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Hypoglycemia in Type-1 Diabetes Mellitus
A 54-year-old army officer presented to a clinic for follow-up of his diabetes. He seemed very particular about his health. He had diabetes since the age of 12 and had been on insulin therapy. He had been regularly monitoring his blood glucose as advised by the physician.
He reported feeling very restless, diaphoretic and felt hunger cramps at 2 AM with the blood sugar in the range of 40 mg/dL. He, however, noted that his morning fasting blood sugar was high without taking any carbohydrates. His physician described the morning high sugars as a result of biochemical processes in response to the night-time hypoglycemia.
What are the biochemical processes that govern the response to the night-time hypoglycemia?
The night-time hypoglycemia stimulates the counter-regulatory hormones to raise the blood glucose levels. These include epinephrine, glucagon, cortisol, and growth hormone, which raise the glucose level by morning.
The patient in the given case has the classic manifestations of Somogyi effect, also known as “rebound hyperglycemia” named after the physician who first described it. The Somogyi effect is a pattern of undetected hypoglycemia (low blood glucose values of less than 70) followed by hyperglycemia (high blood glucose levels of more than 200). Typically, this happens in the middle of the night, but can also occur when too much insulin is circulating in the system.
Over dosage of insulin seems to be the cause of Somogyi effect. The diagnosis is established by measuring a 2 AM blood glucose level, and upon confirmation, the bedtime insulin dose is decreased.
The danger is that if night-time blood glucose levels are not measured, the physician may interpret the patient as having hyperglycemia and require even higher doses of insulin. This would be exactly the wrong treatment, since it would worsen the situation by causing hypoglycemia leading to counter-regulatory hormone reaction, and a very high sugar level in the morning.
Another similar phenomenon is also observed called Dawn phenomenon, named after the time of day it occurs. The “dawn effect,” also called the “dawn phenomenon,” is the term used to describe an abnormal early morning increase in blood sugar (glucose) — usually between 2 a.m. and 8 a.m. — in people with diabetes.
Some researchers believe it’s due to the natural overnight release of hormones —including growth hormones, cortisol, glucagon and epinephrine — that increase insulin resistance.
High morning blood sugar may also have other causes. Insufficient insulin the night before, incorrect medication dosages or eating carbohydrate snacks at bed time cause blood sugar to get elevated in the morning. When necessary, checking blood sugar once during the night — around 2 a.m. or 3 a.m. — can help to differentiate if there is dawn phenomenon or if there’s another reason for an elevated morning blood sugar level.