DVLA medical test

Convicted Driver Insurance

bored waiting

Well-known member
As a Doctor I wonder if I can pick your brains a little. My CDT reading was 'only' 0.30%. In my opinion that is very low and a clear indication I have not been drinking at all for a considerable period of time. THis is on the basis that CDT measures recent alcohol consumption.

Of course, I am probably mistaken in this assumption as I would imagine everyone's metabolism is different and someone else who has not had a drink for the 2.5 years I haven't, may/would produce a different reading.

Can I have your thoughts on this?


Yes your correct 0.3 is low. But its important to remember , there is no absolute zero for this test. General metabolism varies person to person. But things like alcohol metabolism are well studied and have been found to generally have a fixed rate of metabolism or for what most people care about is its elimination i.e zero order kinetics.

Which is the elimination of alcohol from blood is always linear with time.

0.8% is the amount of CDT in my body with no alcohol consumption .
0.3% may well be the amount in your body also with no alcohol.

Its unlikely I will be ever produce a number lower than 0.8%. i.e Thats ive found is normal for me. Ive now had 9 CDTS measured I think over a 2 year period.

If we both start drinking it will eventually rise. If we drink alot it will rise alot and therefore take longer to fall.

The DVLA traffic light system are these figures below ( taken from this website )

  • 2.1% CDT or less are considered to be in the green zone and will be considered as compatible for a driving licence to be issued.
  • between 2.2% - 2.9% CDT are considered to be in the amber zone which is considered to be indicative of possible problematic alcohol consumption, this will trigger further enquiries before a decision to issue a driving licence is made.
  • 3% CDT or more are considered to be in the red zone and will be refused a driving licence.

So essentially we are both well into the green zone, and if the bar is set lower for us as in HRO categories, we still fall into the bracket of very low or no consumption, and as such both results are compatible with issuing a licence.

But the decision is not just based on a blood test. They have to look at our general health. Do we have other conditions that may also contribute to our ability to drive safely. Thats where the quesionaire and the GP reports come into play

I would suggest people dont get hung up on the numbers
The easiest thing to do is to stop drinking completely well before your medical.
The way to not have your CDT result as something to worry about is to stop drinking completly , then it wont be an issue.

BUT binges can cause it to rise. So the person who says , ive cut down but then there was christmas or a wedding or a whatever and gets blasted. That could well affect their blood test.

Ive noticed lots of people trying to almost bargain about their blood test. I only drink this or that and I went to this function and just did 1 bottle of vodka or whatever. These people are taking a risk if their medical is approaching. They also are trying to justify alcohol misuse to an extent.

Everybody can do what they like but we have all clearly at some point proven we cannot always drink safely and so Id suggest if your at all worried about the blood test , just stop drinking. Once youve completed the process you can decide if its something you can do or not.

I made my decision to stop drinking the day i was arrested. My health is too important to me and I can live quite happily without it.
Enter code DRINKDRIVING10 during checkout for 10% off