Day of surgery · Diabetes
Is My Blood Sugar OK for Surgery?
Enter your reading to see whether it's in a typical pre-op range, too low to ignore, or high enough to call your team before you travel in.
Frequently asked questions
What blood sugar is acceptable for surgery?
Many teams aim for roughly 6–10 mmol/L (about 108–180 mg/dL) on the day, and will usually proceed up to around 12 mmol/L (216 mg/dL). A reading much higher than that, or a low below 4 mmol/L (72 mg/dL), needs action before surgery. Exact targets vary by hospital and by person, so follow your own team's plan.
What if my blood sugar is too high on the day of surgery?
A very high reading may lead to a short delay until it's brought into a safer range, particularly before major surgery, and your team may use an insulin drip. Don't try to fix a big high yourself with extra insulin while fasting — call your pre-op team or diabetes team for advice and tell them your reading and any ketones.
What if my blood sugar is low while fasting for surgery?
A low (below about 4 mmol/L / 72 mg/dL) should be treated even while fasting — with a small amount of a clear sugary drink or glucose as you've been advised — and then rechecked. Tell the team. Lows are more likely if you took diabetes medicines that you should have held, so check your medication plan too.