27th May 2025

Hypoglycaemia

Hypoglycaemia is a common complication in diabetes, it is the most common side-effect of insulin or sulfonylurea use in diabetes. Hypoglycaemia is a common concern in individuals with type 1 diabetes mellitus (T1DM) as they depend on exogenous insulin for glucose control. The risk of hypoglycaemia can be a major barrier in the optimal treatment of diabetes and can be life threatening; it should always be ruled out in an acutely unwell patient especially diabetic patients and forms part of the “ABCDE” assessment in the Disability stage.

Hypoglycaemia is defined as a blood glucose level below normal. In non-diabetic people, normal glucose levels are 3.5-7mmol/L and hypoglycaemia is classed as less than 3.5mmol/L. In a diabetic patient, hypoglycaemia is classed as less than 4mmol/L, it is mild if self treated and severe if unable to self treat and requires medical assistance.

Epidemiology and Aetiology

T1DM patients have approximately two episodes of mild hypoglycaemia per week and up to 30-40% of patients experience severe hypoglycaemia per year.

There are a number of factors which can cause hypoglycaemia which should be identified and treated quickly. These include excessive insulin administration, delayed or missed meals, increased physical activity and alcohol consumption.

Clinical presentation

Clinical presentation of hypoglycaemia is a combination of autonomic symptoms, neuroglycopaenic symptoms and general malaise.

Table 3: Clinical presentation of hypoglycaemia

Management

The management of hypoglycaemia is guided by whether the severity is mild, moderate or severe. In all cases, patients should be assessed using an ABCDE approach, stop IV insulin and call for help if required.

Mild hypoglycaemia is when the patient is conscious, orientated and able to swallow. They can be treated orally. Immediately, they should be given 15-20g of a quick-acting carbohydrate. Examples include glucose tablets and fruit juice. This should be followed by giving a long acting carbohydrate such as biscuits, bread, milk or carbohydrate. 

Moderate hypoglycaemia is when the patient is conscious and able to swallow but confused, irritable and disorientated. Initially, these patients can be treated as for mild hypoglycaemia but if the patient is not cooperative, then they should be given two tubes of 40% glucose gel given between the teeth and gums. 

The oral treatment can be repeated up to three times before moving onto parenteral treatment as for severe hypoglycaemia.

Severe hypoglycaemia is when the patient is unconscious, nil by mouth, having seizures or very aggressive. These patients should be given 1mg intramuscular glucagon or intravenous dextrose as 100ml of 20% dextrose or 200ml of 10% dextrose over 15 minutes if intravenous access is available.

Following initial management, it is essential to identify and correct the cause. This includes reviewing the patient’s diabetes treatment regime including oral antihyerglycaemic drugs and insulin. The dose of medications should be adjusted based on the patient’s needs and lifestyle and review the glucose targets as some individuals may benefit from less strict glucose control.

Prevention

The prevention of hypoglycaemia is key in avoiding dangerous side effects. This should be achieved through monitoring blood glucose levels regularly; patient education of self-management including medication adjustments and meal planning and tailoring insulin and oral antihyperglycaemic medication regimes to the individual.