Whether diabetes is dangerous for an 80 year old person needs to be judged according to his own specific situation. If the blood sugar control is stable after treatment and there are no serious complications, then it is usually not dangerous, if the blood sugar control is not good or even induced complications, then it is more dangerous. After the diagnosis of diabetes mellitus, you can use glucose-lowering drugs such as metformin or insulin injections as prescribed by the doctor, together with dietary control, appropriate exercise, etc. If you can keep your blood glucose in a reasonable range without complications such as diabetic nephropathy, cardiovascular disease and other serious complications, then it is not usually dangerous. If blood glucose cannot be controlled within a reasonable range, and even induce diabetic nephropathy, diabetic foot and other complications, then it is more dangerous. Elderly patients in their 80s who have been diagnosed with diabetes should actively cooperate with their doctors.