Is there a gender difference in the effect of insulin? Latest research! A must-read for women!

Below the stomach and next to the duodenum in the human body, there is a long organ called the pancreas. There is a type of islet cells in the pancreas that can secrete insulin, a hormone that regulates the metabolism of the three major nutrients: sugar, fat, and protein, and plays a very important role in the life activities of the human body.

When we eat food, as the food is digested, the glucose (blood sugar) concentration in the blood increases. At this time, the pancreas secretes insulin, which brings glucose from the blood into the cells to provide energy for the cells, and the blood sugar concentration decreases. If the cells respond to insulin quickly, everything works normally. If the cells are resistant to insulin, they cannot use insulin effectively, resulting in excessive blood sugar in the blood, and the pancreas will secrete more insulin to work hard. Over time, the cells in the pancreas that produce insulin will be exhausted, leading to the occurrence of type 2 diabetes. In addition, long-term high blood sugar can also damage nerves and organs.

Therefore, the ability of cells to respond to insulin is very important. The ability of cells to respond to insulin is called insulin sensitivity. Increasing insulin sensitivity means reducing insulin resistance and reducing the risk of many diseases. Insulin resistance is an important pathophysiological mechanism of type 2 diabetes. How to improve insulin resistance and increase insulin sensitivity has always been the focus of medical research.

Adrenaline injector. Source: unsplash.com Photographer: IsensUsa

In the past, scientists have studied insulin sensitivity and found that the brain is also sensitive to insulin. Although insulin is secreted in the pancreas of the body, it can cross the blood-brain barrier after entering the blood circulation and act on specialized neurons and glial cells in the brain to regulate the activity of specific areas of the brain, including the hypothalamus, which in turn affects the outflow of insulin to the periphery, affecting insulin regulation of food intake and systemic metabolism.

However, these studies were all conducted on young men. As a hormone, does insulin have gender differences in regulating systemic metabolism? Does this conclusion still apply to women? This is a topic that Martin Heni and his colleagues at Eberhard-Karls-Universität Tübingen in Germany are concerned about.

Martin Heni and his colleagues conducted a clinical trial on 11 women to understand how women's brain insulin is affected by the menstrual cycle. These women received intranasal insulin drops to measure the activity of brain insulin and compared it with a non-insulin placebo spray. The results showed that women's brain insulin sensitivity increased during the follicular phase of the menstrual cycle, but this phenomenon was not observed during the luteal phase.

Image source: unsplash.com Photographer: SamMoghadam

The researchers also performed functional MRI scans on 15 additional women to assess insulin sensitivity in a specific brain region called the hippocampus, and observed similar insulin sensitivity during the follicular phase of the menstrual cycle, rather than the luteal phase. The researchers believe that women's brains are more sensitive to insulin during the follicular phase of the menstrual cycle, and that brain insulin resistance during the luteal phase may contribute to systemic insulin resistance.

Recently, this research result was published in the journal Nature Metabolism under the title "The effect of brain insulin on peripheral insulin sensitivity in women depends on the menstrual cycle stage".

In the past, various medical studies mainly focused on males. However, the bodies of men and women are different, and the conclusions drawn from males may not be completely applicable to women. I hope that in the future there will be more new studies with females as the research subjects.

Image source: unsplash.com Photographer: ElenSher

References

[1]https://www.nature.com/articles/s42255-023-00869-w?utm_medium=organic_social&utm_source=wechat&utm_campaign=CONR_PF020_ENGM_AP_CNCM_002EA_weeklyS

Author: Zeng Xinyue, popular science creator

Reviewer: Tang Qin, Director and Researcher of the Medical Science Department of the Chinese Medical Association