Criteria
Transient hyperglycaemia
Development of hyperglycaemia is related to the onset of physiological stress (e.g., infection or myocardial infarction), drugs such as corticosteroids, or enteral and parenteral nutrition, typically with resolution when the inciting factor is removed.
Tests:
HbA1c is normal if the period of stress or exposure is short (reflecting normal blood glucose before the illness).
Type 1 diabetes mellitus[1]
May have a genetic predisposition; there may be a personal or family history of autoimmune disease. Can occur at any age, but is usually diagnosed in younger patients (age <35 years) with lower BMI (<25 kg/m²). Patients may have acute symptoms of polydipsia, polyuria, and/or ketoacidosis at the time of diagnosis and/or unintentional weight loss before diagnosis, and a personal or family history of autoimmune disease.
Tests:
Two out of the following tests, or the same test performed twice if the patient does not have unequivocal symptoms of hyperglycaemia:
Fasting plasma glucose: ≥7 mmol/L (≥126 mg/dL)
75 g oral glucose tolerance test: 2-hour plasma glucose ≥11.1 mmol/L (≥200 mg/dL)
HbA1c ≥48 mmol/mol (≥6.5%)
In a patient with unequivocal symptoms of hyperglycaemia or hyperglycaemic crisis:
Random plasma glucose ≥11.1 mmol/L (≥200 mg/dL)
Supporting evidence for type 1 diabetes:
Plasma and urine ketones: elevated in ketoacidosis
Fasting C-peptide: usually low or undetectable (but may be in the normal range)
Autoantibodies: to anti-glutamic acid decarboxylase, insulin, islet antigen 2, and/or zinc transporter 8
Type 2 diabetes mellitus[1]
Usually occurs at an older age than type 1 diabetes (most patients >35 years; greater likelihood with increasing age). May have family history. Higher risk in those with African-American, Latino, American Indian, Asian-American, and Pacific Islander ethnicity.
May have features of metabolic syndrome (hypertension, obesity, and hyperlipidaemia).
Polyuria, polydipsia, and unintentional weight loss (usually when hyperglycaemia is more severe, e.g., >16.7 mmol/L [>300 mg/dL]) may occur.
May have clinical indicators of associated insulin resistance: for example, acanthosis nigricans or polycystic ovary syndrome.
Tests:
Two out of the following tests, or the same test performed twice if the patient does not have unequivocal symptoms of hyperglycaemia:
Fasting plasma glucose: ≥7 mmol/L (≥126 mg/dL)
75 g oral glucose tolerance test: 2-hour plasma glucose ≥11.1 mmol/L (≥200 mg/dL)
HbA1c ≥48 mmol/mol (≥6.5%)
In a patient with unequivocal symptoms of hyperglycaemia or hyperglycaemic crisis:
A random plasma glucose ≥11.1 mmol/L (≥200 mg/dL)
Pre-diabetes[1]
Risk factors and history similar to those of type 2 diabetes.
Tests:
Impaired fasting glucose: fasting plasma glucose 5.6 to 6.9 mmol/L (100-125 mg/dL)
Impaired glucose tolerance: 75 g oral glucose tolerance test 2-hour plasma glucose 7.8 to 11.0 mmol/L (140-199 mg/dL)
HbA1c 5.7% to 6.4% (39-47 mmol/mol)
Hypoglycaemia[1]
Level 1: blood glucose <3.9 mmol/L (<70 mg/dL) and ≥3.0 mmol/L (≥54 mg/dL)
Level 2: blood glucose <3.0 mmol/L (<54 mg/dL)
Level 3: severe event characterised by altered mental and/or physical status requiring assistance for treatment of hypoglycaemia
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