Approach

Inpatient hyperglycaemia and hypoglycaemia can present with a wide range of clinical features and histories. It is important to ask about nutritional intake and to obtain a full drug history, including adherence and any recent changes. Patients may be seriously unwell and may require input from the diabetes care team or referral to critical care services.

History

Hyperglycaemia

  • History is extremely important to determine whether a patient has new-onset hyperglycaemia as opposed to untreated or poorly controlled pre-existing diabetes mellitus. Distinguishing between type 1 diabetes mellitus and type 2 diabetes mellitus is also important, as it informs the approach to inpatient glycaemic management. For example, patients with type 1 diabetes require closer monitoring for diabetic ketoacidosis. See Diabetic ketoacidosis​.

  • Certain acute illnesses, such as myocardial infarction, sepsis, and pneumonia, are strong risk factors for hyperglycaemia.[24]

  • All patients should have their current drug history reviewed.

    • In some patients with no prior history of diabetes, drug history may reveal a recent course of corticosteroids, which may suggest transient hyperglycaemia.

Hypoglycaemia

  • Patients with hypoglycaemia may present with a reduced level of consciousness, behavioural changes, sweating, tachycardia, seizures, or coma. Early recognition of these symptoms and signs is crucial for initiating prompt treatment.

  • In some cases, signs may be masked - particularly in patients who are sedated or taking beta-blockers, and counter-regulatory responses may be impaired.

  • Individuals at increased risk of hypoglycaemia include older adults, malnourished individuals, and those with cognitive impairment, renal or hepatic failure, heart failure, malignancy, infection, or sepsis.[1]​​[3][21]

Examination

Patients should undergo a comprehensive physical examination tailored to their presenting condition. In all patients, it is important to:

  • Assess for signs of infection

  • Assess conscious level using the Glasgow Coma Scale

  • Assess for signs of dehydration: dry mucous membranes, decreased skin turgor or skin wrinkling, slow capillary refill, tachycardia with a weak pulse, and hypotension.

For patients with known or suspected diabetes, additional assessments, such as screening for diabetic neuropathy, may be beneficial. Simple tests such as pinprick sensation, vibration perception (using a 128 Hz tuning fork), 10 g monofilament pressure sensation, and assessment of ankle reflexes can be used to detect signs of neuropathy.

Tests

  • Blood glucose should be checked routinely in all patients admitted to hospital and is the first indication of hyperglycaemia.

  • In patients with pre-existing diabetes or newly discovered hyperglycaemia, capillary blood glucose (CBG) should be checked throughout admission, preferably before meals and at bedtime if the patient is eating, or every 6 hours if the patient is nil by mouth (NBM). Patients with signs of hypoglycaemia should have a CBG test done immediately.

  • Hyperglycaemia in hospitalised patients is defined as blood glucose >7.8 mmol/L (>140 mg/dL).[1]​ In patients without a prior diagnosis of diabetes, an HbA1c ≥48 mmol/mol (≥6.5%) suggests that diabetes was present prior to hospitalisation.[1]​ A normal HbA1c in the face of new hyperglycaemia suggests transient hyperglycaemia, whether related to stress, corticosteroids, or parenteral/enteral nutrition.[3] The oral glucose tolerance test is not usually done during hospitalisation.

  • Renal function should be tested to assess for diabetic nephropathy in all patients with hyperglycaemia and should include serum creatinine, urea, and estimated glomerular filtration rate.

  • In patients with type 1 diabetes and suspected diabetic ketoacidosis (DKA), serum ketones should be measured. Of the ketones, beta-hydroxybutyrate is the most sensitive and specific. Serum ketone measurement may also be useful to monitor progress of recovery from DKA. Urine ketones are not recommended, as they may reflect the patient's state several hours earlier.

  • Post-discharge, all patients admitted to hospital with new-onset hyperglycaemia should undergo follow-up testing with fasting glucose and/or HbA1c. Abnormal results need to be confirmed on a separate day. If the diagnosis remains uncertain, an oral glucose tolerance test may be considered, but is rarely necessary.

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