 diabetes are also associated with fewer pregnancies and difficulty in conceiving. More research needs to be done to fully understand how diabetes directly affects the menstrual cycle.

Preparing for Insulin Resistance During Your Menstrual 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 necessarily the exact same number of days.

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

Step 1: Track Your Cycle

Smith advises tracking your period for three to six 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.

If you’ve never studied your own cycle before—whether for its impact on your blood sugars or for another reason—this is the best place to start. Most women don’t have a need to track when they ovulate or 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 and not a sudden inability to accurately count carbs. Some good tracking apps to try: One Drop, mySugr, and Clue.

Step 2: Study Your Blood Sugar Pattern

“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.

Step 3: Adjust Your Insulin Doses (With Your Provider’s Help)

Once you’ve tracked your period and blood sugar for a few months and identified a pattern, experiment with adjusting your insulin doses with the help of your certified diabetes care and education specialist, certified diabetes educator, or endocrinologist, Smith suggests.

“Most women find they need an increase in their background insulin during the days before their period starts and around the time they ovulate, whether they’re using a pump or injections,” says Smith. Generally, she explains, women notice their fasting blood sugar levels creeping up and staying up during these times. The increase in background insulin needed to compensate for this can range from about 25% to 50%.

Some women may notice they need to slightly increase the insulin doses they take for meals, too.

What to Eat for Better Blood Sugar Balance

If you have diabetes, the foods you eat during your period should mirror the foods you eat throughout the month to keep your blood sugar balanced. That said, there are a few additions that can help with symptom control and compensate for blood loss.

Most importantly, keep your intake of refined sugar and simple carbohydrates to a minimum. This can be challenging, since carb cravings can be pretty common around your period. If you’re craving carbs, choose healthier, complex carbs to help avoid big rises in blood sugar.

Fiber-rich fruits can also help curb cravings without spiking blood sugar. Some tasty and healthy treats include mixed berries topped with a small amount of homemade, sugar-free whipped cream; apples dipped in one or two tablespoons of peanut, cashew, or almond butter; a handful of prunes or dried apricots and a slice of cheese; sliced avocado on whole grain toast; or a handful of pomegranate seeds.

Other healthy complex carbs include beans, legumes, and whole grains. These may not be as exciting as cookies or brownies, but the blood sugar spikes (and drops) aren’t worth a few moments of pleasure.

It’s also helpful to eat foods rich in omega-3 fatty acids (like fish), calcium (dairy products), and magnesium (nuts, seeds, and legumes) to prevent mood swings, cramps, and bloating.

Finally, eating more iron-rich foods can help your body deal with blood loss and the resulting fatigue that occurs during and after menstruation. The richest sources of iron are shellfish, red meat, liver and other organ meat, followed by a few vegetarian foods, such as legumes, dark leafy greens, and pumpkin seeds.

“These steps 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.