Driving And Diabetes- How To Monitor Your Blood Sugars

Driving and diabetes have a close relationship. Diabetes can have an impact on our daily activities. Driving is an activity that a majority of us do on a regular basis, be it of a car, bike or a heavy goods vehicle.

If you suffer from diabetes and have fluctuating blood glucose levels, then you have to take certain precautions before undertaking driving or any form of exercise.

Diabetes and Road Traffic Accidents

There is no clear consensus on whether having diabetes increases the risk of experiencing a road traffic accident, but there are some studies that have shown it. However, most of these studies have been conducted in Western countries where people with bad eyesight or peripheral neuropathy would not be allowed to drive anyway. This would mean that the study results would not be the most accurate. That being said, the graph from a study below depicts an increased incidence of road traffic accidents due to hypoglycemia.


From Signorovitch JE, Macaulay D, Diener M, Yan Y, Wu EQ, Gruenberger JB, et al. Hypoglycaemia and accident risk in people with type 2 diabetes mellitus treated with non-insulin antidiabetes drugs. Diabetes Obes Metab. 2013;15:335–41

In India, there does not appear to be any system in place that requires drivers with diabetes to inform the transport office about their medical condition. In Canada, doctors are paid incentives to report such patients, as this can reduce the accident rate significantly.

Why Check Blood Sugars Before Driving?

Blood sugar levels can vary throughout the day, and are never the same every day. When carrying out physical activity or when driving, there are a number of different factors that can influence the blood glucose levels.

1. The level of blood glucose that is present before driving

2. The quantity of medication taken, particularly the dose of insulin

3. The type of food that has been eaten before driving

4. The stress levels during driving and the level of physical exertion

Self monitoring of blood glucose values is now recommended for all patients with diabetes as it helps to keep track of blood sugar levels in a simple and fast manner.

When driving, monitoring your own blood glucose level can help you eventually learn how to predict how your body responds to the activity. For example, you will be able to know what your sugars are likely to be if you go for a short drive to the local market.

This way, you can take the right precautions to ensure you do not develop hypoglycemia.

Driving and Diabetes – What Is The Relationship?

There are a number of ways diabetes can affect driving.

Hypoglycemia affects driving performance

Having diabetes can influence how well you drive. If you are on insulin injections, there is always a chance of you developing low blood sugars i.e. hypoglycemia. When your blood sugars are low, the speed with which the brain functions is reduced. Cognitive abilities are impaired. If there is danger up ahead, how quickly you react to that situation may also be affected.

In a driving simulation study that assessed the affect of low blood sugars on driving performance, researchers found that subjects who had a moderately low blood sugar inappropriately braked or accelerated, would avoid basic traffic signals and would not stick to their lanes.

But it is not just the low blood sugars that can affect driving. High blood sugars i.e. hyperglycemia also has an effect on driving performance. The primary effect is on cognitive function and mood.

Peripheral neuropathy affects driving performance

Diabetes can also affect the nerves – a condition called peripheral neuropathy. The nerves of the hand and feet are affected, and reduced sensation and occasional burning is the primary symptom. People with peripheral neuropathy lose the sensation on the soles of their feet, and may experience a degree of muscle weakness. Due to this, they may sometimes be unable to gauge how much they are pressing their foot down on the accelerator pedal.

Vision problems in diabetes can affect driving

If the sugars are high, some people may experience mild blurring of vision as the lens in the eye changes its texture.

However, the main problem with diabetes is the development of problems in the retina. The retina is responsible for sending images it receives to the brain. If the retina is affected significantly, it can lead to blindness. Vision is usually tested before a driving license is issued, or at least ought to be.

So What Advice Should You Follow?

Here are some points that you must bear in mind –

1. If you feel your blood glucose levels are fluctuating, then stop driving immediately.

2. Check your glucose levels using a glucometer, which you should carry with you at all times.

3. If your level is <70 mg/dL, then take some glucose tablets. Alternately, you can take 3 – 4 spoons of glucose powder or sugar or eat some glucose biscuits. You can find glucose powder included in our first aid kit Raksha.

Clinical studies have shown that if you ‘feel’ you know what your blood sugar is, then you are probably wrong about it. It is better to be safe and check it first.

Unfortunately, around 40 – 60% of people do not check their sugar before they drive. Causing an accident when you have low blood sugars is a crime, and if proven could end you up in prison. A simple test that takes 20 seconds to do can prevent this headache.

Treating hypoglycemia when driving

Carry a pack of glucose in the vehicle at all times. It is better to have a first aid kit in your car should the need ever arise.

If you have low blood glucose levels and take some glucose or food, make sure you wait at least 45 minutes before you drive. This is the time it takes for the brain to start functioning normally again. However, this is only an estimated time and it could take longer.

Here is a table that details how to manage your sugars when driving –

driving and diabetes

Altered from Graveling et al.

Closing Remarks

Driving is not an easy task. It requires good coordination between mind and movements and constant awareness of the surrounding. Low blood sugar (and even high blood sugars) can cloud judgement and can lead to accidents. Make sure you take the right precautions so that you reach your destination or your family safely.

For more articles by Dr Vivek Baliga for patients, click here.

For academic articles – Click here.


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