October 25, 2007
Question from Istanbul, Turkey:
Is there any way of understanding if the morning glucose level is from a rebound? My son, who is 1.65 m (5 feet, 4 inches) tall, 55 kg (121 pounds) takes Lantus, 14 units at night and four units in the morning, plus 17 daily units of Humalog for meals. Sometimes, we catch 35 mg/dl [1.9 mmol/L] to 50 mg/dl [2.8 mmol/L] levels in the mornings. After a recent trip, his blood glucose was 180 mg/dl [10.0 mmol/L] after dinner at 10 p.m., so we skipped his usual snack. The following morning, his blood sugar was 137 mg/dl [7.6 mmol/L]. We gave him his Lantus (four units) and Humalog (five units). Ten minutes later, he fell nearly unconscious. His blood sugar measured 114 mg/dl [6.3 mmol/L], but we gave him a glucose tablet. He felt better. Was the morning blood glucose level from a rebound? He hadn't eaten for 12 hours. Can this be the reason? Or, should we check him for other reasons?
The only way to know what is happening overnight is by monitoring blood glucose levels. We usually suggest such detective work when there are unexplained morning hyperglycemic events and when nocturnal hypoglycemia with rebound is a possibility. Often, there is no hypoglycemia, just a waning of insulin effect or high fat food effects delaying glucose effects until hours later. Good testing should answer such questions. With the newly available glucose sensors, this type of question will be answered almost automatically since such patterns would be identified by the sensors. For now, intermittent capillary glucose testing will suffice. And, then, changes in either food and/or insulin would be needed to compensate and prevent lows. Be sure to discuss this with your son’s diabetes team.