My diabetes team have been keeping a database of results that they have sent to the DVLA for at least the past 17 years. The database does not include any personal info, the data entered is of the kind of licence applied for, BG results sent (for example 70% between 4 and 9mmol, number of instances of below 3mmol readings, below 3.6mmol readings), length of time taken for DVLA to respond notifying the applicant of next steps, notifying the decision etc. I spoke to my DSN about 6 months before I applied, she literally said hang on a minute checked the database and said "As a bare minimum, you will need 3 months' BG results, preferably a minimum of 6 tests at various times of the day and if you can respond to your hypos faster than you normally do, we are confident that your licence will be renewed".
According to the statistics obtained from this database, the numbers I have quoted are the limits that the DVLA appeared to have settled on over a period of time to decline driving licences for the reason of hypo unawareness, from the applicants who's data has been processed by my hospital anyway.. This is good enough for me. My licence was renewed within a month.
When I telephoned the DVLA a few minutes ago to ask, the medical advisor I spoke to coughed and spluttered and asked me who from the DVLA had issued me with those numbers. I said no-one, just that they seemed reasonable numbers to me . . . we had a 20 minute discussion about would I personally want someone who had suffered BGs under 3mmol several times over the last week to drive me anywhere? My answer was no. Common sense, I guess.