Low blood sugar in older adults: Why severe episodes can be especially dangerous
Low blood sugar can quickly go from a warning sign to a medical emergency. This is because the brain depends on a continuous supply of glucose to function, and it has very little stored glucose to fall back on.
So, when blood sugar drops significantly, the effects aren’t limited to feeling hungry, shaky, or sweaty. Brain function can begin to deteriorate, potentially leading to confusion, seizures, unconsciousness and, in severe cases, death.
We spoke to Dr Rajiv Kovil, Diabetes & Obesity Specialist at Zandra Healthcare, to understand why hypoglycaemia can become particularly dangerous in older adults.
Why does low blood sugar affect the brain so quickly?
"Think of hypoglycaemia as an acute emergency and chronic hyperglycaemia as a cumulative metabolic injury—although either can become an emergency,” Dr Kovil tells.
Unlike some other tissues, the brain has limited glucose stores and relies heavily on glucose circulating in the blood.
Dr Kovil explains, “The brain has limited stored glucose and depends on continuous delivery from the circulation. When glucose falls sufficiently, brain function can deteriorate rapidly.”
This is why severe hypoglycaemia can progress quickly. A person may initially experience warning symptoms such as sweating, tremors, hunger or palpitations, but as glucose falls further, the brain may not receive enough fuel to function normally.
That can result in confusion, unusual behaviour, impaired coordination, seizures or loss of consciousness.
Why are older adults particularly vulnerable?
Age itself is not the only issue. Several factors more common in older adults can make a low blood sugar episode harder to recognise or harder for the body to correct.
“Renal impairment, cognitive impairment, variable appetite, polypharmacy and impaired counter-regulation increase vulnerability,” Dr Kovil says.
Kidney problems, for example, can affect how the body handles some glucose-lowering medicines. Irregular or reduced food intake can also increase the risk of blood sugar falling too low, particularly in someone taking glucose-lowering medicines.
Multiple medications can add another layer of risk, while cognitive impairment may make it harder for a person to recognise symptoms or respond appropriately.
Why can repeated episodes become even more dangerous?
There is another concern when a person experiences hypoglycaemia repeatedly. The usual warning symptoms may become less noticeable over time.
Dr Kovil says, " Repeated hypoglycemia can also blunt warning symptoms, producing impaired hypoglycaemia awareness and increasing the likelihood of another severe episode.”
In other words, a person who previously knew that their blood sugar was dropping because they felt shaky or sweaty may not experience the same clear warning signs during a later episode. This can allow the glucose level to fall further before anyone intervenes.
Which diabetes medicines need particular attention?
For older adults taking glucose-lowering medication, the treatment itself needs to be considered when recurrent or severe hypoglycaemia occurs.
“Insulin and sulfonylureas deserve particular attention,” Dr Kovil says.
This does not mean a person should stop these medicines on their own. Rather, repeated or severe low blood sugar episodes warrant a medical review of the diabetes treatment plan.
In fact, Dr Kovil notes that “Severe or recurrent hypoglycaemia in an older adult should prompt reconsideration and often de-intensification of glucose-lowering therapy, irrespective of an apparently ‘excellent’ HbA1c.”
This is important because diabetes treatment is not simply about achieving the lowest possible HbA1c. In an older adult, avoiding dangerous lows is also an important part of safe glucose management.