Managing diabetes when you have flu

Diabetes nurse educator, Kate Bristow, shares effective tips to manage diabetes when you have flu.

Winter season is here and with it an increase in the incidence of colds and flu. For someone with diabetes, flu can be more than just an irritation as it makes managing blood glucose levels more challenging.

What is the difference between a cold and flu?

A cold is an upper respiratory tract infection. Common symptoms include: starting with a sore throat, followed by a runny nose and some congestion and then a cough. Fever is uncommon in adults.

Colds and flu do share many symptoms, but an infection with influenza also manifests with higher temperatures, body aches, and cold sweats or shivers. This may be a good way to tell the two apart.

Flu symptoms are normally more severe and come on quickly. Both are caused by viruses and generally need to run their course. If they progress to a bacterial infection, then an antibiotic may be necessary. Stay in touch with your healthcare team when you are unwell.

Fever Sometimes – mild Usual – lasts 3 – 4 days
Headache Occasionally Common
General aches and pains Slight Usual – often severe
Fatigue/weakness Sometimes Usual – can last 2-3weeks
Exhaustion Never Usual – especially at the beginning
Stuffy nose Common Sometimes
Sneezing Usual Sometimes
Sore throat Common Sometimes
Cough/chest discomfort Mild to moderate cough Common – can become severe
Complications Sinus congestion/middle ear infection Sinusitis, bronchitis, ear infection, pneumonia
Prevention Wash hands often and avoid contact with sufferers. Wash hands and avoid contact with sufferers,

annual flu vaccine,

possibly pneumococcal vaccine too.

Treatment Decongestants, pain relief medication. Decongestants,

pain relief medication.

Call your doctor – antiviral medication sometimes used.

How best can you manage your diabetes when you have a cold or flu?

When you are sick your body will make more glucose to give itself the energy to fight the infection, and to add to this you may make more of the stress hormone cortisol. Cortisol makes you more insulin resistant. This means that when you are sick you need more insulin and not less.

So, in effect what happens when you are sick is that your liver will produce more glucose and you will be more insulin resistant. It’s a double whammy for your body and your glucose levels. You will probably be thirstier and pass more urine in this case and the cells in the body will start looking for other ways to get energy.

The lack of fuel into the cells means that they will start looking for other energy sources and sometimes the body starts to break down fat to provide this. Fat is converted into ketones by the liver. Ketones are toxic to the body and can be very dangerous.

Look out for signs such as stomach aches, nausea and vomiting along with high blood glucose levels. This is called ketoacidosis and it’s important that you have an individualised sick day management plan that you have discussed with your healthcare team.

If you are not taking insulin

It’s still important to track your glucose levels even if you are not using insulin. Follow the guidance below:

  • Test your blood glucose more regularly; this includes during the night and 2 to 4 hourly during the day depending on your numbers.
  • Drink more water. You may be thirstier than normal. If you are feeling nauseous then sip steadily rather than gulping it down. It’s not necessary to eat if you are feeling nauseous. But do ensure you stay hydrated.
  • Take your medication as prescribed. Your doctor may ask you to stop certain oral diabetes medications when you are sick.

If you are taking insulin

  • Do not stop taking your insulin. You may need more rather than less due to the higher glucose levels.
  • If you are taking insulin to manage your diabetes and your glucose levels are high, check for ketones – see the symptoms of ketoacidosis below.


High blood sugar levels – you will be thirsty and may urinate more often.  This leads to dehydration and further stress on your body.

Possible signs of ketone build-up:

  • Nausea and stomach-ache and eventually vomiting.
  • Be aware of vomiting without diarrhoea.
  • Rapid breathing with no cough or fever
  • Abdominal pain – can be severe.

Call for assistance if you have symptoms that worry you or that are not responding to your efforts to treat them. If you have abdominal pain or difficulty breathing, go straight to the hospital.

  • Have a sick day plan in place as discussed with your healthcare team.

 Take medication as suggested by your pharmacist, nurse, or doctor to relieve the symptoms of your cold or flu.  Be aware that some preparations may contain some sugar – discuss this with the pharmacist. If you are not getting better or start to feel worse call your doctor.

 What you should have on hand

  • Blood glucose meter.
  • Glucose test strips.
  • Other medication.
  • Quick-acting carbs, such as fruit juice, sugary drinks or sweets.
  • Water.
  • Insulin and ketone test strips.
  • Glucagon.
  • Contact details of your healthcare team in case of emergency.
Sister Kate Bristow is a qualified nursing sister and certified diabetes educator.


Kate Bristow is a qualified nursing sister and certified diabetes educator.

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