What is the most imp difference between type 1 and type 2 diabetesby which we will understand that whether we have type diabetics or type 2?

Older definitions: Type 1 (aka: "juvenile onset") diabetes requires Insulin administration due to lack of production. Can occur as youth, or can "burn out" pancreas as type 2 (aka: "adult onset"). The old term "non-insulin dependent" was used w/type 2's, but many 2's need Insulin for tight glucose level control.

Insulin production: People with type 1 diabetes make no insulin, and must take Insulin to control their sugars, and to survive. People with type 2 diabetes make some insulin, but their bodies do not fully respond to it. They may be able to control their sugars with lifestyle (diet/exercise), and/or pills that help improve response to Insulin or the amount of Insulin made. Some, though, do need Insulin at some point.