Hypos and Driving:

Driving requires concentration, quick reaction time, visual clarity and sound judgement. For people using insulin, hypoglycaemia can impair all these functions.

Australian guidelines recommend that people requiring insulin or sulphonylurea medication (e.g. Gliclazide or Glipizide) to manage their diabetes, should not drive if their blood glucose level (BGL) is under 5.0 mmol/L.  This is often summarised as: ‘Don’t drive under five’ (Austroads, 2022; NDSS, 2023).

How Often Do Hypos Occur While Driving?

An Australian study using continuous glucose monitoring (CGM) and trip logging followed 18 drivers with type 1 diabetes across 475 car trips (Trawley et al., 2022).

436 trips started above 5 mmol/L – no hypoglycaemia (<3.9 mmol/L) occurred during these trips.

39 trips started below 5 mmol/L – 10 trips (26%) resulted in hypoglycaemia while driving.

This real-world Australian data supports the >5 mmol/L recommendation as a critical safety threshold.

Driving Low Is Dangerous due to:

• Slower reaction times
• Reduced attention and concentration
• Blurred or altered vision
• Impaired judgement and decision-making
• Confusion or unusual behaviour
• Loss of consciousness or seizure in severe cases

These impairments significantly increase crash risk for the driver, passengers, pedestrians and other road users (Austroads, 2022).

Preparing for your journey:

Preventing Hypos While Driving

• Always check BGL before driving (even short trips).
• Do not drive if BGL is below 5.0 mmol/L, or higher if your GP or Diabetes Health Professional has recommended a higher target for you.
• Recheck BGL every 2 hours on long journeys.
• Keep pre-dosed, fast-acting carbohydrate within reach in the car.
• Follow fast-acting treatment with longer-acting carbohydrate once above 5 mmol/L.
• Having pre-measured carbohydrate available reduces delays in treatment, minimises under- or over-treatment, and supports safer glucose recovery during travel.
• HYPO DUO™ offers a convenient way to carry pre-measured carbohydrates when you’re on the go.

If a Hypo Occurs While Driving

Driving and low glucose

If you experience symptoms of low blood glucose or receive an alert while driving:

• Pull over safely when it is possible to do so.
• Turn off the engine, secure the vehicle and remove the keys.
• Managing low glucose while driving (general guidance):
• Check blood glucose levels if able
• Consume a source of fast-acting carbohydrate (e.g. approximately 15 g, such as jelly beans, a glucose drink, or HYPO DUO Step 1)
• Recheck blood glucose levels after approximately 10–15 minutes
• If levels remain below your usual target range, additional carbohydrate intake may be required
• Once blood glucose levels have returned to your usual target range:
• A longer-acting carbohydrate (e.g. fruit, yoghurt, milk, or HYPO DUO Step 2) may be consumed
• Before resuming driving:
• Allow time for blood glucose levels to recover and for symptoms to resolve
• Follow local driving guidelines and your individual diabetes management plan.

Not checking BGLs prior to driving, puts at risk:

• Yourself.
• Other drivers or pedestrians.
• Your insurance policy to cover you.
• Your license being suspended.

References 

• Austroads (2022) Assessing Fitness to Drive for Commercial and Private Vehicle Drivers. Sydney: Austroads.
• National Diabetes Services Scheme (NDSS) (2023) Diabetes and Driving Quick Guide. Canberra: NDSS.
• Trawley, S. et al. (2022) Blood glucose levels and risk of hypoglycaemia while driving in adults with type 1 diabetes: A continuous glucose monitoring study. Diabetes Research and Clinical Practice, 183, 109169.