Which of the following is an often fatal complication of diabetes and is also the first indication of diabetes in many young patients?

Often the first signs and symptoms of diabetes onset is diabetic Ketoacidosis.  When there is no fuel (i.e., glucose) for the cells to burn, the cells will burn fat and protein which does not burn clean.  The incomplete combustion produces acids which are not cleared.  These acids will build up and can be fatal if not treated aggressively.  Hypertension and cardiovascular disease are long term complications of diabetes.