Hypoglycaemia

Hypoglycaemia refers to low blood sugar, usually less than <4.0mmol/L.

Causes

• Excess insulin
  • Restarting community prescribed insulins in hospital without realising the patient is non-compliant
  • Over-treatment with PRN/STAT doses of rapid insulins
• Changing insulin injection site
• Limb amputation
• Insulinoma
• Inadequate food intake
• Increased physical activity
• Long-term alcohol intake
• Renal failure resulting in decreased insulin clearance

Clinical Features

This can cause a range of symptoms but can easily be thought of in two broad categories – those due to the release of counter-regulatory hormones such as adrenaline and those as a result of low glucose to the brain i.e. neuroglycopenic symptoms.

Whipple’s Triad

Whipple’s triad describes 3 features which are suggestive of a hypoglycaemic episode. They are as follows:

• Symptoms in keeping with hypoglycaemia
• Low capillary blood glucose
• Symptoms resolve after blood glucose rises

Investigations

• Capillary blood glucose
• Capillary ketones
• Urinalysis
• C-peptide: A marker of endogenous insulin production. If this is high, it may suggest presence of an insulinoma
• Serum insulin
• Liver function

Management

The following is based on the Joint British Diabetes Societies – Inpatient Care Group guidelines for managing hypoglycaemia for inpatients. Some basic principles to bear in mind include:

• 15-20g fast-acting carbohydrate: This is to bring the glucose >4.0mmol/L
  • 4-5 glucotabs
  • 150-200ml of fruit juice
  • 3-4 heaped teaspoons of sugar mixed into a glass of water
  • A bottle of Glucojuice   
• Long-acting carbohydrate: Once you’re over 4.0mmol/L
  • A slice of bread
  • Two biscuits
  • 200-300ml of cow’s milk
  • Carbohydrate containing meal
• Glucagon
  • This is a hormone produced by the alpha cells of the pancreas to mobilise glycogen stores from the liver and convert them to glucose.
  • If people are given glucagon, they will require double the amount of long-acting carbohydrate to replenish their glycogen stores.
• Blood glucose is checked every 10-15 minutes.
• You should not omit any due insulin injections although reviewing the insulin regime is sensible.
• If the hypoglycaemic episode occurred as a result of long-acting insulin therapy or sulfonylureas, the risk of having another hypoglycaemic attack persists up to 24-36 hours after the last dose.

Patient conscious, orientated and can swallow

1. Give 15-20g of a fast-acting carbohydrate: This step can be repeated up to 3 times if the blood glucose is not rising to 4.0mmol/L. After 3 cycles of the first step, senior involvement may be required.
2. Glucose still <4.0mmol/L after 3 cycles of step 1
   1. Administer 1mg of IM glucagon or
   2. 150-200ml of 10% glucose over 15 minutes
3. Once glucose is >4.0mmol/L, give long-acting carbohydrate

Patient conscious but confused, disorientated, aggressive or uncooperative but can swallow
 

1. Where possible, an oral fast-acting carbohydrate as mentioned above is preferred.
2. Patient unable or unwilling to cooperate, but able to swallow: 1.5-2 tubes of glucose gel can be squeezed between the teeth and gums.
3. If glucose gel is ineffective: 1mg IM glucagon.
4. IM glucagon can only be given once but the patient should again only receive 3 cycles of treatment. If the blood glucose is still <4.0mmol/L after 3 cycles of glucose gel or 2 cycles of glucose gel + 1 cycle of IM glucagon, IV glucose should be considered i.e. 150-200ml of 10% glucose over 15 minutes.
5. Once glucose is >4.0mmol/L, give a long-acting carbohydrate

Patient unconscious and/or seizing and/or very aggressive

1. A-E approach: the patient may require oxygen
2. If the patient has IV access: you can give either of the following and repeat blood glucose 10 minutes later.
   1. 75-100ml 20% glucose over 15 minutes
   2. 150-200ml 10% glucose over 15 minutes
3. If the patient does not have IV access: 1mg IM glucagon.
4. Once glucose is >4.0mmol/L, give long-acting carbohydrate

Patient Nil-by-mouth

• Any variable rate IV insulin infusions should be adjusted appropriately.
• IV glucose using either of the following are appropriate:
  • 75-100ml 20% glucose over 15 minutes
  • 150-200ml 10% glucose over 15 minutes
• Once glucose is >4.0mmol/L, an infusion of 10% glucose at 100ml/hour can be continued until the patient is not nil by mouth/has been reviewed.

Factors Reducing Efficacy of Glucagon

As glucagon works by mobilising the glycogen stores within the liver and supplying glucose through that mechanism, patients with conditions affecting the liver or those who are malnourished and subsequently have depleted glycogen stores may have inadequate responses to IM glucagon. Examples include:

• Alcohol abuse
• Prolonged starvation
• Advanced liver disease
• People on sulfonylureas

Impaired Hypoglycaemia Awareness

Sometimes people can have an impaired awareness of a hypoglycaemic episode until it is too late and very severe symptoms are developed. This can be quite dangerous, and people who experience hypos are required to inform the DVLA in the UK.

Patients on beta-blockers for example may have reduced awareness considering beta-blockers will block the adrenaline mediated counter-regulatory responses to a hypo.

References

https://www.gov.uk/hypoglycaemia-and-driving

https://www.ncbi.nlm.nih.gov/books/NBK534841/

https://diabetes-resources-production.s3.eu-west-1.amazonaws.com/resources-s3/2018-05/JBDS_HypoGuidelineRevised2.pdf%2008.05.18.pdf

https://bnf.nice.org.uk/treatment-summaries/hypoglycaemia/