This 28-day cycle is an important part of your health but just like hormones related to stress, these hormones can also impact your blood sugars and sensitivity to insulin. 

Hormones involved in your menstrual cycle and their role

These hormones can create varying levels of insulin resistance.

1. Progesterone
2. Estrogen
3. Luteinizing Hormone (LH)
4. Follicle Stimulating Hormone (FSH)

But these hormones do more than just ensure your body is prepared for pregnancy, they also:

• Manage your heart rate
• Keep your skin healthy
• Manage your appetite
• Regulate body hair growth
• Regulate your sex drive
• Produce vaginal lubrication
• Manage your weight

Without healthy levels of these hormones, you wouldn’t just struggle to get pregnant or maintain a desire for sex, you’d also feel extremely sick because the many bodily functions above would go haywire.

Phases of your menstrual cycle

There are also four phases of your menstrual cycle, and pinpointing these in your body’s own menstrual cycle calendar can help you anticipate funky blood sugar challenges.

1. Menstruation (day 1 thru 10): This begins on the day your period starts.
2. Follicular phase (day 11 thru 14): This phase technically overlaps with the start of your period. During this phase, your body is preparing for ovulation by creating a thick lining on the wall of your uterus, creating the best environment for an egg. This phase ends on the day you ovulate — releasing an egg — which is usually day 14 for the average woman. (Birth control prevents the release of the egg.)
3. Ovulatory phase (days 15 to 20): The egg has been released and it travels down the fallopian tube towards the uterus hoping to be fertilized by sperm.
4. Luteal phase (days 21 to 28): This phase can go in two different directions depending on whether or not the egg was fertilized by sperm. The lining of your uterus is growing thicker hoping for a successfully fertilized egg. By day 28, if the egg was not fertilized, your period begins again. 

Impact on your blood sugar and your control options

While every phase in your menstrual cycle can have at least a slight impact on your insulin needs and blood sugar levels, the most significant day in your entire cycle will be the day your period starts.

Most women will see a significant spike in their blood sugar during the hour before and the few hours immediately after your period starts.

What can you do about it?

Predicting exactly when your period is going to start is tricky. Some women are very regular, others may find it varies by a day or two.

And of course, predicting the exact hour that day is rather impossible unless your symptoms (like cramping) are extremely consistent.

The simplest strategy is to adjust your insulin doses as soon as you realize your period has started and you are clearly bleeding, or if you’re cramping, you know it’s about to start, and your blood sugar is already rising.

If you’re on a pump: You could work with your healthcare team to adjust your basal rate specifically for the day of your period, likely increasing your total daily insulin usage by 2 or 3 units.

You could also simply take a correction bolus of insulin when your period starts and you see your blood sugars rising.

If you take injections: Adjusting your long-acting insulin dose is tricky because you’ll need to be certain the day before your period starts that it is indeed going to start soon. Instead, you’re better off working with your healthcare team on taking small doses of rapid-acting insulin to prevent or correct rising blood sugars when your period starts.

Above all else: take good notes! Write down what you did and when you did it, and how it impacted your blood sugars. The more consistencies you can pinpoint, the more easily you can manage your blood sugars every morning on day 1 of your cycle.  

Talk to your healthcare team for support when making adjustments in your insulin doses.

Thinking about pregnancy? Check-out my book, Pregnancy with Type 1 Diabetes: Your Month-to-Month Guide to Blood Sugar Management.