Submitted by Georgie Porgie
One of the most frustrating things that diabetics deal with is an unexpected rise in blood glucose overnight. You go to bed with a BG of 100 mg/dL (5.6 mmol/L), and wake up with a BG of 130 (7.2)! You didn’t eat, so what happened?
This results from two distinctly different processes: Dawn Phenomenon and Somogyi Effect. Here are some basics.
DAWN PHENOMENON
While it has rather an attractive name the Dawn Phenomenon can cause problems for diabetic’s. The Dawn Phenomenon occurs when there is an apparently unexplained morning rise in the fasting blood sugar (blood glucose) levels. That is when the fasting (pre-breakfast) level in the morning is higher than the pre bed-time level.
When fasting blood sugar levels in the morning are much higher than the pre-bedtime reading, with no food eaten in between there is obviously a problem somewhere.
Increased morning blood sugar levels can have two causes –
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The Liver dumps its reserve of glycogen (a form of glucose) when blood sugar levels get too low.
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Insufficient Insulin in the blood together with increased Insulin Resistance due to hormones released in the early morning.
Everyone, diabetic or not, exhibits some Dawn Phenomenon. It is a natural part of our bodies’ circadian rhythms
The hormonal changes are basically preparing the body for the expected exertions of the morning and occur in everyone, both diabetic and non-diabetic. In diabetics though they can raise blood sugar levels too high and cause further difficulties at breakfast time.
Since most of us fast while sleeping, our bodies use stored energy during sleep. The body uses all three macro-nutrients (carbohydrates, proteins, and fats) to store energy.
The most easily used is the storage medium of carbohydrates, called glycogen. Glycogen is made from glucose, and is stored in the liver and muscles. Since it is basically nothing more than a complex matrix of glucose, it is easy for the body to store and use, something the body does all day long. The technical term for the act of creating and storing glycogen is glycogenesis. When the body calls for the conversion of glycogen back to glucose it is called glycogenolysis.
Another macro-nutrient that is available to be converted to glucose is protein. Most of us think of our protein as being stored in muscle, but the body has protective mechanisms to make muscle wasting its last choice. One of the most useful and readily available sources of protein storage is in blood components, i.e., albumin (plasma).
The body uses a process performed in the liver to convert amino acids, the building blocks of proteins, into glucose. The name for this process is gluconeogenesis, literally “the creation of new glucose”.
So, what does all this have to do with a high fasting BG? Overnight, usually between 4am and 11am, your body releases some hormones. These are Growth Hormone (GH) from the anterior pituitary gland, cortisol from the adrenal cortex, glucagon from your pancreatic alpha-cells, and epinephrine (adrenalin). These hormones cause an increase in insulin resistance, raising your BG.
In addition, these hormones trigger glycogenolysis and gluconeogenesis, adding stored or new glucose to your bloodstream. Dawn Phenomenon, and its associated increase in insulin resistance, is the reason most diabetics are far more sensitive to carbs in the morning.
How to Prevent or Lessen the Effect of the Dawn Phenomenon
Since the two causes of the Dawn Phenomenon have two different solutions we need to find out which is occurring first. Check blood sugar (glucose) levels at 2-3am, if they are regularly very low followed by a higher bounce in the morning fasting level, its likely to be a liver dump.
Otherwise if the blood sugar levels are more or less the same as it bed-time followed by a rise in the morning fasting level its likely to be insufficient insulin that may be combined with early morning insulin resistance.
Liver Dumps
Liver dumps cause a sudden release of glucose in the blood leading to a quick increase in blood sugar levels. They may happen after a blood sugar low or hypo that may wake you in the early morning. A small snack last thing at night can help; a mix of carbohydrate, fibre, protein & fat to slow the release of blood sugar. Something like Cheese on Toast, Peanut Butter on Ryvita and so on.
Insufficient Insulin
For diabetics injecting insulin a common cause of high fasting blood sugar levels in the morning, can be if the insulin runs low during the night. That combined with a lessened effect of any remaining insulin due to hormonal changes that occur in the early morning. The remaining insulin is insufficient to cover the background needs of the body even at sleep. So after about 4am, blood sugar levels gradually rise. For Type 2’s on drugs this is likely to be a lesser effect because their pancreas still has some remaining insulin production.
