The cost of major comorbidity in people with diabetes mellitus.

Background: People with diabetes mellitus are more likely to have cardiovascular, renal and ophthalmic comorbidity than those without diabetes. Information on the economic impact of diabetes and its complications on the Canadian health care system is limited.

Methods: To estimate health care expenditures for diabetes and its major complications, we identified people with diabetes in 1996 in Saskatchewan, using the administrative databases of Saskatchewan Health. We grouped utilization and expenditure data for prescription drugs, physician services, hospitalizations, day surgery procedures and dialysis services according to cardiovascular, renal and ophthalmic services, according to billing codes and the American Hospital Formulary Services classification for prescription drugs.

Results: Of the 38 124 people identified (48.5% female and 9.7% registered Indians), 46.6% had cardiovascular-related records, 19.8% ophthalmic-related records and 6.6% renal-related records. Registered Indians had significantly fewer (p < 0.001) cardiovascular-related records than the rest of the diabetic population (35.1% v. 47.9%, respectively) but more renal- related records (11.7% v. 6.0%, respectively). The total 1996 Saskatchewan Health expenditure for the study group, within the observed categories, was estimated to be $134.3 million, of which $35.5 million (26.4%) was for cardiovascular-related services, $10 million (7.5%) for renal-related services and $3.3 million (2.5%) for ophthalmic-related services.

Interpretation: In 1996, 36.4% of health care expenditures for people with diabetes was attributable to major comorbidity. Actions to prevent or control such comorbidity will yield significant cost savings.