Well, if you are hoping to get a pump, proper diagnosis can make a huge difference to insurance coverage. Some require that you get a c-peptide test to prove you don't make much insulin. In reality, your doctor may not feel competent to interpret the tests. Most GPs only get a day or so of training on diabetes and a low has changed in the last decade or two. The current best practice is to test for antibodies (GAD, ICA, IA-2), a positive on any one indicates an autoimmune attack. If the c-peptide it essentially confirms a T1 diagnosis. It still requires some judgement, as only 85-90% of T1s actually have a diagnosis confirmed with these tests, that is why many see a diabetes specialist (an endochronologist) for diagnosis. So a second opinion from an endo is probably a good idea.