Type 1 or 2. Type 1 aka juvenile diabetes aka insulin-dependent diabetes in which the pancreas does not make adequate Insulin so you need to take insulin. And: type 2 aka adult-onset diabetes aka non-insulin-dependent diabetes in which the body is resistant to the Insulin produced so medication is needed to sequester the sugar, carbs, and fats and Insulin may be used as well to help the pancreas.
Types 1 and 2. Type 1 diabetes is when the pancreas fails to produce enough insulin. It is an auto-immune disease usually, meaning that the body attacks the pancreas aberrantly and kills the beta cells that make insulin. Type 2 is a disease of the will. Food abuse results in increased Insulin production to control the blood sugar. Eventually the calories exceed the pancreas' ability and blood sugar rises.
Thirst, hunger... Frequent urination, undue fatigue if concerned at all, see md to catch / treat early and can check sugars before person get these symtoms, to try to catch it early in people with family history of diabetes.
Genetic. Type 1 diabetes is a genetic disorder resulting in the patient's pancreas being unable to produce enough insulin.
Multifactorial. Type 1 diabetes is an autoimmune disease where the body produces antibodies which attack the pancreatic insulin-producing cells. There are genetic factors which contribute to this; however, there is/are environmental trigger (s) which have not yet been identified. So, even if someone has the genetic potential for type 1 diabetes, it's not enough to get it.