This is the part nobody wants to think about — but everyone with T1D needs to understand deeply. What happens when your body doesn't have insulin? The answer involves a dangerous chain reaction that can become life-threatening if not caught early. The good news: once you know the warning signs and have a plan, you can prevent emergencies before they start.

The Cascade: No Insulin → Hyperglycemia → Ketones → DKA

When insulin is absent or severely insufficient, here's what happens step by step:

Stage 1 — Glucose builds up (Hyperglycemia) Without insulin to open cell doors, glucose accumulates in the bloodstream. Blood sugar climbs to 200, 300, 400 mg/dL or higher. Meanwhile, your cells are energy-starved.

Stage 2 — The body switches fuel sources Desperate for energy, your body starts breaking down fat at an accelerated rate. This is not the normal fat-burning of exercise — it's an emergency response.

Stage 3 — Ketones accumulate Fat breakdown produces waste products called ketones. In small amounts, ketones are normal. But without insulin, ketone production spirals out of control.

Stage 4 — Diabetic Ketoacidosis (DKA) Excess ketones make the blood acidic. This is DKA — a medical emergency. Untreated, it can lead to coma or death within hours.

When to Check Ketones

The ADA Standards of Care 2026 recommends checking ketones when:

• Blood sugar is above 250 mg/dL (13.9 mmol/L) for more than 2-3 hours
• You feel nauseous, are vomiting, or have abdominal pain
• You're sick (infection, flu, fever) — illness increases insulin resistance
• Your pump site may have failed (no insulin delivery)
• You notice fruity breath odor or rapid breathing

How to check: Blood ketone meters (measuring beta-hydroxybutyrate) are more accurate than urine strips. Target: below 0.6 mmol/L is normal; above 1.5 mmol/L requires immediate action.

Scenario: Nadia's Pump Site Failure

Nadia, 28, woke up at 3 AM feeling nauseous with a blood sugar of 340 mg/dL. Her CGM showed a steady climb starting around midnight. She checked her pump site and found it was kinked — meaning she'd received no insulin for approximately 3 hours.

Here's what Nadia did (and what you should do):

1. Checked blood ketones: 1.2 mmol/L — elevated but not yet emergency level
2. Gave a correction dose via syringe (not through the pump, since the site was compromised)
3. Changed her pump site completely — new infusion set, new location
4. Drank water — hydration helps the kidneys flush ketones
5. Set alarms to recheck blood sugar and ketones every hour
6. By 6 AM: Blood sugar 165 mg/dL, ketones 0.4 mmol/L — crisis averted

DKA Emergency Decision Card

Print this or save it to your phone:

Insulin Storage and Handling

Bad insulin = no insulin. Proper storage prevents one of the most common causes of unexplained high blood sugar:

Unopened insulin:

• Store in the refrigerator (2-8°C / 36-46°F)
• Check expiration dates regularly
• Never freeze insulin — it destroys the protein structure

In-use insulin (opened vials/pens):

• Room temperature is fine for 28 days (most brands) — check your specific insulin's labeling
• Keep out of direct sunlight and heat above 30°C (86°F)
• Never leave insulin in a hot car, on a windowsill, or in checked luggage

Travel checklist:

• Carry insulin in your carry-on bag (never checked luggage — cargo holds can freeze)
• Use an insulated case with a cool pack in hot climates
• Bring backup supplies: extra pens/vials, syringes, pump supplies
• Carry a letter from your doctor for airport security