Please Note: This post was published in 2014. Since then newer studies on this subject have been published. Look out for an updated post on this topic coming soon!
My roommate joked the other day that I blame absolutely everything on my period. Insomnia, bitchiness, incessant crying, extreme cramps, acne, oily hair, and overheating a week before that time of the month are all things I link to the building and shedding of uterine walls and the hormonal activity that accompanies it.
Yes, woman have been complaining of PMS since the dawn of human-kind; however, as only 3% of the world has type 1 diabetes and judging that close to half of those are women, we’ll estimate that about 1.5% of the worlds population deals with controlling their blood sugar during the luteal phase of their menstrual cycle.
To all my male endocrinoligists: Want to know why my A1C is high?
To my boss: Want to know why I can’t function one week of the month?
Blame it on the Progesterone.
For a type 1 diabetic the luteal phase or the weeks leading up to menstruation are the absolute worst. They are chalk full of hyperglycemia, hypoglycemia, and even diabetic ketoacidosis. Just as everyone experiences different symptoms of PMS, I would assume the hormonal effect on insulin sensitivity varies from diabetic to diabetic; however, a link has been made between the luteal phase and increased insulin resistance.
In my experience, in the week leading up to my period, my blood sugar becomes uncontrollable, my Dexcom CGM a roller coaster of extreme highs and lows, resulting in extreme fatigue and frustration.
Progesterone is secreted by the corpus luteum and is present in significant amounts only during the luteal phase of the menstrual cycle. Progesterone levels increase gradually after ovulation peaking at the same time that estrogen peaks around days 21-23 of the 28-day menstrual cycle. Negative feedback to the anterior pituitary gland and hypothalamus cause gonadotropin levels to fall resulting in decreasing estrogen and progesterone levels. Menstrual bleeding occurs as a consequence of hormonal withdrawal.
Studies on rats have shown that progesterone impairs glucose uptake in skeletal muscle and adipose tissue.(1) Progesterone was also shown to augment pancreatic insulin release in animals, theoretically in response to an increase in insulin resistance. Human trials testing glucose disposal at different phases of the menstrual cycle showed only a 24% decrease in insulin resistance in the luteal phase compared to the follicular phase,(2) not the evidence I would expect from my own personal experience.
Another possible cause of decreasing insulin sensitivity could be low-grade inflammation during this phase. High sensitivity C-reactive protein change with menstrual cycle phase, which is correlated with physical and mood symptoms associated with menstruation. This could in turn affect insulin resistance.
Although, it is not completely clear if a rise in progesterone during the luteal phase is entirely responsible for decrease in insulin resistance, it is clear that progesterone plays a part in this phenomenon.
It’s advisable to set alerts and check your CGM or finger prick at least once an hour. I would also advise greatly decreasing your intake of carbohydrates and increasing your basal rate (if pumping) or lantus dosage. Upon the start of menstruation it is advisable to lower these to avoid hypoglycemia.
As hormone levels fluctuate uncontrollably there is no estimating the exact times when insulin resistance will rise and fall, resulting in what I like to call the roller coaster effect. If I had a perfect method of treatment, I wouldn’t experience DKA (Diabetic Ketoacidosis) almost every month. Right now all I can do is wait for the widely anticipated bionic pancreas estimated to be approved and on the market in 2017.
(1) Rushakoff RJ, Kalkhoff RK. Effects of pregnancy and sex steroid administration on skeletal muscle metabolism in the rat. Diabetes. 1981;30:545–550.
(2)Trout KK, Rickels MR, Schutta MH, et al. Menstrual cycle effects on insulin sensitivity in women with type 1 diabetes: A pilot study. Diabetes Technol Ther. 2007;9:176–182.