Gestational Diabetes ICD-10-CM codes

Subcategory O24.4 covers diabetes that first appears during pregnancy. The fifth character places the encounter in pregnancy (O24.41-), childbirth (O24.42-), or the puerperium (O24.43-). The sixth character reports control: 0 diet controlled, 4 insulin controlled, 5 controlled by oral hypoglycemic drugs, 9 unspecified control. O24.410 (in pregnancy, diet controlled) is the most common assignment; use O24.419 only when the record says nothing about how the condition is managed.

When both diet and insulin are documented, assign only the insulin code (O24.414). When both oral hypoglycemics and insulin are used, again assign only O24.414. Diet plus oral medication is O24.415. Do not add Z79.4 (long-term insulin) or Z79.84 (long-term oral hypoglycemics) to an O24.4- code; the sixth character already carries that information.

Gestational diabetes is not pre-existing diabetes. A patient whose Type 1, Type 2, or unspecified diabetes predates the pregnancy is coded to O24.0-, O24.1-, O24.3-, or O24.9- (for example O24.319 for unspecified pre-existing diabetes in pregnancy, unspecified trimester) followed by the E08 to E13 code for the diabetes itself, plus Z79.4 when insulin is used. An abnormal glucose tolerance result without a diagnosis of gestational diabetes is O99.810 (abnormal glucose complicating pregnancy), not O24.4-.

Chapter 15 codes are used only on the maternal record and are sequenced before codes from other chapters. Add a Z3A weeks-of-gestation code (for example Z3A.28) to each antepartum encounter.