What are the causes of hypoglycemia?

Causes of Hypoglycemia

Hypoglycemia in adults is most commonly caused by diabetes medications—particularly insulin, sulfonylureas, and meglitinides—but can also result from critical illness, endocrine deficiencies, kidney or liver disease, medications outside of diabetes treatment, and rare causes including insulinoma and autoimmune conditions. 1, 2

Medication-Related Causes

Diabetes Medications (Most Common)

• Insulin therapy is the leading cause, with highest rates occurring in intensive insulin regimens (multiple daily injections, insulin pumps, or automated insulin delivery systems), followed by basal insulin alone 1, 2
• Sulfonylureas and meglitinides stimulate insulin release and cause prolonged hypoglycemia, with first-generation sulfonylureas carrying particularly high risk 2, 3
• Combining insulin with sulfonylureas further amplifies hypoglycemia risk 1

Non-Diabetes Medications

• Inadvertent or surreptitious use of insulin or sulfonylureas is the most common cause in non-diabetic individuals 4
• Quinine, quinolones, pentamidine, and certain antibiotics can trigger hypoglycemia 4, 5
• NSAIDs, analgesics, antiarrhythmics, and antidepressants may induce hypoglycemia by stimulating insulin release, reducing insulin clearance, or interfering with glucose metabolism 5

Disease-Related Causes

Kidney Disease

• End-stage renal disease and advanced chronic kidney disease significantly increase risk through decreased renal gluconeogenesis, impaired insulin clearance, poor nutritional status, and accumulation of uremic toxins 2, 4
• Acute kidney injury is an important risk factor for in-hospital hypoglycemia 2

Endocrine Disorders

• Adrenal insufficiency with cortisol deficiency impairs counterregulatory responses to hypoglycemia 2, 4
• Hypopituitarism and other hormone deficiencies disrupt glucose homeostasis 6, 3

Hepatic Dysfunction

• Liver failure impairs gluconeogenesis and glycogen storage 3, 7
• Drug-induced hepatotoxicity can lead to hypoglycemia in certain circumstances 5

Critical Illness

• Sepsis causes dysregulated glucose metabolism 2
• Acute cardiac insufficiency and severe systemic illness alter metabolic homeostasis 7

Tumor-Related Causes

• Insulinoma causes inappropriate insulin secretion from pancreatic beta-cells 8, 6
• Non-islet cell tumors (NICTH) secrete Big-IGF2, causing hypoglycemia with low insulin, C-peptide, and IGF-1 levels 6
• Postbariatric hypoglycemia and noninsulinoma pancreatogenous hypoglycemia represent endogenous hyperinsulinism 8

Rare and Genetic Causes

• Autoimmune hypoglycemia from antibodies against insulin (Hirata syndrome, especially with Graves' disease) or insulin receptors 6
• Monogenic congenital hyperinsulinism with mutations in glucokinase-activating gene or insulin receptors 6
• Inborn errors of metabolism including glycogen storage disorders, fatty acid oxidation defects, and inherited fructose intolerance 6

Nutritional and Toxic Causes

• Alcohol consumption is a frequent cause through impaired gluconeogenesis 6, 7
• Malnutrition or poor nutritional status depletes glycogen stores 4
• Food insecurity with irregular access to adequate nutrition 1, 2

High-Risk Clinical Contexts

Patient-Specific Risk Factors

• Recent (within 3-6 months) level 2 or 3 hypoglycemia is the strongest predictor of recurrence 1, 2
• Impaired hypoglycemia awareness (reduced ability to perceive warning symptoms) 1, 2
• Advanced age ≥75 years with reduced counterregulatory hormone responses 1, 2, 4
• Cognitive impairment or dementia limiting recognition and response 1, 2
• High glycemic variability 1, 2
• Cardiovascular disease, diabetic neuropathy, and retinopathy 1, 2

Hospital-Specific Contexts

• Interruptions in nutritional intake (NPO status, delayed meals) without insulin adjustment 2
• Low albumin levels affecting drug binding and pharmacokinetics 2
• Fasting for religious or cultural reasons 1, 2

Social Determinants

• Low-income status, housing insecurity, and underinsurance are major risk factors 1, 2
• Low health literacy and alcohol or substance use disorder 1

Critical Pitfalls to Avoid

• Failing to adjust insulin doses when kidney function declines is a common error leading to persistent hypoglycemia 2
• Continuing the same insulin regimen when nutrition is interrupted in hospitalized patients 2
• Overlooking multifactorial hypoglycemia in hospitalized, underfed older patients with severe disease or sepsis 7
• Missing surreptitious or malicious insulin administration in unexplained cases 3