Approach

Inpatient hyperglycaemia and hypoglycaemia present with a wide variety of features and history. It is important to ask about nutritional intake and to obtain a full drug history, including medicines adherence and any recent changes to medications. Patients may be seriously unwell and specialist diabetic team or critical care involvement may be required.

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, along with new-onset hyperglycaemia, can help establish a clear plan for glycaemic control during hospital admission. For example, a higher vigilance for diabetic ketoacidosis is important in patients with type 1 diabetes. See Diabetic ketoacidosis

  • Myocardial infarction, sepsis, and pneumonia are strong risk factors for hyperglycaemia.[13]

  • 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 corticosteroid use, which may suggest transient hyperglycaemia.

Hypoglycaemia

  • Patients with hypoglycaemia may present with a reduced level of consciousness, unusual behaviour, sweating, tachycardia, seizures, or coma. Recognising these symptoms and signs urgently is essential to institute immediate management.

  • Sedation or beta-blockers may mask symptoms, and counter-regulatory responses may be impaired.

  • Patients at increased risk of hypoglycaemia include older people, malnourished people, and those with cognitive impairment, renal or hepatic failure, heart failure, malignancy, infection, or sepsis.[1]​​[3][11]

Examination

Patients should undergo a complete physical examination specific to their presenting condition. For all patients also:

  • Assess for any 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, hypotension

Patients with known or suspected diabetes might benefit from the following examinations:

  • Eye examination: a fundus examination with an ophthalmoscope to assess for diabetic retinopathy.

  • Vibration sense and microfilament examination: a screening examination, using simple tests such as pinprick sensation, vibration perception (using a 128-Hz tuning fork), 10-g monofilament pressure sensation, and assessment of ankle reflexes to assess for signs of diabetic 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, fingerstick capillary blood glucose should be checked throughout admission, preferably before meals and at bedtime if eating, or every 6 hours if taking nothing by mouth. Patients with signs of hypoglycaemia should have a fingerstick 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, a 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 ketoacidosis, serum ketones should be measured. Of the ketones, beta-hydroxybutyrate is the most sensitive and specific. These tests may also be useful to monitor progress of recovery from ketoacidosis. Urine ketones are not recommended as they may reflect the patient's state several hours ago.

  • All patients admitted to hospital with new-onset hyperglycaemia should be assessed after discharge for the presence of diabetes with a subsequent fasting glucose and/or HbA1c. Abnormal results need to be confirmed on a separate day. Testing 2-hour post-load glucose after 75 g oral glucose may be needed if there is uncertainty about the diagnosis but is not usually necessary.

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