Morning Insulin Resistance
Insulin Resistance may remain high for many hours including before and after breakfast. Carbohydrates eaten in the morning may cause a greater increase in blood sugar levels than carbohydrates eaten at mid-day or evening. It might be expedient to experiment with the following suggestions to see what works for you.
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Try eating no food after dinner. This works for people whose Dawn Phenomenon isn’t very strong. Basically, it lowers their baseline BG, so that when DP does hit them, the increase keeps them below a certain level, usually 120 (6.7).
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Try eating a small snack of fat and protein before bed. Most find that a tablespoon of peanut butter, or some cheese and deli meat are effective. The theory here is that the slow-digesting fat and protein holds their BG high enough overnight to avoid Somogyi Effect (see below).
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Eventually, you will learn how the two disparate approaches above work for you. Hopefully, you will set personal targets to guide you, eg., if my BG is below XXX (insert your target here), I need a snack. If my BG is over XXX, I don’t need a snack.
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Lastly, the prescription medication Metformin HCl (Glucophage) is often very effective in limiting Dawn Phenomenon for Type-2s and insulin resistant Type-1s. Of course, Type-1s can adjust their basal (slow) insulin regimen to account for Dawn Phenomenon.
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Lastly, EAT BREAKFAST. The resulting increase in blood glucose from food will often turn off the continued rise. If you don’t, some diabetics will continue to rise until 10-11 am.
SOMOGYI EFFECT (or the “rebound” effect)
Somogyi Effect, named for the researcher who first described it, is the tendency of the body to react to extremely low blood sugar (hypoglycemia) by overcompensating, resulting in high blood sugar. This is secondary to a low blood sugar overnight, while fasting overnight. It is most commonly seen with insulin using diabetics, but is also seen with overnight reactive hypoglycemics.
The Somogyi effect is most likely to occur following an episode of untreated nighttime hypoglycemia, resulting in high blood sugar levels in the morning. When the blood glucose levels drop too a low overnight, the body responds by releasing counterregulatory hormones such as glucagon and epinephrine. These hormones (especially glucagon, the strongest blood glucose increasing hormone) spur the liver to convert its stores of glycogen into glucose, raising blood glucose levels.
This can cause a period of high blood sugar following an episode of hypoglycemia, the result of which is that the liver is stimulated to start glycogenolysis and gluconeogenesis to provide enough glucose for the body to survive. This is sometimes referred to as a Liver Dump. Often, this mechanism over-produces, and the diabetic wakes with a significantly higher BG.
People who wake up with high blood sugar may need to test their blood glucose levels in the middle of the night (for example, around 3 AM). If their blood sugar level is falling or low at that time, they should speak with their health-care team about increasing their food intake or lowering their insulin dose in the evening.
The only way to prevent the Somogyi effect is to avoid developing hypoglycemia in the first place. Setting the patient’s BG target a bit higher, will usually prevent them from having a hypoglycemic event overnight.
DAWN PHENOMENON-SUMMARY
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The Dawn Phenomenon refers to a sudden rise in blood glucose levels in the early morning hours.
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This condition sometimes occurs in people with insulin-dependent diabetes and (rarely) in people with noninsulin-dependent diabetes.
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Unlike the Somogyi effect, it is not a result of an insulin reaction.
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People who have high levels of blood glucose in the mornings before eating may need to monitor their blood glucose during the night.
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If blood glucose levels are rising, adjustments in evening snacks or insulin dosages may be recommended.
THE SOMOGYI EFFECT (Rebound hyperglycaemia) –SUMMARY
This refers to a swing to a high level of glucose (sugar) in the blood from an extremely low level, usually occurring after an unrecognised and therefore an untreated insulin reaction and hypoglycaemic attack during sleep in the early hours of the morning or during the night. It presents as hyperglycaemia before breakfast.
The swing is caused by the release of stress hormones to counter low glucose levels, and is also due to the release of the insulin-opposing or counter-regulatory hormones in response to insulin-induced hypoglycaemia. People who experience high levels of blood glucose in the morning may need to test their blood glucose levels in the middle of the night. If blood glucose levels are falling or low, adjustments in evening snacks or insulin doses may be recommended.
It is essential to recognize the Somogyi effect in order to avoid the mistake of increasing (rather than reducing) the dose of insulin in this situation.
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