PET-CT and blood sugar
What Happens If Your — Sugar Is High on the Day?
Arriving for a PET-CT scan with high blood sugar — after fasting, travelling, and paying — is a frightening situation. Most of the time, the scan is postponed rather than cancelled outright, and the tracer is never injected. This page explains what the team checks, what happens next, and the rescheduling cost position.
Medically reviewed by Dr. C. Raghavendra Reddy, Medical Oncologist, MBBS (Gold Medal) · DNB · DM (Medical Oncology, Gold Medal) · Last reviewed September 2026
- Usually a postponement, not a cancellation — The decision is made before the radiotracer is injected, so the most common outcome is rescheduling, not a lost appointment.
- Same-day correction is sometimes possible — If the reading is only slightly outside the centre's range, the team may wait and recheck. Whether this is an option depends on how high the reading is.
- The tracer cost is usually not lost — If the decision to postpone is made before injection, you typically do not incur the tracer cost. Ask the billing team before you leave.
- Preparation next time can reduce the risk — Your oncologist and the imaging centre can advise on managing your sugar on the preparation day. Confirm the plan at booking, not on the morning of the scan.
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If your blood sugar is too high when you arrive for a PET-CT scan, the scan is usually postponed, not cancelled outright. The decision is made before the radiotracer is injected. Whether it can be corrected on the day depends on how high the reading is — confirm the threshold with your treating team and the imaging centre at the time of booking.
CION does PET-CT in Hyderabad from Rs 10,499 — among the lowest published prices in the city, with no hidden charges. Indicative price, as of September 2026.
What does the imaging team do when your sugar reading is too high?
Before the radiotracer is injected, the imaging team takes a blood sugar reading — usually a finger-prick test at the centre. This check happens for every patient, every time, regardless of whether you have diabetes.
If your reading is above the range the centre works within, the tracer will not be injected and the scan cannot go ahead. This is not a mistake or a punishment. A scan done with high blood sugar produces unreliable images because glucose in the blood competes with the tracer and reduces how clearly cancer activity shows up.
The team will tell you the result immediately. You will know before you leave the room, and they will explain the next steps.
What happens after they tell you the scan cannot go ahead?
The team explains your reading
You are told exactly what your blood sugar reading was and why it means the scan cannot proceed as planned. You do not have to ask — this explanation is part of the process.
They assess whether a same-day attempt is possible
If the reading is only slightly above the centre's accepted range, the team may ask you to wait and recheck after a short interval. Whether this is an option depends on how high the reading is and your medical situation on the day.
A new appointment is arranged
If the scan cannot go ahead the same day, the centre will schedule a new appointment before you leave where possible. Ask for the new date and any cost implications to be confirmed before you go.
You are asked to contact your oncologist
The centre will advise you to speak to your treating doctor before the next visit. Medication timing on the preparation day is the key variable, and the right approach depends on what you take and your individual plan — it must be confirmed with your doctor and the centre at booking.
The visit is recorded in your file
A note is made so your oncologist knows what happened and can adjust your preparation instructions before the next appointment.
PET-CT Partner Centres
PET-CT Scan Centres in Hyderabad
CION offers PET-CT scans through 4 trusted partner PET-CT centres across Hyderabad, so you can choose the one closest to you. Call 18002028726 and we’ll guide you to the earliest available appointment.
PET-CT Centre — Punjagutta
PET-CT Centre — Himayatnagar
PET-CT Centre — Narayanaguda
These are partner diagnostic centres within the CION network. Toll-free booking: 18002028726.
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Will you be charged if the scan could not go ahead?
If the postponement happens before the tracer is injected — which is the standard sequence — you will not typically be charged the tracer cost, because none was used.
Whether the preparation or consultation component is charged depends on the individual centre's policy. Ask the billing team before you leave so you know what today's visit costs and what the rescheduled appointment will cost.
If your scan is funded through insurance or a government programme, ask the billing team how a postponement is classified under your coverage. Get this answer before the rescheduled appointment, not on the day of it.
Did you know?
The radiotracer used in most PET-CT scans (FDG) behaves like glucose in the body. When blood sugar is elevated, natural glucose competes with the tracer for uptake into cells, and the signal in areas of cancer activity becomes harder to read accurately.
This is why the centre checks your blood sugar before injecting — not after. A scan done in poor conditions may need to be repeated, which costs more and delays results further.
Source: Society of Nuclear Medicine and Molecular Imaging (SNMMI) FDG PET/CT patient preparation guidelines
CION does PET-CT in Hyderabad from Rs 10,499 — among the lowest published prices in the city — including an oncologist-reviewed report and a free Rs 950 consultation. Indicative price, as of September 2026.
Explore 92 more Preparing For and Having Your Scan Safely topics
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- Contrast Allergy and PET-CT: What to Declare
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- The Cannula: Bruising, Pain and Difficult Veins
- Tracer Leakage at the Injection Site (Extravasation)
- What If You Feel Unwell During the Scan?
Preparing for Your Scan
- A Printable PET-CT Preparation Card
- Can I Drink Water Before a PET-CT Scan?
- Can I Have a PET-CT Scan During My Period?
- Can I Take My Regular Medicines Before a PET-CT Scan?
- Can You Reschedule a PET-CT Scan?
