E-5

Accu-Chek Glucose Meter

Severity: Critical

What it means

Accu-Chek glucose meter E-5 has two distinct meanings documented across Accu-Chek's regional support pages (accu-chek.co.uk, accu-chek.in).
On some Accu-Chek models, E-5 is a test strip error similar to E-1 — the strip is damaged or not reading correctly.
On other Accu-Chek models and on similar brands (TRUE METRIX), E-5 means a very high blood glucose reading above 600 mg/dL (33.3 mmol/L) — the meter's measurement ceiling.
The fix depends on which case you're in.
A genuine E-5 high-glucose reading is a medical emergency.

Affected Models

Accu-Chek Active, Aviva, Aviva Plus, Performa, Performa Nano
Accu-Chek Guide and Guide Me
Accu-Chek Compact Plus (older model)
TRUE METRIX glucose meters use E-5 specifically for very-high-glucose results above 600 mg/dL
Different Accu-Chek model variants use E-5 for slightly different errors — always check your specific model's user guide

Common Causes

Test strip error — code chip from an expired strip lot (some older Accu-Chek meters)
Blood glucose genuinely above 600 mg/dL / 33.3 mmol/L — medical emergency
Test strip damaged or contaminated
Insufficient blood drop on the strip causing under-reading then error code
Strip vial code mismatch (older Accu-Chek models that need code chip insertion)

How to Fix It

Retest with a fresh strip immediately.

Get a brand-new strip from a sealed vial.
Wash and dry your hands thoroughly (residue from food, drink, or lotion can cause spuriously high readings).
Use a fresh lancet and a generous blood drop.
If the second reading is normal, the first was a strip error — discard the suspect strip and continue normally.
If the second reading is also E-5 or extremely high, treat it as real and act.
Recognise diabetic emergency symptoms.

Symptoms of severely high blood glucose (and possible diabetic ketoacidosis): extreme thirst, very frequent urination, blurred vision, fruity or acetone breath, deep rapid breathing, nausea or vomiting, abdominal pain, confusion or drowsiness.
Any of these with E-5 = call emergency services immediately.
Don't wait to retest or drive yourself anywhere — DKA is a life-threatening emergency.
Contact your diabetes care team.

If you're a person with diabetes and you see E-5 (or any reading above 250 mg/dL / 13.9 mmol/L) confirmed by retest, contact your endocrinologist, diabetes nurse, or GP urgently — even without DKA symptoms.
They may advise extra insulin, urgent re-evaluation of your medication, or going to A&E / ER directly.
This isn't 'wait until your next appointment' territory.
Check insulin pump / pen status if applicable.

If you're on insulin and see confirmed E-5, check whether your pump is working (catheter not kinked, infusion site not irritated) or your last pen dose actually delivered.
A pump failure or a missed dose can drive glucose into E-5 territory quickly.
Switch to backup injection (with care provider guidance) if pump is suspect.
If meter shows E-5 from a strip code mismatch.

Some older Accu-Chek meters use a code chip that matches each strip vial.
If E-5 appears alongside a low/odd code chip indication, swap the code chip to match the current strip vial (the chip number is printed on the vial).
Newer Accu-Chek models auto-code and don't have this — check your model.

When to Call a Professional

E-5 needs immediate attention.
If your meter shows E-5 and you have classic high-glucose symptoms (extreme thirst, frequent urination, blurred vision, fruity breath, confusion, deep rapid breathing), this is potentially diabetic ketoacidosis — seek emergency medical care immediately.
If you have no symptoms and the E-5 doesn't repeat on a retest, it was likely a strip error and the next reading is fine.
Never dismiss E-5 without confirming.

Frequently Asked Questions

I just ate a huge meal and got E-5 — is that the cause?

Possibly, but never assume.
A very heavy carbohydrate meal can drive postprandial blood glucose into the 300-400 mg/dL range in some people with diabetes — but reaching 600+ mg/dL from a single meal alone is uncommon unless something else is happening (missed insulin dose, illness raising glucose, dehydration concentrating blood).
Always retest with a fresh strip.
If the second reading is in the 200-400 range, that's still high and needs your care provider's input but isn't an immediate emergency.
If the second reading is also 600+ (E-5), treat as emergency regardless of what you just ate — there's likely an insulin or medication issue going on at the same time.
Don't try to 'walk it off' or wait — high enough glucose can become DKA in hours.