Approach to hypoglycemia: Clinical sciences

Hypoglycemia is defined as a blood sugar below 55 milligrams per deciliter that occurs in the presence of symptoms, but some individuals can become symptomatic at levels like 70. Some important causes of hypoglycemia include medication-induced and alcohol-induced hypoglycemia, as well as endogenous hyperinsulinism and non-insulin-mediated hypoglycemia.

Now, if you suspect hypoglycemia, you should first perform an ABCDE assessment to determine if your patient is unstable or stable. If the patient is unstable, stabilize the airway, breathing, and circulation. Next, obtain a fingerstick glucose level, while obtaining IV access to give IV glucose immediately. In addition, begin continuous vital sign monitoring, such as blood pressure, heart rate, and pulse oximetry; and if needed, provide supplemental oxygen.

Here’s a high-yield fact to keep in mind! Most individuals don’t develop symptoms until their blood glucose level falls below 55 milligrams per deciliter. However, some patients may become symptomatic when their blood glucose falls below 70 milligrams per deciliter; while other patients with diabetes may experience impaired hypoglycemia awareness and experience symptoms only when their glucose falls severely low, which puts them at higher risk for life-threatening consequences. Because this range is highly variable, there’s no glucose value that defines hypoglycemia, so always correlate your patient’s symptoms with lab results.

Hypoglycemia is often observed in the setting of critical conditions, such as renal failure, liver failure, and sepsis. Renal failure leads to reduced clearance of insulin, while liver failure decreases gluconeogenesis, both causing hypoglycemia. Sepsis triggers cytokine release, which increases glucose utilization and also inhibits gluconeogenesis. So, it’s important to treat the underlying condition to normalize your patient’s blood glucose. Lastly, keep in mind that nocturnal hypoglycemia warrants assessment of the basal insulin dose.

Now that we're done with unstable patients, let’s go back to the ABCDE assessment and discuss the stable ones. If your patient is stable, first obtain a focused history and physical examination, obtain a fingerstick glucose and order labs to confirm the blood glucose levels.

Your patient may report fatigue, confusion, lightheadedness, hunger, tremor, and, in severe cases, even seizures. They might have a known history of diabetes requiring treatment with insulin or oral hypoglycemic medications, or recent alcohol overuse. Additionally, physical exam might reveal tachycardia, diaphoresis, or pallor, while fingerstick glucose and laboratory findings will typically show a blood glucose below 55 to 70 milligrams per deciliter.

Ok, so with your patient’s history, physical exam findings, and low blood glucose level, you can diagnose hypoglycemia, but not necessarily a hypoglycemic disorder. To diagnose a hypoglycemic disorder, your patient must meet the Whipple triad criteria, which includes the presence of hypoglycemic symptoms, a blood glucose below 55 to 70 milligrams per deciliter, and relief of symptoms after ingesting glucose. Since you have already identified symptoms and hypoglycemia, give your patient either oral or IV glucose and assess their response. If the patient’s symptoms aren’t relieved with glucose, the Whipple triad is not present, and there’s no hypoglycemic disorder. On the other hand, if giving glucose relieves the symptoms, the Whipple triad is present, so you can diagnose a hypoglycemic disorder.

Here’s a clinical pearl to keep in mind! If your patient no longer has symptoms, order a supervised fast to induce hypoglycemia and perform a diagnostic workup. This is a reliable method to evaluate for a hypoglycemic disorder that occurs in food-deprived conditions.