T1 is pretty much understood to be a combination of Genes and an event, possibly a virus. there's a genetic component in T2 also. I have it and so did my gandmother. My aunt died of a stroke at 68 and I'll bet there was undiagnosed T2 there. She was a disinctly overweight apple shape. My mum seemed to have escaped, but recently was found to have slightly elevated Bgs. she's turned 90 though.
My husband is some kind of T1, diagnosed in his late 20s. His grandmother was a diabetic also, but I don't know which sort. Grandfather was a pharmacist in Ayrshire and although grandma had the district nurse come give her her insulin every morning, she wouldn't eat any carbs. Remembering the pre-insulin treatment, she just refused to eat them . Family lore has it she starved herself to death. ( she died while we were at university, before I married her eldest grandson.) None of her 6 daughters was ever diagnosed diabetic, but 2 died as children. We are now 5 generations from Grandma, so we'll see if it's come down any further. My own daughter is safe, because as she says"we're not biological" She came to us at 6 weeks old.
