The #Dawn Phenomenon – Too Big a Word for this Time of Day
All people have the “dawn phenomenon,” if they have diabetes or not.
The dawn phenomenon is a surge of hormones that the body produces daily around 4:00 a.m. to 5:00 a.m.
People with diabetes don’t have normal insulin responses to adjust for this. They may see their fasting glucose levels go up.
Diabetes is a challenge. Weighing up many things, including hormonal changes that you have little or no control over.
The rise in glucose is mostly because the body is making less insulin and more glucagon (a hormone that increases blood glucose) than it needs.
The less insulin made by the pancreas, the more glucagon the pancreas makes as a result.
Glucagon signals the liver to break down glycogen into glucose. This is why high fasting blood glucose levels are common in people with type 2.
Steps that may help:
Eat dinner earlier in the evening
Do something active after dinner (such as going for a walk)
If your fasting glucose continues to be high (over 6mmols), talk to your diabetes health care team
Who Is Somogyi?
In the 1930s, Dr. Michael Somogyi speculated that hypoglycemia during the late evening induced by insulin could cause a counter-regulatory hormone response that produces hyperglycemia in the early morning.
Normal hypoglycemic counter-regulation
This phenomenon is actually less common than the dawn phenomenon, which is an abnormal early morning increase in the blood glucose level because of natural changes in hormone levels.
Debate continues in the scientific community as to the actual presence of this reaction to hypoglycemia. Shanik, for example, suggested that the hyperglycemia attributed to the Somogyi phenomenon actually is caused by an insulin-induced insulin resistance.
The causes of Somogyi phenomenon include excess or ill-timed insulin, missed meals or snacks, and inadvertent insulin administration. Unrecognized post-hypoglycemic hyperglycemia can lead to declining metabolic control and hypoglycemic complications.
Although no data on frequency are available, Somogyi phenomenon is probably rare.
It occurs in diabetes mellitus type 1 and is less common in diabetes mellitus type 2.
With proper identification and management, the prognosis for Somogyi phenomenon is excellent, and there is no evidence of long-term consequence.
If you are able to effectively identify the of symptoms of hypoglycaemia,; be confident about self adjusting your insulin dose; be careful with the timing of meals, you can reduce your risk of problems.
One tool available to day is the CGMS – a System of Continuous Glucose Monitoring. This can be attached to your body and your BGL will be measured continuously for a few days.
The ability to suppress insulin release is an important physiologic response that people with insulin-requiring diabetes cannot carry out, as they have injected a precise dose of insulin, and this canon change one injected.
Mechanisms of insulin secretion.
Defense against hypoglycemia involves counterregulatory hormones, which stimulate gluconeogenesis and glycogenolysis and counteract the anabolic effects of insulin.
This mechanism is dependent on an intact glucose sensor system in the CNS, pancreas, and afferent nerves.
Counterregulatory hormones include the following:
- Glucagon acts on the liver to stimulate glycogenolysis and gluconeogenesis and is probably the earliest and most important hormone in the Somogyi phenomenon
- Epinephrine increases the delivery of substrates from the periphery, decreases insulin release, stimulates glucagon release, inhibits glucose utilization by several tissues, and stimulates a warning system with sweating, anxiety, and tachycardia
- Cortisol may aid in prolonged and severe cases of Somogyi phenomenon by blocking glucose use and stimulating hepatic glucose output
- Growth hormones are similar to those of cortisol.
Studies have cast doubt on the importance of counter-regulatory hormones in mediating glycemic rebound. Hypo-insulinemia (waning of the insulin dose), insulin resistance, and hypersensitivity to the effects of the counter-hormones also may play a role.
People with Somogyi phenomenon present with morning hyperglycemia out of proportion to their usual glucose control. Nocturnal hypoglycemia is missed or asymptomatic, and post-hypoglycemic hyperglycemia is not considered or is confused with the dawn phenomenon.
The most common cause of morning hyperglycemia is hypo-insulinemia.
People with diabetes have an increased need for insulin in the early morning primarily due to the release of growth hormone, which antagonizes insulin action. Cortisol may play a supporting role.
People with diabetes may experience falling insulin levels due to absorption or dose issues from the previous evening. This occurs as the insulin requirement is rising (dawn phenomenon) and results in a rapid rise of blood sugar at 4-8 AM. This occurrence is common in people with either type 1 or type 2 diabetes mellitus.
Laboratory studies for identifying Somogyi phenomenon include fasting blood glucose, nocturnal blood glucose, hemoglobin A1C (Hgb A1C), and frequent glucose sampling.
The fasting blood glucose level is expected to be inappropriately elevated due to hormonally induced rebound.
A glucose reading in the middle of the night will disclose hypoglycaemia as a result of insulin therapy. This will establish the diagnosis.
Obtaining an Hgb A1C level may be helpful if it is within the reference range or low despite an elevated fasting glucose level. It supports the concept of a rebound fasting hyperglycemia in the face of normal glucose control.
An elevated Hgb A1C does not rule out Somogyi phenomenon.
Frequent glucose monitoring may be necessary to confirm the diagnosis and look for other periods of hypoglycemia that may lead to rebound hyperglycemia. Frequent hypoglycemia is responsible for hypoglycemic unawareness, which may cause the typical symptoms of hypoglycemia to be missed.
Somogyi phenomenon should be suspected if you are having atypical hyperglycemia in the early morning that resists treatment with increased insulin doses.
If nocturnal blood sugar is confirmatory or if suspicion is high, reduce evening or bedtime insulin.
Clinical signs, including weight gain, normal daytime blood sugar levels, and relatively low HbA1C, suggest overtreatment.
Complex, yes.
For more information, write any questions of comment below, or send an email request for some 1:1 diabetes education.
Kind Regards,
David
Diabetes Educator @ Diabetes Counselling Online
