How does menstruation affect blood glucose?

Dr Louise Johnson expands on how menstruation can affect blood glucose levels.


Women living with diabetes know that it’s nearly impossible to predict what blood glucose will do during menstruation. Glucose control is a lot more difficult for Type 1 patients than Type 2 diabetes.

Understanding menstruation

It’s important to realise that there are four hormones at interplay during the 28 to 32-day cycle: follicle-stimulating hormone (FSH), luteinizing hormone (LH), oestrogen and progesterone.

The primary function of these hormones is to prepare the body for pregnancy. There are three phases:

Follicular phase – the growing of the ovarian follicle (day 1-10)

Ovulatory phase – shedding of the egg cell (day 11-14)

Luteal phase – build-up of the endometrium (inner lining of the uterus (womb) and necrosis and shedding (menstruation) (day 15-28)

How hormones affect blood glucose

During each of these phases the different hormones will impact your glucose and insulin resistance differently.

Day 1 to 10: (follicular phase)

The first day of your period (menses) is the start of the first day of your cycle. Insulin sensitivity should be back to “normal” for the period of menstruation since the hormones oestrogen and progesterone are at the lowest value.

At the start of each menstrual cycle, the follicle starts to maturate by forming a large vesicle inside the follicle and then the mature follicle forms. The mature follicle will shed the egg cell (ovulation). The first 10 days, the oestrogen rises slowly.

Day 11-14 (ovulatory phase)

The follicle ruptures at day 14 and the ovum (egg cell) is extruded into the abdominal cavity. This ovum is picked up by the fimbria of the fallopian tubes. This process is ovulation.

During ovulation, the oestrogen level is at its highest and the LH has a burst of secretion from the pituitary. This marks the end of the follicular phase.

Blood glucose will begin to rise as well as insulin resistance. This is due to the rise of oestrogen, LH and FSH to its highest value. This spike of blood glucose will be two to three days. It’s accompanied by a slight rise in body temperature.

Day 15-20

During this phase, LH and FSH drops back to normal values and oestrogen decreases rapidly. Blood glucose values are easier to manage.

Day 21-28

This is the area of highest blood glucose due to rise in progesterone as well as oestrogen and hence insulin resistance. This is the three to seven days leading to your next menstruation. During this time, you would be more ‘resistant’ to basal insulin and would need a few more units to control your blood glucose. This can also be called the premenstrual syndrome (PMS) phase.

A study2 showed beautifully in different Type 1 diabetes patients with continuous glucose monitor (CGM) that the glucose varies between the luteal phase (day 21-28) and the follicular phase (day 1-10).

PMS

Premenstrual syndrome occurs a few days before the next menstruation. The symptoms can be worsened by poorly controlled blood glucose levels.

Symptoms such as tenderness, bloating, grumpiness, and cravings are a few common ones. The food cravings are due to the rise in progesterone. Usually chocolate or sweet things are craved. Manage this by light exercise, sugar-free or fat-free snacks, and extra insulin as needed.

It’s important to remember that not all females have a 28-day cycle. Some may have a slightly longer or shorter cycle. It can vary from 21 to 35 days.

Managing fluctuating hormones every month

  1. Keep a diary of your period for three months to establish the length of your cycle and the time of ovulation. This will help you to adapt better to higher blood glucose. There are apps that can be used such as mySugr, Clue and One Drop.
  2. Diarise your blood glucose for three months to establish the two periods of increased insulin resistance during ovulation and just before menstruation.
  3. There is a need to increase basal insulin with 25 to 40% during these two periods. Start low and slowly document your correct basal increase during these times to keep glucose levels controlled.

Why is it important to know your menstrual cycle?

The menstrual cycle affects your ability to control your glucose for about 35 years. Menarche (start of menstruation) at around 12 years of age to menopause at around 45 years of age is a significant duration of time to struggle with bad glucose control. This can lead to unnecessary complications both microvascular (eyes, feet, kidney) and yeast infections vaginally due to poor control.

Women on the contraceptive pill

There are a variety of contraceptive pills on the market. Your gynaecologist will suggest the correct one for you. It’s important to remember that the pill can increase insulin resistance and that you should increase your insulin accordingly with the help of your doctor.

This increase in insulin resistance occurs three to six months after the oral contraceptive is started. It is thought that the progesterone may induce insulin resistance through its inhibition of insulin signalling in the adipocytes (fat cells).3

Menstruation is the start of womanhood and should be a great time in a woman’s life. Fertility and the prospect to be able to have a baby should always be cherished and respected.

Remember that good control (HbA1c of 6%) is important before planning a baby. Discuss your menstrual problem and proper family planning with your doctor and enjoy being a woman.


References:

  1. Yeung EH, Zhang C, Mumford SL et. al. Longitudinalnstudy of insulin resistance and sex hormones over the menstrual cycle: BioCycle Study. J Clin Endocrinol Metab 2010;95:5435-5442
  2. Goldner WS, Kraus VL, Sivitz WI et. al. Cyclic changes in glycemia assessed by continuous glucose monitoring system during multiple complete menstrual cycles with type 1 diabetes. Diabetes Technol Ther 2004;6:473-480
  3. Wada T, Hori S, Sugiyama M et. al. Progesterone inhibits glucose uptake by affecting diverse steps of insulin signaling in 3T3-L1 adipocytes. Am J Physiol Endocrinol Metab ,2010: 298 ;E881 –E888
Dr Louise Loot

MEET THE EXPERT


Dr Louise Johnson is a specialist physician passionate about diabetes and endocrinology. She enjoys helping people with diabetes live a full life with optimal quality. She is based in Pretoria in private practice.


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