Women with type 1 diabetes often find their menstrual cycle can cause extra challenges for blood glucose management. Credentialled diabetes educator LAUREN EIPE explains why this happens and what might help.

Have you ever felt frustrated that your blood glucose levels are all over the place on the days leading up to and throughout your week of menstruation? You are not alone! This is a common occurrence, and a lot of women living with type 1 diabetes are in the same boat.

Why does this happen? Research has shown that female hormones and the way they fluctuate throughout the menstrual cycle can affect women’s blood glucose levels and insulin sensitivity.

Hormones act as a barrier (like a brick wall), causing the locks on our muscles to seize up, preventing the insulin from effectively moving the glucose through from our blood (we call this reduced insulin sensitivity). The result is higher blood glucose levels.

Estrogen and progesterone are the two main hormones that play a part in this. Estrogen is a sex steroid hormone that induces ovulation and endometrium growth to prepare for egg implantation.

Estrogen levels are at their highest during our menstrual cycle when we are preparing to ovulate. Once ovulation has occurred, those estrogen levels begin to decline but don’t return to normal levels just yet. They will slightly rise again (during the luteal phase) when your body is preparing for an egg to be implanted in the uterus.

If there is no implantation of an egg, the estrogen levels will decline to their base level and menstruation will start. Blood glucose levels will then start to return to normal as insulin sensitivity increases.

Progesterone is another sex steroid hormone. It increases the endothelial lining of the endometrium and thickens the endometrial wall ready for egg implantation and maintenance of the uterus during pregnancy.

Progesterone levels begin to rise as the egg is released from the fallopian tube and navigates its way down into the uterus. Levels peak during this time. If the egg is not implanted the progesterone levels (like the estrogen levels) will start to decline. Blood glucose will return to your usual levels and insulin sensitivity will increase once again.

Progesterone is the hormone that during pregnancy causes insulin resistance (decreased insulin sensitivity) and may be involved in the development of gestational diabetes.

Some women living with type 1 diabetes (not all) might notice that during ovulation and the start of menstruation their blood glucose levels are a little higher than usual. Just as steroid medication can cause a rise in blood glucose levels, so can the steroid hormones that our body produces.

How can we manage this? If you are seeing higher blood glucose levels prior to ovulation or menstruation it may be beneficial to increase the amount of basal or background insulin given (using either an insulin pump or multiple daily injections) two to three days before ovulation or menstruation starts. This may help regulate your blood glucose levels.

You can discuss this with your GP, endocrinologist or credentialled diabetes educator. Managing blood glucose levels around exercise can also be a challenge during ovulation or menstruation. Some women experience fluctuations in blood glucose levels (both high and low levels) when they are active. These fluctuations will depend on the type, intensity, and duration of activity, as well as the phase of your menstrual cycle.

For some women, high blood glucose levels before and during activity can be really frustrating to manage. If this happens to you, we encourage you to check for ketones if your glucose levels are above 15 mmol/L. If you do not have any ketones hanging around, sometimes a 15-minute slow warm-up and cooldown can help with high glucose levels before, during, or after activity.

If you are experiencing ketones in your blood, follow your sick day management plan. You may require some extra insulin and should postpone activity until your blood glucose levels and ketone levels return to target range.

An exercise physiologist with experience in type 1 diabetes may help to support you with strategies to manage blood glucose levels for your chosen activity, particularly during those tricky times during your cycle.

So, who can you see about this?

• general practitioner

• endocrinologist

• credentialled diabetes educator

• accredited exercise physiologist

Know that you are not alone in this. There are many women also living with a similar story. Be assured that health professionals can support you to manage your health and wellbeing.