What should my blood glucose be to drive?

Healthcare professionals and the DVLA would recommend that your blood glucose levels should be reading no lower than 5 mmol/L or 90 mg/dL within 2 hours before driving. You should also check your blood glucose every 2 hours during your journey. Blood glucose checks must be recorded using a blood glucose monitor (a finger prick test) not a CGM or FGM. 

Continuous glucose monitors, such as Dexcom and Freestyle Libre, measure glucose levels in the interstitial fluid, whereas blood glucose meters measure it directly from the blood. Consequently, blood glucose meters are generally more accurate and less influenced by factors like site compression, sensor ‘settle in’ phases and hydration levels compared to CGMs. 

Although most CGMs offer real-time glucose readings, hypoglycemia episodes are usually ‘predicted’. This means the CGM in use can detect if, and how quickly your blood glucose is dropping. It will then alert the user with a possible low glucose prediction up to 20 minutes before, with the intention to prevent severe hypoglycemia. As these are only predictions and not real-time, these readings are not reliable and should not be used as a safe way to prevent low glucose before or during a journey.  

Mobile apps used alongside continuous glucose monitoring often experience data loss or sensor errors, meaning your glucose data isn’t available. These data loss issues can last up to three hours and can happen without warning. You could also face a sensor failure, which means your current sensor needs replacing, resulting in no data at all until a new CGM is inserted. Having access to a blood glucose monitor is extremely important for 24/7 access to your blood glucose readings.

Your blood glucose meter could save your life.

The primary danger to safe driving is the risk of hypoglycemia. If your CGM provides an inaccurate reading and you are unaware of it, you could begin to experience hypoglycemia symptoms while driving. This is a very serious situation that can quickly become dangerous, not just for you but for others as well. Many accidents caused by hypoglycemia have occurred because drivers ignored warning symptoms and continued driving, assuming they would be fine.

Unfortunately, nearly 100% of drivers who have had accidents due to sudden hypoglycemia were caught off guard. Hypoglycemia symptoms can develop and worsen rapidly, making it crucial for drivers with Type One Diabetes to check their blood glucose with a monitor before driving and every two hours while on the road. This practice ensures the most accurate blood glucose readings for your safety and the safety of others. If your blood glucose is too low, do not take the risk of driving. Always wait until your readings are at least 5 mmol/L (90 mg/dL) before getting behind the wheel.

What the UK Government says about driving & Hypoglycemia.

The below points have been taken from the gov.uk website and DVLA guide.

• Always carry your glucose meter and test strips with you, even if you have a CGM.
• You should check your glucose levels less than 2 hours before driving and every 2 hours after the journey has started.
• If glucose is 5.0 mmol/L  or less, eat a snack. If it is less than 4.0 mmol/L l or you feel hypoglycemic, do not drive.

What if I have a hypo while driving?

It is essential to always have an emergency supply of fast-acting glucose in your car, such as glucose tablets, a sugary drink, or sweets. If you experience hypoglycemia while driving, you should stop the vehicle safely as soon as possible. 

Emergency Supply Checklist for T1D Drivers

1. Fast-Acting Glucose:
• Glucose tablets or gel (quick-absorbing and easy to store)
• Juice boxes (sealed, long shelf-life)
• Small candy (like jelly beans or glucose candies)
2. Glucagon Kit:
• Nasal glucagon or injectable glucagon for severe hypoglycemia
3. Blood Glucose Meter:
• Extra test strips
• Lancets
• Spare batteries for the meter
4. CGM Supplies (if applicable):
• Spare CGM sensors
• Alcohol wipes for sensor application
• Backup transmitter (if you have one available)
• Adhesive patches (to secure sensors in emergencies)
5. Finger Prick Testing:
• Fingerstick device for manual blood sugar testing if CGM fails or readings are delayed
6. Spare Insulin:
• Insulin pen or vials (store in an insulated bag with an ice pack to maintain temperature)
• Spare syringes or pen needles
7. Snacks for Slow-Acting Carbs:
• Granola bars, crackers, or snacks with a balance of carbs and protein to stabilize blood sugar after treating a low
8. Water Bottle:
• Staying hydrated is critical, especially during long drives
9. Medical ID:
• A bracelet or card with your condition and emergency contact information
10. Phone Charger:
• To ensure you can call for help if necessary or check diabetes-related apps
11. First-Aid Kit:
• Basic first-aid supplies for minor injuries and emergencies
12. Emergency Contact Information:
• A list of emergency numbers (family, healthcare provider) and a note explaining your condition for first responders
13. Spare Hypo Treatment Kit:
• A pre-packed pouch with everything needed for a hypo: glucose tablets, juice, snacks, and a blood sugar meter.

3 Reasons why it’s important to wait 45 minutes after a hypo to drive

• Takes up to 45 minutes for the brain to recover; this is because it is starved of glucose, and the brain can only use glucose to make energy to power itself.
• We are at a higher risk of passing out, as our brain is lacking energy.
• We are stressed and anxious and may not make the right decisions in the heat of the moment.

This is because it can take up to 45 minutes for the brain to recover from a hypo fully. Hypoglycemia symptoms can cause us to lose control of our bodies because our brains are not functioning correctly without glucose.

How severe hypoglycemia and impaired awareness can disqualify you from a driver’s license

In order to hold a full UK driving licence, whilst living with Type One Diabetes, you must have full hypoglycemia awareness and do not require the need for assistance when your blood glucose is low.

What is impaired Hypoglycemia Awareness?

• Inability to recognize early signs of low blood glucose.
• Increased risk of severe hypoglycemic episodes without warning.

Need for Assistance:

• Requiring help from others during hypoglycemia episodes.
• Inability to self-treat low blood glucose while driving.

License Disqualification:

• Regulatory guidelines prohibiting driving for those with severe hypoglycemia unawareness.
• Mandatory medical evaluations to assess the safety of diabetic drivers.

Safety Concerns:

• High risk of accidents due to sudden hypoglycemia.
• Potential harm to the driver and others on the road.

More information can be found via the link below and you can read more of our blogs here.

https://www.gov.uk/diabetes-driving