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

This code identifies a pregnant patient who has a pre-existing diagnosis of type 1 diabetes mellitus and is currently in her first trimester of pregnancy. It signifies that the patient's diabetes was present prior to conception and is now complicating the current pregnancy.

Use this code for pregnant patients with a documented history of type 1 diabetes mellitus who are in their first trimester (weeks 0-13+6 days). Documentation should clearly state the pre-existing nature of the diabetes and the current gestational stage.

• Always sequence this code as a secondary diagnosis following the appropriate code for the obstetric encounter (e.g., O09.-).
• Ensure documentation specifies "type 1" diabetes; do not use for gestational diabetes or pre-existing type 2 diabetes.
• Verify the trimester documented in the medical record to ensure accurate coding for the first trimester.