Reduction of dipeptidyl peptidase 4 activity in patients with type 2 diabetes mellitus who consumed fruits before meals

Abstract

Objectives: Some patients with type 2 diabetes mellitus (T2DM) have high expression of dipeptidyl peptidase 4 (DPP4) enzymes that breaks down glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP1) hormones. In the process of eating carbohydrates, K and L cells in the human small intestine produce GIP and GLP1 respectively that stimulate pancreatic β cells to release insulin. Recent evidence has revealed that fruit consumption before meals reduces fasting blood glucose level in patients with T2DM. Therefore, this study aimed to investigate the effect of fruit consumption before meals on DPP4 activity among patients with T2DM. Methods: A randomized control trial study with pre-posttest control group design was performed in 18 T2DM patients. They were randomly divided into 2 groups: 10 in the control (C) group eating a standardized diet and the other in the treatment (T) group eating fruit before consumption of standardized diet. Fasting and postprandial serum DPP4 activities in 30 min were measured using an H-Gly-Pro-pNA substrate in the 1st and 7th day's intervention. Paired Sample t-Tests and Wilcoxon were used to analyze mean DPP4 activity in both groups with p value < 0.05. Results: In 1st day intervention, mean fasting DPP4 activity in the C group (189.42+116.27 nmol/ min/ mg protein) was higher than mean fasting DPP4 activity in the T group (121.75±74.86 nmol/ min/ mg protein). Reduced postprandial DPP4 activity was found in the T group (116,86+61.44) and increased in the C group (287,15+146.72). After 7 days intervention, reduction of fasting and postprandial DPP4 activities was observed in the C and T groups respectively. Meanwhile, mean fasting DPP4 activity in the T group remained unchanged but followed by increasing postprandial DPP4activity. Conclusions: Fruit consumption before meals reduces fasting and increases postprandial DPP4 activities in patients with T2DM.