By Andrea Chisholm, MD 

 Medically reviewed by Chioma Ndubisi, MD

A typical menstrual cycle lasts around 28 days with a normal range of between 21 and 35 days. During this roughly month-long cycle, changes in your hormone levels trigger ovulation (the release of a mature egg) and then menstruation (your period) if you don't conceive.

You may not realize that these hormonal changes can affect other body functions as well. This is especially true with regards to women living with diabetes, who are faced with unique challenges and risks when it comes to their reproductive cycle.

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This article looks at how the reproductive cycle can affect a person's ability to control diabetes and, conversely, how diabetes affects a person's reproductive cycle, and the risk of certain gynecological concerns, including cancer.

Blood Sugar Increases During Your Period

If you have problems controlling your blood sugar the week before your period, it may not be caused by anything you are doing. It may, in fact, be due to changes in your hormone levels.

Roughly halfway through the menstrual cycle, ovulation occurs. At that point, progesterone levels increase. Increases in progesterone are, in turn, associated with increased insulin resistance.1

That means that during the second half of your cycle (called the luteal phase) when progesterone levels are naturally higher, you may experience some insulin resistance. This response is known as luteal phase insulin resistance. People with type 1 diabetes tend to be more sensitive to this.

Luteal phase insulin resistance can lead to a hyperglycemic event in which your blood sugar spikes even if you are adhering to your routine diet and exercise plan.

An increase in progesterone can also trigger food cravings for simple carbohydrates and may cause you to lose your motivation to exercise. This can further contribute to poor glycemic (blood sugar) control.

If you are living with diabetes, it is important to be mindful of your diet and exercise during the luteal phase. If you are on diabetes medications, it is extra important to check your blood sugar regularly to maintain glycemic control.

Recap

Increases in progesterone levels during the latter half of the menstrual cycle can lead to increased insulin resistance. During this period, you need to be extra mindful of your diet and regularly monitor your blood sugar if you are on diabetes medications.

Hormonal Contraception and Insulin Resistance

In the same way that natural hormonal fluctuations can affect glycemic control, the use of hormonal contraceptives—including birth control pills, contraceptive patches, and contraceptive rings—may do the same.

These hormonal contraceptives contain forms of estrogen, progesterone, or both. Some studies suggest estrogen may trigger insulin resistance, making it harder to control your blood sugar.2 Other research, however, shows no link between hormonal contraception and daily insulin requirements, long-term diabetes control, or diabetic complications.3

In general, it is absolutely fine to use these forms of birth control if you have diabetes. However, if you have had diabetes longer than 20 years or have diabetic complications, stick to progestin-only formulas.4 Birth control that contains estrogen is linked to an increased risk of blood clots.5

Still, it is important to be aware of the potential effect birth control may have on glycemic control. Pay extra attention to your blood sugar whenever you are starting or changing hormonal contraceptive methods.

Recap

Hormonal contraception, including birth control pills and contraceptive patches and rings, can sometimes contribute to insulin resistance. It is especially important to monitor your blood sugar whenever starting or switching hormonal contraceptive methods.

Late Period, Early Menopause

If you are living with type 1 diabetes, you are likely to experience menopause sooner compared to those living with type 2 diabetes or those without diabetes. Studies show that this type of diabetes causes the premature aging of blood vessels and, in turn, the premature aging of the ovaries that produce eggs.6

In addition, people with type 1 diabetes are more likely to experience menarche (the onset of menstruation) at a later age. This further narrows the window during which conception and pregnancy can occur.7

A person with type 1 diabetes is also more likely to have irregular periods than those without. A 2011 study in Reproductive Biology and Endocrinology suggests that more than a third of teenagers with type 1 diabetes will have irregular menstruation. Scientists don't yet fully understand why this is.7

Recap

Type 1 diabetes is associated not only with early menopause but also irregular periods and delayed menarche (late onset of menstruation).

Weight and Irregular Periods

Although type 2 diabetes can occur in women who are not overweight, it is more commonly associated with being overweight or obese.

Unlike type 1 diabetes in which your body doesn't produce enough insulin, type 2 diabetes is the result of insulin resistance in which your liver, muscles, and fat don't respond well to insulin that is being produced.

