Can be... Life threatening acutely, if sugars very high/ have ketones in urine over long term, if poorly controlled, can get eye, kidney, nerve complications and increased risk heart attacks, strokes however, with good control, lifespan can be normal with low risk of complications.
Multiple symptoms. Typical signs of type 1 diabetes that is untreated include excessive thirst, urinary frequency, and weight loss. Once adjusted on insulin, many diabetics lead a normal life, while monitoring their blood sugar. They are at risk for eye problems and kidney problems.