The cost and time per month needed for medical care in outpatients with diabetes mellitus (DM) and without it (non-DM: hypertension and/or hyperlipidemia) were studied at two clinics. 1) The medical cost for diabetes varied with therapy. The cost for diet therapy (D) or oral hypoglycemic agents (OHA) was 1.6 times that for non-DM, mainly due to examination expenses. 2) The timeused for DM treated with D or OHA was 1.7-1.8 times that for non-DM, i. e., physician's time was 1.1times and medical staff time 2.0 times more. 3) Cost/time for D or OHA was nearly the same or lower than that for non-DM. 4) The cost, time, and ratio of these for insulin-treated DM were higher than those for non-DM and D-or OHAtreated DM. This data indicates that the cost of medical care for DMis high, but not excessive from the perspective of time compared to non-DM. The insurance system does not cover patient education provided by medical staff, although this took the most time. This suggests theneed to reevaluate medical cost based on activity and time.