Effect of pioglitazone and acarbose on endothelial inflammation biomarkers during oral glucose tolerance test in diabetic patients treated with sulphonylureas and metformin

Abstract

What is known: The increased risk of cardiovascular events in diabetic patients has been related to numerous metabolic and haemoreological factors. Some of these factors appear to be particularly evident during the post-prandial phases and to be related to peak plasma glucose level.

Aim: To compare the effect of addition of pioglitazone and acarbose to sulphonylureas and metformin therapy on metabolic parameters and on markers of endothelial dysfunction and vascular inflammation in type 2 diabetic patients.

Materials and methods: We enrolled 473 caucasian type 2 diabetic patients. All patients underwent measurements of height and body weight, body mass index (BMI), glycated haemoglobin (HbA1c) , fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), fasting plasma insulin (FPI), post-prandial plasma insulin (PPI), homeostasis model assessment (HOMA index), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), triglycerides (Tg), sICAM-1, IL-6, high-sensitivity C reactive protein (hsCRP), sVCAM-1, sE-selectin and tumour necrosis factor (TNF-α). Assessments were made at start of titration, after 3 months [before a first oral glucose tolerance test (OGTT)], after 6 months and at the study end (before a second OGTT).

Results: Two-hundred and seventy four patients completed the study: 138 were randomized to double-blind treatment with pioglitazone and 136 with acarbose. Significant BMI and weight increase were observed after full treatment in the pioglitazone group relative to the acarbose group. A decrease in glycated haemoglobin was observed after the titration period in the pioglitazone group compared to both baseline value and the acarbose group. A decrease in glycated haemoglobin was also obtained after full treatment in the pioglitazone group when compared to the end of titration period and to the acarbose group. Significant decrease in FPG was obtained in the pioglitazone group after full treatment compared to the end of titration period. Post-prandial plasma glucose decrease was observed in acarbose group compared to the baseline value and to the end of titration period. Fasting plasma insulin decreased in the pioglitazone group after both the titration period and the full treatment period compared to both the baseline value and the acarbose group. The HOMA index decreased significantly after the full treatment in pioglitazone group compared to the end of titration period and to the acarbose group. Interleukin-6 and tumour necrosis factor-α decreased after full treatment in the pioglitazone group relative to the end of titration period. Significant hsCRP decrease was obtained after the titration period when compared to the baseline value in the pioglitazone group. High-sensitivity C reactive protein decreased in the pioglitazone group after full treatment compared to the end of titration period and to the acarbose group.

What is new and conclusion: Pioglitazone reduces the inflammatory response to a glucose challenge more than acarbose in type 2 diabetic patients, already treated with maximal doses of sulphonylureas and metformin.