Type 1 diabetes is usually diagnosed in children when they are young. The cells in the pancreas that secrete insulin do not function properly. When glucose levels go up, there is no insulin to regulate the levels.
Type 2 diabetes is tied to diet. Type 2 diabetes usually develops in adulthood and is caused by too much glucose intake throughout life and not enough exercise. In type 2 diabetes cells stop recognizing the insulin that is produced and stop taking it in.