How Your Menstrual Cycle Can Affect Your Diabetes


If you’re often frustrated by sudden fluctuations in your blood sugar before or during your menstrual cycle as a person with diabetes, you’re not alone. While some people with type 2 diabetes may not notice any impact on blood sugar levels, others may see a significant impact! It can vary from person to person.

That 28-day cycle is far more complex than we give it credit for—and this is particularly apparent for those of us who manage daily insulin doses and blood sugar levels.

Here, we’ll take a look at the specific hormones involved in your menstrual cycle, how they might impact your diabetes and tips to help you better understand and manage the patterns.

(Even if you can’t predict the start of your cycle, understanding what’s happening and how it might be causing sudden changes in your blood sugar can lead to less frustration!)

First, remember to check your blood sugars frequently right before and during your period.

Before we get into the joys of how your menstrual cycle can cause fluctuations in your blood sugar levels, let’s get clear on one very important thing: During the few days right before and during the week of your period, it’s important to check your blood sugar frequently. Many people experience significant changes in blood sugar levels and insulin needs during this part of the menstrual cycle.

And make sure to take good notes using a blood glucose monitor and a logging app, or a continuous glucose monitor to help you find predictable patterns.

The more often you check your blood sugar, the more data you have to make thoughtful changes in your diabetes management routine during those days.

You can share your blood sugar data with your healthcare team to help you learn how to adjust your insulin doses safely and appropriately.

The Hormones & Phases of Your Menstrual Cycle

We tend to think of the hormones involved in our menstrual cycle as simply managing your body’s fertility cycle, but they do so much more than that!

  • Progesterone
  • Estrogen
  • Luteinizing Hormone (LH)
  • Follicle Stimulating Hormone (FSH)

Throughout every 28-day cycle (which can vary slightly in length from person-to-person), these four different hormones are fluctuating. For example, if your body is about to release an egg then your hormone levels are different from the day your period starts. Every day, these four hormones are shifting in different directions as your body works through that 28-day cycle.

The average length of the entire cycle is 28 days, but it can be as short as 21 days for some or as long as 35 days for others. If your cycle is shorter 21 days or longer than 35 days, you should discuss it with your doctor immediately as it can indicate other health concerns.

Beyond fertility and periods, though, these hormones play a big role in many other parts of your daily health, including:

  • Healthy skin
  • Body weight
  • Heart rate
  • Appetite
  • Hair growth
  • Sex drive
  • Vaginal lubrication

Next, it can be helpful to understand the four phases of your menstrual cycle because these phases indicate significant changes in hormone levels—which can impact your blood sugars and insulin needs.

Keep in mind that everyone is different, so your friend may notice a significant change in insulin sensitivity on the day they ovulate, but you may not. Many people who menstruate notice big changes in the days around the day you start bleeding, but exactly when and for how long that change in your blood sugar occurs also varies significantly from person-to-person.

While your menstrual cycle is a complex process, here are four general phases your body works through every 28 days.

Phase 1: Menstruation (day 1 thru 7-10ish)

Phase 1 of your cycle starts on the day your period starts. Progesterone and estrogen hormone levels are at their lowest as your body sheds the lining of your uterus.

While many people report changes in blood sugar levels and insulin needs right before this phase, the effects can persist through the start of your period week, too. For some, insulin resistance only affects the first few hours or day, and for others it can last several days.

It’s important to take notes and look for patterns in how your diabetes responds to this particular phase of your menstrual cycle. The more you can find patterns using a blood sugar logging app like mySugr, the more you can prepare and create a plan with your healthcare team to adjust your insulin doses during this time.

Phase 2: Follicular phase (day 8-10ish thru day 14)

This phase is about preparing for ovulation. The first two weeks of your menstrual lead up to the day your body releases an egg, but like everything else, this timeline can vary from person-to-person.

Your estrogen levels are rising gradually, and peaking, as you approach ovulation day. If you take birth control, your body does not release an egg and your estrogen levels simply do not rise as much.

Most people do not notice a significant change in insulin needs or blood sugar levels during this phase.

Phase 3: Ovulatory phase (day 15 thru day 20)

Typically in the middle of your entire menstrual cycle—but often earlier or later for many people—ovulation triggers a large spiking in luteinizing hormone levels.

While this phase shouldn’t typically have a big impact on your diabetes management, some people do report significant changes in insulin sensitivity and blood sugar levels. Taking good notes with an app like mySugr and discussing it with your doctor is the best way to determine how this phase affects your diabetes.

Phase 4: Luteal Phase (day 21 thru day 28)

Immediately after your body releases an egg, the lining of your uterus grows thicker in preparation for potential pregnancy.

Progesterone levels rise and eventually peak during this phase which can lead to insulin resistance and higher blood sugar levels nearing day 28. This phase is also traditionally when people feel premenstrual symptoms (PMS).

The moment your period begins (marking the end of this last phase) is when progesterone levels drop very suddenly. This can lead to a sudden change in being very insulin resistant or to being more insulin sensitive.

Some people report insulin resistance persisting through to Phase 1 while others report it changing very quickly.

Diabetes management during your menstrual cycle

Getting a grasp of how your menstrual impacts your diabetes management takes time. To make things even trickier, your period may not be particularly consistent from month-to-month, with varying and unpredictable cycle lengths.

First, start using a “period tracking app” that allows you to mark in the app when your period begins and ends. There are tons of options for iPhone and Android cellphones. From there, you can start to see how consistent the length of your menstrual cycle truly is. If it’s remarkably inconsistent, that’s definitely worth talking to your doctor about.

