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Hypoglycemia

Hypoglycemia is a condition in which blood glucose falls below the level required for normal physiological function. It is particularly important in people with diabetes treated with insulin or insulin-secretagogues, but it can also occur in people without diabetes.

Also called

Low Blood Sugar

ICD-10

E15

Specialty

Endocrine

Onset

Acute

Reviewed

August 2026
On This Page

Overview

  • In adults, a plasma glucose level <70 mg/dL (3.9 mmol/L) is generally considered an alert value requiring attention, particularly in people at risk of hypoglycemia.

     

  • Clinically significant hypoglycemia can cause autonomic symptoms such as sweating and palpitations and neuroglycopenic symptoms such as confusion, seizures, and loss of consciousness.

     

  • Severe hypoglycemia can be life-threatening.

Etiology & Risk Factors

-Etiology

In people with diabetes

Common causes include:

  • Excess insulin

  • Sulfonylureas or other insulin-secretagogues

  • Missed or delayed meals

  • Reduced carbohydrate intake

  • Excessive physical activity

  • Incorrect insulin administration

  • Changes in diabetes medication

In people without diabetes

Possible causes include:

  • Prolonged fasting

  • Alcohol

  • Non-insulinoma pancreatic disorders

-Risk Factors

  • Insulin therapy

  • Sulfonylurea therapy

  • Older age

  • Renal impairment

  • Impaired awareness of hypoglycemia

  • Long duration of diabetes

  • Intensive glycemic control

Pathophysiology

Reduced glucose availability or excessive insulin effect → falling plasma glucose → activation of counter-regulatory hormones → epinephrine/norepinephrine release → autonomic symptoms → continued glucose reduction → inadequate cerebral glucose supply → neuroglycopenia → confusion → seizures → coma

Clinical Presentation

-Symptoms:

Autonomic symptoms

  • Sweating

  • Tremor

  • Palpitations

  • Hunger

  • Anxiety

Neuroglycopenic symptoms

  • Difficulty concentrating

  • Confusion

  • Dizziness

  • Weakness

  • Drowsiness

  • Seizures

-Signs

  • Sweating

  • Tremor

  • Tachycardia

  • Pallor

  • Altered mental status

  • Seizures in severe cases

-Severe Disease

Severe hypoglycemia can cause:

  • Seizures

  • Loss of consciousness

  • Coma

  • Death

Hypoglycemia Case Overview
Hypoglycemia Case Overview

History Taking

-Ask about:

  • Onset and timing of symptoms
  • Relationship to meals
  • Blood glucose measurement during symptoms
  • Diabetes history
  • Type of diabetes
  • Insulin use
  • Type and dose of insulin
  • Sulfonylurea or other diabetes medications
  • Recent medication changes
  • Missed or delayed meals

Physical Examination

-General Examination

Assess:

  • Airway

  • Breathing

  • Circulation

  • Level of consciousness

  • Heart rate

  • Blood pressure

Look for:

  • Sweating

  • Tremor

  • Pallor

  • Tachycardia

  • Altered mental status

-System-Specific Examination

-Neurological Examination

Assess:

  • Consciousness

  • Orientation

  • Motor function

  • Seizure activity

-Cardiovascular Examination

Assess:

  • Heart rate

  • Rhythm

  • Blood pressure

-Endocrine Examination

Look for features suggesting:

  • Adrenal insufficiency

  • Other endocrine disorders

Investigations

-During a suspected spontaneous hypoglycemic episode, obtain plasma:

  • Glucose
  • Insulin
  • C-peptide
  • Proinsulin
  • β-hydroxybutyrate
  • Electrolytes
  • Renal function
  • Liver function

-Additional tests may include:

  • Cortisol
  • Sulfonylurea/meglitinide screen
  • Insulin antibodies when indicated

-HbA1c

Useful for assessing long-term glycemic control in patients with diabetes but does not diagnose an acute hypoglycemic episode.

-Special / Confirmatory Tests

Whipple’s Triad

Hypoglycemia is supported by Whipple’s triad:

  • Symptoms consistent with hypoglycemia
  • Documented low plasma glucose during symptoms
  • Resolution of symptoms after plasma glucose is raised

-Supervised Fasting Test

A supervised prolonged fast, often up to 72 hours, may be used when endogenous hyperinsulinism is suspected and spontaneous hypoglycemia has not been documented.

