Part 2: Sick days

Why illness changes your sugar

When you are ill, the body releases stress hormones that raise glucose, even if you are eating less. Vomiting and diarrhoea also dehydrate you, and some medicines become risky when you are dehydrated.

The rule that surprises people: if you take insulin, don't stop it, even if you can't eat. The ADA says people on insulin should not stop their basal, long-acting insulin when they are not eating. The doses may need to change, and your team should give you a written plan for exactly this.

Check more often

Check your glucose at least every four hours while you are ill.

If you have type 1 diabetes or take an SGLT2 inhibitor, check ketones too — especially if your glucose is above 200 mg/dL or you are vomiting. A blood ketone meter is the most accurate; urine strips are the alternative. Ask your team which to keep at home.

What ketone numbers mean

• Below 0.6 mmol/L: normal.
• 0.6 to 1.5 mmol/L: slightly high — follow your sick-day plan and check again in 2 hours.
• 1.6 to 3.0 mmol/L: at risk of ketoacidosis — contact your diabetes team now.
• Above 3.0 mmol/L: you may have ketoacidosis — go to hospital.

On a urine strip, 2+ or more counts as high. Don't drive yourself to hospital.

Fluids and food

Drink plenty of unsweetened fluids, such as water and thin soup, a little at a time and often.

If you can't eat, take some carbohydrate as a drink instead: sip juice or a regular cold drink, so your body still gets sugar — especially if you take insulin or a sulphonylurea.

Medicines to pause, and medicines to keep

When you are vomiting, have diarrhoea or can't keep fluids down, some medicines can harm the kidneys or drop your blood pressure too far. An international expert consensus lists these to pause until you are eating and drinking normally: metformin; SGLT2 inhibitors such as empagliflozin and dapagliflozin; blood pressure tablets of the ACE-inhibitor and ARB kind, such as ramipril and losartan; water tablets; and painkillers such as ibuprofen and diclofenac. Restart them within 24 to 48 hours of feeling better. The ADA adds that GLP-1 injections such as semaglutide may need pausing if vomiting is severe.

Insulin and sulphonylureas are different: they are held only if your sugar is low. Agree your own list with your doctor before you need it, and keep it with your prescription.

Go to hospital if…

• you can't keep fluids down;
• ketones are above 3.0 mmol/L, or 2+ or more on a urine strip;
• you are breathing fast and deep, have stomach pain, or your breath smells fruity;
• you are drowsy or confused;
• you have a fever with a racing heart, or feel faint when you stand.

Call Rescue 1122 rather than driving yourself.