Very high and low glycaemic states can occur in people with type 2 diabetes. Both have significant impacts and implications. People with type 2 diabetes should be well educated and an active management plan should be developed about both states.
Hypoglycaemia
Hypoglycaemia is defined as a blood glucose level (BGL) ≤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 exhibit symptoms (known as ‘pseudo-hypoglycaemia’); this might occur, for example, when someone has experienced persistent, prolonged hyperglycaemia (defined below) 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 people where the morbidity of hypoglycaemia poses particular problems and symptoms may be unrecognised. People at higher risk include older people, people with renal impairment, people with poor cognitive function and those with low health literacy.1,6
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, a 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, excessive alcohol ingestion and a change in physical activity.
Asymptomatic hypoglycaemia (or biochemical hypoglycaemia) occurs when a person’s BGLs are low (≤3.9 mmol/L), but the typical symptoms of hypoglycaemia are not present.4 There are assessment tools for hypoglycaemic unawareness, such as the Clark hypoglycaemia awareness survey, where more than 4 ‘R’ response indicates unawareness.7
Severe hypoglycaemia is defined as signs of hypoglycaemia whereby the person is functionally impaired and requires the assistance of another person to actively administer corrective action, such as carbohydrate, and/or glucagon and glucose infusion. A BGL <3.0 mmol/L may carry a risk of severe hypoglycaemia.4 Severe hypoglycaemia carries specific risks, such as driving restrictions, and requires planning for prevention of any recurrence.
Impaired hypoglycaemia awareness occurs where the pathophysiological symptoms that arise in response to mild or severe hypoglycaemia (refer to Appendix 3) are reduced or absent and the person loses the ability to detect the early symptoms of hypoglycaemia. In such cases, symptoms may be recognised by other family members and carers before they are recognised by the person, and the person is more likely to have episodes of severe hypoglycaemia.
The development of impaired hypoglycaemia awareness is associated with recurrent episodes of hypoglycaemia and a longer duration of type 2 diabetes. People with impaired hypoglycaemia awareness may benefit from options such as review of pharmacological and hypoglycaemia management, and continuous or ambulatory glucose monitoring, because this condition may be reversible.
Hyperglycaemia
Hyperglycaemic states include emergencies such as undiagnosed type 1 diabetes, HHS (formerly known as hyperosmolar non-ketotic coma [HONC]) and diabetic ketoacidosis (DKA) or euglycaemic ketoacidosis (in which blood glucose elevation may not be extreme but ketosis is present) when using sodium–glucose cotransporter 2 inhibitors (SGLT2i).
Signs of hyperglycaemic states include:
- severe dehydration with polyuria and polydipsia
- abdominal pain, nausea and vomiting
- altered consciousness
- shock
- ketotic breath in people with DKA.
The presence of these signs imply 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 SGLT2i use and is important to recognise because glucose levels may not be as extreme as other forms of DKA (Appendix 3).
Venous or self-monitored 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. If ketosis is not able to be tested for in the clinic, consider urgent referral for emergency assessment: 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 the 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’.