Great thread idea!
A1C = blood test indicating your average glucose over a 2-3 month period (doctors are usually happy with a result under 7 [7 is roughly equivalent to a sugar reading of 150 mg/dL])
endo = short for endocrinologist, the type of doctor type 1 diabetics often see
T1D = type 1 diabetes
IDDM = insulin dependent diabetes mellitus, another term for type 1 diabetes (sometimes also applies to type 2 diabetics who now take regular insulin)
JDRF = Juvenile Diabetes Research Foundation, the most well-known foundation for type 1 diabetics (actively involved in research)
ADA = American Diabetes Association (another well-known diabetes organization; focus primarily on type 2 but also help out those with type 1)
BG = blood glucose