From our ability to concentrate at work to our sense of taste and smell, the fluctuations in our sex hormones that occur throughout the menstrual cycle can affect almost every area of the body. And that includes how other systems in the body behave – including the regulation of blood sugar.

While most non-diabetics won’t need to worry about these small fluctuations in blood sugar regulation, these changes mean you might notice a slight change in your appetite and be more predisposed to blood sugar dips (ie feeling a bit lightheaded and shaky) at different points in your cycle.

But why do these fluctuations happen? And when can you expect them? We spoke to Dr Shashi Prasad, a GP specialising in women’s hormonal health and chronic disease management, and a team member at The Marion Gluck Clinic, to find out more.  

Both oestrogen and progesterone can affect the way our body regulates blood sugar – which is why you might find your blood sugar skews both higher and lower at different points in the cycle.

“During the follicular phase [when oestrogen levels rise], insulin sensitivity increases and blood sugar levels may drop,” Dr Prasad explains. The term insulin sensitivity simply refers to insulin’s ability to remove glucose from the blood, so when you have high insulin sensitivity, your blood sugar is likely to run on the lower side. It’s for this reason why you might experience low blood sugar during this phase. 

As you enter the second half of the cycle – also known as the luteal phase – things change again. “As oestrogen levels drop and progesterone levels increase, women may experience a higher blood sugar level,” Dr Prasad adds. “Some women also note an increase in their appetite.”

For many of us, this impact on blood sugar will be small; a Harvard study that investigated the impact of the menstrual cycle on blood sugar levels in non-diabetic women found that participants spent 66.8% of the day at a healthy blood sugar level during the luteal phase, compared to 68.5% in the follicular phase. 

While the fluctuations that occur during the menstrual cycle may not have a huge impact on blood sugar, hormonal imbalance – such as that which occurs during perimenopause – can have a bigger effect.

This is because oestrogen helps to make the body more sensitive to oestrogen, so when levels of the hormone drop or disappear during perimenopause, your risk of developing insulin resistance – a condition where cells in the muscles, fat and liver don’t respond well to insulin – increases.

“During perimenopause, women often note that they are having difficulty in regulating their blood sugar, and may have sugar cravings,” Dr Prasad explains. Add to that the fact that the hormonal changes that occur during perimenopause can also lead to changes like weight gain and higher blood pressure, and you won’t be surprised to learn that perimenopausal women are also at higher risk of type two diabetes. 

It’s worth noting that women with polycystic ovary syndrome (PCOS) are also at a higher risk of insulin resistance, although variations in the sex hormones may not drive this. Instead, it’s thought that insulin resistance – either caused by genetics or other factors – may be one of the driving factors behind PCOS, as elevated insulin levels can contribute to the inflammation and metabolic issues often associated with the condition.  

Images: Getty