Diabetes sick day rules overview

Overview

Diabetes sick day rules are a set of simple guidelines to follow when you are ill and have diabetes. Being sick – even with a cold, flu, or stomach bug – can make your blood sugar levels unpredictable. These rules help you stay safe, avoid serious problems, and know when to get help.

Illness is very common, and almost everyone with diabetes will need to use sick day rules at some point. It is a normal part of managing diabetes.

These rules are important for anyone with type 1 or type 2 diabetes, especially if you take insulin or certain oral medications that can cause low blood sugar.

Symptoms

Common symptoms

• Fever, cough, sore throat, or runny nose
• Nausea, vomiting, or diarrhoea
• High blood sugar levels (hyperglycaemia)
• Feeling very thirsty or dehydrated
• Extreme tiredness or weakness

Symptoms in children

• Rapid changes in blood sugar levels
• Nausea and vomiting
• Fast, deep breathing (a sign of ketoacidosis)
• Unusual sleepiness or confusion

Symptoms in older adults

• Confusion or disorientation
• Weakness or dizziness
• Very dry mouth and eyes
• Low urine output

Causes

Main causes

• Any illness such as cold, flu, stomach bug, or infection
• Stress from being sick releases hormones that raise blood sugar levels
• Not eating or drinking enough due to illness

Risk factors

• Having type 1 diabetes (higher risk of diabetic ketoacidosis)
• Taking insulin or certain diabetes medications
• Poor blood sugar control before getting ill
• Having other health problems like kidney disease

When to see a doctor

See a doctor urgently if:

• If you cannot keep fluids or food down for more than 4 to 6 hours
• If your blood sugar remains very high despite following your sick day plan
• If you have moderate to large ketones in your urine or blood
• If you have signs of dehydration (dizziness, dry mouth, dark urine)

Book a routine appointment if:

• If you have a mild illness and are managing well, but want advice on adjusting your medication
• If your sick day plan is unclear or you need a new one

Diagnosis

Sick day rules are not a diagnosis, but your diabetes team will create a personalised plan based on your type of diabetes, medications, and overall health. They may review your blood sugar patterns and past experiences with illness.

Tests that may be done

• Blood sugar monitoring (finger prick test) every 2 to 4 hours
• Urine or blood ketone testing to check for ketones

What to expect at your appointment

Your healthcare provider or diabetes educator will explain the sick day rules step by step. They may give you a written plan and tell you exactly when to call them or go to the hospital. You will learn how to adjust your insulin or other medications safely during illness.

Treatment

Treatment during a sick day focuses on careful monitoring, staying hydrated, and managing blood sugar levels. The main goal is to prevent serious complications like diabetic ketoacidosis or severe hypoglycaemia. Always follow your personal sick day plan.

Self-care at home

• Check your blood sugar every 2 to 4 hours, even through the night if needed.
• Test for ketones if your blood sugar is high or if you are vomiting.
• Drink plenty of sugar-free fluids – about a cup every hour – to stay hydrated.
• Eat small, frequent meals or snacks if possible (for example, toast, soup, crackers).
• Continue taking your insulin or diabetes medication as prescribed, unless your doctor tells you to change the dose.
• Rest as much as possible and avoid strenuous activity.

Medical treatments

Your healthcare provider may advise temporary changes to your insulin dose or add short-acting insulin to control high blood sugar during illness. They might also prescribe anti-sickness medication or recommend hospital care if dehydration or ketones are severe. Never change your medication dose without consulting your doctor.

Living with this condition

Having a sick day plan ready is part of everyday diabetes management. Keep a written copy of your plan, a blood sugar meter, testing strips, ketone strips, and quick-acting carbs (like glucose tablets or fruit juice) at home. Make sure family members know the rules too.

Lifestyle tips

• Get regular vaccinations: flu shot, pneumonia vaccine, and COVID-19 vaccine as recommended.
• Wash your hands often to reduce your risk of catching infections.
• Keep a healthy routine with balanced meals and regular physical activity when well.

Diet and exercise

During illness, focus on staying hydrated and eating easy-to-digest foods such as broth, crackers, or applesauce. Avoid exercise if you are very sick, dehydrated, or have ketones. Once you recover, gradually return to your usual diet and activity.

Mental health and emotional wellbeing

Being sick can be stressful, especially when you have diabetes. You may feel anxious about high or low blood sugar, or frustrated by the extra monitoring. It is normal to feel this way. Talk to your family, friends, or diabetes care team for support.

Prevention

You cannot prevent all illnesses, but you can reduce your risk by getting recommended vaccinations, washing your hands regularly, and managing your diabetes well to keep your immune system strong.

Vaccines

The flu vaccine, pneumonia vaccine, and COVID-19 vaccine are especially important for people with diabetes. Ask your healthcare provider about which vaccines are right for you.

Complications

If left untreated

• Diabetic ketoacidosis (DKA) – a serious condition where acids build up in the blood, mostly in type 1 diabetes.
• Hyperosmolar hyperglycemic state (HHS) – very high blood sugar leading to severe dehydration, mostly in type 2 diabetes.
• Severe dehydration that can cause kidney problems or confusion.
• Coma or even death in extreme cases.

Long-term outlook

With a good sick day plan and quick action, most people with diabetes get through illnesses safely without serious problems. Learning these rules and having a plan in place gives you confidence and control. If complications do occur, getting medical help early leads to the best recovery.

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