Baseline factors affecting the efficacy of troglitazone on plasma glucose in Japanese patients with non-insulin-dependent diabetes mellitus.

In order to assess the relationship between clinical efficacy of troglitazone on glycemic control and baseline characteristics of patients with NIDDM, we analyzed the data of ten clinical studies on troglitazone carried out in Japan. The study consisted of 604 subjects with NIDDM whose glycemic control had been unsatisfactory (fasting plasma glucose (FPG) > or = 8.3 mM) with diet or sulfonylureas (SU) and who had been assigned to one of ten clinical studies at a dose of 400 mg/day troglitazone for 12-16 weeks. In patients who had been treated with SU, troglitazone was given in combination with the SU drugs. The percentage decrease in FPG was adopted as the index of clinical efficacy. The relationship between this index and various baseline parameters of patients was analyzed. It was found that FPG and triglycerides decreased significantly with troglitazone (pre- and post-treatment: FPG 10.3 +/- 2.0 and 8.7 +/- 2.2 mM; triglyceride 1.82 +/- 1.27 and 1.51 +/- 0.99 mM, respectively). The percentage decrease in FPG after treatment did not differ between groups treated with troglitazone alone and those treated with troglitazone in combination with SU drugs (14.7 vs. 15.5%). Patients were classified into two groups according to the percentage decrease in FPG, greater and less than 15%. The group with greater decrease in FPG included more females and had the older mean age, greater body mass index (BMI), higher pre-treatment FPG, and higher pre-treatment C-peptide values. In the multiple regression analysis, female gender, age, BMI and pre-treatment FPG level were selected as the variables for the best regression model. The results indicate that troglitazone at 400 mg/day decreased FPG significantly in patients with NIDDM and the percentage decrease in FPG was positively correlated with female gender, higher pre-treatment FPG, older age, greater BMI and higher C-peptide level. The results suggest that this drug is more effective in patients with greater insulin resistance, in keeping with its proposed mode of effect.