Approach

Inpatient hyperglycemia and hypoglycemia 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

Hyperglycemia

  • History is extremely important to determine whether a patient has new-onset hyperglycemia as opposed to untreated or poorly controlled preexisting diabetes mellitus. Distinguishing between type 1 diabetes mellitus and type 2 diabetes mellitus, along with new-onset hyperglycemia, can help establish a clear plan for glycemic 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 hyperglycemia.[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 hyperglycemia.

Hypoglycemia

  • Patients with hypoglycemia may present with a reduced level of consciousness, unusual behavior, sweating, tachycardia, seizures, or coma. Recognizing 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 hypoglycemia 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 exam 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 exams:

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

  • Vibration sense and microfilament exam: a screening exam, 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 the hospital and is the first indication of hyperglycemia.

  • In patients with pre-existing diabetes or newly discovered hyperglycemia, 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 hypoglycemia should have a fingerstick done immediately.

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

  • Renal function should be tested to assess for diabetic nephropathy in all patients with hyperglycemia and should include serum creatinine, blood urea nitrogen, 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 the hospital with new-onset hyperglycemia 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 postload 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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