Diabetes & PET-CT preparation
A Diabetic Patient's — PET-CT Day Plan
Your blood sugar level on the morning of your scan determines whether the scan can go ahead. Getting the preparation right — starting the night before — is what prevents a wasted journey.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed September 2026
- Starts the night before — What you eat in the evening affects your blood sugar the next morning. A high-carbohydrate meal can cause the scan to be cancelled.
- Fasting is required — Diabetic patients fast before PET-CT, but the exact cutoff and what to do with medicines differs from the standard preparation. Confirm at booking.
- Blood sugar is checked on arrival — The scan team will ask for your reading. If it is above the centre's accepted range, the scan cannot go ahead that day.
- You can eat as soon as it is done — Do not wait after the scan. Eating promptly is part of looking after yourself, especially after a long fast.
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A diabetic patient preparing for PET-CT should eat light and low-carbohydrate the evening before, fast from the cutoff time the centre gives at booking, and carry medicines, a snack, and a morning blood sugar reading. Tell the team your reading on arrival. They will confirm whether the scan can go ahead.
At CION, a whole-body PET-CT starts from Rs 10,499 — among the lowest published prices in Hyderabad. Indicative price, as of September 2026.
What should you eat and do the evening before your PET-CT?
Eat a normal meal in the evening, but keep it light and low in carbohydrate. High-carbohydrate food — rice, chapati, bread, sweet dishes — raises your blood sugar overnight and can lead to a cancellation the next morning.
Stop eating after the cutoff time your scan centre gives you when you confirm your appointment. This window may be shorter for you than for a non-diabetic patient, so do not assume the standard fasting time applies.
Take your evening diabetes medicines as you normally do, unless your treating doctor has specifically told you otherwise. Do not adjust any medicine or its timing without first checking with both your oncologist and the scan centre.
What should you carry to the scan centre?
Bring all your diabetes medicines — including any you have been asked to hold until after the scan. You will need them as soon as you eat.
Pack a small snack to eat immediately once the scan is done. The centre does not provide food. Something plain and filling — a banana, a small chapati with dal, a handful of nuts — works well.
Write down your blood sugar reading from that morning before you leave home. The scan team will ask for this number on arrival. A reading you cannot remember is as unhelpful as no reading at all.
Carry a list of all your current medicines and your prescriptions. This includes diabetes medicines, anything your oncologist has prescribed, and anything else you take regularly.
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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How does preparation differ depending on how your diabetes is managed?
| How your diabetes is managed | Evening before | Morning of scan | Key things to carry |
|---|---|---|---|
| Diet-controlled | Light, low-carb meal; stop eating at the cutoff your centre gives | Fast; no medicine timing to adjust | Blood sugar meter, snack, prescription list |
| Managed with tablets | Light, low-carb meal; take evening tablet as normal unless your doctor says otherwise | Confirm at booking whether to take morning tablet before or after the scan | All tablets, blood sugar meter, snack, prescription list |
| Managed with insulin | Light, low-carb meal; ask your doctor about evening insulin timing before your scan date | Confirm morning dose timing with your doctor and the centre before the day — not on the morning itself | Insulin kit, blood sugar meter, snack, emergency sugar, prescription list |
Your hour-by-hour plan: from waking up to after the scan
Wake up and check your blood sugar
Check your blood sugar first thing, before doing anything else. Write the number down. This is the reading you will give the scan team on arrival.
Continue fasting
Do not eat or drink anything except plain water. Water is not only allowed — it helps the tracer distribute evenly and makes it easier to find a vein for the injection.
Take or hold your medicines as advised
Follow the specific advice your doctor and the scan centre gave you at booking. Do not guess, and do not adjust medicine timing on the morning itself.
Pack your bag before leaving
Confirm you have: your written blood sugar reading, all your medicines, a snack, your prescription list, and any documents the centre asked you to bring.
Arrive and give your blood sugar reading
Tell the scan team your reading as soon as you check in. They will confirm whether your blood sugar is within the range for the scan to proceed that day.
Wait during the uptake period
A small amount of radioactive tracer is injected into a vein. You then wait quietly while it travels through your body. Stay still and rest — walking around reduces the quality of the images.
