Glucocorticoid treatment produces a deterioration of blood glucose control in diabetics. Recent reports have indicated that deflazacort is less diabetogenic than prednisone in healthy subjects. Ten insulin-treated diabetics who required steroid drugs were treated with deflazacort (30 mg/d for four weeks) and prednisone (25 mg/d for four weeks) in randomized, double-blind design after a pretreatment period of four weeks. At the end of each treatment, plasma glucose profile (five determinations per day), hemoglobin A1 level, and insulin requirements were compared. Mean (+/- SEM) plasma glucose level (139 +/- 28 vs 169 +/- 32 mg/dL [7.7 +/- 1.5 vs 9.4 +/- 1.8 mmol/L]) and hemoglobin A1 values (8.81% +/- 1.19% vs 10.71% +/- 1.17% of total hemoglobin) were significantly lower after deflazacort than after prednisone. Also, insulin requirement was significantly lower after deflazacort than after prednisone (29.3 +/- 11.6 vs 47.3 +/- 2.0 U/d). These results indicate that deflazacort, when employed in an anti-inflammatory dose equivalent to prednisone, should prove advantageous in insulin-treated diabetics who require steroid treatment.