heathcote wrote:
Thought doctors could do a blood a blood test which would give the average sugar levels for a 12month period.
Not sure about 12 months, but the HbA1c test provides an average figure for the past 3 months/12 weeks or thereabouts. (Many diabetics will have the test on an annual basis, but the test only covers your levels for the past 3 months/12 weeks.)
Problem is that the average can disguise the peaks and troughs, and it's the troughs that diabetics need to worry about when driving - too low and you can pass out.
So if the average over the past few months is 8, you could be peaking at 12 and troughing at 6, which is fine. But you could be peaking at 13 and troughing at 3, and 3 means you're in danger of passing out. But the HbA1c test can only tell you the average, and not the highs and lows.
And even if the HbA1c numbers could tell you the lows and highs as well as the average, they're not much use as far as driving is concerned - you need to know your level there and then to work out whether it's safe to drive, not what your lows were several weeks ago.
The highs are important as well for your long term health - in fact a lot more important than the lows - but unless they're sky high for a long period then there's little chance of you passing out at the wheel - it's the lows that are the problem in that regard.
Unless you're on insulin (and certain tablets) then you're unlikely to get low enough to pass out, so day to day testing isn't really necessary, although it can be useful to work out what the highs are, which will be disguised by the average HbA1c figure - thus some diabetics test regularly so they can work out which foods (for example) cause them to get dangerously high 'spikes', which won't kill you instantly, but will increase the chance of long term damage.
But regular testing every few hours is expensive and obviously a pain for those doing it, so for many the HbA1c test is a simpler alternative, especially if your levels are fairly stable in the long run.
But if you're driving and on insulin, or want to know precisely your blood sugar levels to fine tune your food intake etc, then regular day to day testing is necessary.
(By the way, the figures I'm using above are the old units - they've changed the figures in the last few years, so the numbers are completely different to those above. Also, if reading the official literature from DVLA or whatever, 'blood sugar' and 'blood glucose' just means the same thing.)