The scan itself
You lie on a table that moves slowly through the scanner. Lie still and breathe normally. The scan team will tell you when it is finished.
Eat immediately after
As soon as the scan is complete, eat your snack. Take any medicines you held back, following what your doctor told you to do. Check your blood sugar.
Did you know?
PET-CT uses a tracer that cancer cells absorb more strongly than normal cells — but only when blood sugar is controlled. When blood sugar is elevated, normal tissues absorb the tracer too, which can make a tumour appear smaller than it is or cause it to be missed entirely.
The blood sugar check on arrival is not just a safety measure. It determines whether the images will give your oncologist a reliable answer.
Source: SNMMI/EANM practice guidelines for FDG PET/CT tumour imaging
PET-CT at CION starts from Rs 10,499 — among the lowest published prices in Hyderabad — across 4 partner centres in Banjara Hills, Punjagutta, Himayatnagar and Narayanaguda. Indicative price, as of September 2026.
Explore 92 more Preparing For and Having Your Scan Safely topics
Diabetes & Blood Sugar for PET-CT
- A Diabetic Patient's PET-CT Day Plan
- Best Appointment Time for a Diabetic PET Scan
- Can Diabetics Take Their Tablets Before a PET Scan?
- Does Diabetes Change Your SUV Reading?
- Fasting Safely With Diabetes Before a Scan
- Insulin and PET-CT: Timing Rules
- Newly Diagnosed Diabetes Found Before a Scan
- PET-CT Scan With Diabetes: The Complete Preparation Guide
- PET-CT With Steroid-Induced High Sugars
- What Blood Sugar Level Is Needed for a PET-CT Scan?
- What Happens If Your Sugar Is High on the Day?
- What to Eat the Day Before if You Have Diabetes
Contrast, Cannula & Procedure Safety
- Can You Have a PET-CT If You Are on Blood Thinners?
- Can You Have a PET-CT Through a Port or PICC Line?
- Contrast Allergy and PET-CT: What to Declare
- Contrast Reaction Symptoms: What to Watch For
- Contrast and Kidney Function: The Creatinine Rule
- Infection Risk and Hygiene at a Scan Centre
- Is Contrast Used in a PET-CT Scan?
- Metformin and Contrast: What Is the Rule?
- Side Effects of a PET-CT Scan
- 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
- Breastfeeding and PET-CT: How Long to Pause
- PET-CT Scans for Children: A Parent's Guide
- PET-CT With Kidney Disease or on Dialysis
- 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
Your next step
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Common questions
Frequently asked questions
What happens if my blood sugar is too high on the morning of the scan?
The scan will most likely need to be rescheduled. If your reading is above the range the centre accepts, the tracer will not distribute correctly and the images will not give your oncologist reliable information. Do not fast for longer than planned to try to bring the number down on your own. If you are worried about your morning reading, call the centre before you travel — not after you arrive.
Can I drink water or tea while I am fasting for PET-CT?
Plain water is not only allowed — it is encouraged. Staying hydrated helps the tracer spread evenly through your body and makes it easier to place the injection. Avoid anything with sugar, milk, or flavouring. Whether black tea or plain coffee is permitted depends on the centre's own protocol, so confirm at booking rather than assuming.
When exactly can I eat after the PET-CT scan is finished?
Immediately after the scan is complete — you do not need to wait. For a diabetic patient who has been fasting for several hours, eating promptly is important. Have a snack packed in your bag so you are not searching for food in the centre or travelling home hungry.
My morning diabetes medicine is due during the fast. What should I do?
Raise this at booking, not on the morning of the scan. Both your oncologist and the scan centre need to advise on this together, because the right answer depends on what medicine you take and how your diabetes is managed day to day. Do not skip a dose or change the timing on your own initiative — and do not assume that general advice from your diabetologist applies without checking with the scan team specifically.
I have had hypoglycaemia before. Is fasting for PET-CT safe for me?
Tell the scan centre about your history of low blood sugar when you book — not on the day of the scan. The centre may schedule you for an early morning slot to shorten the fast, or provide adjusted preparation instructions. Fasting with a history of hypoglycaemia is manageable with the right plan in place. The risk comes from not disclosing it and arriving unprepared.