Spendercat, with respect, I think your explanation may confuse people. Type 1 and Type 2 aren't about pancreatic functionality, and by comparing the functionality figures like that people listening may assume they're different stages of the same disease. In addition, FAR more people with Type 1 diabetes are slim on diagnosis because they'd have probably lost weight very quickly, even if they weren't slim to start with ( and I'd imagine most Type 1s probably are slim, or at least just as slim as any non-diabetic of a similar age.)
I have Type 1 and when people don't understand or say things that suggest they're getting muddled with Type 2' I usually say that Type 1 is an auto-immune disease where my body has turned on itself and destroyed the crucial insulin-producing cells in my pancreas. I sometimes add that it's not related to being overweight nor to eating the wrong things. I often give examples of other auto-immune diseases that no-one thinks are the fault of the people who get them. That helps a lot, I find.
Having said that, some people just won't be told. I had one woman who insisted I'd got diabetes because I was fat in the past (I've always had a BMI of 18.5 to 20) and when I'd patiently explained that it was an auto-immune disease, etc, she simply said "Well, you must have been fat once". And no, I didn't leave it. I was furious - furious that she'd ignored what I'd said. Smug people who stand their judging others because they 'know ' all about a disease because of a sentence they read in the gutter press, infuriate me. It's like the people who think they know about autism because they've seen Rain Man.