Effects of pioglitazone vs glibenclamide on postprandial increases in glucose and triglyceride levels and on oxidative stress in Japanese patients with type 2 diabetes.

To investigate the relationship between insulin resistance, postprandial hyperglycemia, postprandial hyperlipidemia, and oxidative stress in type 2 diabetes, changes in postprandial glucose, triglyceride, and nitrotyrosine levels vs baseline after diet loading were examined in type 2 diabetic patients given pioglitazone (PG) or glibenclamide (GB). Twenty-four outpatients with type 2 diabetes treated with oral PG for 6 mo (BMI, 26.3 +/- 0.9; HbA1c, 8.2 +/- 0.2%) and 10 type 2 diabetic patients treated with GB (BMI, 27.4 +/- 1.6; HbA1c, 8.1 +/- 0.2%) at our institutions were compared. These patients were given meal tolerance tests (MTT; each consisting of energy 400 kcal, protein 8.7 g, fat 22.4 g, carbohydrate 41 g) before and 6 mo after administration of either agent. PG produced a significant decrease in FPG, HbA1c, HOMA-R, and TG levels in the subjects compared to baseline. In contrast, GB significantly decreased FPG and HbA1c levels, while not affecting HOMA-R and TG values. While PG produced a significant increase in LPL, HDL-cholesterol, and adiponectin levels, GB did not affect these values. At MTT 6 mo after PG administration, insulin levels before and 4 h after MTT, free fatty acid (FFA) levels 1, 2, and 4 h after MTT, glucose, TG, and RLP-TG levels before and 1, 2, 4, and 6 h after MTT were significantly decreased compared to baseline. At MTT 6 mo after GB administration, while a significant decrease in fasting and 2 h, postprandial glucose values compared to baseline MTT levels was observed, fasting and postprandial TG and RLP-TG levels remained unchanged compared to baseline. After 6 mo of PG and GB administration, serum nitrotyrosine levels before and after MTT were significantly decreased compared to baseline in both groups, while the decrease in nitrotyrosine levels before and after MTT was more marked in the subjects given PG. Our study results suggest that PG suppresses increases in postprandial glucose and TG levels, and improves insulin resistance; and, in addition, that PG may have a favorable impact on oxidative stress in type 2 diabetic patients.