I have been doing some digging around on the web this morning on this very subject - there are two main groups, primary and secondary. The Primary group contains all the different types of diabetes discussed so far, T1, T2, MODY and LADA, Gestational, whereas secondary includes diabetes that has developed due to drugs, toxins etc, so is very uncommon.
I was interested as to how I, being relatively old at 30 when I was diagnosed, was given a DX of Type 1, and not Type 2. Turns out that it is a clinical reference to the treatment, Insulin dependent and Non-Insulin dependent, although Type 2 can also require insulin, so it's not always that straight forward.
The main creiteria for initial diagnosis seems to be the presenting symptoms - Hyperglycaemia on its own tends towards Type 2, whereas symptoms leading to DKA (which I had in abundance, being off the end of the scale of the testing gear) is an indication of Type 1, apparantly Type 2s don't go on to develop DKA.
Diagnosis can be confirmed by other blood tests, to check on the presence of amino acids and other markers indicating the destruction of the beta-cells in the pancreas.
I will have a look for some of the good web links (not wikipaedia, my univeristy supervisor would have a fit) and post them for you
Richard
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