Management of acute hypoglycaemia

What it is

Hypoglycaemia is set at a glucose level below 3.9 mmol/L, checked by glucometer, and at a blood glucose below 70 mg/dL in the hospitalized or emergency room patient. The national guideline sets it out in three levels, adopted from ADA 2019: level 1, glucose 3.9 mmol/L and glucose 3.0 mmol/L; level 2, glucose below 3.0 mmol/L; and level 3, a severe event requiring the help of another person due to a change in the conscious state, with or without physical impairment. So level 3 is named by the need for help and not by a number.

Causes and risk

Evaluate for cause in all patients and treat the cause: a change in medication, diet or activity, or an infection.

The diabetes drugs differ in this risk. Metformin, a biguanide, is the initial therapeutic agent for most type 2 diabetics; it is weight neutral and is the drug with the least risk for the development of hypoglycemia. In the UKPDS the risk for mild hypoglycemia on metformin monotherapy was only 0.3% per year, with no risk for severe hypoglycemia on metformin alone. Since metformin increases insulin sensitivity, it may carry an increased risk when combined with agents increasing insulin levels, such as sulfonylurea or exogenous insulin.

Sulfonylureas are generally added in patients with metformin failure, and weight gain and hypoglycemia are their main side effects. The sulfonylurea glyburide carries a risk of significant hypoglycemia, especially in elderly patients, and it is listed on the Beers Criteria, the American Geriatrics Society list of potentially inappropriate medication use in older adults of 65 years or more, for its potential to cause prolonged hypoglycemia. The drugs put on that list here are: 1) glyburide, for prolonged hypoglycemia; 2) amitriptyline, imipramine and paroxetine, highly anticholinergic and sedating and able to cause orthostatic hypotension, with an avoid recommendation; 3) donepezil, to be avoided in patients with syncope because of an increased risk of bradycardia. DPP-IV inhibitors such as sitagliptin, pioglitazone, and GLP-1 receptor agonists such as exenatide all carry a low risk of hypoglycemia.

In the first 24 h of baby life the causes of hypoglycaemia are IUGR, macrosomia and polycythaemia.

The guideline groups the conventional risk factors under relative or absolute insulin excess and names six routes in: insulin or oral hypoglycemic agents, especially the insulin secretogogues such as the sulfonylureas; exogenous glucose delivery decreased, as after missed meals or during the overnight fast; glucose utilisation increased, as during exercise; endogenous glucose production decreased, as after alcohol ingestion; sensitivity to insulin increased, as after weight loss or an increase in regular exercise; and insulin clearance decreased, as with renal failure.