HbA1c targets loosen with age, and most people are never told

A patient who has spent twenty years being told to get their HbA1c below 53 mmol/mol (7 per cent) is understandably confused when, at eighty-two, a geriatrician suggests that 64 (8 per cent) would be fine and that one of their diabetes drugs should probably come off. It sounds like giving up. It is not; it is the same reasoning applied to a different set of numbers.

What tight control buys, and when

The landmark trials established that lowering glucose reduces microvascular complications — retinopathy, nephropathy, neuropathy. The UK Prospective Diabetes Study showed this clearly in newly diagnosed type 2 diabetes, and its ten-year follow-up showed a legacy effect on macrovascular outcomes too.

The important detail is the timescale. Microvascular benefit emerged over roughly eight to ten years. Macrovascular benefit took longer still. Tight control is an investment with a long maturity.

Then three large trials — ACCORD, ADVANCE and VADT — tested intensive versus standard control in older patients with longer-standing diabetes and established cardiovascular risk. None showed a clear cardiovascular benefit from intensive control. ACCORD was stopped early because the intensive arm had higher mortality. The excess has never been fully explained, though severe hypoglycaemia is the leading suspect.

Hypoglycaemia is the reason the targets change

Low blood glucose is dangerous at any age and considerably more so in older adults, for reasons that compound.

Hypoglycaemia awareness diminishes with age and with duration of diabetes — the adrenergic warning symptoms of sweating, tremor and palpitations become blunted, so the first sign may be confusion or collapse. Those neuroglycopenic symptoms are easily mistaken for a transient ischaemic attack, dementia, or simply "having a funny turn", so episodes go unrecognised and unreported.

Renal function declines with age, so sulfonylureas and insulin clear more slowly and their effect lasts longer than intended. Appetite and intake become irregular, so a dose calibrated to a normal meal becomes an overdose when the meal is skipped. And the consequences of a fall are far worse.

Severe hypoglycaemia in older adults is associated with falls, fractures, cardiac arrhythmia, hospital admission, and — in several cohort studies — with subsequent dementia. It is a serious adverse event, not an inconvenience.

Overtreatment is common and measurable

Several analyses of large health systems have found that a substantial fraction of older adults with diabetes — often a quarter or more — have HbA1c below 48 mmol/mol (6.5 per cent) while taking insulin or a sulfonylurea. That combination is close to a definition of overtreatment: a target well below what any guideline recommends for the age group, achieved with the two drug classes that cause hypoglycaemia.

Deintensification rates in that group are low. The number stays good, the review does not happen, and the risk sits unaddressed until an episode forces it.

Which drugs, and which to worry about

Metformin does not cause hypoglycaemia on its own and remains first-line at any age. It needs dose adjustment as kidney function falls and is generally stopped below an eGFR of 30. Long-term use depletes B12, which is worth checking periodically and is routinely forgotten.

Sulfonylureas (gliclazide, glipizide, glimepiride) cause hypoglycaemia, and glibenclamide in particular is on most lists of drugs to avoid in older adults because of its long duration.

Insulin is effective and carries the highest hypoglycaemia risk, particularly complex regimens with multiple daily doses in someone whose eating is irregular or whose cognition is declining. Simplification — moving to a single long-acting dose — is often more appropriate than the textbook regimen.

DPP-4 inhibitors are well tolerated and low-risk for hypoglycaemia, which makes them attractive here despite modest efficacy.

SGLT2 inhibitors and GLP-1 agonists have genuine cardiovascular and renal benefits that apply in older adults, but both carry age-relevant cautions: SGLT2 inhibitors increase genital infection and volume depletion risk, and GLP-1 agonists cause weight loss, which is not always desirable in someone already losing muscle.

What to raise at the review

Ask what your target is and why that number for you. Ask whether you have had any episodes that might have been hypoglycaemia — the confusion, the sweating at night, the unexplained fall — because these are systematically under-reported. Ask whether the regimen could be simplified.

And if your HbA1c has been drifting downward without a change in medication, say so. In an older adult that is often not improved control. It is reduced intake, weight loss, or declining kidney function, and it means the dose is now too high for the person taking it.