diabetes flare ups
Informed by recognized medical guidance
Overview
A diabetes flare-up is a period when your blood sugar levels run higher than usual or swing up and down a lot, leaving you feeling unwell. It is not a different disease, but a sign that something has put extra strain on your body's ability to keep blood sugar in balance.
Key facts
- Flare-ups can happen to anyone with diabetes, even when you follow your care plan.
- Common triggers include illness, stress, hormones, and changes in routine.
- Most flare-ups improve with the right care and support from your diabetes team.
Yes. Many people with diabetes have periods like this from time to time, especially during infections or stressful events.
It can affect anyone with type 1 or type 2 diabetes. People who use insulin are at higher risk, and so are older adults, pregnant women, and those with other health conditions.
Symptoms
- Unconsciousness or fainting
- Seizures (convulsions)
- Severe confusion or inability to speak clearly
- Rapid deep breathing with a fruity smell on the breath
- Blood sugar very high or very low with these symptoms
- ⚠Persistent vomiting or diarrhoea lasting more than a few hours
- ⚠Very high blood sugar readings that do not come down as expected
- ⚠Fever with a diabetes illness such as flu
- ⚠Signs of dehydration like dark urine, dry mouth, or dizziness
- ⚠Ketones in your urine (if you check) that keep rising
Common symptoms
- Extreme thirst and dry mouth
- Urinating more often than usual
- Feeling tired, weak, or sleepy
- Blurred vision
- Headaches
- Unexpected weight changes
- Feeling unusually hungry or shakiness (low blood sugar)
Symptoms in children
- Irritability or mood swings
- Wetting the bed after being dry at night
- Stomach aches or nausea
- Lack of energy during play
Symptoms in older adults
- Confusion or forgetfulness
- Dizziness and falls
- Dehydration (dry mouth, sunken eyes)
- Being more sleepy than normal
- Not feeling thirsty despite high blood sugar
Causes
Main causes
- Illness or infection, like a cold or chest infection
- Physical or emotional stress
- Hormone changes during pregnancy or around periods
- Missing doses of diabetes medicine or insulin
- Eating more carbohydrate than usual or less activity than usual
- Certain medicines used for other conditions (for example, steroids)
Risk factors
- Taking insulin or certain other diabetes medicines
- Long-standing diabetes
- Being over 65
- Having other health conditions like heart or kidney disease
- Living alone without regular support
When to see a doctor
See a doctor urgently if:
- Call your local health service or emergency number if you have any of the emergency symptoms listed above
- If your blood sugar is below a safe level or above a dangerously high level and will not improve with your home plan
- If you cannot keep fluids down or become very confused
Book a routine appointment if:
- If you have blood sugar readings above your target for several days
- If you are missing more doses than usual and struggling to manage
- If you need help adjusting your medicines or insulin doses
- If you notice signs of a flare-up that keep coming back
Diagnosis
A flare-up is usually diagnosed from your symptoms and your blood sugar readings. Your doctor will ask about what has changed in your routine and may check for an underlying cause, like an infection.
Tests that may be done
- Finger-prick blood glucose test
- Blood test called HbA1c that gives average blood sugar over 3 months
- Urine or blood test for ketones
- Tests for infections or other triggers if needed
What to expect at your appointment
You may be asked to keep a record of your home blood sugar readings, symptoms, and any changes in diet, stress, or illness. Your diabetes care team will use this information to suggest small adjustments to your treatment plan.
Treatment
The goal of treatment is to bring blood sugar back into a safe range, manage any symptoms, and treat whatever is causing the flare-up. Your diabetes team will guide you on any changes to your medicines.
Self-care at home
- Drink plenty of unsweetened fluids (water is best) to stay hydrated
- Eat small, balanced meals if you can, and avoid sugary drinks
- Take your diabetes medicines as prescribed, unless told otherwise
- Rest and look after yourself while you recover from an illness
- Check your blood sugar more often than usual
- If you use insulin, be aware that your needs may change during illness
Medical treatments
Your healthcare team may advise temporary changes to your insulin dose or other diabetes medicines. For example, extra insulin doses may be needed during an infection, but only with advice from a professional. You should never make major changes to your medicines without talking to your doctor, nurse, or pharmacist.
When is surgery considered?
If you are having a procedure or surgery, your diabetes plan will be adjusted beforehand, but this is planned and managed by your care team.
Living with this condition
A flare-up is something you can navigate. Keep a simple 'sick-day plan' agreed with your diabetes team, and know when to ask for help. Write down your target blood sugar range and keep it somewhere visible.
Lifestyle tips
- Keep your medicines somewhere you will not forget them
- Carry treatment for very low blood sugar (like fast-acting sugar) if advised
- Learn the signs of a flare-up so you can act early
- Stay in touch with your diabetes team during difficult times
Diet and exercise
Try to keep regular meal times and aim for balanced meals containing fibre, healthy fats, and some carbohydrates. If you are unwell, you may not feel like eating, but small snacks like toast or soup can help. Light activity, when you feel up to it, also helps your body use insulin better. Always ask your team about eating plans during illness.
Mental health and emotional wellbeing
Living with the ups and downs of diabetes can be exhausting and worrying. You might feel anxious, frustrated, or low when your blood sugar is hard to control. These feelings are common. Talk to your diabetes team or your doctor about them; they can support you.
Prevention
You cannot always prevent a flare-up, but you can reduce how often they happen and how severe they become. Knowing your triggers and acting early makes a real difference.
Vaccines
Staying up to date with recommended vaccines, such as the flu and COVID-19 vaccines, can lower your risk of illnesses that make diabetes harder to control.
Screening programmes
Regular checks on your feet, eyes, kidneys, and heart help catch problems early and keep you well. Ask your diabetes team about the schedule that is right for you.
Complications
If left untreated
- Very high blood sugar can lead to dehydration and a dangerous build-up of acids in the blood (diabetic ketoacidosis, mainly in type 1)
- Very low blood sugar can make you confused, pass out, or have a seizure
- Frequent flare-ups can strain your heart, kidneys, eyes, and nerves over time
- Infections may become harder to fight off
Long-term outlook
With the right help, flare-ups are usually temporary. You can get back to feeling more like yourself in days to a week. Most people with diabetes live full, active lives, and a flare-up is something you can learn to manage with your diabetes team.
Find support
International organisations
External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.
Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Related conditions
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 31, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.