Additional effects of pioglitazone in the patients with type 2 diabetes treated with biphasic insulin therapy

Purpose : We examined the additional effects of pioglitazone treatment combined with biphasic insulin on glucose and lipid metabolism and B-type natriuretic peptides (BNP) in Japanese patients with type 2 diabetes. Methods : This was a prospective observational study carried out with a follow-up period of 24 weeks. Twelve patients with type 2 diabetes treated with biphasic insulin therapy (daily insulin dosages with 29.9±3.5 (mean±SEM) units) received additional treatment with 15mg pioglitazone (INS+PIO group). In addition, another group consisting of 12 patients treated with biphasic insulin alone (INS group : daily insulin dosages with 29.6±3.8 units) was observed. Daily insulin dosages, as well as several clinical parameters of glycemic and lipid metabolism and BNP levels, were compared before and after 24 weeks of treatment. Results : Pioglitazone treatment significantly reduced daily insulin dose requirements (from 29.9±3.5 to 27.2±3.5 units) after treatment (p<0.05). Fasting plasma glucose, hemoglobin A1c (HbA1c) decreased significantly, high-density lipoprotein cholesterol (HDL-C) levels increased significantly, while body weight gained significantly in INS+PIO group. BNP levels tended to increase in INS+PIO group. Conclusion : This study indicates potential benefits of the addition of pioglitazone to biphasic insulin therapy in terms of decreasing daily insulin dosages and improvement of glucose and lipid metabolism. However, this combination therapy requires attention to weight gain and increasing BNP levels.