Wow! - thanks for all the replies guys. I don't know where to start with my response.
First of all, thanks to graham64, I'm pleased to know that there are at least 2 other underweight T2s out there! With regard to diet, I did alter my diet as my BG started to increase. Basically I ate less, but I did increase the amount of fat I was consuming. Sadly that had little or no effect on my weight loss, so what worked for you didn't appear to work for me.
To Jem, thanks for your comments. I have spent many happy hour googling the subject of diabetes. Sadly, whenever one uses the words "diabetes" and "weight" all you seem to get back are sites dealing with the links between obesity and T2 diabetes! I have read information from many sites about the subject of diabetes as a whole, but I haven't seen anything that seemed to match my specific symtoms and experiences.
With regard to my current treatment plan it actually does seem to suit me, at least at the moment! For the first time in ages I am actually putting weight on and feeling much more energetic. My hba1c readings had climbed from 6.3 in November 2006 to 8.2in August this year. My morning BG tests were I guess averaging about 10 at the start of this summer, but I am now averaging about 5. I am due to have a further hba1c test early in December so it will be very interesting to see if it has returned to an acceptable level. BUT...... I do have a concern about whether my BGs climb too high after meals and don't drop quickly enough. So.....
Thanks to trinkwasser for the links. The first one was particularly useful for setting out a BG testing method. I will use it before my next visit to the diabetes clinic and use the results to spark off a further discussion on the whole subject.
For the record, whilst the weight loss was bugging me no end, I did have my own theory about what was going on. Basically my BGs were rising. I tried to compensate by eating less. My body was producing less and less insulin and/or I was getting more insulin resistant. Whatever, the net result was that I was producing insufficient energy from my food intake to support the exercise I was doing. My body had nowhere else to go but to use body fat (what was left!) to find energy. Consequently I was losing weight and feeling tired. With the introduction of Lantus I now have more insulin converting what I eat and indeed there is an excess of energy that is being used to rebuild some of my body fat. As it happens, I am a fairly fit and active person.
Final point - I regard my diet as a "balanced" diet, which for me means eating a variety of sensible foods, including some carbohydrates, but not an excess, and nothing sugary. I am comfortable with this and the dietician I saw seemed to approve. My cholesterol is fairly constant at around 4.5.
So, thanks again for the comments. I'll see how I progress during the next few months and I'll re-open the discussion if the wheels start falling off!! Best wishes to you all.