The Somogyi effect and the Dawn phenomenon

(Last Updated On: December 11, 2017)

Somogyi effect and the Dawn phenomenon: hyperglycemia on wake up hours



omogyi effect and the Dawn phenomenon are conditions related to diabetes and blood sugar fluctuations. Somogyi effect involves hyperglycemia when you wake up, even though you might have increased insulin before going to sleep. This is sometimes called “rebound hyperglycemia” and it is counter intuitive since increased insulin would most likely result in low blood sugar and not high.

A low around at 07:00 AM is usually followed by previous high at around 02:00 AM. The idea behind Somogyi is that too much insulin can cause low blood sugar during the night and a subsequent high in the morning hours; according to Somogyi this may be caused by an insulin atagonistic action created by some hormones, such as hypothalmic-pituitary adrenal axis.

The risk involved in this condition is an increased by NPH insulin use which reaches peak concentration in 4-5 hours after injection. You should suspect you have Somogyi effect if glucose levels are increasingly higher in the morning after increasing insulin units prior to going to bed.

Also if you check you blood glucose at around 03:00 AM and it is low it could mean you might be having Somogyi effect by early morning. The Somogyi effect is more likely to happen with type I diabetics and less common with type II.

The Dawn phenomenon

The name Dawn is a simple reference to the time of the day this phenomena occurs. The main difference between Dawn phenomenon and Somogyi effect is that the down happens to everyone whether you have diabetes or not. Down is a spike in glucose due to hormonal responses in your body preparing you for the day. When we are sleeping, regulatory hormones such as growth hormone, cortisol and catecholamines are released in order to repair cells and that can increase your glucose level. If you have diabetes and have less circulating insulin, your blood sugar may be even higher in the morning. This is even more pronounced for pregnant woman due to additional hormones being released at night.


The concept was first introduced by Austro-Hungarian scientist named Michael Somogyi in 1949 at a ACS meeting in Atlantic City. On the basis of his findings patients using high doses of insulin were exposed to a “chronic insulin poisoning”. His paper titled “Exacerbation of diabetes by excess insulin action” is a intriguing study which shows that insulin treatment has severe management issues.

Insulin can cause hypoglycemia episodes which not only represent a danger in itself but also lead to an increase blood glucose levels instability. It can lead to abrupt fluctuations on an estimated 10% of diabetics.

Michael Somogyi also points out that insulin use leads to an ever increasing need for higher doses never improving diabetes.

Even though the study was made in 1959, it has not been fully evaluated and more research is needed. There is a lack of scientific research about the Somogyi effect. Most journals about Somogyi that can be found are at least 25 years old. The Somogyi effect has its dose of controversy as researchers who support the theory claim glucose levels raise in the morning regardless of insulin use.

How to avoid the Somogyi effect

To best way to avoid the Somogyi effect is to prevent your blood sugar to be low in the first place and this might involve changing or adjusting insulin doses before you go to sleep.

Have a nutritious fat rich meal before you go to bed. Nothing will hold your blood glucose more stable than fatty foods. Use slow burning carbohydrates but fat is more efficient. Non starchy vegetables, sweet potatoes, barley, rolled or steel-cut oats, oat bran, 100-percent stone-ground whole wheat or pumpernickel bread, and pasta preferably made with whole wheat.

Avoid fast burning starches such as white potatoes, white rice, white bread, fruit juice. Go to bed preferably with the blood sugar slightly higher then usual. Wake up between 02:00-03:00 A.M. ad test your blood sugar and keep a log. Make adjustments to your medication as needed like lowering insulin units, reducing oral medication. See your doctor in order to organize these changes correctly.

The 3-day continuous glucose monitoring (CGMS)

The most important is to be on top of your blood sugar because insulin use is not an easy task by any means. We not always know if blood sugar will be low during the night. If you have wide fluctuations of blood sugar for some time you might have a condition called autonomic neuropathy which impairs your ability to just “feel” when you are having hypoglycemia. This condition blocks the body’s ability to detect your low blood sugar and unfortunately this is more likely to occur during the night so you have to perform tests to really know. One effective way to know exactly what your blood glucose is doing and how much fluctuation are occurring the best is to perform the  3-day continuous glucose monitoring (CGMS) exam. It consists of a device that is attached to your skin for 3 days and is about the size of a pager. The device reads your BG several times a minute and can keep track of highs and lows. Data collected should be interpreted by a physician.

How to avoid down phenomenon

If you exercise (and I hope you do) try switching your exercise routine to later time in the day. That will produce a lowering glucose effect during the night. Eat less carbohydrates before you go to bed. Eat more fat and protein, nuts, meat, peanut butter and cheese. Eat a hefty breakfast to limit the dawn action mechanism. By eating you’ll signal your body to turn off the counter regulatory hormones. Even though this may appear counter intuitive in this instance it has the opposite effect because the high blood glucose is being fueled by a different mechanism.


It is important to know the difference between Somogyi and down because they are tools that can lead you to a more accurate mapping of our blood glucose control. Knowledge of these processes can enhance our blood glucose management by having more transparency. Insulin regimen is not an easy task and involves many variables. We are in a constant 3 point balancing act which involves 1) amount and type of insulin; 2) foods we eat; 3) how much energy we spend and when. So anything that affects or interferes with this delicate balance matter a lot. Understanding some of these conditions may help us refine and keep blood glucose stable which is the main challenge. We are trying to mimic the natural balance our bodies are no longer able to perform and that’s no easy task.



A quick video on how to use the Medtronic Continuous Glucose Monitoring System – how to prepare the monitor, transmitter and insert the sensor into your body.



Dr. Oller talks about rebound hyperglycemia or the somogyi effect.



Dr. Oller talks about this diabetes phenomenon that occurs in the morning hours.




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In Category: DIABETES

Marcos Taquechel

Marcos is an RN. Thanks for stopping by and reading my posts. I hope you are able to get something useful out of this blog. Take good care of yourself and don’t worry about anything until you have something to worry about.

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