An HbA1c Target in Someone Older or Frail
A relaxed target is not a lower standard of care. It reflects a genuine change in the balance. The benefits of tight control accumulate over decades, while the harms of a glucose that falls too low arrive immediately, and in an older adult those harms are falls, fractures, confusion and hospital admissions. An HbA1c that looks impressively low in this group can be the most worrying number on the report.
The pattern on your report
- HbA1c High-normal Key
- eGFR Low Key
- Hemoglobin Low-normal Key
- Fasting glucose Normal Key
Printed as: eGFR in mL/min/1.73m2— Determines whether current doses are still appropriate, since several treatments accumulate as it falls.Fasting glucose in mmol/Lor mg/dLHemoglobin in g/Lor g/dL— Anemia is common in this group and makes the HbA1c less reliable.HbA1c in mmol/molor %— Targets here are individualized, so two people with the same value can reasonably be given opposite advice.
Why the numbers look like this
Tight glucose control works by preventing damage to the small blood vessels of the eyes, the kidneys and the nerves, and that damage takes many years to develop. The benefit therefore accrues over a long horizon.
The risks work on a different timescale entirely. A low glucose causes harm within minutes, and several things make it both more likely and more dangerous with age. Kidney function declines, so insulin and some tablets are cleared more slowly and accumulate. Appetite and intake become less predictable. The warning symptoms that normally prompt someone to eat, among them sweating, shakiness and a racing heart, become blunted, so the first sign can be confusion or a fall.
That blunting is the crux. Someone can go from feeling normal to being unable to help themselves without the intermediate stage that used to give them time.
The drugs differ sharply in this respect. Metformin and several newer agents rarely cause a low glucose at all; sulfonylureas and insulin frequently do. So which drug produces a given HbA1c matters as much as the number.
Not being flagged is not the same as normal
Targets in this group are individualized, not universal, and they take account of how long someone is likely to benefit, what other conditions they have, and how much risk a low glucose carries for them. That is why two people with the same HbA1c can reasonably be given opposite advice. It also means a value below the target range is a finding in its own right on treatment that can cause low glucose, and it should prompt a review, not congratulation.
What else on the report can hide this
Establish which drugs are being taken before anything else, because the same HbA1c means something entirely different on metformin than on insulin or a sulfonylurea.
Kidney function determines whether doses are still appropriate. Several treatments accumulate as filtration falls, and a dose that was right five years ago can be causing low glucose now.
Asking directly about episodes matters, and the question has to be specific: falls, unexplained confusion, waking sweaty, or eating in the night. People do not report these as low glucose because they do not recognize them as such.
A full blood count is worth including, since anemia is common in this group and distorts the HbA1c, so the number may be less reliable than it looks.
Deprescribing deserves to be raised explicitly rather than left unspoken. Reducing or stopping a treatment once the target has changed is a considered clinical decision with evidence behind it, not neglect, and by the time anyone raises it the change is often overdue.
What usually causes it
Listed from most to least common — not from most to least serious.
- Very common
A target set years ago and never revisited
Appropriate when it was set and no longer matched to the current situation. Reviewing it is the commonest useful action here.
- Very common
Declining kidney function
Insulin and some tablets accumulate as filtration falls, so an unchanged dose becomes progressively stronger.
- Common
Reduced or irregular food intake
Treatment doses assume a pattern of eating that may no longer hold. A frequent and correctable cause of low glucose.
- Common
Treatment that can cause low glucose
Sulfonylureas and insulin, as distinct from metformin and several newer agents that rarely do. Which drug produces the number matters as much as the number.
- Common
Blunted warning symptoms
The usual signs fade with age and long-standing diabetes, so the first indication can be a fall or confusion.
- Common
Anemia distorting the HbA1c
Common in this group and it makes the value less reliable, in a direction that depends on the cause.
- Common
Weight loss
Reduces the dose required, so an unchanged prescription becomes too strong. Worth investigating in its own right as well.
- Common
Genuinely good control on low-risk treatment
A low HbA1c on metformin alone carries little risk of a low glucose, which is why the drug list changes the interpretation.
- Uncommon
Cognitive impairment affecting dosing
Doses missed or repeated. Suspected when control becomes erratic without any change in prescription.
What is usually checked next
- The current medication list The same HbA1c carries a very different risk on metformin than on insulin or a sulfonylurea.
- Kidney function against the current doses Several treatments accumulate as filtration falls, so a long-stable dose can become too strong.
- Specific questions about falls, confusion and night sweating People do not report these as low glucose because they do not recognize them as such.
- Full blood count Anemia is common here and distorts the HbA1c, so the number may be less reliable than it appears.
- An explicit review of the target and of deprescribing A considered decision with evidence behind it, and one that is frequently overdue.
When to seek care sooner
- Emergency Loss of consciousness or a seizure
- Same day Confusion, or a fall with no clear explanation
- Soon Waking sweaty or shaky at night
- Soon An HbA1c below the target range on insulin or a sulfonylurea
- Soon Unintentional weight loss
- Soon Eating much less than usual while on unchanged treatment
Questions worth bringing to your appointment
- What target is right for me now, and when was it last reviewed?
- Do any of my medicines carry a risk of low glucose?
- Does my kidney function mean any dose should come down?
- Could my falls or confusion be low glucose?
- Is there anything I could safely stop taking?