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What to do if…
your blood sugar or ketones are very high and you feel sick

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy UK guide

Short answer

Call 999 or go to A&E now. Very high blood sugar or ketones together with feeling sick can require emergency treatment, so do not drive yourself or wait to see whether it settles.

Do not do these things

  • Do not delay getting help while waiting for another reading or trying to identify the cause.
  • Do not drive yourself to A&E.
  • Do not stop or skip insulin if you use it, even if you are not eating.
  • Do not guess an extra insulin dose outside your personal sick-day plan or instructions from a healthcare professional.
  • Do not exercise while your blood sugar or ketones are very high and you feel unwell.
  • Do not force food or drinks if you are very drowsy, struggling to swallow or repeatedly vomiting.
  • Do not spend time troubleshooting equipment before contacting emergency help.

What to do now

  1. Call 999 or arrange immediate travel to A&E. Say that your blood sugar or ketones are very high and that you feel sick. Mention vomiting, stomach pain, deep or fast breathing, drowsiness, confusion or fruity-smelling breath if present.
  2. Do not drive yourself. Ask someone to take you, or request an ambulance if you cannot travel safely or your condition is worsening.
  3. If it will not delay help, check your blood sugar and blood or urine ketones. Note the readings and times, but do not postpone leaving or calling 999 to repeat the tests.
  4. Tell the emergency service if blood ketones are over 3 mmol/L, urine ketones are over 2+, or you cannot check ketones. Also say if you have not previously been diagnosed with diabetes.
  5. If you use insulin, continue your prescribed background or long-acting insulin unless an emergency clinician tells you otherwise. Take correction insulin only according to your existing sick-day plan or direct clinical instructions.
  6. If you are fully awake, able to swallow and not repeatedly vomiting, take small, frequent sips of water or another sugar-free drink while help is being arranged.
  7. Ask someone to stay with you if possible. Gather your medicines, insulin, testing equipment, pump supplies and recent readings for the ambulance crew or hospital team.
  8. If you use an insulin pump, note any alarms, disconnection or infusion-set problem, but do not delay emergency assessment while trying to fix it.

What can wait

You do not need to work out why the readings are high, plan meals, make long-term medication changes, contact work or solve routine diabetes-management problems now. Those decisions can wait until you have been medically assessed.

Important reassurance

Seeking emergency care for very high blood sugar or ketones while feeling sick is appropriate. You do not need to know the cause before asking for help, and emergency teams can check what is happening and start treatment.

Scope note

This guide covers immediate first steps only. Later decisions about insulin doses, other diabetes medicines, equipment problems and preventing another episode may require your diabetes team or another healthcare professional.

Important note

This is general information, not medical advice or a substitute for emergency assessment. Follow instructions from emergency services and your personal diabetes sick-day plan where they do not delay urgent care.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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