I did, and cynically I'm sure because of my age that I would have been diagnosed as T2 in the UK.
Significant weight loss is relatively uncommon as a 'symptom' of T2. If someone has significant weight loss at diagnosis, it might call into question whether the person has in fact T2. Around 10% of people who are diagnosed with T2 actually have LADA and can, if diagnosed rather late in the process have very small amounts of beta cell function left. There are also other forms of diabetes for example ketosis prone T2 also categorised as T1b ( a genetic diabetes known in certain ethnic groups which presents like t1 but then goes into 'remission'.)
It is possible that someone with T2 and has been asymptomatic or perhaps ignored things for a long time could eventually get to the point of having very high glucose levels. These cause glucotoxicity which in turn may cause a greater loss of beta cell function and insulin resistance.
One of the ways the body attempts to get rid of this excess glucose is through urination, causing the frequent urination, a symptom of diabetes of either type.The threshold varies from person to person but it is at about 10mmol/l that glucose 'spills' into the urine. A person who is very hyperglycaemic can become extremely dehydrated and this can account for some loss of bodyweight .
Normally though someone with T2 would have enough insulin present to stop the significant breakdown of fats for fuel. (lipolysis). [
unless beta cell function has got to the point of being almost nil, does this ever happen before diagnosis,not sure]
However, if there is another precipitating event, for example, an illnesss or infection ,this could cause the small amount of insulin present to be totally insuffcient. The illness will increase the release of glucagon and also the 'stress' hormone adrenalin , these hormones 'switch' on lipolysis. The glucagon also surpresses the already low insulin production which would normally acts as a brake on lipolysis. This is a similar scenario to T1 and causes rapid weight loss and ultimately result in DKA.
This has a couple of case studies of T2s with DKA, they were already diagnosed but I think that it is quite possible for similar scenarios to happen before diagnosis.
http://clinical.diabetesjournals.org/co ... 4/198.full