Insulin resistance index as a predictor for pioglitazone treatment in type 2 diabetes

It is difficult to predict the hypoglycemic effect of pioglitazone (a thiazolidinedione) as an insulin sensitizer. The purpose of the present study was to investigate whether insulin resistance index, homeostasis model assessment index (HOMA-IR) is a useful predictor of hypoglycemic effect of pioglitazone in comparison with body mass index (BMI).

Thirty-four type 2 diabetic patients (14 men and 20 women, mean age 60 +/- 14 years) were treated with pioglitazone, 15 mg per day for 3 months. Eighteen subjects showed a decrease of 0.5% or more in HbA1C after treatment and were considered responders while 16 subjects were non-responders. A receiver operating characteristic (ROC) analysis was performed to determine HOMA-IR and BMI sensitivity and the false positive rate (1-specificity) for discriminating responders from non-responders.

Although there was no significant difference in age, sex, fasting plasma glucose, HbA1C and BMI between responders and non-responders, fasting insulin levels and HOMA-IR prior to treatment were significantly higher in the responders than in the non-responders. In ROC analysis, the sensitivity, false positive rate, and efficiency for HOMA-IR at the cut-off value, 4.6, with the highest efficiency were 81.2%, 22.2%, and 79.4%, respectively, and those for BMI at the cut-off value, 29.1, were 87.5%, 53.3%, and 67.7%, respectively.

HOMA-IR is a useful predictor of pioglitazone treatment in type 2 diabetic patients.