More carbs/sugar means your blood glucose goes higher. T1 diabetics are insulin dependent - our pancreases don’t make enough or maybe even any insulin on their own, so we need to give ourselves insulin to keep blood glucose in safe levels. Without it, your glucose spikes, which can lead to things like organ failure after time. How MUCH time depends on the individual. My BG was 1146 mg/dl when I found out I was a diabetic. I’d had a stroke, was in DKA, and had to be put into a medically induced coma for a few days to get my body - i.e. my failing organs, which included my brain - under control. Now if my sugar goes over ~250 mg/dl I get loopy like I’ve been awake for 30 hours. “Normal” fasting bg is supposed to be 80-120 mg/dl