Diabetes and Intercurrent Illness

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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also: Glucose Tolerance Test written for patients

The stress of illness can increase basal insulin requirements in all types of people with diabetes. Being ill may also render the person with diabetes unable to monitor and manage their condition as they would normally. Some people with diabetes may associate insulin dosing with eating, so during a period of anorexia or vomiting they may feel that they do not need to take their normal insulin regimen, whereas they ought to maintain it, or even increase the dose. There is also a need to keep up carbohydrate intake.

These measures help reduce the risk of diabetic ketoacidosis and poor diabetes control. Patients taking metformin should receive special attention, as continuing this medication during periods of dehydration or acute illness can increase the risk of lactic acidosis or a hyperosmolar hyperglycaemic state.

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  • Education of the patient as to the correct action to take when ill.
  • Consider what arrangements need to be made to monitor blood glucose in patients who do not normally do so - may require education of the patient and/or carer, or involvement of community services.
  • Patients should increase the frequency of glucose monitoring to four-hourly or more as necessary.
  • Treat the underlying cause of the intercurrent illness sufficiently.
  • Maintain carbohydrate intake using sugary drinks or fruit juice, soups or snack foods if the patient has difficulty eating.
  • Fluid intake is important and patients should be advised to have a glass of water every hour, aiming for three litres in 24 hours.
  • Antiemetics may be useful for symptomatic treatment of vomiting but establish the likely cause of the symptoms first and admit if necessary.

Mobile phone support is associated with reduced progression of ketosis to diabetic ketoacidosis in young adults despite poor diabetes control.[2] 

Advise patients to keep a 'sick-day supply box' which might contain:

  • Long-life fruit juice.
  • Bottle of ordinary Lucozade® or non-diet fizzy drink.
  • Two 2 L bottles of still water.
  • Soup.
  • Ice-cream.
  • Unopened box of blood glucose monitoring strips.
  • Unopened box of ketone strips (if on insulin).

All items should have their expiry dates checked (especially the last two items) every six months. Written information on sick-day rules should be kept with these, such as those available at the Diabetes UK website.[3]

  • The patient should take their tablets and normal dosage, providing carbohydrate intake continues in solid or liquid form (see above) and glucose monitoring continues at least four-hourly.
  • If glucose level increases beyond 13 mmol/L and/or the patient feels unwell, medical advice should be sought.
  • Metformin should be stopped if the patient is becoming dehydrated. Hospital admission/sliding scale insulin may need to be considered (see 'Indications for hospital admission', below).
  • INSULIN SHOULD NOT BE STOPPED - hyperglycaemia can arise from intercurrent illness irrespective of the patient's calorie intake.
  • There are no hard and fast rules regarding insulin dosage, as response depends on the individual patient's metabolism and the type of insulin they are taking (long-acting insulin will have a slower response time than fast-acting). Sick-day rules should follow those agreed with consultants/specialist units at the time of initiation of insulin or follow local guidelines. In the absence of these the following rule of thumb could be followed:
    • Blood glucose less than 13 mmol/L - continue with current dosage.
    • Blood glucose 13-22 mmol/L - patient should increase by two units each injection, even if unable to eat.
    • Blood glucose greater than 22 mmol/L - patient should increase by four units each injection, even if unable to eat.
    • Return dose to normal when blood glucose returns to normal.
  • Glucose and ketone monitoring should continue until the glucose level returns to 13 mmol/L or below, a normal diet is being taken and ketones are absent from the urine.
  • Patients should stick test for ketonuria once or twice a day, more frequently if ketones are present.

Patients should be advised to seek medical advice if:

  • They are unable to eat or drink.
  • They have persistent vomiting or diarrhoea.
  • Their blood glucose is higher than 25 mmol/L despite increasing insulin.
  • They have very low glucose levels.
  • There are persistent ketones or large amounts of ketones in the urine.
  • They become drowsy or confused (make sure carers are aware of this).
  • They have any other concern.

Hospital admission should be considered in the following circumstances:

  • A suspicion of underlying diagnosis that requires hospital admission (eg, myocardial infarction, intestinal obstruction) – admit immediately.
  • Inability to swallow or keep down fluids - admit if this persists for more than a few hours.
  • Significant ketosis in a person with type I diabetes despite optimal management and supplementary insulin.
  • Persistent diarrhoea.
  • Blood glucose persistently >20 mmol/L despite best therapy.
  • Any clinical signs of ketosis or worsening condition (eg, Kussmaul's respiration, severe dehydration, abdominal pain).
  • The patient is unable to manage adjustment of normal diabetes care.
  • The patient lives alone, has no support and may be at risk of slipping into unconsciousness.

Further reading & references

  1. Edelstein E Cohen A; Sick-day management for the home care client with diabetes. Home Healthc Nurse. 2005 Nov;23(11):717-24
  2. Farrell K, Holmes-Walker DJ; Mobile phone support is associated with reduced ketoacidosis in young adults. Diabet Med. 2011 Aug;28(8):1001-4. doi: 10.1111/j.1464-5491.2011.03302.x.
  3. Dealing with illness; Diabetes UK
  4. Rosindale S; Ensuring good management of diabetes in intercurrent illness Nursing Times.net 2004; 100 (22);34
  5. Cohen AS, Edelstein EL; Sick-day management for the home care client with diabetes. Home Healthc Nurse. 2005 Nov;23(11):717-24, quiz 725-6.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Laurence Knott
Current Version:
Peer Reviewer:
Dr Adrian Bonsall
Document ID:
2045 (v24)
Last Checked:
Next Review:

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