How long can someone with type 1 diabetes survive without insulin?

In type 1 diabetes the pancreas makes essentially no insulin, and without it cells cannot take up glucose no matter how much is in the blood. The body responds as though it is starving, breaking down fat and flooding the blood with ketone acids while blood glucose climbs. That is diabetic ketoacidosis: dehydration from glucose spilling into urine, acidified blood, vomiting, rapid deep breathing, and then loss of consciousness. Before insulin was isolated in 1921 a child diagnosed with type 1 diabetes usually lived months, not years. Anyone with type 1 diabetes who has run out of insulin, or who is vomiting and testing high, needs emergency medical care immediately.

What happens, in order

This is descriptive only and is not medical advice. Running out of insulin is a reason to contact emergency services or a pharmacy immediately.

Physiology, not instruction. Every figure here is a population range under particular conditions, and individual variation is large — temperature, exertion, fitness and health move all of them substantially. Nothing on this page is medical advice.

Going without something

• How long can you survive without water? About three days in mild conditions — but under a day in desert heat, and up to a week at rest in the cold.
• How long can you survive without food? Weeks rather than days — one to three weeks is typical, and water runs out long before calories do.
• How long can you survive without air? Consciousness goes in about a minute and brain injury begins around four to six minutes.
• How long can you survive without sleep? No one has died of sleep deprivation alone; the record is 11 days, and severe impairment arrives within two.
• How long can you survive without food and water? About three days — water sets the limit and food barely enters into it.
• How long can you survive without sunlight? Indefinitely, provided vitamin D comes from food or a supplement — sunlight itself is not a requirement.
• How long can you survive without human contact? Indefinitely in the direct sense — but isolation measurably raises the risk of dying early.
• How long can you survive without gravity? Indefinitely with exercise countermeasures — the record for one continuous flight is 437 days.
• How long can you survive without salt? Weeks to months at rest — kidneys are very good at conserving sodium — but days if you are sweating heavily.
• How long can you survive without vitamin C? Scurvy appears after roughly one to three months of near-zero intake, and is fatal in a few months more.
• How long can you survive without protein? Months, because the body cannibalises its own muscle — which is exactly why it eventually kills you.