QUICKI is useful for following improvements in insulin sensitivity after therapy in patients with type 2 diabetes mellitus.

To investigate whether quantitative insulin sensitivity check index (QUICKI) would be useful as an index of insulin resistance during the clinical course of type 2 diabetes mellitus, correlation between QUICKI and the index of the euglycemic hyperinsulinemic clamp study [clamp insulin resistance (clamp IR)] was evaluated in 60 patients with type 2 diabetes mellitus before and after treatment. The therapy program consisted of diet (1440-1720 kcal/d) and exercise (walking 10,000 steps daily) for 6 wk. QUICKI and clamp IR were significantly correlated before (r = 0.598, P < 0.0001) and after (r = 0.583, P < 0.0001) treatment. Neither the slope nor the intercept of the linear correlation between QUICKI and clamp IR measured before treatment was significantly different from those measured after treatment (slopes; F = 0.002, P = 0.96, intercepts; F = 2.65, P = 0.11). During treatment, the values of both QUICKI (8% change; P < 0.0001) and clamp IR (38% change; P < 0.0001) significantly increased and their changes were significantly correlated (r = 0.415, P < 0.01). In conclusion, QUICKI may become a useful method for the follow-up of insulin resistance during the treatment of patients with type 2 diabetes mellitus.