Abstract: Abstract: Objective To investigate the changes of pancreatic islet α and β cell function in patients with type 2 diabetes mellitus (T2DM) and impaired glucose regulation (IGR). Methods From April 2014 to April 2016, 120 patients with T2DM and IGR were selected in our hospital including 68 patients with T2DM (T2DM group) and 52 patients with IGR (IGR group), 40 healthy persons were selected as control group. Insulin homeostasis model secretion index (HOMA-β) and insulin homeostasis model insulin resistance index (HOMA-IR) under fasting state were observed in each group. Results In the T2DM group, blood glucose, glucagon and free fatty acid were significantly higher than those the IGR group (P < 0.05). The insulin level in the T2DM group was significantly lower than that of the control group, and the insulin level in the IGR group was higher than that in the control group (P < 0.05). HOMA-IR in the T2DM group was significantly higher than that of the IGR group and the control group, and the HOMA-β in the T2DM group was significantly lower than that of the control group (P < 0.05). In each group fasting pancreatic glucagon was positively correlated HOMA-IR (P < 0.05), and negatively correlated with HOMA-β (P < 0.05). In the T2DM group and the IGR group fasting pancreatic glucagon and free fatty acids were positively correlated (P < 0.05). At 30, 60, 90 and 120 min of the OGTT experiment the insulin level in the T2DM group was lower than that in the IGR group and the control group, while the insulin level in the IGR group was lower than that in the control group (P < 0.05). At 30, 60, 90 and 120 min of OGTT experiment the glucagon level in the T2DM group was higher than that in the IGR group and the control group, while the glucagon level in the IGR group was higher than that in the control group (P < 0.05). Conclusions In the patients with IGR and T2DM, the secretion of islet α and β cells is abnormal wherein the glucagon and free fatty acid levels are significantly increased, the glucagon level is correlated with HOMA-IR and HOMA-β.