Insulin, used for people with type 1 diabetes and some people with type 2, can cause your blood sugar to drop too low - so-called hypoglycaemia episodes, or hypos. So too can some tablets used to treat type 2 diabetes - mostly tablets called sulfonylureas, but also glinides.
Hypos can cause drowsiness, dizziness and confusion: in severe cases they can lead to loss of consciousness or even be fatal. But hypos can also affect your ability to drive safely. So the DVLA has set out guidelines for people with all diabetes - and whether you have type 1 or type 2 diabetes, you need to know about them.
Diabetes is diagnosed on the basis of high blood sugar. High blood sugar in the long term can cause serious complications, regardless of which kind of diabetes you have. This is why your team will work with you to prevent your blood sugar from going too high. On the whole, however, keeping your blood sugars very tightly controlled may increase your risk of hypoglycaemia if you take medication that can cause it.
Unless otherwise stated, the regulations below apply only to people with a Group 1 (car and motorcycle) licence. Your medical team can give you details about the requirements for Group 2 (bus and lorry) drivers.
What are the symptoms of hypoglycaemia?
Low blood sugar usually causes symptoms when your blood sugar is below 4 mmol/L. These include:
- Feeling irritable, anxious or tearful.
- Poor concentration.
- Feeling trembly or shaky.
- Blurred vision.
- Palpitations and sweating.
- Tingling around the lips or blurred vision.
- Feeling very hungry.
- Sudden tiredness.
If you don't act on these early symptoms with treatment to increase your blood sugar, later symptoms include:
- Slurred speech
- Irrational behaviour
- Loss of consciousness
What terms does the DVLA use?
According to the DVLA, an episode of severe hypoglycaemia doesn't specifically depend on the level of your blood sugar, but whether or not you are able to treat the episode yourself. An episode of severe hypoglycaemia is any episode where you need outside assistance, including help to treat the episode and increase your blood sugar.
Impaired awareness of hypoglycaemia
The DVLA defines this as 'an inability to detect the onset of hypoglycaemia because of total absence of warning symptoms' .The risk of impaired or absent awareness of the warning signs rises the longer you have diabetes, the older you are and the more hypos you have. This increases the risk of a severe hypoglycaemic episode which can affect your driving ability even more than milder ones.
You are not allowed to drive if you have impaired awareness of hypoglycaemia and are treated with insulin.
Do I need to inform the DVLA about my diabetes?
Rules for everyone with diabetes
Regardless of which treatment you use for your diabetes, you must inform the DVLA if:
- You need laser treatment for diabetic retinopathy to both eyes (or your seeing eye if you only have vision in one eye).
- You develop vision problems in both eyes (or your seeing eye if you only have vision in one eye).
- You cannot read a number plate in good daylight at 20 metres, with your usual aids (glasses or contact lenses).
- Your vision drops below 6/12 on testing with both eyes open, with your usual aids.
- You develop problems with the sensation in your legs or feet, or with circulation, affecting your ability to operate foot levers.
- Any existing medical condition that may affect your driving gets worse, or you develop a new condition.
- If you use insulin treatment, severe kidney complications may mean you may need to stop driving and notify the DVLA (your doctor can advise about these).
Diabetes managed with diet and tablets
As long as you satisfy all the conditions above and you have a Group 1 (car and motorcycle) licence, you do not need to inform the DVLA if your diet is managed with diet and lifestyle alone, or if your diabetes medication does not include insulin, sulfonylureas or glinides.
If you have a Group 1 licence and you use sulfonylureas or glinides, you do not need to inform the DVLA if you:
- Satisfy all the general conditions above; and
- Are having regular medical reviews of your diabetes; and
- You have had fewer than two episodes of severe hypoglycaemia during waking hours in the last 12 months; and
- Are (if needed) measuring your blood sugar 'at times relevant to driving', ie no more than two hours before the start of the first journey and every two hours while driving.
If you have a Group 2 (bus and lorry) licence, you need to inform the DVLA if you take tablets for your diabetes, even if these do not include sulfonylureas or glinides
Diabetes requiring insulin treatment
Temporary treatment is defined as treatment with insulin for up to three months (or up to three months after delivery if you have had a baby). If you are using temporary insulin treatment (including for gestational diabetes and after a heart attack), you may keep driving without informing the DVLA if you :
- Are a Group 1 driver.
- Are under medical supervision.
- Have not been advised by a doctor that you are at risk of disabling hypoglycaemia; and
- Have never had an episode.
Otherwise, you must inform the DVLA.
If you are a Group 1 driver, you may be issued a licence for one, two or three years as long as you fulfil the general standards above and all the criteria below:
- You are having regular medical reviews.
- You have adequate hypo awareness.
- Your medical team does not think you will be a danger on the roads; and
- You monitor your blood glucose within two hours of driving and at least every two hours while driving - more often if you're exercising or have disrupted your usual eating routine. This is a recommendation rather than a legal requirement if you are a Group 1 driver, but it is important to minimise the risk of accidents.
- You haven't had an episode of severe hypoglycaemia (one needing outside assistance) when awake in the last three months, or you haven't had two or more episodes in the last 12 months
Note: the regulations about severe hypoglycaemia changed on 1st January 2018. Until then, episodes of severe hypoglycaemia while asleep could also lead to you losing your licence. In addition, until then you could not apply to renew your licence for at least two years: you can now apply to renew your licence from three months after your last episode.
Dr Sarah Jarvis, February 2019.
Using continuous and flash glucose monitoring systems for driving
Some people on insulin use continuous or 'flash' glucose monitoring systems to monitor their blood sugar. Until February 2019, they were not allowed to rely on these systems to monitor their blood sugar. Instead, they were required to use fingerprick testing at the same frequency as anyone else while they were driving.
From February 2019, if you use continuous of flash glucose monitoring, you can use this system alone to check your blood glucose around times of driving. However, you must also use fingerprick testing if:
- Your blood sugar reading on your flash or continuous glucose monitoring device is below 4 mmol/L.
- You have symptoms of a hypo.
- You develop symptoms which might be caused by low blood sugar, even if your existing glucose monitoring tells you that your blood sugar is not low.
Following pancreas or islet cell transplant
You may drive, but must inform the DVLA. If you are using insulin treatment, you must follow the guidance for all people on insulin treatment above.
What precautions should I take if I have diabetes and drive?
Because hypoglycaemia can cause serious complications, it is important to take steps to avoid hypoglycaemia, and to know how to treat the early symptoms. To do so, you will need to keep treatment with a supply of fast-acting carbohydrate to hand at all times.
You can find out more about avoiding and treating episodes of hypoglycaemia in our leaflet called Why low blood sugar is dangerous.