Diagnosis

Hypoglycemia is established by:

  • Compatible symptoms
  • Documented low plasma glucose
  • Improvement after glucose correction

In patients without diabetes or with unexplained recurrent episodes, determine whether hypoglycemia is:

  • Fasting
  • Postprandial
  • Medication-related
  • Endogenous hyperinsulinemic
  • Related to critical illness or organ failure
  • Hormonal deficiency
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Related Topics

Management

1. First-Line / Emergency Management

Conscious patient who can swallow

Give 15–20 g of rapidly absorbed carbohydrate, such as:

  • Glucose tablets

  • Glucose gel

  • Fruit juice

  • Regular sugary drink

Recheck glucose after approximately 15 minutes.

If hypoglycemia persists, repeat treatment.

Once glucose has recovered, provide an appropriate longer-acting carbohydrate-containing meal or snack when needed.

Unconscious or unable to swallow

  • Do not give food or drink orally.

  • Protect the airway.

  • Give intravenous glucose when IV access is available.

  • Give glucagon when IV access is unavailable or in appropriate community settings.

  • Reassess glucose and neurological status.

2. Definitive Treatment

The underlying cause must be identified and treated.

Examples:

  • Adjust insulin dose

  • Stop or modify causative medication

  • Treat renal or hepatic disease

  • Treat adrenal insufficiency

  • Treat sepsis or critical illness

  • Treat insulinoma or other endogenous hyperinsulinism

3. Medical Treatment

Glucose

  • Oral glucose for mild symptomatic hypoglycemia in patients who can swallow.

  • Intravenous dextrose for severe hypoglycemia or inability to take oral carbohydrate.

Glucagon

Useful for severe hypoglycemia when:

  • The patient cannot safely swallow

  • IV access is unavailable

Complications

  • Seizures
  • Coma
  • Neurological injury
  • Hypoglycemia unawareness
  • Recurrent hypoglycemia
  • Fear of hypoglycemia
  • Death

Prognosis

The prognosis is generally excellent when mild hypoglycemia is recognized and treated promptly.

Severe or prolonged hypoglycemia can result in:

  • Neurological injury
  • Cardiovascular complications
  • Coma
  • Death

Prognosis depends mainly on the severity and duration of hypoglycemia and how quickly treatment is provided.

Key Points / Clinical Pearls

  • Hypoglycemia is a clinically important low blood glucose state.
  • A glucose level <70 mg/dL (3.9 mmol/L) is an important alert threshold.
  • It is most commonly caused by insulin or insulin-secretagogue therapy in people with diabetes.
  • Common triggers include missed meals, excessive exercise, alcohol, and medication errors.
  • Early symptoms are usually autonomic, including sweating, tremor, hunger, and palpitations.
  • Severe glucose deficiency causes neuroglycopenic symptoms, including confusion, seizures, and coma.
  • Whipple’s triad supports the diagnosis of clinically significant spontaneous hypoglycemia.
  • A conscious patient who can swallow should receive 15–20 g of rapid-acting carbohydrate.
  • Glucose should generally be rechecked after about 15 minutes.
  • An unconscious patient should not receive anything orally.
  • Severe hypoglycemia can be treated with IV glucose or glucagon.
  • Recurrent episodes require identification and treatment of the underlying cause.
  • Cryer PE, Axelrod L, Grossman AB, et al. Evaluation and Management of Adult Hypoglycemic Disorders: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2009;94(3):709-728. Journal of Clinical Endocrinology & Metabolism .
  • American Diabetes Association Professional Practice Committee. 6. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1). Diabetes Care .
  • International Hypoglycaemia Study Group. Glucose Concentrations of Less Than 3.0 mmol/L (54 mg/dL) Should Be Reported in Clinical Trials of Diabetes: A Joint Position Statement. Diabetes Care. 2017;40(1):155-157. Diabetes Care .
  • Seaquist ER, Anderson J, Childs B, et al. Hypoglycemia and Diabetes: A Report of a Workgroup of the American Diabetes Association and The Endocrine Society. Diabetes Care. 2013;36(5):1384-1395. Diabetes Care .
  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Low Blood Glucose (Hypoglycemia) . National Institutes of Health.
  • National Library of Medicine (NIH). Hypoglycemia . StatPearls.