The brain relies on a constant supply of glucose to function optimally and there are mechanisms in place to ensure that glucose levels are always maintained. For example when glucose levels drop below 4 mM glucose, termed hypoglycaemia, hormones such as glucagon, adrenaline and others bring glucose levels back up. This is known as hypoglycaemia glucose counterregulation. Behavioural changes also occur whereby feelings of hunger increase. Additionally, adrenaline activates the ‘fight or flight’ state that increases self-awareness of the lack of glucose in the blood. So hypoglycaemia (too low blood sugar) is rare in people who don’t have diabetes.
But in those that do have diabetes, particularly those treated with insulin or sulphonylreas, the ability to sense a lack of glucose becomes less pronounced. After even several ‘mild’ hypoglycaemic episodes, or after 5 years of disease duration, the counterregulatory response becomes weaker, for poorly understood reasons. This causes the symptom awareness to diminish leading to more hypoglycaemic episodes. Once symptom awareness has diminished the likelihood of a severe episode of hypoglycaemia is greater and blood sugar levels can drop to very low levels.
Often this manifests as nocturnal hypoglycaemia, where an individual sleeps not knowing their blood sugar levels and too low. This can have negative effects on the brain as it is being starved of its fuel and is a comparable situation to stroke.
Is this an issue that is widely talked about? What would be the best way to prevent this scenario? (For example- eating some carbohydrates before bed, using a different type of insulin after evening meals, waking up to check blood sugar levels…)
How should we prevent impaired hypoglycaemia awareness? Or how should we try to restore hypoglycaemia awareness? Is a pharmacological therapy a feasible option and how would it be administered?
Information about the discussion leader
The discussion will be moderated by Dr Craig Beall, Research fellow at the RILD centre, Royal Devon and Exeter Hospital, Exeter, Devon, United Kingdom.
1. RD Lawrence Lecture 2015 Old habits are hard to break: lessons from the study of hypoglycaemia R. J. McCrimmon
3. Acute symptomatic hypoglycaemia mimicking ischaemic stroke on imaging: a systemic review