Determinants of an optimal response to pioglitazone in terms of HDL-cholesterol

Objective: The effect of pioglitazone on high-density lipoprotein cholesterol (HDL-C) has been attracting attention. However, there are limited data on the characteristics of patients who are likely to respond to pioglitazone in terms of the improvement in HDL-C levels (lipid responders). In the present study, the characteristics of lipid responders were investigated. Methods: Five hundred and sixty-three patients with type 2 diabetes who started pioglitazone treatment were followed for six months. They were divided into two groups according to the response to pioglitazone. Subjects whose HDL-C levels increased by 10% or more from the baseline were defined as lipid responders. The odds ratios (OR) for becoming lipid responders were calculated using logistic regression. Results: Significant patients' characteristics of lipid responders were age, HbA1c, HDL-C and low-density lipoprotein cholesterol (LDL-C), yielding adjusted ORs of 0.76 [95% confidence interval (CI) =0.61-0.93] for an increment of 10 years, 0.79 (95% CI=0.66-0.95) for an increment of 1 %, 0.83 (95% CI=0.72-0.96) for an increment of 10 mg/dL and 0.93 (95% CI=0.87-1.00) for an increment of 10 mg/dL, respectively. Patients with sulfonylurea treatment and those with both sulfonylurea and metformin treatment were less likely to become lipid responders than diet-treated patients with ORs of 0.32 (95% CI=0.15-0.69) and 0.41 (95% CI= 0.19-0.87), respectively. Conclusion: Pioglitazone could be beneficial especially for patients with young age, low HbA1c, low HDLC or low LDL-C levels at baseline in terms of the improvement in HDL-C levels. Use of sulfonylureas at baseline could attenuate the effect of pioglitazone on HDL-C.