Nerve pain in the first weeks of better control: what treatment-induced neuropathy is
Some people get sudden burning nerve pain after a big drop in HbA1c. It has a name, it is recognised, it usually settles, and it is worth telling your team.
If your glucose has come down a long way in a short time, and a few weeks later your feet start burning or feel like electric shocks, that pattern has a name: treatment-induced neuropathy of diabetes, once called insulin neuritis. It is uncommon, it is not a sign that bringing your glucose down was a mistake, and in most reported cases it eases over months. Tell your diabetes team early rather than sitting with it quietly, because new nerve pain always needs assessing properly, and this is only one of the things that can cause it.
- It typically starts within about eight weeks of a big drop in HbA1c, the blood test showing your average glucose over two to three months.
- The pain is usually burning, stabbing or electric, starts in both feet, and tends to be worse at night.
- Some people also get autonomic symptoms, such as feeling faint on standing, because the same small nerves help run your blood pressure.
- It is reported more often in type 1 than type 2, though it can happen to anyone with diabetes.
- It is never a reason to let your glucose run high again: the pace of change is worked out with your team.
What it feels like, and when it turns up
The timing is what gives it away. A review pooling 26 published studies, covering 181 people between them, found symptoms appearing anywhere from a week to six months after treatment was stepped up, with most starting at four to eight weeks. The pain arrives while everything else is going the right way, which is exactly why so few people connect the two.
It usually sits in both feet first and creeps upwards: burning, stabbing, tingling, or oddly hot and cold, and it is often worse at night. Light touch can hurt, so a bedsheet across your feet becomes unbearable and sleep goes with it. Some people also notice the automatic stuff misbehaving: greying out when they stand, changes in sweating, a stomach that empties more slowly. Before you speak to anyone, write down when it started, where it is, and what your last two HbA1c results were. That short timeline is what lets a clinician recognise the pattern quickly.
Why an improvement can hurt
Nobody has fully worked out the mechanism, and it is worth being straight about that. The leading idea is that nerves which have spent a long time in high glucose adapt to it, and are caught out when their supply changes quickly: the small nerve fibres and the tiny blood vessels feeding them seem to react to the speed of the change rather than to the new level itself. That picture comes from case reports and clinic records, not trials, so it is a reasonable theory rather than a settled fact.
The clinic study that first described this in detail also found that eye and kidney measures could shift after a large fall in HbA1c. Eye screening and kidney checks are part of routine UK diabetes care anyway, and they are worth keeping up to date around a big change. Longer term the direction of travel is not in doubt: lower glucose protects nerves, eyes and kidneys. This is a question about the speed of the change, not about the destination.
How often this happens, honestly
The largest description comes from a specialist diabetic neuropathy clinic: of 954 people referred there over five years, 104, or 10.9%, fitted the pattern. Within that group the size of the fall mattered enormously. Where HbA1c dropped by two to three percentage points in three months on the older percentage scale, roughly one in five had it. Where it dropped by more than four points, more than eight in ten did. UK results are reported in mmol/mol, where two percentage points is a fall of a little over 20.
Those are not the odds for someone starting insulin. Everyone counted had already been referred to a specialist because of nerve symptoms, and nearly all had lived with very high glucose for a long stretch beforehand. That a review of the published literature could find only 181 cases in total tells you how rarely this turns up. Most people whose numbers improve, including most people newly diagnosed, will never meet it.
Not a reason to run high
Nothing here is a reason to ease off your insulin, skip doses, or let your glucose sit high to protect your nerves. High glucose is what damages nerves in the first place, quietly, and once they are badly affected that is far harder to undo. This particular pain settles for most people over months to a year, though a minority are left with lasting symptoms, which is another reason to have it looked at early.
The pace question is real, and it belongs to your diabetes team. Specialists who study this suggest bringing HbA1c down more steadily in someone who has been very high for a long time, and they also say plainly that no trial has shown a slower pace prevents it. So if you are worried about how fast your numbers have moved, or how fast you are being asked to move them, that is an appointment conversation, never a change to make on your own.
What changes how this plays out
The clearest pattern in the research is the plainest one: the bigger and faster the fall, the more likely and the more severe the symptoms. Past that, a great deal varies. Some people get pain and no dizziness, some get both, some notice the dizziness first. Nerve pain has other causes too, several nothing to do with diabetes, so what fits one person will not fit the next. Medicines for it help some people a lot and barely touch it for others, which is normal.
How it tends to show up
Examples, not instructions or doses.
Your sensor now sits mostly between 5 and 9 mmol/L instead of the teens, and you feel better in nearly every other way. Then one evening your feet start burning like sunburn, and the duvet on them is unbearable.
You get off the sofa and the room fades for a couple of seconds, and it keeps happening for weeks. Worth mentioning even if the pain bothers you more, because it points at the same small nerves.
You are 5.8 mmol/L, shaky, and certain you are low. After a long spell in the teens, an in-range number can feel like a hypo for a while. Checking rather than assuming is the only way to tell, because a genuine low still needs treating.
Worth paying attention to
Questions that make an appointment useful
When it's urgent
Some things need help straight away, whatever else is going on. A severe hypo, where someone is confused, unable to swallow safely, fitting, or cannot be woken, is a 999 call. Do not put food or drink into the mouth of anyone who cannot swallow safely, put them in the recovery position if they are unconscious but breathing, and never let a finger prick delay the call. Sudden weakness or numbness down one side, a face dropping on one side, or slurred speech is not this kind of nerve pain and needs 999 too.
Being sick, drowsy, breathing heavily or fast, with stomach pain or fruity-smelling breath alongside high glucose can mean DKA (diabetic ketoacidosis, where a shortage of insulin turns the blood dangerously acidic): call 999 or go to A&E straight away, and do not wait to see whether it settles. Unwell with high glucose but not that ill means checking ketones if you can, and ringing your diabetes team or NHS 111.
And if the pain and the lost sleep get on top of you, support is there any time you need it. Samaritans, 116 123, free, any time. Shout, text SHOUT to 85258. 999 if you or someone else is in immediate danger.