If you've got diabetes, you need to be aware of the risks involved when you're driving. If you know the risks, you can take steps to manage them.

[Some of the comments on this webpage are specifically aimed at drivers in New Zealand, but most of these thoughts are applicable everywhere — The Editors]

Newly diagnosed?

Hypoglycaemia (low blood sugar)

Low blood sugar levels are dangerous for drivers with diabetes. If you're taking insulin or tablets for diabetes (except metformin), it's very important that you avoid low blood sugar levels, which can greatly impair your driving and cause crashes.

Hyperglycaemia (high blood sugar)

High blood sugar levels could leave you feeling unwell or tired, and may affect your ability to drive safely. You should avoid driving while you're hyperglycaemic.

Passenger services and heavy vehicles

People with insulin-dependent diabetes are not normally allowed to drive taxis, heavy trade and passenger service vehicles. If a diabetes specialist wrote on your behalf to the Chief Medical Advisor of the Land Transport Safety Authority (LTSA), we might make an exception. Strict conditions would apply.

Precautions while driving

If your diabetes is well controlled you can drive a private car safely. However, there are times when you need to take precautions.

1. Always have meals and snacks before and during long journeys. It's safest not to delay meal times. Take regular short breaks from driving.
2. Check your blood sugar levels regularly. If you feel that your blood sugar is low, stop driving and treat with a quick acting sugar, eg three glucose tablets. Follow this up with a plain muesli bar (not recommended on a regular basis) or biscuits. Wait until the sugar has started to work before you start driving again.
3. Keep a supply of plain muesli bars, biscuits, glucose tablets, dried fruit and long lasting fruit juice in your pocket or in the glove box.
4. Don't delay treating low blood sugar levels. The brain becomes confused when the blood sugars reach low levels. Be aware of your own warning signs. Although a mild hypo may not seem to impair your driving it's vital to act before your judgment is affected.
5. If you experience hypoglycaemia unawareness (hypos without warning signs), it may be unwise for you to drive. You should discuss this with your doctor or diabetes nurse specialist.
6. Remember that changing a car tyre or pushing a car could result in low blood sugar levels. Be prepared!
7. If you have diabetes, alcohol can be particularly dangerous because it can cause hypoglycaemia or worsen its effects. We recommend that people with diabetes avoid consuming any alcohol if they're going to drive.

When you shouldn't drive.

In some situations you may need to refrain from driving. If you have a mild hypoglycaemic episode we recommend that you don't drive for at least an hour, to give your brain time to recover.

If you have a severe hypoglycaemic episode (eg when you need someone else's help to deal with it), you shouldn't drive for 24 hours. If you have several hypoglycaemic episodes you should talk to your doctor before you return to driving.

If you have a severe hypoglycaemic episode while you're driving, whether you're involved in a crash or not, you shouldn't drive for at least a month. It's likely you'll need to be reviewed by a specialist before you can safely return to driving, and you need to talk to your doctor.

Long term complications

Your driving ability could be affected by long term complications of diabetes, such as eyesight deterioration and the loss of normal sensation in your feet. Check with your doctor.

Licence conditions

Some drivers with diabetes may be issued with a licence that has certain conditions attached. The conditions will depend on the type of licence (classes and endorsements), how the diabetes is controlled, any history of hypoglycaemic attacks, compliance with medications and an assessment of any medical complications that're commonly associated with the diabetes. The LTSA's Director decides the type of conditions to impose, having regard to the Medical Aspects of Fitness to Drive booklet and in consultation wth the LTSA's Chief Medical Adviser.

Legal note

Insulin and tablets for the control of diabetes are classified as drugs under the Land Transport Act 1998. You may be prosecuted under this Act if you’ve been misusing or abusing diabetes medications and your driving results in crashes or injuries. For a case to proceed, however, there would need to be proof that the way you’d used the drugs was contrary to medical advice.

Where can I find out more?

Don't hesitate to see your doctor or your diabetes educators if you have any questions. A handbook that includes a chapter on diabetes, Medical Aspects of Fitness to Drive [PDF file], has been issued to all doctors.

For more information contact the Land Transport Safety Authority, PO Box 2840, Wellington, visit the website (www.ltsa.govt.nz) or freephone 0800 699 000.