Instead, you should always code diabetes first, at least based on ICD-9 guidelines. The July 2005 Family Practice Coding Alert reader question "Visit Purpose Drives Diabetes Order" incorrectly recommended coding foot ulcer as primary because it was the main reason for the patient's visit.
ICD-9, however, clearly directs you to report diabetes for the primary diagnosis. "Code, if applicable, any causal condition first: diabetes mellitus (250.80-250.83)," states ICD-9's parenthetical instruction following the 707.1x series (Ulcer of lower limbs, except decubitus).
The diabetes instructions reinforce this sequencing. If you look up the diabetes codes in ICD-9's Tabular List, you'll find the instruction "Use additional code to identify manifestation, as: any associated ulceration (707.10-707.9)."
"It would be up to the provider to determine if the ulceration was unrelated to the diabetes," says Cindy R. Walden, CPC, CCP, coding specialist at Group Health Cooperative in Spokane, Wash. For a Medicare beneficiary, you should contact the patient's carrier for its diagnostic sequencing requirement.