Circadian Rhythm and Blood Sugar Control

A class of steroid hormones called glucocorticoids helps regulate our biological clock, the immune system, and blood glucose levels.

| Oct 15, 2009

The human body is an amazing machine. The biological clock that ticks inside us to keep the machine running efficiently not only prompts us to sleep and eat on regular basis, but also apparently regulates blood sugar.

Dr. Brian Feldman at Stanford University School of Medicine recently published a study suggesting that a class of steroid hormones called glucocorticoids have a direct effect on a number of genes that affect our biological clock, or circadian rhythm. The circadian rhythm, from the Latin words circa (around) and diem (day), is a 24-hour cycle of biochemical, physiological, and behavioral processes. Glucocorticoids are secreted from the adrenal gland, sometimes at high levels and sometimes at very low levels, depending upon the time of day, when we eat, and the types of food we consume. When blood sugar is lowest, glucocorticoid levels are highest, initiating gluconeogenesis to break down fat in the liver and thereby provide additional glucose to the blood.  

Glucocorticoids affect the immune system by up-regulating anti-inflammatory proteins and down-regulating pro-inflammatory proteins. In fact, glucocorticoids are marketed as nasal sprays, which alleviate inflamed nasal membranes, and as asthma inhalers, which reduce inflammation in the lungs. Prednisone, for example, is a prescribed corticosteroid (glucocorticoid) for the treatment of severe asthma or severe allergies. Although it is a valuable treatment option for some conditions, people with diabetes should be especially wary of taking such a powerful steroid because of the fact that glucocorticoids also stimulate gluconeogenesis. The consequent increase in available glucose would be a very serious side-effect for someone whose blood sugar levels are not well-controlled.

While it was thought that glucocorticoids triggered or synchronized the up-regulation and down-regulation of some circadian clock-associated genes, the how's and why's had not yet been well described.  Therefore, the first phase of Dr. Feldman's study consisted of applying synthetic glucocorticoids to human and mouse stem cells grown in a dish, to see which genes in the stem cells were activated by the glucocorticoids. The researchers found that glucocorticoids directly activated several of the genes that control the circadian clock. 

The next step was to look at how the hormone's control of the circadian clock was associated with other biological processes. Using mice that were genetically engineered to be missing a gene involved in circadian rhythm (Per2; one of the activated circadian clock genes), scientists were able to determine that while glucocorticoids had an effect on glucose homeostasis in normal control mice, there was no effect in mice missing the Per2 gene. This finding suggests that glucocorticoid regulation of circadian rhythm (by way of activating the Per2 gene) is directly involved in glucose homeostasis. Mice lacking the biological clock gene Per2 did not respond normally to glucose homeostasis challenges. These genetically engineered mice also had increased leptin levels as compared to controls. Leptin is a hormone that helps regulate energy expenditure and cycles with the circadian rhythm opposite to the cycle seen with glucocorticoids.

In the study discussion, Dr. Feldman noted that glucocorticoids act "as a synchronization signal to coordinate the circadian rhythm with energy balance. Taken together, our results imply that glucocorticoids regulate glucose homeostasis, in part, through direct control of the circadian clock, which in turn modulates leptin levels." 

The study was published online October 5, 2009, in the Proceedings of the National Academy of Sciences (PNAS).

* * *

Sources:

PNAS research article

Stanford University Medical School press release

Click Here To View Or Post Comments

Categories: Blood Sugar, Diabetes, Diabetes, Food, Pre-Diabetes, Research, Type 1 Issues, Type 2 Issues


Take the Diabetes Health Pump Survey
See What's Inside
Read this FREE issue now
For healthcare professionals only
  • What's on the Horizon with Diabetes Research and Therapy
See the entire table of contents here!

You can view the current or previous issues of Diabetes Health online, in their entirety, anytime you want.
Click Here To View

See if you qualify for our free healthcare professional magazines. Click here to start your application for Pre-Diabetes Health, Diabetes Health Pharmacist and Diabetes Health Professional.

Learn More About the Professional Subscription

Free Diabetes Health e-Newsletter

Latest
Popular
Top Rated
Print | Email | Share | Comments (1)

You May Also Be Interested In...


Comments

Posted by Anonymous on 15 October 2009

Huh?


Add your comments about this article below. You can add comments as a registered user or anonymously. If you choose to post anonymously your comments will be sent to our moderator for approval before they appear on this page. If you choose to post as a registered user your comments will appear instantly.

When voicing your views via the comment feature, please respect the Diabetes Health community by refraining from comments that could be considered offensive to other people. Diabetes Health reserves the right to remove comments when necessary to maintain the cordial voice of the diabetes community.

For your privacy and protection, we ask that you do not include personal details such as address or telephone number in any comments posted.

Don't have your Diabetes Health Username? Register now and add your comments to all our content.

Have Your Say...


Username: Password:
Comment:
©1991-2014 Diabetes Health | Home | Privacy | Press | Advertising | Help | Contact Us | Donate | Sitemap

Diabetes Health Medical Disclaimer

The information on this site is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. All content, including text, graphics, images, and information, contained on or available through this website is for general information purposes only. Opinions expressed here are the opinions of writers, contributors, and commentators, and are not necessarily those of Diabetes Health. Never disregard professional medical advice or delay seeking medical treatment because of something you have read on or accessed through this website.