A short history
As soon as Banting and Best began treating patients with insulin in 1922, doctors saw that too much caused seizures and coma. In 1924 American physician Seale Harris described low blood sugar in people without diabetes, caused by the body overproducing insulin. Once tight glucose control became standard in the 1990s, hypoglycemia emerged as the main barrier to treatment, and in 2017 the International Hypoglycaemia Study Group proposed the 70 and 54 mg/dL tiers used in guidelines today.
Symptoms and causes
Early on, adrenaline kicks in: shaky hands, sweating, a pounding heart, sudden hunger. As levels fall further the brain runs short on fuel, bringing trouble concentrating, slurred speech, confusion, and seizures. The usual triggers in diabetes are too much insulin or a sulfonylurea, a skipped meal, extra exercise, or drinking on an empty stomach. Reactive hypoglycemia one to three hours after eating, especially after stomach surgery, is a form of dumping syndrome. Frequent lows can blunt warning signs—so-called hypoglycemia unawareness.
Treatment and prevention
If you're alert, use the 15-15 rule: take 15 grams of fast sugar (4 oz of juice or regular soda, glucose tablets), wait 15 minutes, recheck, and repeat if still under 70. Skip chocolate—its fat slows absorption. If someone is unconscious, don't put food in their mouth; call 911 and use glucagon injection or nasal spray if available. Regular meals, checking glucose before workouts, eating when you drink, and continuous glucose monitors help prevent lows; frequent episodes mean your A1C target or medication needs adjusting.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Can you get hypoglycemia without diabetes?
- Rarely—after gastric surgery, with an insulinoma, adrenal insufficiency, or heavy drinking. Recurrent episodes deserve a workup.
- How can I tell if I go low at night?
- Nightmares, waking up drenched in sweat, and morning headaches are clues.
Sources reviewed: 2026-10-26
References
- International Hypoglycaemia Study Group. (2017). Glucose concentrations of less than 3.0 mmol/L (54 mg/dL) should be reported in clinical trials. Diabetes Care, 40(1), 155–157.
- Cryer, P. E. (2013). Mechanisms of hypoglycemia-associated autonomic failure in diabetes. NEJM, 369(4), 362–372.
- American Diabetes Association. (2025). Standards of Care in Diabetes—2025: 6. Glycemic goals and hypoglycemia.