A lack of consistency in your menstrual cycle can be a sign of other health concerns like:

  • Anemia (low iron)
  • Thyroid issues (hypo- or hyper-)
  • Fibroids
  • Polycystic ovarian syndrome (PCOS)
  • Menopause
  • Endometriosis
  • Obesity
  • Over-exercising
  • Under-eating
  • Severe stress
  • Certain medications
  • Certain types of cancer

Next, track your blood sugars more closely with an app like mySugr—especially right before and during the start of your period—to notice patterns. By talking about these patterns with your doctor, you can determine some simple and hopefully consistent changes to make in your insulin doses.

For example:

  • People who use insulin pumps could create a “basal profile” that delivers 10 to 20 percent more insulin than you normally need to use during the most insulin resistant days of your cycle.
  • People on multiple daily injections could determine that you need a boost of two or three units in your background (long-acting) insulin dose during the most insulin resistant days of your cycle.

Diabetes is frustrating, and often confusing. While we can’t predict everything, even simply tracking can also help us understand the spikes when they happen. The more you understand why the spike happened, the less frustrating it might feel. Reacting with knowledge is better than not knowing at all!

We asked, you shared: How does your menstrual cycle affect your diabetes?

Here, you’ll find a variety of personal examples that demonstrate just how differently our bodies each respond to the hormone fluctuations that come with every menstrual cycle.

“I trend very low when I’m menstruating / when I’m on my placebo pills week with my bc. I lower my basal dose that week.” @flycantbird

“My blood sugars are definitely a bit higher, often needing a lot more checks throughout the day and higher insulin doses to avoid DKA because I have gotten into DKA before because of my menstrual cycle.” @semenyathapi

“Getting a CGM completely changed my understanding of how my menstrual cycle affects my BG. After having it a few months I noticed my insulin sensitivity changes when I am ovulating and menstruating. I use a period tracker to figure out when to adjust my insulin.” @Chloe_Roxanne

“I have noticed that they go low in the days leading up to my period and then trend high the first few days … so I think that hormones definitely affect your blood sugars!” @Carmen14312590

“The last week of my cycle I’m less insulin sensitive but my first week my body is very sensitive to insulin and I have lows all over the place! Still haven’t figured out how much to back off my ratios but I know I need to at least a little for that first week.” @Lillilamae7

“Mine are significantly higher in the week prior, but a few days before I have stubborn persistent lows. The shift started when I entered peri, so definitely hormone related.” @sarahb_SBEEC

“I have a problem with rising blood sugars specifically between 11pm and 4-5am for about 10 days of my cycle—which can be a bit hard to deal with. Sometimes it comes on over a week before my cycle starts but the timing is unpredictable. Sometimes my blood sugars do this during a cycle, sometimes not. It feels a bit unpredictable for me and I definitely check a lot.” @sarahbetterdia

“Although I have a regular menstrual cycle, it really affects my insulin needs and blood sugar—I need more insulin during PMS, since I couldn’t do any workout during menstruation. It influences my insulin absorption which makes me need to increase my insulin needs.” @anitasabidi

“My insulin requirements go through the roof.  Depending on what your hormones are doing, I can be 100 percent on target one day and the next I’m lucky if I get to 20 percent.  I suppose this won’t get any easier as we head towards the menopause.  Oh the joys of diabetes.” @kareneb381

“Slightly insulin resistant for two days before my period starts and then really sensitive for a couple of days. Two-to-three days pre-ovulation I’m really resistant and run on 140-150 percent basal.” @PretendPancreas

“When I used to menstruate there was a vague correlation, i.e. blood sugars were somewhat higher and harder to manage the two weeks prior and more stable for two weeks after…However, I’ve been menopausal for over a decade now and still have similar vague cycles like that, so…” @MiriamETucker

“I usually trend lower for a couple days before but go back to fairly normal during my cycle. Dexcom and ControlIQ help.” @EditorMichelleK

“Before Control IQ, my blood sugars would sky rocket!” @T1dchick_

“Super high for WEEKS due to ovulation. And then once the blood comes, sometimes I drop and it’ll go up and down. And then I’m normal for like two days lol and repeat. This process makes me Suicidal at times too.” @TheColorOfJess

“Ah, the monthly struggle is real. Five days of significant insulin resistance leading up to my period then my blood sugars drop like a rock the day of.” @ChronicIndepend

“I’m insulin resistant the week before my period for sure! It usually evens out to normal during tho.” @SweetSamanthaa

“It depends and it’s really exhausting because I can’t anticipate what my body will need! Every month could be different, so I wait until it arrives and then depending on the results I act.” @rosavidalal

“I actually just got out of the hospital again. Me & the doctors both noticed how I’m admitted to the hospital once a month always during that time , sometimes DKA or a gastroparesis flare up. I just got diagnosed with anemia, my body also loses a lot.” @fckdiabetes

“I’ve had diabetes for 19 years and have never even thought to notice a difference! I’ll be on alert now!” @OhBeane

Editor’s Note: This content was made possible by Roche.

WRITTEN BY Ginger Vieira, POSTED 01/20/21, UPDATED 12/12/22

Ginger Vieira is an author and writer living with type 1 diabetes, celiac disease, fibromyalgia and hypothyroidism. She’s authored a variety of books, including “When I Go Low” (for kids), “Pregnancy with Type 1 Diabetes,” and “Dealing with Diabetes Burnout.” Before joining Beyond Type 1 as digital content manager, Ginger wrote for Diabetes Mine, Healthline, T1D Exchange, Diabetes Strong and more! In her free time, she is jumping rope, scootering with her daughters, or walking with her handsome fella and their dog.