Please tell me this appointment is tomorrow? Or that they got a normal finger prick blood sugar test and urine dip before delaying things? On that story, if a GP rang me up, I'd be saying "Send them up to the ward today, because this is a lot more likely to be type 1, and we don't want to wait until they get poorly". Did the GP try ringing up either the local paediatric diabetes team, or for that matter the local general paediatrician?
I'm only a general jobbing paed, but I'd expect someone with that history to be seen by at least us same day, unless the GP had got a normal fingerprick and urine tests, so was only doing tests to rule it out. I know for a fact that our local paediatric diabetes team, which sees the local kids until they turn 18, does not have one single type 2 diabetic on their books, despite us having a major childhood obesity problem. Type 2 is starting to appear in young people, but any health care professional who assumes type 2 in a 15 year old needs their head examining.
Seriously, your young man needs seeing by someone who is used to diabetes in young people, rather than in older adults. Please push. Demand your GP speaks to paeds. Tomorrow. And that's if he's well. If he's unwell: looking dehydrated (dry mouth, sunken eyes), or breathing funny (big sighing breaths), or vomiting, or complaining of abdominal pain, then please go straight to A&E. Immediately. If not sooner.
Sorry to be pushy, but I'm both frustrated and worried. You can't mess around with diabetes in children/young people, but a GP can go years without seeing it. So they tend to think it's like adults with type 2. And it's actually something that if not caught promptly can be very dangerous.
Obviously you have no idea if I have any idea what I'm talking about. So here are 2 links.
The first, you're only going to read a bit of, I would suggest section 1.1.2 "Refer children and young people with suspected type 1 diabetes immediately (on the same day) to a multidisciplinary paediatric diabetes team with the competencies needed to confirm diagnosis and to provide immediate care."
www.nice.org.uk/guidance/ng18/chapter/1-Recommendations#diagnosis
The second is more readible as aimed at normal people, rather than professionals, but explains why I'm being so pushy.
www.aboutkidshealth.ca/en/resourcecentres/diabetes/treatmentofdiabetes/handlinghighslows/pages/diabetic-ketoacidosis-dka.aspx