Pre-existing type 1 diabetes, in pregnancy, second trimester

This code signifies a pregnant patient with a pre-existing diagnosis of type 1 diabetes mellitus who is currently in her second trimester of pregnancy. It indicates that the diabetes was present prior to conception, rather than developing during the pregnancy (gestational diabetes). The patient requires ongoing management of her type 1 diabetes throughout this stage of pregnancy.

Apply this code when documentation clearly states the patient has a pre-existing diagnosis of type 1 diabetes and is currently in her second trimester of pregnancy. This code is appropriate for encounters related to the management of her diabetes during this specific gestational period. Supporting documentation would include physician notes confirming the type of diabetes, its pre-existing nature, and the current trimester.

• Always sequence this code as a primary diagnosis when the encounter is for the management of the diabetes during pregnancy.
• Do not confuse with codes for gestational diabetes (O24.4-) or pre-existing type 2 diabetes (O24.1-).
• Ensure the documentation specifies "type 1" and "pre-existing" to differentiate from other diabetes types and onset.