In patients with type 2 diabetes, very high and low glycaemic states can occur. Both have significant impacts and implications. Patients should be well educated and informed about both states, and an active management plan should be developed.
Hypoglycaemia is defined as a blood glucose level (BGL) of ≤3.9 mmol/L and/or to a level that causes neurogenic and neuroglycopenic symptoms and signs.2,3 Rarely, a person who has normal BGLs can display symptoms (known as ‘pseudo-hypoglycaemia’); this might occur, for example, when someone has experienced persistent, prolonged hyperglycaemia and the elevated glucose levels have become normalised.4,5
Hypoglycaemia in people with type 2 diabetes is common,5 and its impact must not be underestimated, particularly in patients where the morbidity of hypoglycaemia poses particular problems and symptoms may be unrecognised. Higher risk patients include older people, people with renal impairment, people with poor cognitive function and those with low health literacy.6,7
Symptoms of hypoglycaemia vary between people, and include:
- adrenaline activation symptoms, including pale skin, sweating, shaking, palpitations and a feeling of anxiety or dizziness
- neuroglycopenic symptoms, including hunger, change in intellectual processing, confusion and changes in behaviour (eg irritability), paraesthesia, then coma and seizures.
Hypoglycaemia is more common in people taking insulin, alone or in combination with other glucose-lowering medications; it can also occur with sulfonylurea therapy. Other causative factors are insufficient carbohydrate intake, renal impairment and excessive alcohol ingestion, and change in physical activity.
Asymptomatic hypoglycaemia (or biochemical hypoglycaemia) occurs when someone’s BGLs are low (≤3.9 mmol/L), but the typical symptoms of hypoglycaemia are not present.4
Severe hypoglycaemia is defined as signs of hypoglycaemia whereby the person requires the assistance of another person to actively administer corrective action such as carbohydrate, and/or glucagon and glucose infusion. A BGL of <3.0 mmol/L may carry a risk for severe hypoglycaemia.4
Impaired hypoglycaemia awareness occurs where the pathophysiologic symptoms that arise in response to mild or severe hypoglycaemia (refer to Appendix 3) are reduced or absent and the patient loses the ability to detect the early symptoms of hypoglycaemia. In such cases, symptoms may be recognised by other family members and carers before the patient, and the patient is more likely to have episodes of severe hypoglycaemia.
The development of impaired hypoglycaemia awareness is associated with recurrent episodes of hypoglycaemia and longer duration of type 2 diabetes. Patients with impaired hypoglycaemia awareness may benefit from options such as review of pharmacological and hypoglycaemia management, and continuous or ambulatory glucose monitoring, as this condition may be reversible.
Hyperglycaemic states include emergencies such as HHS (formerly known as hyperosmolar non-ketotic coma [HONC]) and DKA. Signs of hyperglycaemic states include:
- severe dehydration with polyuria and polydipsia
- abdominal pain, nausea and vomiting
- altered consciousness
- ketotic breath, in patients with DKA.
These conditions occur due to very unstable glucose levels, implying diabetes management issues or underlying causes such as infection or myocardial infarction, which require concomitant management. DKA is rare in people with type 2 diabetes relative to type 1 diabetes, but it has increased with sodium glucose co-transporter 2 (SGLT2) inhibitor use and is important to recognise (Appendix 3).
Hyperglycaemic thresholds related to acute elevations of venous or self-monitoring of blood glucose results >15 mmol/L on two subsequent occasions, two hours apart, with clinical symptoms of metabolic disturbance, should be considered a hyperglycaemic emergency and require assessment and intervention; refer below or to The Royal Australian College of General Practitioners (RACGP) and Australian Diabetes Society (ADS) clinical position statement Emergency management of hyperglycaemia in primary care.
More information about management of hypoglycaemia and hyperglycaemia can be found in Appendix 3. Sick day management of hyperglycaemia is discussed in the section ‘Managing risks and other impacts of type 2 diabetes’.