When you are overweight, the greater volume of body fat generates larger amounts of hormones that directly contribute to insulin resistance. This, in turn, causes your pancreas to produce even more insulin.

For reasons not fully understood, high levels of insulin can interact with hormones that regulate menstruation, leading to irregular or missed periods. In some cases, there may even be anovulation in which a person doesn't ovulate.

People with polycystic ovarian syndrome (PCOS) are at a particularly high risk of insulin resistance and type 2 diabetes.8

Recap

Being overweight or obese increases the risk of insulin resistance and type 2 diabetes. Insulin resistance can contribute to irregular or missed periods due to the overproduction of insulin that can indirectly influence menstrual cycles.

Risk for Endometrial Cancer

Endometrial cancer is the most commonly diagnosed gynecologic cancer and one that is most often occurs after menopause. 

Type 2 diabetes increases your risk of endometrial cancer. People with polycystic ovary syndrome (PCOS) and those who are significantly overweight or obese are at an even greater risk. This may be due to insulin resistance and chronically high insulin levels, which can trigger an imbalance between estrogen and progesterone.9

Hormonal imbalances interfere with menstruation and can also cause the lining of the uterus (endometrium) to overgrow (endometrial hyperplasia). This is also linked to an increased risk of endometrial cancer.9

Recap

Type 2 diabetes is linked to an increased risk of endometrial cancer irrespective of your weight. However, the risk is further increased if you are significantly overweight or obese.

Summary

Diabetes can affect normal menstruation, and menstruation can affect diabetes control. It's a Catch-22 situation that can make life challenging for people living with diabetes.

Prior to your period, increases in progesterone can lead to temporary insulin resistance and a spike in your blood sugar. The same is true if you have diabetes and use hormonal contraceptives that further increase progesterone levels.

On the flip side, diabetes can increase the risk of irregular periods and anovulation (no ovulation) due to an imbalance in estrogen and progesterone levels. With type 1 diabetes, there is also an increased risk of delayed menarche (late onset of menstruation) and early menopause.

Type 2 diabetes is also linked to an increased risk of endometrial cancer irrespective of a person's weight. The risk only increases if a person is overweight or obese.

Sources

Yeung EH, Zhang C, Mumford SL, et al. Longitudinal study of insulin resistance and sex hormones over the menstrual cycle: the BioCycle Study. J Clin Endocrinol Metab. 2010;95(12):5435–5442. doi:10.1210/jc.2010-0702

Gupte AA, Pownall HJ, Hamilton DJ. Estrogen: an emerging regulator of insulin action and mitochondrial function. J Diabetes Res. 2015;2015:916585. doi:10.1155/2015/916585

Centers for Disease Control and Prevention. Classifications for combined hormonal contraceptives.

Centers for Disease Control and Prevention. Table C1. Classifications for progestin-only contraceptives.

Gialeraki A, Valsami S, Pittaras T, Panayiotakopoulos G, Politou M. Oral contraceptives and HRT risk of thrombosis. Clin Appl Thromb Hemost. 2018;24(2):217–25. doi:10.1177/1076029616683802

Yazdkhasti M, Tourzani AM, Roozbeh N, et al. The association between diabetes and age at the onset of menopause: a systematic review protocol. Syst Rev. 2019;8:80. doi:10.1186/s13643-019-0989-5

Schweiger BM, Snell-Bergeon JK, Roman R, McFann K, Klingensmith GJ. Menarche delay and menstrual irregularities persist in adolescents with type 1 diabetes. Reprod Biol Endocrinol. 2011;9:61. doi:10.1186/1477-7827-9-61

Cleveland Clinic. Does being overweight affect your chances of getting pregnant?

American Cancer Society. Endometrial cancer risk factors.

Centers for Disease Control and Prevention. PCOS (polycystic ovarian syndrome) and diabetes.

Centers for Disease Control and Prevention. Diabetes risk factors.

By Andrea Chisholm, MD
Andrea Chisolm, MD, is a board-certified OB/GYN who has taught at both Tufts University School of Medicine and Harvard Medical School.