- Cold Weather, Shivering and Brown Fat: Why You Are Asked to Stay Warm
- Fasting Before a PET-CT Scan: How Long and Why
- How to Prepare for a PET-CT Scan: The Complete Checklist
- Preparing a Very Elderly or Frail Person for a PET-CT
- Preparing a Wheelchair-Bound or Bedridden Patient
- Preparing for a PSMA, DOTATATE or FAPI PET-CT
- Should I Avoid Exercise Before a PET-CT Scan?
- Smoking, Alcohol and Caffeine Before a PET-CT Scan
- What Happens If You Break the Fast by Mistake?
- What to Carry to Your PET-CT Appointment
- What to Eat the Day Before a PET-CT Scan
- What to Wear to a PET-CT Scan
- Why Your Kidney Function Test Is Needed Before a PET-CT
Radiation Safety & After-Scan Precautions
- Are You Radioactive After a PET-CT Scan?
- Being Around Pregnant Women After a PET-CT Scan
- Can I Hold My Child or Grandchild After a PET-CT Scan?
- Can a PET-CT Scan Cause Cancer?
- Cumulative Radiation From Repeated Scans
- Do You Need Precautions After a PSMA or DOTATATE Scan?
- Do You Need Separate Utensils or a Separate Toilet After a PET-CT?
- How Long Does the Tracer Stay in Your Body?
- How Long Should You Avoid Close Contact After a PET-CT?
- How Many PET-CT Scans Are Safe in a Year?
- How Much Radiation Is in a PET-CT Scan?
- Is PET-CT Radiation Different From Radiotherapy?
- Is the Radiation From a PET-CT Scan Dangerous?
- PET-CT Radiation Compared With CT, X-Ray and Natural Background
- Radiation Safety at Home After Your Scan: A Family Checklist
- Radiation Safety for Staff and Attendants at the Centre
- Simple Steps to Clear the Tracer Faster
- Travelling Home After a PET-CT Scan: Public Transport and Airports
Scan Day: What Actually Happens
- Can Someone Stay With Me During the Scan?
- Can You Drive Yourself Home After a PET-CT Scan?
- Can You Have Sedation for a PET-CT Scan?
- Can a PET-CT Scan Be Done on the Same Day as Other Tests?
- Contrast in a PET-CT Scan: When It Is Used and Why
- Eating and Drinking After Your PET-CT Scan
- How Long Does a PET-CT Scan Take?
- Is a PET-CT Scan Painful?
- Is a PET-CT Scanner Closed Like an MRI? Claustrophobia Explained
- The Tracer Injection: Does It Hurt?
- What Happens If the Scan Cannot Be Completed?
- What If You Cannot Lie Still or Have Tremors?
- What to Expect Immediately After the Scan
- Why Was My Scan Repeated or Extended on the Day?
- Why You Have to Wait an Hour After the Injection
- Your PET-CT Scan Day: What Happens, Step by Step
Special Populations
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- PET-CT With a Pacemaker, Stent or Metal Implant
- PET-CT for Claustrophobic Patients
- PET-CT for Patients Who Cannot Lie Flat
- PET-CT for Patients With Anxiety or Panic Disorder
- PET-CT for Patients With Dementia or Confusion
- PET-CT for Patients With Incontinence or a Catheter
- PET-CT for Patients With a Stoma
- PET-CT for Patients on Long-Term Steroids
- PET-CT for Very Elderly or Frail Patients
- PET-CT for Very Heavy Patients: Weight and Bore Limits
- PET-CT for Wheelchair and Bedbound Patients
- PET-CT in Pregnancy: Why It Is Avoided
- Sedation and Fasting for a Child's PET Scan
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Common questions
Frequently asked questions
Can my blood sugar be corrected on the same day so the scan can still go ahead?
Sometimes, but it depends on how high the reading is and your medical situation. If the reading is only slightly above the centre's acceptable range, the team may ask you to wait and recheck after a short interval. If it is significantly elevated, a same-day attempt is not usually possible. Do not eat, drink, or take any medication without checking with the centre's staff first — doing so could affect a recheck or make a same-day attempt impossible.
Will I be charged for a wasted day if I am sent home?
If the postponement happens before the tracer is injected — which is the usual sequence — you will not typically be charged the tracer cost, because none was used. Whether the preparation or consultation component is charged varies by centre. Ask the billing desk before you leave so you know exactly what today's visit costs and what the rescheduled appointment will cost. If you are covered by insurance or a government scheme, ask specifically how a postponement is classified under your coverage.
Why does high blood sugar affect a PET-CT scan?
The radiotracer used in most PET-CT scans (FDG) behaves like glucose in the body. When blood sugar is high, natural glucose in the blood competes with the tracer for uptake into cells. Less tracer reaches areas of cancer activity, and the images become less accurate — the scan may miss things or produce misleading results. A scan done under these conditions may need to be repeated, which is why centres postpone rather than proceed and repeat.
How do I avoid this happening at the next appointment?
Contact your oncologist after this appointment and tell them what happened. Ask for specific advice on managing your blood sugar on the preparation day for the next scan. The timing of your diabetes medication is the key variable, and the right approach depends on what you take and your individual situation — it is not something to decide on your own. Confirm the plan with both your treating doctor and the imaging centre at the time of booking, not on the morning of the scan.
Can I eat or drink while I wait to see if the reading comes down?
Ask the centre's staff before you eat or drink anything. You will typically have been fasting, and taking food or drink without checking could affect a recheck or rule out a same-day attempt entirely. The staff will tell you what, if anything, is permitted while you wait, based on whether another attempt the same day is being considered for you.